Artículos de revistas: "Refractory nitrogen and COD"

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Song, Yu Lin, Masanobu Uchida y Sotaro Higuchi. "Effects of Incinerator Exhaust Gas Treatment Agents and Fly Ash Processing Chelates on MSW Landfill Management". Applied Mechanics and Materials 768 (junio de 2015): 233–39. http://dx.doi.org/10.4028/www.scientific.net/amm.768.233.

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Lime used to treat flue gas from incinerators and organic chelating agents used to remove heavy metals from fly ash create a highly saline and alkaline environment at landfill sites, causing nitrification inhibition that hampers nitrogen treatment and generating refractory COD in the processes of organic stabilization by microbes and leachate treatment. The authors analyzed organic chelating agents and fly ash treated with the chelating agents, and monitored leachate from lysimeters, or simulated landfills. The results showed that organic chelating agents acted as nitrification inhibitors, and that higher water levels in landfill layers resulted in higher concentrations of thiourea and refractory COD, which are chelating compounds, hindering leachate treatment.

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Deng, Miao, Keming Wu, Tao Yang, Deyou Yu, Gaojie Liu, Shuai Gong, Dongni Sun y Michal Petru. "Construction of Novel Electro-Fenton Systems by Magnetically Decorating Zero-Valent Iron onto RuO2-IrO2/Ti Electrode for Highly Efficient Pharmaceutical Wastewater Treatment". Water 14, n.º 7 (26 de marzo de 2022): 1044. http://dx.doi.org/10.3390/w14071044.

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The Electro-Fenton (E-Fenton) technique has shown great potential in wastewater treatment, while the sustainable and continuing supply of Fe2+ remains challenging. Herein, we demonstrate the construction of a novel E-Fenton system by magnetically decorating zero-valent iron (ZVI) onto a RuO2-IrO2/Ti (ZVI-RuO2-IrO2/Ti) electrode for high-efficient treatment of pharmaceutical wastewater, which is considerably refractory and harmful to conventional biological processes. By using ZVI as a durable source of Fe(II) irons, 78.69% of COD and 76.40% of TOC may be rapidly removed by the developed ZVI-RuO2-IrO2/Ti electrode, while the ZVI-RuO2-IrO2/Ti electrode using ZVI only reduces 35.64% of COD under optimized conditions at initial COD and TOC values of 5500 mg/L and 4300 mg/L, respectively. Moreover, the increase in BOD5/COD from 0.21 to 0.52 highlights the enhanced biodegradability of the treated effluent. The analysis of a simultaneously formed precipitation on electrodes suggests that the coagulation process dominated by Fe3+/Fe2+ also plays a non-negligible role in pharmaceutical wastewater treatment. In addition, the monitoring of the evolution of nitrogen elements and the formation of by-products in the E-Fenton process verifies its great capacity toward those organic pollutants found in pharmaceutical wastewater. Our study offers a practical solution for enhancing the performance of E-Fenton systems, and effectively treating refractory pharmaceutical wastewater.

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3

Wang, C. R., Z. F. Hou, M. R. Zhang, J. Qi y J. Wang. "Electrochemical Oxidation Using BDD Anodes Combined with Biological Aerated Filter for Biotreated Coking Wastewater Treatment". Journal of Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/201350.

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Coking wastewater is characterized by poor biodegradability and high microorganism toxicity. Thus, it is difficult to meet Grade I of Integrated Wastewater Discharge Standard of China by biological treatment technology; specifically, COD cannot meet above standard due to containing refractory organics. A novel coupling reactor, electrochemical oxidation using BDD anodes and biological aerated filter (BAF), has been developed for carbon and nitrogen removal from biotreated coking wastewater, focusing on COD, BOD5,NH4+-N, andNO3--N removal on operation over 90 days with average effluent value of 91.3, 9.73, 0.62, and 13.34 mgL−1, respectively. Average value of BOD5/COD and BOD5/NO3--N was enhanced from 0.05 to 0.27 and from 0.45 to 1.21 by electrochemical oxidation, respectively, with average energy consumption of 67.9 kWh kg−1COD. In addition, the refractory organics also were evidently mineralized in the unit based on the data of the three-dimensional fluorescence spectra. Meanwhile, its effluent provided excellent substrate for biological denitrification in BAF. At hydraulic retention time (HRT) of 13.08 h, about 12 mgL−1 NO3--N was depleted through denitrification, and it mainly occurred at top of 0.25 m height of BAF. Therefore, it is feasible to apply the coupling reactor for biotreated coking wastewater treatment and achieve desirable effluent quality.

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Wang, Jian, Cong Du, Feng Qian, Yonghui Song y Liancheng Xiang. "Enhanced Treatment of Pharmaceutical Wastewater by an Improved A2/O Process with Ozone Mixed Municipal Wastewater". Water 12, n.º 10 (5 de octubre de 2020): 2771. http://dx.doi.org/10.3390/w12102771.

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A pilot-scale experiment is carried out for treating mixed wastewater containing pharmaceutical wastewater (PW) and domestic wastewater (DW), by a process that is a combination of hydrolysis acidification-ozone-modified anaerobic–anoxic–aerobic-ozone (A2/O) (pre-ozone) or hydrolysis acidification-modified A2/O-ozone (post-ozone). The effects of different mixing ratios of PW and DW and pre-ozone treatment or post-ozone treatment on the removal of nitrogen and phosphorus and chemical oxygen demand (COD) are compared and studied. The optimal ratio of PW in mixing wastewater is 30%, which has the optimal COD removal efficiency and minimum biotoxicity to biological treatment. The pre-ozone treatment shows more advantages in removing nitrogen and phosphate but the post-ozone treatment shows more advantages in COD removal. Analysis of dissolved organic matter (DOM) demonstrates that post-ozone treatment has a more significant effect on the removal of fulvic acid and humic acid than the effect from the pre-ozone treatment, so the COD removal is better. Overall DOM degradation efficiency by post-ozone treatment is 55%, which is much higher than the pre-ozone treatment efficiency of 38%. Microbial community analysis reveals that the genus Thauera and the genus Parasegetibacter take great responsibility for the degradation of phenolics in this process. All the results show that the post-ozone treatment is more efficient for the mixed wastewater treatment in refractory organics removal.

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5

Hosomi, Masaaki, Inamori Yuhei, Kazuo Matsushige y Ryuichi Sudo. "Denitrification of Landfill Leachate by the Modified Rotating Biological Contactor (RBC)". Water Science and Technology 23, n.º 7-9 (1 de abril de 1991): 1477–85. http://dx.doi.org/10.2166/wst.1991.0600.

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In order to remove high-strength nitrogen and organics in landfill leachate simultaneously, the modified RBC which was combined with the standard RBC and the anaerobic biofilter was proposed. The treatability for actual landfill leachate of the standard RBC and the modified RBC was evaluated. The capability of COD removal in the modified RBC is much greater than that in the standard RBC, although both RBCs showed a BOD removal rate of more than 95%. This suggested that the combination method of aerobic and anaerobic treatment was effective in reducing refractory organic compounds. The nitrogen removal in the modified RBC was about 90% compared to 50% in Che standard RBC. The modified RBC had the advantage of nitrogen removal because nitrification and denitrification proceeded efficiently, even if a carbon source was not added. The performance of the modified RBC was superior to that of the standard RBC in both BOD surface loading and BOD volumetric loading.

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6

Zhang, Dejin, Weicheng Han, Yujun Zhou, Cheng Yan, Dianzhan Wang, Jianru Liang y Lixiang Zhou. "Feasibility of Bio–Coagulation Dewatering Followed by Bio–Oxidation Process for Treating Swine Wastewater". International Journal of Environmental Research and Public Health 20, n.º 4 (8 de febrero de 2023): 2990. http://dx.doi.org/10.3390/ijerph20042990.

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The unsatisfactory performance of the conventional swine wastewater treatment is drawing increasing attention due to the large amount of refractory chemical oxygen demand (COD), nitrogen, and phosphorus attached to the suspended solids (SS). In this study, for the first time, a novel process based on bio–coagulation dewatering followed by a bio–oxidation (BDBO) system was developed to treat swine wastewater containing high–strength SS, COD, TN, and TP. Firstly, after the bio–coagulation process, the removal efficiencies of SS, COD, NH3–N, and TP reached as high as 99.94%, 98.09%, 61.19%, and 99.92%, respectively. Secondly, the filtrate of the bio–coagulation dewatering process was introduced into the subsequent bio–oxidation process, in which the residual COD and NH3–N were further biodegraded in a sequence batch reactor. In addition, the dewatering performance of the concentrated swine slurry was substantially improved, with the specific resistance to filtration decreasing from 17.0 × 1012 to 0.3 × 1012 m/kg. Moreover, the concentrated swine slurry was pressed and filtered into a semi–dry cake after pilot–scale bio–coagulation dewatering treatment. Finally, the concentrations of COD and NH3–N in the effluent after the BDBO process, ranging between 150–170 mg/L and 75–90 mg/L, met the relevant discharge standard. Compared to traditional treatments, the BDBO system has excellent large–scale potential for improving the treatment efficiency, shortening the operation period, and reducing the processing costs, and is emerging as a cost–effective alternative for the treatment of wastewater containing high concentrations of SS, COD, TN, and TP.

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Martínez-Cruz, Alfredo y María Neftalí Rojas-Valencia. "Assessment of Phytotoxicity in Untreated and Electrochemically Treated Leachates through the Analysis of Early Seed Growth and Inductively Coupled Plasma-Optical Emission Spectroscopy Characterization". Horticulturae 10, n.º 1 (9 de enero de 2024): 67. http://dx.doi.org/10.3390/horticulturae10010067.

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The treatment of stabilized leachates with high refractory organic matter content, which are over 10 years old, presents a challenge. This study explored the potential of electro-coagulation (EC) and electro-oxidation (EO) treatment systems to address this issue. The objective of this study was to investigate the phytotoxicity of the proposed treatment system on seed growth and examine possible relationships between phytotoxicity results and the characterization of leachates, effluents, soil, and radicles. Phytotoxicity tests were conducted on seeds of Lactuca sativa, Cucumis sativus, and Phaseolus vulgaris, using Inductively Coupled Plasma-Optical analysis. The evolution of organic matter was monitored by fractionating the chemical oxygen demand (COD) and humic substances. The biodegradability index increased from 0.094 in raw leachate to 0.26 and 0.48 with EC and EO, respectively. Removal rates of 82%, 86%, 99%, and 81% were achieved for COD, dissolved organic carbon, color, and ammoniacal nitrogen, respectively. The biodegradable COD increased from 26% in raw leachate to 39% in the EC process and 58% in the EO process effluent. The proposed treatment system successfully broke the aromatic structures of the humic substances present in the raw leachate, thereby increasing the content of biodegradable material. Phytotoxicity tests revealed that the proposed treatment system significantly reduced the phytotoxicity of the generated effluents.

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8

Wang, Jiaqi, Zhengguang He, Yuzhong Wang y Manjing Lu. "Electrochemical/Peroxymonosulfate/NrGO-MnFe2O4 for Advanced Treatment of Landfill Leachate Nanofiltration Concentrate". Water 13, n.º 4 (4 de febrero de 2021): 413. http://dx.doi.org/10.3390/w13040413.

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A simple one-pot method was used to successfully embed manganese ferrite (MnFe2O4) nanoparticles on the nitrogen-doped reduced graphene oxide matrix (NrGO), which was used to activate peroxymonosulfate to treat the landfill leachate nanofiltration concentration (LLNC) with electrochemical enhancement. NrGO-MnFe2O4 and rGO-MnFe2O4 were characterized by various means. This indicates that nitrogen-doped could induce more graphene oxide (GO) spall and reduction to produce more active centers, and was favorable for uniformly loading MnFe2O4 particles. The comparison between electrochemical/peroxymonosulfate/NrGO-MnFe2O4 (EC/PMS/NrGO-MnFe2O4) system and different catalytic systems shows that electrochemical reaction, NrGO and MnFe2O4 can produce synergies, and the chemical oxygen demand (COD) removal rate of LLNC can reach 72.89% under the optimal conditions. The three-dimensional (3D-EEM) fluorescence spectrum shows that the system has a strong treatment effect on the macromolecules with intense fluorescence emission in LLNC, such as humic acid, and degrades into substances with weak or no fluorescence characteristics. Gas chromatography-mass spectrometry (GC-MS) indicates that the complex structure of refractory organic compounds can be simplified, while the simple small molecular organic compounds can be directly mineralized. The mechanism of catalytic degradation of the system was preliminarily discussed by the free radical quenching experiment. Therefore, the EC/PMS/NrGO-MnFe2O4 system has significant application potential in the treatment of refractory wastewater.

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9

Graja, S. y P. A. Wilderer. "Characterization and treatment of the liquid effluents from the anaerobic digestion of biogenic solid waste". Water Science and Technology 43, n.º 3 (1 de febrero de 2001): 265–74. http://dx.doi.org/10.2166/wst.2001.0146.

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The process wastewater generated by the fermentation of biogenic fractions of solid waste (biowaste) is characterized by very specific composition features, which sets it apart from the well known categories of wastewater. Up to now, there is a definite lack of practical experience and know-how in the treatment of those effluents. In view of the increasingly wide acceptance awarded to the fermentation process, it appears necessary, however, to include the treatment of the generated wastewater in the overall process and to grant it the same priority as the fermentation step. In this study, pilot-scale experiments were conducted over 200 days in a sequencing batch reactor (SBR), with the wastewater from a full-scale Bavarian biowaste digestion plant. Characterization of the influent implementing molecular size distribution studies showed that 97% of the components were either in particular form or <1 kD. The main classes of compounds present in these fractions have been identified. The treatment objectives of the SBR plant were carbon and nitrogen removal. Soluble COD removal efficiencies were comprised between 40 and 60%, yielding a residual, refractory COD concentration of about 2000 mg/L in the effluent. Ammonium removal efficiencies averaged 96% and denitrification occurred with the addition of acetic acid or pretreated biowaste as a carbon source. Pretreated biowaste also showed synergetic effects as a co-substrate for COD removal.

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10

Capodici, M., D. Di Trapani y G. Viviani. "Co-treatment of landfill leachate in laboratory-scale sequencing batch reactors: analysis of system performance and biomass activity by means of respirometric techniques". Water Science and Technology 69, n.º 6 (16 de enero de 2014): 1267–74. http://dx.doi.org/10.2166/wst.2014.005.

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Aged or mature leachate, produced by old landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of leachate co-treatment with synthetic wastewater, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBRs), named SBR1 and SBR2, were fed with synthetic wastewater and two different percentages of landfill leachate (respectively 10% and 50% v v−1 in SBR1 and SBR2). The results showed good chemical oxygen demand (COD) removal efficiency for both reactors, with average COD removals equal to 91.64 and 89.04% respectively for SBR1 and SBR2. Furthermore, both SBRs showed good ammonia-nitrogen (AN) removal efficiencies, higher than 60%, thus confirming the feasibility of leachate co-treatment with a readily biodegradable wastewater. Significant respiration rates were obtained for the heterotrophic population (average values of maximum oxygen uptake rate equal to 37.30 and 56.68 mg O2 L−1 h−1 respectively for SBR1 and SBR2), thus suggesting the feasibility of leachate co-treatment with synthetic wastewater.

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11

Chen, Jie, Xiaoling Jin, Chunxia Zhao, Zhe Qin, Jingfei Wang y Shu-xuan Liang. "Biotoxicity and by-product identification of dye wastewaters". Water Practice and Technology 14, n.º 2 (10 de mayo de 2019): 449–56. http://dx.doi.org/10.2166/wpt.2019.029.

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Abstract Dyeing effluent is a typical refractory wastewater containing toxic pollutants. It is difficult to treat it to meet discharge regulations. The biotoxic effects of pollutants on microorganisms are one of the main constraints on efficient wastewater degradation. The aim of this study was to evaluate biotoxic effects and try to screen toxic substances from dye wastewater. The toxic effects of wastewaters collected at different treatment stages from a wastewater treatment plant in a dye industrial park were determined using bioluminescent bacteria (Vibrio qinghaiensis sp.-Q67). Toxic substances from both influent and effluents were identified by gas chromatography-mass spectrometry. Spearman's rank correlation coefficients indicated significant positive correlations between the toxicity values, and chemical oxygen demand (COD), NH3-N, and total nitrogen (TN). After identifying the toxic levels, phenol, pyridine, and esters were confirmed as the principal organic pollutants in dye wastewater, and increase its toxicity.

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Ma, Cui, Panfeng Ma, Zhengguang He y Xiao Mi. "A Combined Catalytic Ozonation-MBR Approach to Remove Contaminants from the Mature Landfill Leachate in the Yellow River Basin". Toxics 10, n.º 9 (28 de agosto de 2022): 505. http://dx.doi.org/10.3390/toxics10090505.

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The mature landfill leachate (MLL) is characterized by a large number of fulvic acids and humic acids, which is refractory organic matter and can be cleaned by ozone oxidation. However, the poor property of mass transfer prohibits the widespread use of ozone oxidation in actual leachate treatment. Meanwhile, some combined processes are adopted to treat the mature landfill leachate, which places catalytic ozonation before the membrane bioreactor (MBR) process to enhance the biodegradability of MLL. Thus, this research is conducted to investigate the practicability of applying nano-Fe3O4 loaded cow-dung ash (Fe3O4@CDA) and biological post-treatment with MBR for the effective removal of pollutants from MLL and puts forward the variation of organics in leachate between catalytic ozonation and MBR. The addition of catalytic ozonation not only improved the removal of hazardous organics but also enhanced the biodegradability of the leachate and favored the subsequent MBR process. Chemical oxygen demand (COD) removal in the catalytic ozonation step was optimized, and 53% removal was obtained at pH = 7, catalyst dosage = 1.0 g/L, and O3 dosage = 3.0 g/L. After the MBR process, COD in effluent stabilized in the range of 57.85–65.38 mg/L, and the variation range of the ammonia nitrogen (NH3-N) concentration was 5.98–10.24 mg/L. The catalytic ozonation-MBR integrated process showed strong feasibility in dealing with the biologically pre-treated leachate.

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Li, Na, Yu Xia, Xuwen He, Weijia Li, Lianhua Yuan, Xu Wu, Yihe Qin, Run Yuan y Xun Gong. "Glucose Addition Enhanced the Advanced Treatment of Coking Wastewater". Water 13, n.º 23 (28 de noviembre de 2021): 3365. http://dx.doi.org/10.3390/w13233365.

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Biological processes have high removal efficiencies and low operational costs, but the secondary effluent of coking wastewater (CWW), even at a low concentration, is difficult for microorganisms to degrade directly. In this study, glucose was used as a carbon source and co-metabolic substrate for microbial acclimation in order to enhance the advanced treatment of coking wastewater (CWW). The removal performance of the pollutants, especially recalcitrant compounds, was studied and the changes in the microbial community structure after activated sludge acclimation were analyzed. The effect of glucose addition on the secondary biochemical effluent of coking wastewater (SBECW) treatment by the acclimated sludge was further studied by a comparison between the performance of two parallel reactors seeded with the acclimated sludge. Our results showed that the concentrations of chemical oxygen demand (COD), total organic carbon (TOC), and UV absorption at 254 nm (UV254) of the wastewater decreased in the acclimation process. Refractory organic matter, such as polycyclic aromatic hydrocarbons and nitrogen-containing heterocyclics, in the SBECW was effectively degraded by the acclimated sludge. High-throughput sequencing revealed that microbes with a strong ability to degrade recalcitrant compounds were enriched after acclimation, such as Thauera (8.91%), Pseudomonas (3.35%), and Blastocatella (10.76%). Seeded with the acclimated sludge, the reactor with the glucose addition showed higher COD removal efficiencies than the control system without glucose addition (p < 0.05). Collectively, glucose addition enhanced the advanced treatment of coking wastewater (CWW).

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Wen-Chin, Chen y Cheng Sheng-Shung. "Characterization of immobilized cells in biodegradation of ABS resin manufacturing waste-water". Water Science and Technology 34, n.º 10 (1 de noviembre de 1996): 51–58. http://dx.doi.org/10.2166/wst.1996.0238.

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Because of the presence of refractory and biologically inhibitory organic compounds in ABS resin wastewater, which would retard the bioactivity of the autotrophic nitrifier and make the efficiency of nitrification process unstable, the application of cell immobilization for ABS wastewater treatment has been investigated by immobilizing the enrichment culture of nitrifying bacteria with alginate. The characterization of the immobilized cells in various alignate concentrations was conducted by a series of biodegradability studies with electrolytic respirometry and compared with the differences from the dispersed cells. Results clearly indicated that immobilized cells achieved higher efficiency of COD and TKN removal than that of the dispersed cells during the period of high initial concentration of wastewater. Meanwhile, high concentration of cells were growing near the gel surface and reduced the effects of diffusional restriction. No remarkable difference was found while the concentration of alginate ranged from 3% to 5%. According to mass balance of total nitrogen, more than 25% of total nitrogen was removed in the batch system of the immobilized cell. Simultaneous nitrification and denitrification could occur due to the oxygen gradient throughout the gel matrix. Compared with the complete mixing system of the dispersed cell, the approach for the immobilized-cell system provided a more effective method for treating the special wastewater with high strength of nitrogenous and inhibitory compounds.

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Peixoto, André Luis de Castro, Rodrigo Fernando dos Santos Salazar, Jayne Carlos de Souza Barboza y Hélcio José Izário Filho. "Characterization of controlled landfill leachate from the city of Guaratinguetá - SP, Brazil". Ambiente e Agua - An Interdisciplinary Journal of Applied Science 13, n.º 2 (20 de marzo de 2018): 1. http://dx.doi.org/10.4136/ambi-agua.2136.

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This research evaluated the physicochemical parameters of a leachate sample from a controlled landfill in the city of Guaratinguetá-SP. The evaluation was conducted using spectrometric and spectrophotometric methods in order to assess the formation of persistent compounds. The selection of parameters was based on the CETESB Article 18 and CONAMA 357/05 Article 34, as well as organic characterization methods, such as FTIR, NMR (1H-NMR, 13C-NMR and APT), GC-MS, molar mass distribution and elemental analysis (CHN). Chemical and physical stability were also verified. The ammoniacal nitrogen concentration is 20 times greater than tolerance limit established by law (20 mg L-1). The Ba and Ni presented concentrations above those permitted by the legislation (CETESB Article 18 and CONAMA 357/05 Article 34). Those values of chemical oxygen demand (COD) and total organic carbon (TOC) were 1013 mg L-1 and 286 mg L-1, respectively. It was not possible to determine the biochemical oxygen demand (BOD) of slurry sample. In this sense, the biodegradability parameter for the slurry studied was Non-Determinable (ND), indicating that the organic matter of the slurry studied is recalcitrant. Recalcitrant humic substances of landfill leachate the present low polydispersity. These refractory acids play a detached role in carrying pollutants in the environment with regard to carrying toxic metals and pesticides. Finally, it was possible to verify that the humic acids’ complexing capacity indicates that hydroxyl and carboxyl groups may exist in larger quantities than the nitrogen and sulfur groups. Further, the high content of metals may indicate that the waste was not properly separated.

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Yan, Yuan, Yajun Wang, Tianjing Chen, Hongwei Sun y Lijuan Cai. "Decontamination and Ecological Restoration Performance of a Bioretention Cell-Microbial Fuel Cell under Multiple-Antibiotics Stress". Applied Sciences 13, n.º 4 (10 de febrero de 2023): 2320. http://dx.doi.org/10.3390/app13042320.

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Antibiotics are refractory pollutants that have been widely found in various environmental media such as soil and surface water. Existing sewage treatments perform poorly at preventing antibiotics in urban sewage from polluting natural environments. In this study, we designed a bioelectrically enhanced bioretention cell system (bioretention cell-microbial fuel cell, BRC-MFC) that utilizes the unique structure of the BRC system to improve the removal of sewage antibiotics. This new system can efficiently remove antibiotics by using a synergy of plant absorption, filler adsorption, filler filtration and microbial degradation. To study the influences of multiple-antibiotics stress on the decontamination performance of BRC-MFC, ofloxacin (OFLX) and tetracycline (TC) were selected as target antibiotics, and five BRC-MFCs were built to treat sewage containing antibiotics of different concentrations. The concentrations of pollutant in the influent and effluent were measured and the pollutant removal performance of BRC-MFC was studied. The diversity of rhizosphere microorganisms and the abundance of denitrifying functional genes were analyzed. Experimental results showed that over 90% of OFLX and TC in each BRC-MFC were removed, with the removal rates positively correlating with the concentration of antibiotics. In addition, the removal rates of chemical oxygen demand (COD) in BRC-MFC were both over 90%, while the removal rate of total nitrogen (TN) was around 70%. Meanwhile, antibiotics could significantly improve the removal of ammonia nitrogen (NH4+-N, p < 0.01). The microbial richness decreased, and we found that combined antibiotic stress on microorganisms was stronger than single antibiotic stress. The abundance of denitrifying functional genes was reduced by antibiotic stress. The results of this study provide reference values for other projects focusing on removing various antibiotics from domestic sewage using BRC-MFC.

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Semenov, Petr B., Anfisa A. Pismeniuk, Sergei A. Malyshev, Marina O. Leibman, Irina D. Streletskaya, Elizaveta V. Shatrova, Alexander I. Kizyakov y Boris G. Vanshtein. "Methane and Dissolved Organic Matter in the Ground Ice Samples from Central Yamal: Implications to Biogeochemical Cycling and Greenhouse Gas Emission". Geosciences 10, n.º 11 (10 de noviembre de 2020): 450. http://dx.doi.org/10.3390/geosciences10110450.

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Permafrost thawing leads to mobilization of the vast carbon pool into modern biogeochemical cycling through the enhanced release of dissolved organic matter (DOM) and production of greenhouse gases (CO2 and CH4). In this work, we focus on the study of methane and DOM distribution and genesis in the ground ice samples of thermodenudational exposure in the Central Yamal (Russian Arctic). We propose that the liberation of the ice-trapped CH4 and generation of CO2 by DOM mineralization are the earliest factors of atmospheric greenhouse gases emission as a result of permafrost thawing. The observed enormously “light ” isotope signatures of methane (δ13C < −80‰, δD < −390‰) found in the tabular ground ice units significantly divergent in morphology and localization within the exposuremay be related to subzero (cryogenic) carbonate reduction a as significant factor of the local methane enrichment. DOM is mainly formed (>88%) by biochemically refractory humic acids. Distribution of the labile protein-like DOM reflects the specific features of carbon and nitrogen cycles in the tabular ground ice and ice wedge samples. Tabular ground ice units are shown to be a significant source of methane and high quality organic matter as well as dissolved inorganic nitrogen (DIN). Ice wedges express a high variation in DOM composition and lability.

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18

Mai, Sofia, Elli Barampouti, Adamadios Koumalas y Athanasios Dounavis. "Leachates From Landfill Sites In Thessaloniki, Greece: Effect Of Aging". Environmental Research, Engineering and Management 75, n.º 4 (20 de diciembre de 2019): 30–39. http://dx.doi.org/10.5755/j01.erem.75.4.23073.

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Sanitary landfilling still is one of the most common management systems of solid urban wastes. The persistent environmental impact of landfills depends on leachate characteristics. The present study aimed at the characterisation of leachate from two landfill sites in the prefecture of Thessaloniki, Greece. Mavrorachi landfill stands in our study as a representative Greek active landfill site, that started operating in 2008. Tagarades landfill has stopped receiving waste from 2008 after 27 years of full operation. In this investigation, leachate samples were physico-chemically characterised so as to assess their pollution potential and their concentration in regard to the type and age of landfill. Elevated concentrations of inorganic and organic constituents were observed in the leachate composition. COD ranged from 2,490 mg/L to 19,700 mg/L, while the respective range for BOD was 390-14,850 mg/L during a 35-year period. The pH values of the leachate samples presented more moderate fluctuations between 7.3 and 8.5. In addition, the ammoniacal nitrogen content increased as landfill age increased, whereas heavy metals concentrations showed significant variations with a slight decreasing trend. The results presented in this paper proved that as time passed, the values of most parameters decreased as the biodegradable compounds are broken down while the refractory compounds resist to biodegradation. Thus, the age has a pronounced influence on the composition of leachate. This study also focused on quantifying the level of contamination that leachates can be potentially cause on a comparative basis by Leachate Pollution Index (LPI). LPI values showed that pollution load was declining but is still not negligible after 33 years.

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Xie, H., S. Bélanger, G. Song, R. Benner, A. Taalba, M. Blais, V. Lefouest, J. É. Tremblay y M. Babin. "Photoproduction of ammonium in the Southeastern Beaufort Sea and its biogeochemical implications". Biogeosciences Discussions 9, n.º 4 (13 de abril de 2012): 4441–82. http://dx.doi.org/10.5194/bgd-9-4441-2012.

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Abstract. Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen : carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO2:CO:NH4+ molar ratio of 165:11:1 in the estuary, 60:3:1 on the shelf, and 18:2:1 in the Canada Basin. The NH4+ efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l−1 d−1 on the Mackenzie Shelf and 3.7 nmol l−1 d−1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m−2 d−1 and 11.3 μmol m−2 d−1. The offshore depth-integrated rate in August (8.0 μmol m−2 d−1) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH4+ photoproduction in the entire study area was estimated to be 1.4 × 108 moles, with 85 % of it being generated in summer when riverine DIN input is low. Photoammonification could mineralize 4 % of the annual dissolved organic nitrogen (DON) exported from the Mackenzie River and provide a~DIN source corresponding to 7 % of the riverine DIN discharge and 1400 times the riverine NH4+ flux. Under a climate warming-induced ice-free scenario, these quantities would increase correspondingly to 6 %, 11 %, and 2100 times. Photoammonification is thus a significant nitrogen cycling term and may fuel previously unrecognized autotrophic and heterotrophic production pathways in the surface SE Beaufort Sea.

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20

Xie, H., S. Bélanger, G. Song, R. Benner, A. Taalba, M. Blais, J. É. Tremblay y M. Babin. "Photoproduction of ammonium in the southeastern Beaufort Sea and its biogeochemical implications". Biogeosciences 9, n.º 8 (10 de agosto de 2012): 3047–61. http://dx.doi.org/10.5194/bg-9-3047-2012.

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Abstract. Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen:carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO2 : CO : NH4+ molar ratio of 165 : 11 : 1 in the estuary, 60 : 3 : 1 on the shelf, and 18 : 2 : 1 in the Canada Basin. The NH4+ efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l−1 d−1 on the Mackenzie Shelf and 3.7 nmol l−1 d−1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m−2 d−1 and 11.3 μmol m−2 d−1. The offshore depth-integrated rate in August (8.0 μmol m−2 d−1) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH4+ photoproduction in the entire study area was estimated to be 1.4 × 108 moles, with 85% of it being generated in summer when riverine DIN input is low. Photoammonification could mineralize 4% of the annual dissolved organic nitrogen (DON) exported from the Mackenzie River and provide a DIN source corresponding to 7% of the riverine DIN discharge and 1400 times the riverine NH4+ flux. Under a climate warming-induced ice-free scenario, these quantities could increase correspondingly to 6%, 11%, and 2100 times. Photoammonification is thus a significant nitrogen cycling term and may fuel previously unrecognized autotrophic and heterotrophic production pathways in the surface SE Beaufort Sea.

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21

Wright, R. F., C. Beier y B. J. Cosby. "Effects of nitrogen deposition and climate change on nitrogen runoff at Norwegian boreal forest catchments: the MERLIN model applied to Risdalsheia (RAIN and CLIMEX projects)". Hydrology and Earth System Sciences 2, n.º 4 (31 de diciembre de 1998): 399–414. http://dx.doi.org/10.5194/hess-2-399-1998.

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Abstract. The catchment scale-experiments of the RAIN and CLIMEX projects conducted on boreal forest ecosystems at Risdalsheia, southernmost Norway, provide a unique set of data on the flux of nitrogen (N) in runoff following changes in N deposition, carbon dioxide (CO2) level and temperature. MERLIN (Model of Ecosystem Retention and Loss of Inorganic Nitrogen), a recently-developed model that focuses on N leaching, provides a means by which these data can be placed into a quantitative framework. The features of the N flux in runoff at Risdalsheia to be explained include (1) leaching of about 30-50 mmol m-2 yr-1 (30-40% of N deposition) during the period 1985-1997 at reference catchments, (2) rapid and dramatic reduction in N leaching following experimental reduction in N deposition in 1985 at KIM catchment, (3) increased flux of about 5 mmol m-2 yr-1 following onset of 3-5°C warming and increased CO2 in 1995 at KIM catchment, and (4) increased flux of about 12 mmol m-2 yr-1 following 3-5°C warming of soil in 1995 at EGIL catchment. One set of calibrated model parameters is sufficient to simulate the changes in N runoff at both experimental catchments for both of the manipulations. The model support the conceptual picture of the soil as the major sink for N inputs from deposition with N accumulating in both the forest floor (labile organic matter LOM) and the bulk soil (refractory organic matter ROM). As the molar carbon/nitrogen (C/N) ratio of LOM decreases to below 23, progressively less N is immobilised and more goes to runoff. The model also supports the conceptual picture of increased rate of decomposition of old soil organic matter in response to higher temperature. An increase of 5% is sufficient to produce the 5-12 mmol m-2 yr-1 increase in N flux in runoff observed at the 2 experimental catchments. The MERLIN simulations are consistent with measurements of increase in net mineralisation rates (per catchment area by 70 mmol m-2 yr-1) and N contents in foliage in treated and reference areas before and after onset of treatment. Runoff provides a very sensitive indicator of changes in N cycling within the ecosystem. Small changes in key processes such as N mineralisation give rise to large relative changes in N flux. Uncertainties in measurements are generally much larger than changes indicated by the model calibration.

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22

Accolla, M., G. Pellegrino, G. A. Baratta, G. G. Condorelli, G. Fedoseev, C. Scirè, M. E. Palumbo y G. Strazzulla. "Combined IR and XPS characterization of organic refractory residues obtained by ion irradiation of simple icy mixtures". Astronomy & Astrophysics 620 (diciembre de 2018): A123. http://dx.doi.org/10.1051/0004-6361/201834057.

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Context. Multi-year laboratory experiments have demonstrated that frozen icy mixtures containing simple organic and inorganic molecules (such as H2O, N2, CH4, CO, CO2, C2H6, etc.), if exposed to a flux of energetic ions or UV photons, give rise to new more complex molecules at low temperatures (10–50 K). A fraction of the new synthesized molecules is volatile while the remaining fraction is refractory and therefore it is preserved after the warm-up of the substrate to room temperature. Moreover, a part of the refractory material is formed during the annealing to room temperature, when molecules and radicals into the processed ice become mobile and react to form non-volatile molecules. By means of similar mechanisms, complex organic materials may be formed on the icy surfaces of some objects in the outer solar system, such as trans-Neptunian objects, comets and some satellites of the giant planets: in fact the interaction with solar wind and solar flares ions, solar photons and galactic cosmic rays could produce more refractory materials, analogous to those produced in the laboratory. In some cases, the materials thus synthesized may contain functional groups considered relevant to the pre-biotic chemistry in the hypothesis that interplanetary dust particles, comets and meteoroids contributed to seed the early Earth with the building blocks of life. Aims. The aim of this work is to investigate the chemical similarities and differences between some organic residues left over after ion bombardment (200 keV H+) of different ice mixtures followed by subsequent warm up under vacuum to room temperature. Methods. Seven organic residues have been prepared in our laboratory following a procedure involving the proton irradiation of seven different icy mixtures and their warm-up to room temperature. All the organic samples were characterized by FTIR spectroscopy with measurements performed in situ, in the ultra-high vacuum condition preventing any sample degradation. Three of them were selected to be characterized by XPS spectroscopy as well. Results. Among the organic residues presented in this paper, only those containing nitrogen and carbon exhibit the multi-component band centred at 2200 cm−1. This multi-component band presents interest from the astrobiological point of view due to its attribution to nitriles (–C≡N) and isonitriles (–N≡C). Our results demonstrate that this band is present in the IR spectra of organic nitrogen residues regardless the use of oxygen-bearing species in the icy mixture. This finding is of interest since the 2200 cm−1 band has been observed in some extraterrestrial samples (micro-meteorites) collected in the Antarctica.

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23

Filkov, Michael y Andrei Kolesnikov. "Plasmachemical Synthesis of Nanopowders in the System Ti(O,C,N) for Material Structure Modification". Journal of Nanoscience 2016 (27 de octubre de 2016): 1–8. http://dx.doi.org/10.1155/2016/1361436.

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Refractory nanoparticles are finding broad application in manufacturing of materials with enhanced physical properties. Production of carbide, nitride, and carbonitride nanopowders in high volumes is possible in the multijet plasmachemical reactor, where temperature and velocity distributions in reaction zone can be controlled by plasma jet collision angle and mixing chamber geometry. A chemical reactor with three Direct Current (DC) arc plasma jets intersecting at one point was applied for titanium carbonitride synthesis from titanium dioxide, propane-butane mixture, and nitrogen. The influence of process operational parameters on the product chemical and phase composition was investigated. Mixing conditions in the plasma jet collision zone, particles residence time, and temperatures were evaluated with the help of Computational Fluid Dynamics (CFD) simulations. The synthesized nanoparticles have predominantly cubic shape and dimensions in the range 10–200 nm. Phase compositions were represented by oxycarbonitride phases. The amount of free (not chemically bonded) carbon in the product varied in the range 3–12% mass, depending on synthesis conditions.

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24

Cartwright, Richard J., David R. DeColibus, Julie C. Castillo-Rogez, Chloe B. Beddingfield, William M. Grundy y Tom A. Nordheim. "Evidence for Nitrogen-bearing Species on Umbriel: Sourced from a Subsurface Ocean, Undifferentiated Crust, or Impactors?" Planetary Science Journal 4, n.º 3 (1 de marzo de 2023): 42. http://dx.doi.org/10.3847/psj/acbc1f.

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Abstract Near-infrared spectra of Umbriel and the other classical Uranian moons exhibit 2.2 μm absorption bands that could result from ammonia (NH3) bearing species, possibly exposed in the geologically recent past. However, Umbriel has an ancient surface with minimal evidence for recent endogenic activity, raising the possibility that more refractory species are present, and/or that NH3 is retained over long timescales. We analyzed 33 spectra of Umbriel to investigate its 2.2 μm band, along with three other absorption features we identified near 2.14, 2.22, and 2.24 μm. We assessed the subobserver longitudinal distributions of these four bands, finding that they are present across Umbriel and may be spatially associated with geologic features such as craters and large basins. We compared the bands to 15 candidate constituents. We found that Umbriel’s 2.14 μm and 2.22 μm bands are most consistent with the spectral signature of organics, its 2.24 μm band is best matched by NH3 ice, and its 2.2 μm band is consistent with the signatures of NH3–H2O mixtures, aluminum-bearing phyllosilicates, and sodium-bearing carbonates. However, some of these candidate constituents do not match Umbriel’s spectral properties in other wavelength regions, highlighting the gaps in our understanding of the Uranian moons’ surface compositions. Umbriel’s 2.14 μm band may alternatively result from a 2ν 3 overtone mode of CO2 ice. If present on Umbriel, these candidate constituents could have formed in contact with an internal ocean and were subsequently exposed during Umbriel’s early history. Alternatively, these constituents might have originated in an undifferentiated crust or were delivered by impactors.

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25

Bradford, Mike, Chris McDonald y Ed Helmig. "REFRACTORY COD IN WASTEWATER". Proceedings of the Water Environment Federation 2003, n.º 8 (1 de enero de 2003): 54–71. http://dx.doi.org/10.2175/193864703784640316.

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26

Fang, Hua, Xiao Ru Fu, De Fu Xu, Yuan Wang y Ji Lai Lu. "Degradation of Refractory Wastewater by Chlorine Dioxide Oxidation". Applied Mechanics and Materials 90-93 (septiembre de 2011): 2987–90. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2987.

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The ClO2 chemical oxidation system and ClO2 catalytic oxidation system are studied in this paper. The results show that pH=6~8, 1000mg ClO2/L wastewater, reacting 60min are the most efficient and economical, when treating Acid Brilliant Scarlet GR dyestuff wastewater, the COD of which is 3500mg/L, by ClO2 chemical oxidation. The COD removal ratio exceeds 50%, and the oxidation index (COD removal amount/ ClO2 used amount) is 2.3. When treating the wastewater by catalytic oxidation which is composed of ClO2 and special catalyst, pH≈2, 800mg ClO2/L wastewater, reacting 45~60min are the most efficient and economical. The COD removal ratio exceeds 80%, and the oxidation index (COD removal amount/ ClO2 used amount) is 3.5. The cost of oxidant removing 1kg COD is ¥3.7. The effect is superior to that of ClO2chemical oxidation apparently. The study indicates that ClO2 catalytic oxidation is an efficient method to treat refractory wastewater and it’ll have a broad prospect.

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27

Ittigi, Vivekananda y Soumya G. Hegde. "Chromoblastomycosis complicated with co-morbidities, curbed by cryotherapy: a case report". International Journal of Research in Dermatology 5, n.º 3 (24 de julio de 2019): 656. http://dx.doi.org/10.18203/issn.2455-4529.intjresdermatol20193247.

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<p>Chromoblastomycosis is a chronic mycosis affecting skin and subcutaneous tissue. Treatment of chromoblastomycosis is challenging due to refractory nature of the condition and varied antifungal sensitivity of the organism. Though systemic antifungals are commonly used modality of treatment, there is no “gold standard” treatment. The array of treatment options include chemotherapy and physical methods (cryosurgery/ CO2 laser/superficial X-rays/ surgical excision), either alone or in combination. A 60 year old male farmer presented with history of congestive cardiac failure (CCF), presented with gradually increasing painful, reddish elevated skin lesions over right knee since 2 years. On examination, there was a well-defined solitary, tender plaque of size 2×3 cm with smooth surface, elevated peripheral margin. Blood investigations were within normal limits except for deranged LFT. Diagnosis of chromoblastomycosis was made based on KOH mount which revealed typical sclerotic bodies and histopathology which revealed neutrophilic abscesses, muriform cells, mixed granulomatous response. In view of his comorbidities like congestive cardiac failure and deranged liver function test, we couldn’t consider the possibility of systemic drugs like Itraconazole. So, he was treated only with liquid nitrogen cryotherapy on a weekly basis for 8 weeks. Marked improvement in lesion was observed after 8 sittings. In our case, due to cardiac complications and deranged liver function test we treated the patient with cryotherapy solely and achieved marked improvement in skin lesions. Cryotherapy alone serves as an effective treatment modality when systemic antifungals can’t be given.</p>

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Manning, D. A. C., E. Lopez-Capel y S. Barker. "Seeing soil carbon: use of thermal analysis in the characterization of soil C reservoirs of differing stability". Mineralogical Magazine 69, n.º 4 (agosto de 2005): 425–35. http://dx.doi.org/10.1180/0026461056940260.

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AbstractTo understand the rates of turnover of soil carbon, and hence interactions between soil carbon pools and atmospheric CO2 levels, it is essential to be able to quantify and characterize soil organic matter and mineral hosts for C. Thermal analysis is uniquely suited to this task, as different C compounds decompose during a heating cycle at different temperatures. In ‘air’ (80% He or N2, 20% O2), relatively labile cellulosic material decomposes between 300 and 350°C and more refractory lignin and related materials decompose between 400 and 650°C. Calcite and other common soil carbonate minerals decompose at 750–900°C. Using thermal analysis connected to a quadrupole mass spectrometer and to an isotope ratio mass spectrometer, it is possible to simultaneously determine mass loss during combustion, evolved gas molecular compositions, and carbon isotope ratios for evolved CO2. As an example of the potential of the technique, the evolution of a fungally-degraded wheat straw shows initial isotopic heterogeneity consistent with its plant origins (–23.8% v-PDB for cellulosic material; –26.1% v-PDB for ligninic material), which homogenizes at heavier δ13C values (–21.0% v-PDB) as lignin is preferentially degraded by fungal growth. Simultaneously, it is shown that the evolution of nitrogen compounds is initially dominated by decomposition of aliphatic N within the cellulosic component, but that with increasing fungal degradation it is the ligninic component that contributes N to evolved gases, derived presumably from pyrrolic and related N groups produced during soil degradation through condensation reactions. Overall, the use of thermal analysis coupled to quadrupole and stable isotope mass spectrometry appears to have considerable potential for the characterization of discrete carbon pools that are amenable to the modelling of carbon turnover within soil systems.

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Larrea, L., A. Abad y J. Gayarre. "Improving nitrogen removal in predenitrification-nitrification biofilters". Water Science and Technology 48, n.º 11-12 (1 de diciembre de 2004): 419–28. http://dx.doi.org/10.2166/wst.2004.0890.

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The effect on NH4-N removal rates in nitrification biofilters of filtered biodegradable COD and particulate COD leaving predenitrification biofilters was studied in a lab scale plant configured with the separated system of biofilters for secondary nitrogen removal from urban wastewaters. Applying a typical COD load of 11 kg/m3.day to the predenitrification biofilter and maximizing its COD removal by adding nitrates or by operating an improved control of the internal recycle, only 60% removal of filtered biodegradable COD was found. This value corresponds to the complete removal of the readily biodegradable substrate (30% of influent filtered COD) and 36% of filtered slowly biodegradable substrate (50% of influent COD). The remaining 64% of the latter entered the nitrification biofilter, causing competition between heterotrophs and nitrifiers for dissolved oxygen in the inner layers of the biofilm. Consequently the nitrification rate had relatively low values (0.5 kgN/m3.d) at 14°C despite using dissolved oxygen levels of 6 mg/l. This behaviour may explain the lower nitrification rates obtained in some cases of nitrification biofilters compared to those in tertiary nitrification after activated sludge processes. The particulate COD entering the nitrification biofilter is associated with the suspended solids leaving the denitrification biofilter which are adsorbed by the external layers of the biofilm, increasing its thickness. The activity of the nitrifiers was affected because of a lack of oxygen when the thickness was left to grow considerably. Therefore no significant particulate COD effect is expected to occur as long as backwashing is carried out with the appropriate frequency.

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30

Tuan, Le Van. "PERFORMANCE OF H2O2 - AERATED BIOFILTER IN TREATMENT OF WASTEWATER CONTAINING HUMIC ACID". Vietnam Journal of Science and Technology 54, n.º 2A (19 de marzo de 2018): 149. http://dx.doi.org/10.15625/2525-2518/54/2a/11924.

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This work presents the results of adding H2O2 into a modified aerated biofilter (ABF) for treatment of refractory organic constituents in wastewater. The activated sludge, taken from wastewater treatment system of Hue Beer Company, was long-time cultured in laboratory with beef extract-peptone solution. The synthetic wastewater was prepared from solutions of glucose, ammonium acetate, sodium bicarbonate, potassium dihydrogen phosphate, sodium chloride, potassium chloride, calcium chloride and magnesium sulphate. As a refractory organic compound, humic acid (HA) was added into the wastewater; and parameters of chemical oxygen demand (COD) and color were measured to estimate the treatment performance. The experiments were conducted in continuous mode to observe the effects of H2O2 concentration (25–100 mg/L) and hydraulic retention time (HRT: 24–18 hours; according to organic loading rate, OLR: 0.51–0.67 kg-COD/m3/d) on the aerated biofilter system, under identical treatment conditions (COD: 505 ± 10 mg/L, HA concentration: 25 mg/L, pH: 7.0 ± 0.2, temperature: 25 ± 3.0 oC, and air flow rate: 1.0 ± 0.1 L/min). At the concentration of H2O2 50 mg/L and HRT of 24 hours, the ABF reactor yielded highyielded highyielded high yielded high yielded highyielded highyielded highyielded highyielded highest treatment est treatmentest treatmentest treatmentest treatmentest treatment est treatmentest treatmentest treatment efficienc efficiencefficiencefficiencefficiencefficienc efficiency (95(95 % COD and COD and COD and COD and COD and COD and COD and 74 % color colorcolorcolor). Consequently, H2O2 could be used to improve the effectiveness of activated sludge process in treatment of wastewater containing refractory organic compounds.

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Zheng, Fanping, Chaoquan Tan, Wanyuan Hou, Linli Huang, Jing Pan y Shiyue Qi. "Does influent COD/N ratio affect nitrogen removal and N2O emission in a novel biochar-sludge amended soil wastewater infiltration system (SWIS)?" Water Science and Technology 78, n.º 2 (10 de julio de 2018): 347–57. http://dx.doi.org/10.2166/wst.2018.304.

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Abstract Nitrogen removal and N2O emission of a biochar-sludge amended soil wastewater infiltration system (SWIS) with/without intermittent aeration under different influent COD/N ratios was investigated. Nitrogen removal and N2O emission were affected by influent COD/N ratio. Under a COD/N ratio between 1:1 and 15:1, average chemical oxygen demand (COD), NH4+-N and total nitrogen (TN) removal rates decreased with COD/N ratio increase in non-aerated SWISs amended with/without biochar-sludge; an increasing COD/N ratio hardly affected COD and NH4+-N removal in a biochar-sludge amended SWIS with intermittent aeration; the N2O emission rate decreased with COD/N ratio increase in the studied SWISs. The biochar-sludge amended SWIS with intermittent aeration achieved high COD (92.2%), NH4+-N (96.8%), and TN (92.7%) removal rates and a low N2O emission rate (10.6 mg/(m2 d)) under a COD/N ratio of 15:1, which was higher than those in non-aerated SWISs amended with/without biochar-sludge. Combining the biochar-sludge amended SWIS with intermittent aeration enhanced the number of nitrifying bacteria, denitrifying bacteria, nitrate reductase activities, nitrite reductase activities, and improved the abundance of nitrogen removal functional genes under a high influent COD/N ratio. The results suggested that the joint use of intermittent aeration and biochar-sludge in a SWIS could be an effective and appropriate strategy for improving nitrogen removal and reducing N2O emissions in treating high COD/N ratio wastewater.

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Song, Siyu, Jing Pan, Shiwei Wu, Yijing Guo, Jingxiao Yu y Qingchi Shan. "Effects of chemical oxygen demand (COD)/N ratios on pollutants removal in the subsurface wastewater infiltration systems with/without intermittent aeration". Water Science and Technology 73, n.º 11 (4 de marzo de 2016): 2662–69. http://dx.doi.org/10.2166/wst.2016.125.

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The matrix oxidation reduction potential level, organic pollutants and nitrogen removal performances of eight subsurface wastewater infiltration systems (SWISs) (four with intermittent aeration, four without intermittent aeration) fed with influent chemical oxygen demand (COD)/N ratio of 3, 6, 12 and 18 were investigated. Nitrification of non-aerated SWISs was poor due to oxygen deficiency while higher COD/N ratios further led to lower COD and nitrogen removal rate. Intermittent aeration achieved almost complete nitrification, which successfully created aerobic conditions in the depth of 50 cm and did not change anoxic or anaerobic conditions in the depth of 80 and 110 cm. The sufficient carbon source in high COD/N ratio influent greatly promoted denitrification in SWISs with intermittent aeration. High average removal rates of COD (95.68%), ammonia nitrogen (NH4+-N) (99.32%) and total nitrogen (TN) (89.65%) were obtained with influent COD/N ratio of 12 in aerated SWISs. The results suggest that intermittent aeration was a reliable option to achieve high nitrogen removal in SWISs, especially with high COD/N ratio wastewater.

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33

Mirkin, Bernard L. y Thomas J. Newman. "Efficacy and Safety of Captopril in the Treatment of Severe Childhood Hypertension: Report of the International Collaborative Study Group". Pediatrics 75, n.º 6 (1 de junio de 1985): 1091–100. http://dx.doi.org/10.1542/peds.75.6.1091.

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The safety and efficacy of captopril therapy in children with severe and refractory hypertension has been evaluated in a collaborative international study which enrolled a group of 73 patients, 15 years of age or younger. Most patients had hypertension associated with renal disease or vascular abnormalities. Captopril was administered for periods of less than 3 months to more than 1 year. A significant decrease in both systolic and diastolic blood pressures was produced by the administration of captopril, usually in conjunction with other antihypertensive agents (most commonly diuretics and/ or β-blockers). Systolic blood pressures were normalized in 62% and 53% and diastolic blood pressures in 56% and 45% of reported patients after the second and sixth months of captopril therapy, respectively. The response to captopril was sustained over a 12-month period. Adverse reactions were reported in 49% of the 73 patients; 48% of patients had experienced adverse reactions to other antihypertensive agents prior to entering the study. The reactions most frequently observed during captopril therapy were hypotension, vomiting, postural symptoms, anemia, rash, and anorexia. Leukopenia was reported in six patients, all of whom had renal impairment. Two of these patients had received concomitant therapy with immunosuppressants, and one had systemic lupus erythematosus. Captopril was discontinued in two of these six children. Statistically significant increases in mean serum urea nitrogen and potassium concentrations and decreases in mean serum CO2 levels were observed during the course of therapy. These effects could not be exclusively attributed to captopril administration as the study population received multidrug therapy and had significant intrinsic disease. Captopril was demonstrated to be an effective and safe drug for the treatment of children with severe hypertension.

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34

Yu, Yang, Hai Jiao Yu y Chen Ci Ma. "Study on the Impact of DO and Organic Matter on Aerobic Granular Sludge Treating Municipal Sewage". Advanced Materials Research 989-994 (julio de 2014): 603–6. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.603.

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The experiment uses municipal sewage as the research object and runs SBR reactor in completely aerobic conditions. Through controlling different of DO concentration and COD concentration, we study spreading comparison. The results show that when DO concentration was 1mg/L, the removal effect of aerobic granular sludge process in SBR treating municipal sewage was best, the average removal rate of COD, ammonia nitrogen, total nitrogen and phosphorous was 90.12%,98.95%,87.65% and 83.74% respectively. When COD concentration of influent was about 400mg/L, the treatment effects of aerobic granular sludge for COD, ammonia nitrogen, total nitrogen and phosphorous were all better, the average removal rate was up to 92.33%,98.83%,88.17% and 80.25% respectively.

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Ma, Juan, Chengyao Peng, Akio Takigawa, Shuying Wang, Li Wang, Ningping Ma, Yang Liu y Yongzhen Peng. "Effect of influent nutrient ratios and temperature on simultaneous phosphorus and nitrogen removal in a step-feed CAST". Water Science and Technology 62, n.º 9 (1 de noviembre de 2010): 2028–36. http://dx.doi.org/10.2166/wst.2010.518.

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A step-feed cyclic activated sludge technology (CAST) with a working volume of 72 L treating real municipal wastewater was operated to examine the effect of varying ratios of influent COD/TN and COD/P on the nutrient removal. With the increased COD/P and COD/TN, the phosphorus and nitrogen removals exhibited an upward trend. The TN removals had a positive linear correlation with the phosphorus removal efficiencies, mainly because the presence of nitrate in the anaerobic zone negatively affected the phosphorus release thus the nitrogen removal process took priority over the phosphorus removal process to utilize the limited carbon source in the influent in step-feed CAST where simultaneous removals of nitrogen and phosphorus were achieved. By employing the effective step-feed strategy with alternating anoxic/oxic operation, efficient phosphorus and nitrogen removals of 95.8 and 89.3% were obtained with lower influent COD/P and COD/TN ratios of 61.9 and 5.2, respectively. It was also found that lower temperature, e.g. 13 ∼ 16°C, did not deteriorate the phosphorus removal, though the nitrogen removal decreased significantly due to incomplete nitrification. As the temperature increased further, TN removal efficiency increased gradually and nitrogen removal via nitrite pathway was successfully achieved with average nitrite accumulation rate above 90% in the system.

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Chen, Su, Lei Chao, Ning Chen, Lin Shan Wang, Xue Shao y Li Na Sun. "An Experimental Study on Compatible Solute Ectoine Dosing of High Salinity Wastewater". Advanced Materials Research 955-959 (junio de 2014): 1907–10. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1907.

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When the reactor is added with ectoine of concentrations of 0, 0.1, 1 and 10 mmol/L, the impacts on brine waste treatment efficiency are investigated. The results show that the outflow COD and ammonia nitrogen removal rates are the highest, when the ectoine concentration is 0.1 mmol/L. The brine waste treatment efficiency under addition of ectoine of 1 and 10 mmol/L is even worse than that without ectoine addition. It can be preliminarily determined that the best ectoine dosage is in between 0.1-1.0 mmol/L. When ectoine concentrations added in reactors are 0.2, 0.5, 0.8 and 1.0 mmol/L, the results show that the average reactor outflow COD and ammonia nitrogen removal rates are increased compared with those of reactor without adding ectoine. But when ectoine of 1.0 mmol/L is added, the outflow COD and ammonia nitrogen removal rates decrease. When ectoine dosage is 0.5 mmol/L, the reactor outflow COD and ammonia nitrogen values are the lowest, the removal rates are the highest, the average COD removal rate is 74.46%, and the average ammonium nitrogen removal rate is 54.97%. Compared with reactor without adding ectoine, COD and ammonium nitrogen removal rates are increased by 13.16% and 26.81%. Therefore, the best dosage of ectoine is 0.5 mmol/L.

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Chen, Ming Hui, Wei Liu, Ze Sen Wang y Yu Li. "Based on IF-PSO River Basin Water Pollutant Total Amount Control Optimization Model". Applied Mechanics and Materials 508 (enero de 2014): 269–74. http://dx.doi.org/10.4028/www.scientific.net/amm.508.269.

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This research based on the total amount control of river basin water pollution reducing, and with YiTong river basin as the study case, to obtain the optimal decision scheme of water environmental pollution control, acquired in 2015 the smallest reduction of COD and ammonia nitrogen is 77804.53 tons and 6644.92 tons, in 2020 obtained the smallest reduction of COD and ammonia nitrogen is 33518.49 tons and 2887.69 tons; acquired in 2020 the smallest reduction of COD and ammonia nitrogen is 77103.39 tons and 6584.52 tons, in 2010 obtained the smallest reduction of COD and ammonia nitrogen is 34219.62 tons and 2948.09 tons, provided decision-making support for the basin water pollution control, improve watershed management and control of water pollutants.

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38

Tanaka, S. y A. Suzuki. "Removal of organics and nitrogen in sewage treatment using anoxic-aerobic recirculated filter". Water Science and Technology 46, n.º 9 (1 de noviembre de 2002): 309–14. http://dx.doi.org/10.2166/wst.2002.0267.

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The anoxic-aerobic recirculated filter (AARF) process was investigated on removal effciencies of organics and nitrogen with regard to loading rates, recirculation ratios of nitrified liquor and contribution of methane production and sulfate reduction in the treatment of the municipal sewage. The AARF process is composed of an anoxic filter for denitrification and an aerobic filter for nitrification and some of the nitrified liquor in the aerobic filter is recirculated to the anoxic filter. The AARF process successfully removed organics and nitrogen achieving high removal rates of 88% for COD and 64-74% for nitrogen. The recirculation ratio (Re) did not affect the COD removal efficiency but did affect the nitrogen removal, which was enhanced at a higher ratio (Re = 4). The methane production was not contributive to the COD removal but the COD consumed by the sulfate reduction was equivalent to 17% of total COD removed at Re = 2. We confirmed that the AARF process was applicable to the sewage treatment including nitrogen removal at a hydraulic retention time close to that of the conventional activated sludge process.

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39

Jiao, Er Long, Chun Di Gao, Hao Li, Wei Xiao Wang y Shi Xin Fan. "Effects of Alternating Oxic-Anoxic Model on Nitrite Accumulation in Biological Nitrogen Removal System". Advanced Materials Research 1030-1032 (septiembre de 2014): 422–25. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.422.

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The effects of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen removal rates and nitrite accumulation are investigated under alternating oxic-anoxic model in biological nitrogen removal system——sequencing batch reactor (SBR). The system operational effect was studied by analyzing pollutants removal and nitrite accumulation changes. The results showed that the ammonium nitrogen removal rate increased gradually and reached 60% at last. The average removal rate of ammonia nitrogen was 50.2%. The average total nitrogen removal rate was 31.0% due to the low ammonia nitrogen removal and the low carbon in the inflow. The average COD removal rate was 41.7%, finally the COD removal rate reached near 60%. The average nitrite accumulation rate was 68.71%. The alternating oxic-anoxic model reached stable nitrite accumulation.

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40

Tokarek, Travis W., Charles A. Odame-Ankrah, Jennifer A. Huo, Robert McLaren, Alex K. Y. Lee, Max G. Adam, Megan D. Willis et al. "Principal component analysis of summertime ground site measurements in the Athabasca oil sands with a focus on analytically unresolved intermediate-volatility organic compounds". Atmospheric Chemistry and Physics 18, n.º 24 (14 de diciembre de 2018): 17819–41. http://dx.doi.org/10.5194/acp-18-17819-2018.

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Abstract. In this paper, measurements of air pollutants made at a ground site near Fort McKay in the Athabasca oil sands region as part of a multi-platform campaign in the summer of 2013 are presented. The observations included measurements of selected volatile organic compounds (VOCs) by a gas chromatograph–ion trap mass spectrometer (GC-ITMS). This instrument observed a large, analytically unresolved hydrocarbon peak (with a retention index between 1100 and 1700) associated with intermediate-volatility organic compounds (IVOCs). However, the activities or processes that contribute to the release of these IVOCs in the oil sands region remain unclear. Principal component analysis (PCA) with varimax rotation was applied to elucidate major source types impacting the sampling site in the summer of 2013. The analysis included 28 variables, including concentrations of total odd nitrogen (NOy), carbon dioxide (CO2), methane (CH4), ammonia (NH3), carbon monoxide (CO), sulfur dioxide (SO2), total reduced-sulfur compounds (TRSs), speciated monoterpenes (including α- and β-pinene and limonene), particle volume calculated from measured size distributions of particles less than 10 and 1 µm in diameter (PM10−1 and PM1), particle-surface-bound polycyclic aromatic hydrocarbons (pPAHs), and aerosol mass spectrometer composition measurements, including refractory black carbon (rBC) and organic aerosol components. The PCA was complemented by bivariate polar plots showing the joint wind speed and direction dependence of air pollutant concentrations to illustrate the spatial distribution of sources in the area. Using the 95 % cumulative percentage of variance criterion, 10 components were identified and categorized by source type. These included emissions by wet tailing ponds, vegetation, open pit mining operations, upgrader facilities, and surface dust. Three components correlated with IVOCs, with the largest associated with surface mining and likely caused by the unearthing and processing of raw bitumen.

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41

Pastorelli, G., G. Andreottola, R. Canziani, C. Darriulat, E. de Fraja Frangipane y A. Rozzi. "Organic carbon and nitrogen removal in moving-bed biofilm reactors". Water Science and Technology 35, n.º 6 (1 de marzo de 1997): 91–99. http://dx.doi.org/10.2166/wst.1997.0247.

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Pilot moving-bed biofilm reactors (MBBRs), fed on primary settled wastewater, were used in order to study organic carbon removal and nitrification. Nitrate uptake rate (NUR) tests were performed by feeding sodium acetate and potassium nitrate to a bench-scale moving-bed batch biofilm reactor. In both experiments the same polyethylene biofilm carriers were used. Both particulate and filtered COD removal rates appear to be proportional to the corresponding loading rates. Particulate COD removal is the net effect of adsorption onto and release from the biofilm surface. Filtered COD removal is the sum of the influent filtered COD removal and the removal of hydrolysed colloidal COD. Filtered COD removal rates could not be evaluated with a kinetic expression because back-diffusion from biofilm is not always negligible. Nitrification tests, performed at oxygen limiting conditions, show that the reaction rate was nearly first order with respect to dissolved oxygen due to liquid film diffusion. Denitrification batch tests showed denitrification rates very close to other reported data. Since the process proved reliable and easy-to-operate, it is suitable for application to small WWTPs, either in designing new plants or in upgrading existing overloaded activated sludge systems.

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42

Thayalakumaran, N., R. Bhamidimarri y P. O. Bickers. "Biological nutrient removal from meat processing wastewater using a sequencing batch reactor". Water Science and Technology 47, n.º 10 (1 de mayo de 2003): 101–8. http://dx.doi.org/10.2166/wst.2003.0549.

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Meat processing effluents are rich in nutrients (nitrogen: 75-200 mg L−1 and phosphorus: 20-40 mg L−1) and COD (800-2,000 mg L−1) after primary treatment. A laboratory scale sequencing batch reactor (SBR) was operated for the treatment of a beef processing effluent from slaughtering and boning operations. An effective SBR cycle was found for removal of COD, nitrogen and phosphorus at 22°C. The solid retention time was 15 days while the hydraulic retention time (HRT) was 2.5 days. The total nitrogen in the wastewater was reduced to less than 10 mg L−1, while the total phosphorus decreased to less than 1.0 mg L−1. The residual effluent soluble COD was found to be non-biodegradable as reflected by no further soluble COD removal following prolonged aeration. Removal of biodegradable soluble COD, ammonia nitrogen and soluble phosphate phosphorus of greater than 99% was achieved in the SBR. Good prediction of ammonia and nitrate nitrogen removal was obtained using IWA Activated Sludge Model. The operating cycle is shown to be appropriate to achieve simultaneous removal of COD and nutrients from the meat processing wastewater. Alkalinity and pH have an inverse relationship during the initial anaerobic and aerobic stages due to production and stripping of CO2. Use of a low level of DO in the final aerobic stage ensured complete ammonia removal and enhanced denitrification.

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43

Yin, Jun, Yan Kai, Wei Liu, Ying Hu y Fan Xin Meng. "The Performance Impact of Hair Dyeing Sewage on Biological Treatment". Applied Mechanics and Materials 522-524 (febrero de 2014): 672–77. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.672.

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To domestic sewage, mixed sewage with hair dyeing sewage and low concentrations of hair dyeing sewage as objects, studied by experiments SBR remove its COD, total phosphorus, ammonia, nitrogen efficiency, the results show that the hair dyeing sewage on SBR to remove COD, total phosphorus, ammonia has little effect, the low concentration hair dyeing sewage can be handled through biological methods, its COD, total phosphorus, total nitrogen removal efficiency can reach 79.11%, 92.16%, 74.51%, 55.93%, However, due to the hair dyeing sewage has cyclic organic matter may inhibit the role of heterotrophic bacteria, affecting the biological nitrogen removal, the nitrogen removal rate of hair dyeing sewage decreased 14.70% than domestic sewage.

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44

Guo, Yan-Li, Feng Gao, Tai-Wei Dong, Yang Bai, Qiao Liu, Ruo-Lan Li, Shu-Ting Yan, Mei Chen, Pei-Feng Wei y Miao-Miao Xi. "Meta-Analysis of Clinical Efficacy and Safety of Tripterygium wilfordii Polyglycosides Tablets in the Treatment of Chronic Kidney Disease". Evidence-Based Complementary and Alternative Medicine 2021 (13 de mayo de 2021): 1–27. http://dx.doi.org/10.1155/2021/6640594.

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Objective. Tripterygium wilfordii polyglycosides tablet (TGt) is an oral preparation extracted from plant Tripterygium wilfordii. It has the effects of anti-inflammation and inhibition of cellular and humoral immunity. However, many reports of adverse reactions caused by TGt have limited its application. In this paper, the clinical efficacy and safety of TGt in the treatment of chronic kidney disease (CKD) were verified by data mining and analysis, so as to provide theoretical data support for the application and development of TGt. Methods. A computer search of the following databases was conducted: PubMed, Web of Science, CBM, VIP, Wanfang Data, and CNKI. The search time limit is from the establishment of the database to September 2020. We searched for clinical randomized controlled trials of TGt in the treatment of CKD. The main types of CKD involved are nephrotic syndrome (NS), primary nephrotic syndrome (PNS), refractory nephrotic syndrome (RNS), and IgA nephropathy (IgAN). RevMan 5.2 and Stata 12.0 software were used to evaluate the literature quality and analyze the data. Finally, GRADEpro software was used to evaluate the quality of evidence. Results. According to the inclusion and exclusion criteria, 75 articles with a total of 6418 subjects were included. The results of the meta-analysis showed that TGt could reduce 24-hour urinary protein, increase serum albumin, improve clinical efficacy, and reduce disease recurrence rate in patients ( P < 0.05 ) with CKD compared with adrenocortical hormones or immunosuppressants. TGt could significantly reduce the level of serum creatinine (Scr) in patients with CKD ( P < 0.05 ), but it was not significant in reducing the level of blood urea nitrogen ( P > 0.05 ). In terms of safety evaluation, in patients with CKD, it could significantly reduce the incidence of gastrointestinal adverse reactions and neurogenic dizziness and headache ( P < 0.05 ). However, in terms of adverse reactions such as liver injury, respiratory infection, and leukopenia, TGt was as harmful as corticosteroids or immunosuppressants ( P < 0.05 ). The quality of the evidence was evaluated with GRADEpro software, and the results showed that TGt was strongly recommended for the treatment of CKD. Conclusion. TGt has certain efficacy in the treatment of CKD and has fewer side effects in certain types of diseases. The effect of TGt combined with other drugs is better than that of single use. This paper also has some limitations. Due to the limited number of the included studies, with all being from China, there may be methodological differences. Therefore, more high-quality literature data from different countries are needed.

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45

Ong, S. L., J. Y. Hu, L. Y. Lee, W. J. Ng y L. F. Song. "Packed bed columns for high rate nitrogen and carbon removals". Water Science and Technology 46, n.º 11-12 (1 de diciembre de 2002): 57–62. http://dx.doi.org/10.2166/wst.2002.0717.

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Two packed bed column (PB) systems, namely anoxic-anoxic and anoxic-oxic were investigated for treatment of wastewater containing high concentrations of nitrogen (N) and COD. The anoxic-anoxic PB system was able to achieve N and COD removal rates of up to 6.70 kg N/m3.d and 26.02 kg COD/m3.d, respectively. The responding removal rates of the anoxic-oxic PB system were 7.41 kg N/m3 and 28.00 kg COD/m3.d, respectively. The N and COD removal efficiencies of anoxic anoxic PB system were in the range of 99.2-100% and 97.2-98.8%, respectively. The corresponding removal efficiencies of anoxic-oxic PB system were 97.5-100% and 98.6-99.4%, respectively. These findings showed that a PB system consisting of anoxic-oxic columns in series has a high capacity to remove nitrogenous and carbonaceous compounds even though the influent to the anoxic stage was oxygenated. Better system stability in terms of denitrification was, however, obtained with the anoxic-anoxic system.

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46

Abdul-Rahman, R., H. Tsuno y N. Zainol. "Nitrogen nutrient removals from wastewater and river water". Water Science and Technology 45, n.º 12 (1 de junio de 2002): 197–204. http://dx.doi.org/10.2166/wst.2002.0427.

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Elevated levels of nutrients in agroindustry wastewaters, and higher reliance on chlorination pose health threats due to formation of chlorinated organics as well as increased chlorination costs. Removals of ammonium and nitrate compounds were studied using activated carbon from palm shells, as adsorbent and support media. Experiments were carried out at several loadings, F:M from 0.31 to 0.58, and hydraulic residence times (HRT) of 24 h, 12 h and 8 h. Results show that the wastewater treatment process achieved removals of over 90% for COD and 62% for Total-N. Studies on removals from river water were carried out in sequencing batch reactor (SBR) and activated carbon biofilm (ACB) reactor. Removals achieved by the SBR adsorption-biodegradation combination were 67.0% for COD, 58.8% for NH3-N and 25.5% for NO3-N while for adsorption alone the removals were only 37.0% for COD, 35.2% for NH3-N and 13.8% for NO3-N. In the ACB reactor, at HRT of 1.5 to 6 h, removals ranged from 12.5 to 100% for COD, 16.7 to 100% for NO3-N and 13.5 to 100% for NH3-N. Significant decrease in removals was shown at lower HRT. The studies have shown that substantial removals of COD, NO3-N and NH3-N from both wastewater and river water may be achieved via adsorption-biodegradation by biofilm on activated carbon processes.

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47

Kalyuzhnyi, S., M. Gladchenko y A. Epov. "Combined anaerobic-aerobic treatment of landfill leachates under mesophilic, submesophilic and psychrophilic conditions". Water Science and Technology 48, n.º 6 (1 de septiembre de 2003): 311–18. http://dx.doi.org/10.2166/wst.2003.0417.

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As a first step of treatment of landfill leachates (total COD - 1,430-3,810 mg/l, total nitrogen 90-162 mg/l), a performance of laboratory UASB reactors has been investigated under mesophilic (30°C), sub-mesophilic (20°C) and psychrophilic (10°C) conditions. Under hydraulic retention times (HRT) of around 7 h, when the average organic loading rates (OLR) were around 5 g COD/l/day, the total COD removal accounted for 81% (on the average) with the effluent concentrations close to anaerobic biodegradability limit (0.25 g COD/l) for mesophilic and sub-mesophilic regimes. The psychrophilic treatment conducted under the average HRT of 8 h and the average OLR of 4.22 g COD/l/day showed a total COD removal of 47% producing the effluents (0.75 g COD/l) more suitable for subsequent biological nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulphides inside the sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated wastewater.

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48

How, Seow Wah, Jia Huey Sin, Sharon Ying Ying Wong, Pek Boon Lim, Alijah Mohd Aris, Gek Cheng Ngoh, Tadashi Shoji, Thomas P. Curtis y Adeline Seak May Chua. "Characterization of slowly-biodegradable organic compounds and hydrolysis kinetics in tropical wastewater for biological nitrogen removal". Water Science and Technology 81, n.º 1 (1 de enero de 2020): 71–80. http://dx.doi.org/10.2166/wst.2020.077.

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Abstract Many developing countries, mostly situated in the tropical region, have incorporated a biological nitrogen removal process into their wastewater treatment plants (WWTPs). Existing wastewater characteristic data suggested that the soluble chemical oxygen demand (COD) in tropical wastewater is not sufficient for denitrification. Warm wastewater temperature (30 °C) in the tropical region may accelerate the hydrolysis of particulate settleable solids (PSS) to provide slowly-biodegradable COD (sbCOD) for denitrification. This study aimed to characterize the different fractions of COD in several sources of low COD-to-nitrogen (COD/N) tropical wastewater. We characterized the wastewater samples from six WWTPs in Malaysia for 22 months. We determined the fractions of COD in the wastewater by nitrate uptake rate experiments. The PSS hydrolysis kinetic coefficients were determined at tropical temperature using an oxygen uptake rate experiment. The wastewater samples were low in readily-biodegradable COD (rbCOD), which made up 3–40% of total COD (TCOD). Most of the biodegradable organics were in the form of sbCOD (15–60% of TCOD), which was sufficient for complete denitrification. The PSS hydrolysis rate was two times higher than that at 20 °C. The high PSS hydrolysis rate may provide sufficient sbCOD to achieve effective biological nitrogen removal at WWTPs in the tropical region.

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49

Zuo, Jin Long. "The Nitrogen Variation of Sauce Wastewater with Different Influent COD Concentration". Advanced Materials Research 183-185 (enero de 2011): 255–58. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.255.

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With rapid development of sauce industry, the production of the sauce is increasing in recent years. The sauce wastewater is doing greater harm to the water environment in China. In order to tackle this problem, the influent COD concentration influence on nitrogen variation of sauce wastewater was investigated. The results showed that the influent COD has a different effect for ammonia nitrogen, nitrite and nitrate. When the influent COD concentration was 600mg/L, 500mg and 300mg/L respectively, the effluent ammonia nitrogen was at 4.3mg/L, 1.8mg/L and 1.0mg/L. And the ammonia nitrogen removal efficiency was more than 90%. Meanwhile the nitrate and nitrite accumulated steadily with the same variation tendency.

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50

Li, Jun Sheng, Cheng Zhang, Chun Bo Che, Jin Long Zuo, Fang Gu y Rong Jun Su. "Study on Wastewater Treatment by Biological Aerated Filter". Advanced Materials Research 113-116 (junio de 2010): 1289–92. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.1289.

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In order to study the pollutants removal effect, the reactor operating conditions were studied with Biological Aerated Filter (BAF) process. The results showed that when HRT was at 8h, the effluent COD and ammonia nitrogen were 37 mg/L and 8.6 mg/L with the aeration flow was 0.3 m3/h, the effluent COD and ammonia nitrogen were 53 mg/L and 12.2 mg/L respectively. And the range of effluent pH is at 6.0-8.8. Furthermore the effluent COD was stable, while the effluent ammonia nitrogen will gradually affect by aeration flow. So the BAF process for residential sewage treatment is feasible.

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