Статті в журналах: "Precipitation fouling"

1

Amaral, M. C. S., H. V. Pereira, E. Nani, and L. C. Lange. "Treatment of landfill leachate by hybrid precipitation/microfiltration/nanofiltration process." Water Science and Technology 72, no. 2 (May 5, 2015): 269–76. http://dx.doi.org/10.2166/wst.2015.218.

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This paper describes a promising method to treat stabilized landfill leachate. Such method consists of a combination of chemical precipitation processes, a cost-effective technique with high potential to remove contaminants with foulant nature, microfiltration aimed at removing the produced precipitate and nanofiltration (NF) for final polishing. This study was carried out on a bench unit comprising a precipitation reactor associated with a submerged hollow-fiber microfiltration membrane module and a flat NF membrane cell operated in batch and continuous mode with a treating capacity of 0.1 L h−1. Combining these processes yielded a clear and colorless permeate and proved to be very efficient at removing organic and inorganic matter. The results showed the importance of membrane processes to ensure treated landfill leachate quality. Also the precipitation associated with microfiltration as a pretreatment process is able to guarantee low membrane fouling due to the significant retention of humic substances which are known for their high potential to cause NF membrane fouling.

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2

Li, Wei. "The Performances of Internal Helical-Rib Roughness Tubes Under Fouling Conditions: Practical Cooling Tower Water Fouling and Accelerated Particulate Fouling." Journal of Heat Transfer 125, no. 4 (July 17, 2003): 746–48. http://dx.doi.org/10.1115/1.1571090.

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This paper addresses fouling in a family of seven copper helically ribbed tubes. Series of semi-theoretical linear fouling correlations for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and for accelerated particulate fouling were developed.

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3

He, Chang-wei, Hui Wang, Luo-chun Wang, Zi-yang Lou, Li Bai, Hai-feng Zong, and Zhen Zhou. "Fouling Identification for Nanofiltration Membrane and the Potential Reduction of Pollutants in the Leachate by Using Fe/Al/PAC Coagulation." Sustainability 13, no. 3 (January 21, 2021): 1114. http://dx.doi.org/10.3390/su13031114.

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The reduction in the fouling is an important way to maintain the steady operation for the nanofiltration (NF) process in leachate treatment. The fouling components from the real leachate treatment process were identified using a scanning electron microscope equipped with X-ray microanalysis (SEM-EDS), infrared spectroscopy (FTIR), atomic analysis and three-dimensional fluorescence (EEM) analysis, and the coagulation of Fe/Al/PAC was selected to reduce the potential pollutants in the leachate, to reduce the potential fouling. It was found that organic humic acid and calcium-magnesium precipitates were the main pollutants in NF fouling. The foulant layer was the result of the combination of organic matter, inorganic precipitation, colloids and microorganisms, and the colloids precipitation is more important, and should be removed in advance. PAC was found to be more efficiency to reduce the colloids and the inorganic matter, among the coagulants selection, with the chemical oxygen demand (COD) removal rate of 55.1%. The commercially available coagulant-poly aluminum chloride (PAC) was chosen as a coagulant. The removal rate of leachate reached 55.1%, and the flow rate through the membrane was increased by 35.8% under the optimum condition (pH was 5.0, PAC dosage was 100 mg/L, and the membrane pressure was 0.4 MPa). Through the pilot scale test, the effluent was connected to the microfiltration membrane and then to the nanofiltration membrane and the practical engineering application is feasible.

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4

Xuefei, Miao, Xiong Lan, Chen Jiapeng, Yang Zikang, and He Wei. "Experimental study on calcium carbonate precipitation using electromagnetic field treatment." Water Science and Technology 67, no. 12 (June 1, 2013): 2784–90. http://dx.doi.org/10.2166/wst.2013.161.

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The present study investigated the effectiveness of electromagnetic fields in preventing calcium carbonate (CaCO3) fouling in cooling water. Four different frequencies and two different voltages were adopted to induce electromagnetic fields directly in water with constant water temperature and constant flow velocity. Artificial hard water was used. The solution conductivities decreased by 17–25% from their initial values in the electromagnetic anti-fouling treatment (EAT) cases, depending on different frequencies of electric pulses, whereas the untreated case dropped by 31%. The particle size became small and the crystal structure changed into loose style after EAT. The EAT device independently developed by the State Key Laboratory had been validated as an effective apparatus in preventing CaCO3 fouling in cooling water.

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5

Sheriff, M., and M. Gehr. "Laboratory Investigation of Inorganic Fouling of Low Pressure UV Disinfection Lamps." Water Quality Research Journal 36, no. 1 (February 1, 2001): 71–92. http://dx.doi.org/10.2166/wqrj.2001.005.

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Abstract Iron(III) (mainly dosed as FeCl3) is one of the main inorganic constituents associated with the fouling of UV lamps during disinfection of wastewater. A low pressure mercury lamp UV system was operated under laboratory conditions to assess the effects of heat and UV light on fouling. Iron(III) was dosed at different concentrations and fouling was monitored by measuring the UV irradiance. The potential for ferric phosphate fouling and the effects of organics were also studied. Results showed that fouling did not occur in recirculating systems over 12 days of observation. However, in flow-through systems, the extent and rate of fouling depended on the solution Fe concentration. Furthermore, addition of phosphorus increased the fouling rate. Bulk precipitation appeared to be significant at iron(III) dosing over 3 mg/L. Theoretical predictions of an equilibrium model (MINEQL+) showed similar trends with measured concentrations of soluble Fe and P from batch tests. However, model predictions of temperature effects alone could not account for the observed solids deposition on the quartz sleeve. Bulk precipitation, followed by sedimentation, was considered to be the dominant mechanism at high iron (III) concentrations.

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6

Schäfer, A. I., A. G. Fane, and T. D. Waite. "Direct coagulation pretreatment in nanofiltration of waters rich in organic matter and calcium." Water Supply 1, no. 4 (June 1, 2001): 25–33. http://dx.doi.org/10.2166/ws.2001.0063.

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Nanofiltration (NF) can remove natural organic matter (NOM) and multivalent ions from surface waters. Large hydrophobic organics and calcium ions are responsible for irreversible fouling of nanofiltration membranes and thus a decrease of process efficiency and increase in cleaning requirements. Fouling due to the precipitation of organic-calcium complexes and the impact of colloids and coagulant (FeCl3) on the precipitation of these species was investigated. Coagulation in solution (as opposed to in the boundary layer) did not cause significant flux decline and was able to prevent irreversible fouling under conditions which were previously determined as detrimental. The rejection was varied if a strongly charged solid was deposited on the membrane.

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7

Cho, Young I., Chunfu Fan, and Byung-Gap Choi. "THEORY OF ELECTRONIC ANTI-FOULING TECHNOLOGY TO CONTROL PRECIPITATION FOULING IN HEAT EXCHANGERS." International Communications in Heat and Mass Transfer 24, no. 6 (October 1997): 757–70. http://dx.doi.org/10.1016/s0735-1933(97)00063-8.

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8

Wang, Yuan, Chao Shen, Zhenbo Tang, Yang Yao, Xinlei Wang, and Benjamin Park. "Interaction between particulate fouling and precipitation fouling: Sticking probability and deposit bond strength." International Journal of Heat and Mass Transfer 144 (December 2019): 118700. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118700.

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9

Zou, Long Sheng, De Zhen Chen, and Wei Guo Zhou. "Numerical Simulation of SiO₂ Fouling While Evaporating High Concentration Extracted Oil Wastewater." Advanced Materials Research 518-523 (May 2012): 3231–35. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3231.

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This article aims at fouling situation while extracted oil wastewater evaporating and has analyzed the change process in wastewater SiO2. We point out influence of the formation of fouling SiO2pre-condition—supersaturation and establish SiO2crystallization precipitation model and equation. The results show that concentration ratio and evaporation temperature increase to help fouling formation to give rise to fouling heat resistance elevating. The increase of extracted oil wastewater flow rate loop reduce the fouling heat resistance and improve the efficiency of heat utilize. Through simulation , we master main influencing factors of fouling heat resistance and grain a good foundation to design the experiment scheme in the future.

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10

Sheng, Jian, and Hua Zhang. "Precipitation Characteristics of CaCO₃ Scaling on Stainless Steel in Cooling Tower Condition." Applied Mechanics and Materials 226-228 (November 2012): 1029–33. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1029.

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Stainless steel 304 and 316 (ss304 and ss316) are widely used in heat exchangers, and the precipitation characteristics of CaCO3 is the first step to research anti-fouling technology. CaCO3 scaling precipitated on coupons from 1.0mmol/l CaCO3 solution at 35°C. By weighing the coupons before and after static reaction experiments to get the mass of scaling and the morphology was taken by Scanning Electron Microscope (SEM). The results show that at the same condition there is more fouling on ss304 than ss316. Higher pH not only promotes square aragonite and calcite and square aragonite gradually recrystallize to calcite but also makes both homogeneous and heterogeneous nucleation rate increasing, and the former increases more, so the fouling mass is bigger at lower pH than higher pH; fouling grows at the place with higher surface energy first and then extend to surrounding place, and when the number increases and crystals grow big and connect each other to form fouling layer.

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11

Nevstrueva, Daria, Arto Pihlajamäki, Juha Nikkola, and Mika Mänttäri. "Effect of Precipitation Temperature on the Properties of Cellulose Ultrafiltration Membranes Prepared via Immersion Precipitation with Ionic Liquid as Solvent." Membranes 8, no. 4 (September 25, 2018): 87. http://dx.doi.org/10.3390/membranes8040087.

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Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by the immersion precipitation technique. The effects of coagulation bath temperature and polymer concentration in the casting solution on the membrane morphology, wettability, pure water flux, molecular weight cut-off, and fouling resistance are studied. Scanning electron microscopy, contact angle measurements, atomic force microscopy, and filtration experiments are carried out in order to characterise the obtained ultrafiltration cellulose membranes. The results show the effect of coagulation bath temperature and polymer concentration on the surface morphology and properties of cellulose ultrafiltration membranes. Optimisation of the two parameters leads to the creation of dense membranes with good pure water fluxes and proven fouling resistance towards humic acid water solutions.

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12

E, Hong, and A. Paul Watkinson. "Precipitation and Fouling in Heavy Oil–Diluent Blends." Heat Transfer Engineering 30, no. 10-11 (October 2009): 786–93. http://dx.doi.org/10.1080/01457630902744143.

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13

Meng, Wang, Zhang, Meng, Liu, and Wang. "Insights into the Fouling Propensities of Natural Derived Alginate Blocks during the Microfiltration Process." Processes 7, no. 11 (November 17, 2019): 858. http://dx.doi.org/10.3390/pr7110858.

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Membrane technology has been one of the most promising techniques to solve the water problem in future. Unfortunately, it suffers from the fouling problem which is ubiquitous in membrane systems. The origin of the bewilderments of the fouling problem lies in the lack of deep understanding. Recent studies have pointed out that the molecular structure of foulant affects its fouling propensity which has been ignored in the past. In this study, the filtration behaviors of alginate blocks derived from the same source were comprehensively explored. Alginate blocks share the same chemical composition but differ from each other in molecular structure. The alginate was first extracted from natural seaweed using calcium precipitation and ion-exchange methods. Extracted alginate was further fractionized into MG-, MM- and GG-blocks and the characteristics of the three blocks were examined by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) observations, and transparent exopolymer particles’ (TEPs) measurements. Results showed that MG-, MM- and GG-blocks had the same functional groups, but they showed different intermolecular interactions. TEP formation from MG-, MM- and GG-blocks revealed that the molecule crosslinking of them decreased in the order of MM-blocks > GG-blocks > MG-blocks. It was further found from microfiltration tests that these alginate blocks had completely different fouling propensities which can be explained by the TEP formation. TEPs would accumulate on membrane surfaces and worked as a pre-filter to avoid serious pore blocking of membrane. That all suggested that the membrane fouling was closely related to the molecular structure of foulant. It is expected that this study can provide useful insights into the fouling propensities of different types of polysaccharides during filtration processes.

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14

Cho, Young I., Byung-Gap Choi, and Bennat J. Drazner. "Electronic anti-fouling technology to mitigate precipitation fouling in plate-and-frame heat exchangers." International Journal of Heat and Mass Transfer 41, no. 17 (September 1998): 2565–71. http://dx.doi.org/10.1016/s0017-9310(97)00347-5.

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15

Natig Abbasov, Natig Abbasov, and Rashad Babayev Rashad Babayev. "DESIGN GUIDELINES FOR CHEMICAL TREATMENTS IN DISTILLATION COLUMNS." ETM - Equipment, Technologies, Materials 10, no. 02 (April 2, 2022): 109–19. http://dx.doi.org/10.36962/etm10022022-109.

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Distillation is the application and removal of heat to separate hydrocarbons by their relative volatility or boiling points. This necessary addition of heat normally in the feed stream or at the tower bottoms via a reboiler can also lead to unwanted consequences such as polymerization, corrosion and reverse solubility. The removal of heat can lead to sedimentation, solubility effects, corrosion and precipitation. The concentration of certain constituents by the distillation process can cause corrosion, polymerization, sediment fouling and flow phenomena effects. Keywords: solubility, corrosion, polymerization, distillation, heat, hydrocarbons, sediment, precipitation, fouling

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16

Deng, Ai Hua, Hui Min Huang, and Wen Jin Ji. "Influence of Magnetic Field on Calcium Carbonate Precipitation in the Presence of Foreign Ions." Advanced Materials Research 554-556 (July 2012): 649–56. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.649.

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In this paper, the effect of the adjustable permanent magnetic field with the maximum magnetic flux density as 4100mT on the calcium carbonate(CaCO3) precipitation process was investigated from hard water in the absence and in the presence of foreign ions Al3+、Fe2+、Mg2+、SO42+. By changing the strength of the magnetic field, the fouling resistance efficiency, the total CaCO3precipitation and precipitation in the bulk solution were determined by measurement of the mass of CaCO3precipitation, and the polymorph composition of CaCO3precipitated in bulk solution and particle size fouling on the loading slice was determined by XRD and electron microscope. The effect of MF on the precipitation process of CaCO3was tested by degassifying dissolved CO2in calcocarbonic pure water containing foreign ions. The results showed that magnetic water treatment increased the total precipitation and favored the precipitation in bulk solution instead of precipitating on the walls regardless the presence of foreign ions. The effect is intensifying with the strengthening of the magnetic flux indendity. The Magnetic field (MF) did not affect the polymorph composition of CaCO3in the absence of foreign ions. While in the presence of foreign ions, the precipitation and structure of precipitated CaCO3were significantly affected. The MF favored the precipitation of aragonite and inhibited the formation of calcitein the presence of Mg2+and SO42-. In the case of Al3+and Fe2+, the precipitation of aragonite is favored, calcite and vaterite is inhibited. The MF influenced CaCO3precipitation process by influencing the hydration process of the ions in the solution and changing the dehydration process of hydrated CaCO3as the precursor of crystal nuclei for the magnetic field change the structure of water cluster. The reason that foreign ions can change the polymorph composition of CaCO3is probably owing to its hydration and dehydration.

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17

Shen, Chao, Yuan Wang, Zhenbo Tang, Yang Yao, Yudong Huang, and Xinlei Wang. "Experimental study on the interaction between particulate fouling and precipitation fouling in the fouling process on heat transfer tubes." International Journal of Heat and Mass Transfer 138 (August 2019): 1238–50. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.04.136.

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18

Renou, S., S. Poulain, J. G. Givaudan, C. Sahut, and P. Moulin. "Lime treatment of stabilized leachates." Water Science and Technology 59, no. 4 (February 1, 2009): 673–85. http://dx.doi.org/10.2166/wst.2009.014.

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Reverse Osmosis is the most widely used method for treating municipal solid waste landfill leachates, since it produces a permeate in compliance with reject requirements. However, the efficiency of this process at the industrial scale is limited mainly because of membrane fouling and the high osmotic pressures involved. Although lime precipitation is traditionally used to eliminate the temporary hardness of water by decarbonation, it has also been shown to be highly efficient in removing humic substances which are known to have strong fouling potential towards membranes. Our objective is to study the lime/leachate physico-chemistry, in order to determine the potential of the lime precipitation as pre-treatment for reverse osmosis. The results show that the lime treatment makes it possible (i) to act efficiently on the inorganic fraction of leachates through a decarbonation mechanism which entails massive precipitation of the carbonates under the form of CaCO3, (ii) to eliminate by co-precipitation the high Molecular Weight (MW) organic macromolecules (>50,000 g.mol−1) such as humic acids, and (iii) to generate a stable residue that can be easily stored at a landfill. The reverse osmosis step will be facilitated through significant reduction of the osmotic pressures and prevention of membrane fouling.

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19

Suárez, Francisco, María B. del Río, and Jazmín E. Aravena. "Water Flux Prediction in Direct Contact Membrane Distillation Subject to Inorganic Fouling." Membranes 12, no. 2 (January 28, 2022): 157. http://dx.doi.org/10.3390/membranes12020157.

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Freshwater is a limited resource, which has driven the development of new purification and water-reuse technologies. One promising technology for water treatment is membrane distillation (MD). One of the main problems of MD, and of many desalination technologies, is membrane fouling, which reduces the performance of the membrane. This work presents a mathematical model that aims to predict distillate fluxes in direct-contact MD when fouling occurs as salts are deposited onto the membrane surface, forming an inorganic fouling layer. The mathematical model uses a heat- and mass-transfer formulation for prediction of the distillate flux under steady state conditions, and it is combined with the cake-filtration theory to represent the distillate fluxes after the onset of membrane fouling. Model results agree well with experimental observation of distillate fluxes, both before (~12–14 kg m−2 h−1) and after the onset of membrane fouling, with root-mean-square errors smaller than 1.4 kg m−2 h−1 in all the experiments. These results suggest that the cake-filtration theory can be used to represent water flux decline in MD membranes prone to inorganic fouling. From our experiments and from the modelling exercise, we found that the onset of membrane failure was relatively constant; the precipitation reaction constant is conditioned by the physicochemical interaction between the feed solution and the membrane; and the rate of flux decline after membrane fouling depends on flow conditions as well as on the precipitation compound. However, the proposed model has limitations that must be addressed in future investigations to validate it under a wider range of operating conditions, for membranes composed by other materials and with different feed solutions to address organic, biological, and/or colloidal fouling, which typically occur under real conditions.

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20

Zhou, Zhi Gang, and Hua Zhang. "Precipitation Characteristics of Crystallization Fouling on Metal Surface from 0.5mmol/l CaCO₃ Solution at 35°C." Advanced Materials Research 614-615 (December 2012): 31–35. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.31.

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The comparative experiments on CaCO3 crystallization fouling on brass, copper and stainless steel 304 and 316 at different pH at 35°C were carried out. The growing curves of fouling were got by direct weighing after static reaction experiments, and the morphology of crystals at different conditions was obtained by scanning electron microscope (SEM) and the parameters such as polymorphism, crystal size and so on were got, so the growing characteristics of CaCO3 crystallization fouling were known. The experimental results show the mass of crystallization fouling on stainless steeSubscript textl surfaces are almost equal and increasing a little when pH increased, but the mass of fouling on brass and copper surfaces are close and far less than on stainless steel and increasing a lot when pH increased; not only the homogeneous nucleation rate in bulk solution and heterogeneous nucleation rate on metal surface are increased to generate more new crystal nuclear but also square aragonite and calcite are formed more by higher pH, so the mass of metal surfaces is more and the phenomenon is more obvious that single crystal has a size extremum by higher pH.

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21

Pulles, W., G. J. G. Juby, and R. W. Busby. "Development of the Slurry Precipitation and Recycle Reverse Osmosis (SPARRO) Technology for Desalinating Scaling Mine Waters." Water Science and Technology 25, no. 10 (May 1, 1992): 177–92. http://dx.doi.org/10.2166/wst.1992.0246.

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Conventional desalination technologies such as electrodialysis reversal and reverse osmosis cannot be directly used to economically treat those waters encountered in the South African gold mining industry which are scaling with regard to calcium sulphate. The Chamber of Mines of South Africa Research Organisation therefore decided, in the early 1980's, to undertake research into the development of seeded reverse osmosis technology for treating scaling mine waters. This research culminated in the development of foe Slurry Precipitation and Recycle Reverse Osmosis (SPARRO) technology. Extensive pilot plant investigations were undertaken and it was shown that the SPARRO process is technically capable of producing a high quality product water at water recoveries of around 95 per cent. Problems were encountered, however, with fouling of the tubular cellulose acetate membranes, resulting in declines in the flux rate. It is postulated that the fouling is mainly due to the presence of quartzitic suspended material, although the mechanism of fouling cannot be explained. Further research is being undertaken to clarify the potential fouling mechanisms and to optimize the membrane cleaning regimes. The capital cost for a 46.3 1/s (4Ml/d) SPARRO plant has been estimated at R16.2 million, with an estimated operating cost of R 1.48/m3 of product water.

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22

Miyoshi, Taro, Yuhei Nagai, Tomoyasu Aizawa, Katsuki Kimura, and Yoshimasa Watanabe. "Proteins causing membrane fouling in membrane bioreactors." Water Science and Technology 72, no. 6 (June 2, 2015): 844–49. http://dx.doi.org/10.2166/wst.2015.282.

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In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

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23

Kostoglou, M., and A. J. Karabelas. "Comprehensive Modeling of Precipitation and Fouling in Turbulent Pipe Flow." Industrial & Engineering Chemistry Research 37, no. 4 (April 1998): 1536–50. http://dx.doi.org/10.1021/ie970559g.

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24

Sheikholeslami, R. "Calcium Sulfate Fouling-Precipitation or Particulate: A Proposed Composite Model." Heat Transfer Engineering 21, no. 3 (July 2000): 24–33. http://dx.doi.org/10.1080/014576300270870.

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25

Gilron, J., and D. Hasson. "Analysis of Laminar flow precipitation fouling on reverse osmosis membranes." Desalination 60, no. 1 (January 1986): 9–24. http://dx.doi.org/10.1016/0011-9164(86)80002-9.

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26

Rezania, B., N. Cicek, and J. A. Oleszkiewicz. "Quantifying inorganic fouling in a membrane bioreactor treating nitrate-contaminated groundwater using hydrogen as energy source." Water Supply 6, no. 3 (July 1, 2006): 115–21. http://dx.doi.org/10.2166/ws.2006.750.

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A hydrogenotrophic denitrification system, which consisted of a sequencing batch membrane bioreactor, was evaluated for removal of nitrate from a synthetic groundwater feed. A hollow fiber microporous membrane diffuser was used for bubble-less diffusion of hydrogen into the bioreactor, and a membrane filter was used for separating the biomass from treated water. The nitrate loading of 0.328 kg N m−3 d−1 was completely denitrified to below detectable levels; however, inorganic fouling of both membrane filter and diffuser occurred. The increase in pH during denitrification caused inorganic precipitation and clogging of the membranes. The foulant material was quantified as beta three calcium phosphate βCa3 (PO4)2.

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27

Kweon, J. H., and D. F. Lawler. "Effects of characteristics of softening as a pretreatment for ultrafiltration." Water Supply 3, no. 5-6 (December 1, 2003): 429–35. http://dx.doi.org/10.2166/ws.2003.0199.

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Softening was proposed as a pretreatment for ultrafiltration, which reduces foulants prior to membrane processes. The objectives of this research were to understand the nature of the fouling mechanisms for ultrafiltration when used for waters that either require softening or have been softened, and to use that understanding to determine promising options for the use of softening as a pretreatment before ultrafiltration (UF). Several characteristics of softening, including extent of softening, precipitation kinetics, and hydrophobicity of membrane materials, were investigated as independent variables. Because of softening, both the organic matter concentration and the particle concentration of feed water to ultrafiltration were reduced, thus reducing the degree of fouling. The slow kinetics of softening had little effect on membrane fouling although precipitation directly occurred on the membrane surface in the system during the operation. Detailed images of the membrane surface obtained by scanning electron microscopy confirmed substantial amounts of the precipitates on the surface. In contrast, the hydrophobicity of the membrane material showed a significant effect on the flux decline behavior. Overall, the integrated water treatment of softening and ultrafiltration is shown to be a promising option for hard waters.

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28

Loewenthal, R. E., U. R. C. Kornmüller, and E. P. van Heerden. "Modelling struvite precipitation in anaerobic treatment systems." Water Science and Technology 30, no. 12 (December 1, 1994): 107–16. http://dx.doi.org/10.2166/wst.1994.0592.

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Struvite precipitation is common in waste water systems containing high concentrations of dissolved orthophosphates, free and saline ammonia and magnesium ions, such as in anaerobic fermentation systems, often leading to severe fouling. It appears that a reduction of the partial pressure of CO2, ie. pCO2 is a trigger mechanism for struvite precipitation. An algorithm was developed, based on equilibrium chemistry, to quantitatively predict the struvite precipitation potential of the water in such a process. This was then extended, to predict the change in state together with precipitation potential due to chemical perturbations, particularly variations of pCO2. Experimental verification of the algorithms is presented.

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29

Maddah, Hisham A. "Simulating fouling impact on the permeate flux in high-pressure membranes." International Journal of ADVANCED AND APPLIED SCIENCES 8, no. 8 (August 2021): 1–8. http://dx.doi.org/10.21833/ijaas.2021.08.001.

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Porous high-pressure membranes have been widely used for saline water desalination. However, fouling (concentration polarization) extensively reduces permeate flux in reverse osmosis (RO) and/or nanofiltration (NF) modules. Fouling arises from pore blocking, organic adsorption, cake formation, inorganic or biological precipitation reducing water flux. Herein, we investigated the effect of feed water with various NaCl concentrations on fouling of RO and/or NF and the permeate water flux. A parabolic (or diffusion) partial differential equation (PDE) was used to model salt concentration profile or gradient inside the membrane. Subsequently, the numerical PDE equation, solved by the forward finite difference (FFD) explicit method, estimated flux decline rates resulted from NaCl fouling. It was found that salt accumulation occurs at the feed-side with a noticeable decrease in flux as fouling increases. Previous works reported similar findings as those identified from our analysis: (1) fouling increases with feed concentration and surface roughness, (2) fouling becomes intensified with higher pressure and flux, (3) fouling from long operation times can reduce flux by 65% within 24 h, (4) NaCl fouling can decrease flux rates by 70% (67-22 LMH) for brackish water with an initial concentration of 10000 ppm, and (5) reversible organic fouling may be avoided from lowering flux rates below the membrane critical flux. Results showed fouled RO modules would decrease flux rates from the increased surface polarization, where reverse flow (negative flux) was estimated for feed-side accumulations >10000 ppm for waters with an initial NaCl concentration of 10000 ppm and average diffusivity of 1.3×10-6 cm2/s.

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Gilron, Jack, M. Waisman, N. Daltrophe, N. Pomerantz, M. Milman, I. Ladizhansky, and E. Korin. "Prevention of precipitation fouling in NF/RO by reverse flow operation." Desalination 199, no. 1-3 (November 2006): 29–30. http://dx.doi.org/10.1016/j.desal.2006.03.136.

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31

Kazi, Salim N. "Fouling and fouling mitigation of calcium compounds on heat exchangers by novel colloids and surface modifications." Reviews in Chemical Engineering 36, no. 6 (August 26, 2020): 653–85. http://dx.doi.org/10.1515/revce-2017-0076.

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AbstractFouling is the accumulation of unwanted materials on surfaces that causes detrimental effects on its function. The accumulated materials can be composed of living organisms (biofouling), nonliving substances (inorganic and/or organic), or a combination of both of them. Mineral fouling occurs when a process uses cooling water supersaturated with mineral salt crystals (i.e. hard water). Precipitation ensues on heat transfer surfaces whenever the inversely soluble dissolved calcium salt ions are exposed to high temperature. Mineral salts, dirt, waxes, biofilms, whey proteins, etc. are common deposits on the heat exchanger surfaces, and they create thermal resistance and increase pressure drop and maintenance costs of plants. Fouling of dissolved salts and its mitigation have been studied in detail by varying process parameters, surface materials, coatings on surfaces, additives, etc. by many researchers. In the present stage, researchers have considered polymeric additives, environmental friendly nanoparticles, natural fibers, and thermal conductive coatings (metallic and polymeric) in the study of mitigation of fouling. A better understanding of the problem and the mechanisms that lead to the accumulation of deposits on surfaces will provide opportunities to reduce or even eliminate the problem in certain situations. The present review study has focused on fouling phenomena, environment of fouling, heat exchanger fouling in design, and mitigation of fouling. The findings could support in developing the improved heat exchanger material surfaces, retain efficiency of the heat exchangers, and prolong their continuous operation.

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32

Moreno, J., H. Monclús, M. Stefani, E. Cortada, J. Aumatell, N. Adroer, S. De Lamo-Castellví, and J. Comas. "Characterisation of RO fouling in an integrated MBR/RO system for wastewater reuse." Water Science and Technology 67, no. 4 (February 1, 2013): 780–88. http://dx.doi.org/10.2166/wst.2012.619.

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Membrane filtration has gradually gained acceptance as the preferred pre-treatment for reverse osmosis (RO). In this paper, an integrated membrane bioreactor (MBR)/RO system for wastewater reuse treating real sewage water has been evaluated and the RO fouling has been characterised. The MBR achieved low values of organic matter, total nitrogen, PO43−, total organic carbon, turbidity and conductivity. Filtration with two different RO commercial membranes was performed after the MBR pre-treatment and the same average fouling rate (0.08 bar day−1) was noted. These results gained from the characterisation of the high quality MBR/RO permeate show its potential for water reuse. Inorganic precipitation appears to be the predominant form of fouling in the RO membranes. Calcium phosphate and alumino-silicates were identified by a scanning electron microscope combined with an energy dispersive X-ray and polysaccharides, amide and aliphatic structures were detected with attenuated total reflection infrared microspectroscopy.

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33

Kang, Nam Wook, Seockheon Lee, Dooil Kim, Seungkwan Hong, and Ji Hyang Kweon. "Analyses of calcium carbonate scale deposition on four RO membranes under a seawater desalination condition." Water Science and Technology 64, no. 8 (October 1, 2011): 1573–80. http://dx.doi.org/10.2166/wst.2011.671.

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Inorganic fouling is one of the critical operational issues in reverse osmosis membrane. Few researches investigated effects of membrane surface characteristics on inorganic fouling and on anti-scaling techniques although the fouling occurs on the membrane surface. The objective of this paper was to examine whether different characteristics of deposition of calcium carbonate solids would occur on four membranes having distinctive surface properties. A lab-scale cell reactor with a crossflow velocity was installed and two coupons were used for one type of membranes. Two feed waters were examined: concentrated synthetic seawater simulating a 30% recovery and a concentrate from a seawater RO plant in operation at Changwon, Korea. The amounts of solid deposition on the attached membranes were increased in all four membranes but the degree of deposition on each membrane was different. Various types of calcium carbonate solids were clearly detected by both XRD and SEM analyses. In general, a membrane with greater roughness and negative surface charge appeared to form more scales. This implied that membrane surface characteristics such as roughness and surface charge affected inorganic fouling, presumably by providing favourable sites for precipitation and enhancing attraction of species to the membrane surface.

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34

Hanemaaijer, J. H., T. Robbertsen, Th van den Boomgaard, and J. W. Gunnink. "Fouling of ultrafiltration membranes. The role of protein adsorption and salt precipitation." Journal of Membrane Science 40, no. 2 (January 1989): 199–217. http://dx.doi.org/10.1016/0376-7388(89)89005-2.

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35

Dong, Leilei, B. D. Crittenden, and M. Yang. "Fouling Characteristics of Water−CaSO4 Solution under Surface Crystallization and Bulk Precipitation." International Journal of Heat and Mass Transfer 180 (December 2021): 121812. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121812.

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36

Myronchuk, Valeriy, Yuliya Dzyazko, Yurii Zmievskii, Anatoliy Ukrainets, Alexander Bildukevich, Ludmila Kornienko, Ludmila Rozhdestvenskaya, and Alexey Palchik. "Organic-inorganic membranes for filtration of corn distillery." Acta Periodica Technologica, no. 47 (2016): 153–65. http://dx.doi.org/10.2298/apt1647153m.

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Organic-inorganic membranes were obtained by modification of polymer microfiltration membrane with inorganic ion-exchangers, which form secondary porosity inside macroporous substrate (zirconium hydrophosphate) or simultaneously in the macroporous substrate and active layer, depending of the particle size (from ?50 nm up to several microns). Precipitation of the inorganic constituent is considered from the point of view of Ostwald-Freundlich equation. Such processes as pressing test in deionized water and filtration of corn distillery at 1-6 bar were investigated. Theoretical model allowing to establish fouling mechanism, was applied. It was found that the particles both in the substrate and active layer prevent fouling of the membrane with organics and provide rejection of colloidal particles.

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37

Van Ginkel, Steven W., Youneng Tang, and Bruce E. Rittmann. "Impact of precipitation on the treatment of real ion-exchange brine using the H2-based membrane biofilm reactor." Water Science and Technology 63, no. 7 (April 1, 2011): 1453–58. http://dx.doi.org/10.2166/wst.2011.330.

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The H2-based membrane biofilm reactor (MBfR) was used to remove nitrate and perchlorate from real ion-exchange brine at two different salinities (30- and 50-g/L NaCl). Base production from nitrate reduction to N2 gas caused the pH to increase, and this exacerbated precipitation of calcium and magnesium carbonates onto the MBfR fibers. The precipitates lowered the H2 flux to the biofilm and caused a deterioration of denitrification performance that could be reversed by mild citric-acid washing. The addition of acid seems to be the only mechanism to avoid serious precipitation, membrane fouling, and non-optimal pH for denitrification.

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38

Campuzano, Susana, María Pedrero, Paloma Yáñez-Sedeño, and José Pingarrón. "Antifouling (Bio)materials for Electrochemical (Bio)sensing." International Journal of Molecular Sciences 20, no. 2 (January 19, 2019): 423. http://dx.doi.org/10.3390/ijms20020423.

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(Bio)fouling processes arising from nonspecific adsorption of biological materials (mainly proteins but also cells and oligonucleotides), reaction products of neurotransmitters oxidation, and precipitation/polymerization of phenolic compounds, have detrimental effects on reliable electrochemical (bio)sensing of relevant analytes and markers either directly or after prolonged incubation in rich-proteins samples or at extreme pH values. Therefore, the design of antifouling (bio)sensing interfaces capable to minimize these undesired processes is a substantial outstanding challenge in electrochemical biosensing. For this purpose, efficient antifouling strategies involving the use of carbon materials, metallic nanoparticles, catalytic redox couples, nanoporous electrodes, electrochemical activation, and (bio)materials have been proposed so far. In this article, biomaterial-based strategies involving polymers, hydrogels, peptides, and thiolated self-assembled monolayers are reviewed and critically discussed. The reported strategies have been shown to be successful to overcome (bio)fouling in a diverse range of relevant practical applications. We highlight recent examples for the reliable sensing of particularly fouling analytes and direct/continuous operation in complex biofluids or harsh environments. Opportunities, unmet challenges, and future prospects in this field are also pointed out.

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39

Navarrete, B., L. F. Vilches, M. Rodriguez-Galan, B. Alonso-Fariñas, and L. Cañadas. "A pilot scale study of the rapping reentrainment and fouling in electrostatic precipitation." Environmental Progress & Sustainable Energy 34, no. 1 (January 17, 2014): 7–14. http://dx.doi.org/10.1002/ep.11934.

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40

Kaiser, J. M., and C. E. Glatz. "Use of Precipitation to Alter Flux and Fouling Performance in Cheese Whey Ultrafiltration." Biotechnology Progress 4, no. 4 (December 1988): 242–47. http://dx.doi.org/10.1002/btpr.5420040408.

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41

Thelin, Willy Røstum, Edvard Sivertsen, Gema Raspati, Kamal Azrague, and Herman Helness. "Concentration of Municipal MBBR Effluent by FO for Resource Recovery: Batch Experiments in Side-Stream Configuration." Membranes 11, no. 4 (April 10, 2021): 278. http://dx.doi.org/10.3390/membranes11040278.

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A novel approach for resource recovery includes forward osmosis (FO) as a concentration step in municipal wastewater treatment. The current study investigates different pre-treatment strategies including biological treatment with a moving-bed bioreactor (MBBR) at different loading rates and particle removal by filtration and sedimentation. Membrane performance and recovery potential for energy and nutrients were investigated in laboratory-scale FO experiments in batch mode using pre-treated municipal wastewater as feed and 35 g/L NaCl as a draw solution. Initial water fluxes were in the range of 6.3 to 8.0 L/(m2·h). The baseline fluxes were modelled to account for flux decline due to concentration effects and to enable the prediction of flux decline due to membrane fouling. Fouling-related flux decline varied from 0 to 31%. Both organic fouling and precipitation of CaCO3 and CaHPO4 were identified by using SEM–EDS. High-rate flushing resulted in complete flux recovery under most conditions. Scaling could be avoided by lowering the pH. Two operation strategies were tested to achieve this: (1) applying a bioreactor with a low organic loading rate to achieve high nitrification, and (2) adding a strong acid. A low organic loading rate and the use of additional particle removal were efficient measures that reduced organic/particulate fouling. The recovery potentials for COD and phosphorous in FO concentrate were close to 100%.

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42

Wang, Jian Bing, Jun Yang Cheng, Ting Shi, Qing Huang, and Xu Wen He. "Membrane Fouling Mechanism and its Control in the Treatment of Brackish Water with Reverse Osmosis Process." Advanced Materials Research 788 (September 2013): 268–74. http://dx.doi.org/10.4028/www.scientific.net/amr.788.268.

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Brackish water was treated with reverse osmosis process. The fouling mechanism of RO and its control method was studied. In the treatment of brackish water, the salt removal efficiency was above 95% and the effluent quality was up to the standard for drinking water quality (GB5749-2006). The SDI of the influent of RO was less than 5 after the raw water was pretreated by the combination of coagulation and sedimentation process and filtration process, which met the demand of the water quality of the RO influent. If ultrafiltration was added, the water quality of the pre-treatment was better. Coagulation and precipitation was not very effective for the removal of dissolved organic compounds, especially for the removal of organic compounds with molecular amount ranging from 1000 to 10000. The formation of RO membrane fouling can be divided into five stages, which is membrane surface coarseness stage by inorganic substrate, organic compounds adsorption stage, organism adhesion stage, microbial film development stage, and irreversible membrane block stage. The membrane fouling was effectively alleviated by the strategy of first alkali solution cleaning and then acid solution cleaning.

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43

Park, Yong-Min, Kyung-Min Yeon, and Chul-hwi Park. "Silica treatment technologies in reverse osmosis for industrial desalination: A review." Environmental Engineering Research 25, no. 6 (January 3, 2020): 819–29. http://dx.doi.org/10.4491/eer.2019.353.

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Reverse osmosis (RO) is the main process of current industrial desalination, and its performance is affected by the quality of water source. Natural water contains a certain level of silica, which is originated from metal silicate in the earth crust. Due to its complexity, silica fouling is difficult to control, which often causes less efficient design of RO system for safe operation. In the present work, we review the current state of silica treatment technology in RO desalination. Silica chemistry is investigated in standpoint of the scale formation mechanism among multiple forms of silica species and its synergistic interaction with other foulants such as organic matter. Then, pretreatment methods to remove silica in the RO feed water are outlined. They include softening/coagulation, seed precipitation/aggregation, tight ultrafiltration, ion exchange, adsorbents media, and electro coagulation. We finally highlight the mitigation of RO fouling under silica rich conditions, whose concept can be implemented in different ways of antiscalant dosing, high/low pH operation, and intermediate softening of the RO concentrate, respectively. This review will provide comprehensive information and insight about the optimal operation of industrial RO susceptible to silica fouling.

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44

Choo, K.-H., I.-J. Kang, S.-H. Yoon, H. Park, J.-H. Kim, S. Adiya, and C.-H. Lee. "Approaches to membrane fouling control in anaerobic membrane bioreactors." Water Science and Technology 41, no. 10-11 (May 1, 2000): 363–71. http://dx.doi.org/10.2166/wst.2000.0681.

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Various fouling control methods were investigated for polymeric and ceramic microfiltration membranes in the anaerobic membrane bioreactors where inorganic precipitates and/or fine colloids have been recently known as the most significant foulants: (i) Substantial improvement of flux was achieved by backfeeding of acidic wastewater through the membrane module. The backfeeding mode formed an acidic environment around the membrane pores and thus suppressed struvite formation. (ii) Struvite precipitation was also mitigated when an additional combined dialysis/zeolite unit was attached to the bioreactor. With this combined unit the flux improvement for the ceramic membrane, where struvite had a severer fouling effect, was achieved more significantly than that for the polymeric membrane. (iii) To control the deposition of organics and fine colloids onto the polymeric membrane, powdered activated carbon (PAC) was added into the bioreactor, which gave rise to the reduction of specific cake resistances of biosolids through the sorption and/or coagulation of dissolved and colloidal matter. (iv) The hydrophilic modification of polypropylene (PP) membranes by graft polymerization reduced membrane fouling. Its effectiveness was most substantial at 70% of the degree of grafting, indicating that there was an optimal degree of grafting. This is possibly due to the steric hindrance of grafted polymer chains and the increase in the hydrophilicity of the grafted PP membrane.

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45

Xie, Manman, Xia Feng, Juncheng Hu, Zhengyi Liu, Zijian Wang, Li Chen, and Yiping Zhao. "Preparation and characterization of anti-fouling PVDF membrane modified by chitin." Journal of Polymer Engineering 37, no. 3 (March 1, 2017): 313–21. http://dx.doi.org/10.1515/polyeng-2015-0532.

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Abstract Poly(vinylidene fluoride) (PVDF)/chitin (CH) blend membranes were prepared via the method of immersion-precipitation phase transformation with the solvent system N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl) as solvent and water as coagulant. The effect of CH on membrane structure and performance was investigated. Owing to the strong hydrophilicity, CH chains enriched on the blend membrane surface and improved the hydrophilicity of the membrane. The addition of CH also led to the formation of finger-like pores and the increase of pore size and porosity. The flux and the flux recovery ratio (FRR) of the blend membrane were higher than that of pure PVDF membrane. The fouling resistance of the blend membrane was lower than that of PVDF original membrane. In a word, the addition of CH to PVDF membrane improved the hydrophilicity and the anti-fouling ability of PVDF membrane.

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46

Fahiminia, Feridoun, A. Paul Watkinson, and Norman Epstein. "Early Events in the Precipitation Fouling of Calcium Sulphate Dihydrate under Sensible Heating Conditions." Canadian Journal of Chemical Engineering 85, no. 5 (May 19, 2008): 679–91. http://dx.doi.org/10.1002/cjce.5450850515.

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47

Fahiminia, Feridoun, A. Paul Watkinson, and Norman Epstein. "Early Events in the Precipitation Fouling of Calcium Sulphate Dihydrate under Sensible Heating Conditions." Canadian Journal of Chemical Engineering 85, no. 6 (May 19, 2008): 948. http://dx.doi.org/10.1002/cjce.5450850618.

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48

Nikolskaya, Ekaterina, Mika Liukkonen, Janne Kankkunen, and Yrjö Hiltunen. "A non-fouling online method for monitoring precipitation of metal ions in mine waters." IFAC-PapersOnLine 48, no. 17 (2015): 98–101. http://dx.doi.org/10.1016/j.ifacol.2015.10.085.

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49

Kockmann, N. "Convective micromixers — design and industrial applications." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 5 (May 1, 2008): 807–16. http://dx.doi.org/10.1243/09544062jmes717.

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Convective static micromixers operate with high Reynolds numbers ( Re from 100 to 1000) in relatively large microchannels (100–1000 μm) for high flowrates and low risk of fouling and blocking. Typical flow characteristics of symmetrical mixing in T-shaped micromixers are presented with transient flow for Re number larger than 240. The simulation results are assisted by experimental data. Parallel mixing elements increase the mass flowrate up to 25 kg/h with 100 kPa pressure loss. The typical flow characteristics are described, which are essential for successful mixing devices. Three dimensionless parameters are introduced to describe the mixing performance and effectiveness of such devices. Particle generation are critical in microchannels due to fouling issues. The gas phase particle generation from homogeneous condensation of vitamin E acetate is described, reaching to particle diameters of 20 nm from temporal temperature gradients of about 1.6×106 K/s. In liquid phase, the reactive precipitation of BaSO4 is investigated, leading to particle diameters below 100 nm.

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50

Shahid, Muhammad Kashif, and Younggyun Choi. "Sustainable Membrane-Based Wastewater Reclamation Employing CO2 to Impede an Ionic Precipitation and Consequent Scale Progression onto the Membrane Surfaces." Membranes 11, no. 9 (September 6, 2021): 688. http://dx.doi.org/10.3390/membranes11090688.

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CO2 capture and utilization (CCU) is a promising approach in controlling the global discharge of greenhouse gases (GHG). This study details the experimental investigation of CO2 utilization in membrane-based water treatment systems for lowering the potential of ionic precipitation on membrane surface and subsequent scale development. The CO2 utilization in feed water reduces the water pH that enables the dissociation of salts in their respective ions, which leave the system as a concentrate. This study compares the efficiency of CO2 and other antifouling agents (CA-1, CA-2, and CA-3) for fouling control in four different membrane-based wastewater reclamation operations. These systems include Schemes 1, 2, 3, and 4, which were operated with CA-1, CA-2, CA-3, and CO2 as antiscalants, respectively. The flux profile and percent salt rejection achieved in Scheme 4 confirmed the higher efficiency of CO2 utilization compared with other antifouling agents. This proficient role of CO2 in fouling inhibition is further endorsed by the surface analysis of used membranes. The SEM, EDS, and XRD examination confirmed the higher suitability of CO2 utilization in controlling scale deposition compared with other antiscalants. The cost estimation also supported the CO2 utilization for environmental friendly and safe operation.

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