Tesi sul tema "Pre-coagulation"

Landfill leachate is considered as a complex wastewater with various organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. In order to modify and assist in membrane technology's common drawback, which is dealing with foulants, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs. Fenton oxidation was able to lessen the chemical oxygen demand (COD) concentration of leachate up to 55% while increasing the conductivity and reducing the concentration of NH4-N. The membrane flux and volume had a significant increase with a use of lower COD leachate after Fenton treatment coupled with MD.
Master of Science
Landfilling has been recognized as a principal disposal process of municipal solid wastes globally over the past decades, and this disposal method has been one of the leading concerns for a continuous production of landfill leachate. Leachate is considered as a complex wastewater with a variety of organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. MD has several advantages which include reduced operating temperature compared to conventional distillation processes, fewer requirements of membrane cleaning, and lower operating hydraulic pressure than other conventional pressure-driven membrane processes such as reverse osmosis (RO). This technology has a common drawback along with other membrane-required technologies which is dealing with foulants. For a reduction in membrane fouling, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs.

Thesis (MScFoodSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Large volumes of high strength wastewater are generated annually by distilleries. Treatment of this wastewater is essential to increase its reuse potential. Anaerobic digestion (AD) has been widely applied as high strength wastewater treatment. Additionally, grain distillery wastewater (GDWW) is high in fats, oils and grease (FOG) which can cause problems during AD. Pre-treatment is therefore often required to make the AD process more efficient. The overall objective of this study was to investigate the operational efficiency of upflow anaerobic sludge blanket (UASB) reactors while treating GDWW as substrate. The first aim was to investigate the pre-treatment of the GDWW specifically for the removal of FOG by evaluating the effect of pH adaption, coagulant concentration and ozone (O3) dosages on the FOG reduction efficiency. Secondly, the effect of two different pre-treatments (only coagulant and coagulant and ozone) on the subsequent UASB treatment step was investigated. The pH of raw GDWW (pH 3.4) was adapted to three different pH values (5.0, 6.0, and 7.0) and the coagulant, aluminium chlorohydrate (ACH) (140 mg.L-1), was added. To make the process more economically viable, the lowering the coagulant concentration (to 100 mgACH.L-1) was also investigated. Optimal reductions for chemical oxygen demand (COD) (33.2% ± 4.93), total suspended solids (TSS) (91.9% ± 1.73) and FOG (84.1% ± 1.98) were, however, achieved at a higher coagulant concentration of 140 mgACH.L-1, and at a wastewater pH of 7.0. The effect of additional ozone treatment was also investigated. Maximum reductions for the ozone treatment were obtained at 100 mgO3.L-1 for COD (3.6% ± 4.08), and at 900 mgO3.L-1 for TSS (27.7% ± 5.58) and FOG (23.9% ± 1.83). The ozone treatment was most efficient for FOG reduction (in terms of mg FOG reduced per mg ozone) at 100 mgO3.L-1. An ozone dosage of 300 mgO3.L-1, was decided on based on economic feasibility, findings in literature on toxicity of ozone and the potential degradation of recalcitrant compounds at this dosage. The final pre-treatment thus included pH adaption to 7.0, coagulant dosage of 140 mgACH.L-1, and an ozone dosage of 300 mgO3.L-1. The second part of this study involved the operation of two 2 L laboratory scale UASB reactors for 277 days. The substrate of the first reactor contained GDWW that had only undergone coagulant pre-treatment (Rcontrol), while the substrate of the second UASB reactor consisted of GDWW that had undergone coagulant and ozone pre-treatment (Rozone). Both reactors treated the pre-treated GDWW successfully at ca. 9 kgCOD.m-3d-1. COD reductions of 96% for Rcontrol and 93% for Rozone, were achieved. FOG reductions (%) showed variations throughout the study and maximum reductions of 88% and 92% were achieved for Rcontrol and Rozone, respectively. The Rozone produced more biogas, but the methane content was similar for both reactors. The additional ozone pre-treatment did not show any added benefits to the reactor performance results. UASB granule washout in Rcontrol did, however, suggest possible toxicity of unsaturated fatty acids present in the non-ozonated substrate. The feasibility of FOG removal was shown as both reactors successfully treated pre-treated GDWW. Ozonation, after a coagulant dosage, which resulted in further reduction in the FOG content of the GDWW, is thus not essential to ensure the success of an anaerobic digestion step. Ozonation of the pre-treated GDWW could, however, be beneficial to gas production and the efficiency of a tertiary biological process.
AFRIKAANSE OPSOMMING: Groot volumes hoë-sterkte afloopwater word jaarliks deur distilleerderye opgelewer. Die behandeling van hierdie afloopwater is noodsaaklik om die hergebruiksmoontlikheid daarvan te verhoog. Die toepassing van anaërobiese vertering (AV) is wydverspreid in hoë-sterkte afloopwaterbehandeling. Graandistillerings-afloopwater (GDAW) is boonop hoog in vette, olies en ghries (VOG), wat probleme kan veroorsaak tydens AV. Voorbehandeling word dus dikwels verlang om die AV meer doeltreffend te maak. Die oorhoofse doelstelling van hierdie studie was om die doeltreffendheid van opvloei-anaërobieseslykkombers- (OAS-) reaktore wat GDAW as substraat behandel, te ondersoek. Die eerste mikpunt was om die voorbehandeling van die GDAW, te ondersoek vir die verwydering van VOG. Dit is uitgevoer deur die uitwerking van pH aanpassing, koagulantkonsentrasie en osoon(O3)dosis op VOG vermindering te evalueer. Tweedens is die uitwerking van twee verskillende voorbehandelings (slegs koagulant asook koagulant en osoonbehandeling) op die opvolgende OAS-behandelingsstap ondersoek. Die pH van rou GDAW (pH 3.4) is aangepas tot drie verskillende pH waardes (5.0, 6.0 en 7.0) en die koagulant, aluminium-chlorohidraat (ACH), is bygevoeg (140 mg.L-1). Om die proses meer ekonomies uitvoerbaar te maak is ‘n verlaagde koagulantkonsentrasie (verlaag tot 100 mgACH.L-1) ook ondersoek. Die optimale afnames vir chemiese suurstofvereiste (CSV) (33.2% ± 4.93), totale oplosbare vastestowwe (TOV) (91.9% ± 1.73) en VOG (84.1% ± 1.98) is egter bereik teen ‘n hoër koagulant konsentrasie van 140 mgACH.L-1, en teen ‘n afloopwater-pH van 7.0. Die uitwerking van ‘n bykomende osoonbehandeling is ook ondersoek. Die hoogste afnames tydens die osoonbehandeling is bereik teen 100 mgO3.L-1 vir CSV (3.6% ± 4.08), en teen 900 mgO3.L-1 vir TOV (27.7% ± 5.58) en VOG (23.9% ± 1.83). Die osoonbehandeling was mees doeltreffend vir VOG (in terme van mg VOG verwyder per mg osoon) teen 100 mgO3.L-1. Daar is besluit op ‘n van 300 mgO3.L-1, as gevolg van die ekonomiese uitvoerbaarheid, bevindinge in literatuur vir die toksisiteit van osoon, en die moontlike afbraak van moeilik-afbreekbare komponente teen hierdie dosis. Die finale voorbehandeling het dus bestaan uit ‘n aanpassing van die afloopwater-pH na 7.0, ‘n koagulantdosis van 140 mgACH.L-1, en ‘n osoondosis van 300 mgO3.L-1. Tydens die tweede gedeelte van hierdie studie is twee 2 L laboratoriumskaal OAS reaktore bedryf vir 277 dae. Die substraat van die eerste reaktor het GDAW bevat wat slegs ‘n koagulant-voorbehandeling ondergaan het (Rkontrole), terwyl die substraat van die tweede OAS-reaktor GDAW bevat het wat koagulant- en osoon-voorbehandeling ondergaan het (Rosoon). Beide reaktore het die voorbehandelde-GDAW suksesvol behandel teen ‘n organieseladingstempo van ca. 9 kgCSV.m-3d-1. Afnames in CSV van 96% vir Rkontrole en 93% vir Rosoon, is bereik. Tydens die studie is deurlopende wisseling in VOG verwydering (%) waargeneem, en die hoogste verwyderings wat bereik is, is onderskeidelik 88% en 92% vir Rkontrole en Rosoon. Die Rosoon het meer biogas geproduseer, maar die metaanpersentasie was soortgelyk vir beide reaktore. Die osoon-voorbehandeling het nie enige toegevoegde voordele getoon in die reaktorprestasie resultate nie. Die uitwas van die OAS-granules vir die Rkontrole het egter moontlike toksisiteit van onversadigdevetsure aangedui, wat moontlik teenwoordig kon wees in die nie-geösoneerde substraat. Die uitvoerbaarheid van VOG verwydering is getoon aangesien beide reaktore voorbehandelde GDAW suksesvol behandel het. Osonering, wat verdere afname in die VOG inhoud van GDAW teweeggebring het (na ‘n koagulant dosis), is dus nie noodsaaklik vir die suksesvolle verloop van ‘n anaërobiese-verteringsstap nie. Osonering van die voorbehandelde GDAW kan egter voordelig wees vir gasvorming, en kan ook verder die doeltreffendheid van ‘n tersiêre biologiese behandeling verhoog.

A forma de tratamento e destinação final ainda mundialmente preponderante para os resíduos sólidos urbanos é o aterro sanitário, método que gera, além de uma massa sólida residual, parcialmente estabilizada, subprodutos finais líquidos e gasosos. O efluente líquido, conhecido como lixiviado, necessita tratamento específico, devido a sua elevada nocividade ao meio ambiente, em função, principalmente, de suas elevadas concentrações de nitrogênio amoniacal e de matéria orgânica, em elevado percentual, recalcitrante. O presente trabalho avaliou em escala de bancada o tratamento, via processo físico-químico, através de coagulação-floculação, de lixiviado bruto proveniente de aterro sanitário Central de Resíduos do Recreio (operado pela Companhia Riograndense de Valorização de Resíduos), desprovido de qualquer tratamento prévio, e de lixiviado pré-tratado biologicamente em reatores sequenciais em batelada (RSB). Para o processo de coagulação-floculação foram testados os coagulantes policloreto de alumínio (PAC), cloreto férrico, sulfato férrico e tanino. Sucessivas etapas foram planejadas para a determinação de dosagem e ajuste de pH ótimos, para cada coagulante empregado, e para a verificação da influência de tempos e gradientes de misturas, bem como foi testada a aplicação de polímeros auxiliares de floculação. As variáveis resposta utilizadas para o monitoramento e a avaliação de eficiências foram a cor verdadeira, turbidez (com e sem prévia filtração), DQO, volume de lodo gerado e pH. O uso de reator sequencial em batelada objetivou nitrificação/desnitrificação convencional das elevadas concentrações de nitrogênio amoniacal e eventual oxidação de matéria carbonácea. Verificou-se que os diferentes tempos e gradientes de mistura testados, assim como a utilização de polímeros auxiliares, não produziram impactos nos resultados. Os coagulantes inorgânicos apresentaram elevadas eficiências de remoção, com destaque para o cloreto férrico, o qual na dosagem de 1102 mgFe+3/L e ajuste inicial de pH em 6,2 removeu 98% da cor verdadeira e da turbidez filtrada, 63% da DQO, 40% da DBO5, e 88% de turbidez não filtrada do lixiviado bruto. Apesar da recalcitrância de considerável fração da matéria orgânica do lixiviado, o RSB2 removeu 40% da DQO e 60% da DBO5 originais. A coagulação-floculação do efluente do RSB2 necessitou inferiores dosagens dos coagulantes em relação ao processo com lixiviado bruto. O cloreto férrico, em dosagem ótima de 826 mgFe+3/L e ajuste de pH em 6,3, removeu 95% da cor, 77% da DQO, 82% da DBO5, 94% da turbidez filtrada e 92% da turbidez não filtrada. Concluiu-se por elevada viabilidade técnica do processo de coagulação-floculação para o lixiviado com e sem pré-tratamento, a partir da otimização das condições de contorno do processo. O pré-tratamento em RSB, quando utilizado controle de pH, demonstrou grande potencial para nitrificação/desnitrificação e oxidação de significante parcela da matéria carbonácea do lixiviado bruto.
The form of treatment and disposal still prevalent worldwide for solid waste is the landfill, a method that generates, in addition to a solid mass residual partially stabilized, liquid and gas end products. The effluent liquid, known as leachate, requires specific treatment, due to its high harmfulness to the environment, due mainly to its high concentrations of ammonia nitrogen and organic matter in high percentage, recalcitrant. This study evaluated the treatment on bench scale, via physico-chemical process, by coagulation-flocculation, of raw leachate from Central de Resíduos do Recreio landfill (operated by Companhia Riograndense de Valorização de Resíduos), devoid of any previous treatment, and biologically pretreated leachate reactors in sequential batch reactors (SBR). For the process of flocculation-coagulation were tested polyaluminum chloride (PAC), ferric chloride, ferric sulfate and tannin. Successive stages were designed for determining dosage and optimum pH adjustment for each coagulant employed and for verifying the influence of times and gradients mixtures, as well as tested in the application of polymers flocculation auxiliaries. The answers used for parametric monitoring and evaluation of efficiencies were the true color, turbidity (with and without prior filtration), COD, sludge volume and pH. The use of sequential batch reactor aimed conventional nitrification/denitrification of the high concentrations of ammonia nitrogen and eventual oxidation of carbonaceous matter. It was found that the different gradients and mixing times tested, as well as the use of auxiliary polymers, did not produce impact on the results. The inorganic coagulants showed high removal efficiencies, especially ferric chloride, which at a dose of 1102 mgFe+3/L and initial pH adjusted to 6.2, removed 98% of the true color and filtered turbidity, 63% of COD, 40% of BOD5 and 88% of unfiltered turbidity. Despite the considerable fraction of the recalcitrance of organic matter in the leachate, the SBR2 removed 40% of COD and 60% of BOD5 of the original. The coagulation-flocculation of the effluent from SBR2 required lower dosages of coagulants in relation to the similar process with raw leachate. Ferric chloride in optimum dosage of 826 mgFe+3/L and adjusting pH to 6.3, removed 95% of color, 77% of COD, 82% of BOD5, 94% of the filtered turbidity and 92% of unfiltered turbidity. It was concluded by high technical feasibility of the process of flocculation-coagulation for the leachate with and without pre-treatment, based on the optimization of the boundary conditions of the process. The pre-treatment with SBR, when pH control, demonstrated high potential for nitrification/denitrification and oxidation of a significant portion of the carbonaceous of the raw leachate.

Introduction: It is recommended to place all the vacuum tubes directly on a sample cradle after vein puncture to prevent analytic error. This recommendation is not always easy to follow because the samples are taken by different professionals under different situations.  The three most common analyses, platelets count, haemoglobin and prothrombin time were tested.  Therefore, it was interesting to compare results from the three most common analyses with or without sample cradle, to evaluate the influence of this step on the result. Methods: Three analyses were preformed, using blood from 50 different persons. Each person gave two vacuum tubes, each contained 4.5mL of venous blood for the study. Tubes containing EDTA were used for platelet counts and measurement of haemoglobin and tubes containing citrate were used for prothrombin time-analysis. One of the tubes was placed, as recommended, directly on the sample cradle while the other tube was placed flat on a bench for 10 minutes before it was placed on the sample cradle. Results: There was a clear difference in platelet counts with and without immediate cradling but only minor difference between the results for haemoglobin and International Normalized Ratio. Conclusion: Some analyses seem to be more sensitive for variation in cradling than others. For platelet count it was important to immediately rock the tubes but for determination of prothrombine time and hemoglobin it had a small impact. The small impact on the results is probably due to the efficiency of the anticoagulant in the vacuum tubes.

Coagulation has and continues to be one of the most important elements in medicine. Issues from a lack of hemostasis range from poorer clinical outcomes to sudden death. The evolution of treatments for hemostasis have evolved from the use of Tamponade with direct pressure and bandages, the use of materials such as cobwebs and dust, the use of heat with hot oil or heated irons, to the use of suture, glues, plasmas, staplers, and electricity. This evolution has continued to bring about the prophylactic use of technology in an effort to prevent blood loss. This change from reactive treatments to proactive continue to be on a localized or superficial basis. One of the largest opportunities to proactively reduce blood loss in surgical patients is during the resection of solid organs such as the liver, kidney, and spleen. Few options have existed to help improve hemostasis short of the complete occlusion of blood supplying the tissue such as in the Pringle Maneuver. Recent studies have begun to show that practices such as this may have a significant detrimental effect on morbidity. It has been found that by applying radio frequency electrical energy in a particular way that large amounts of tissue can be pre-coagulated prior to resection. A series of animal and human clinical work has been completed to help evolve and confirm the method and the device that was created and refined during this effort. During the course of this work fifty-three patients were treated at four institutions on three continents. Average blood loss for liver resections performed with this pre-coagulation technique using the developed device in a multicenter control trail was 3.35 ml/cm2 as compared to 6.09 ml/cm2 (p < 0.05) for resections performed using standard surgical techniques alone. Additionally, the transection time necessary was also reduced from mean value of 27 minutes (2 -- 219 minutes) to 35 minutes (5 -- 65 minutes). Patients treated included those suffering from liver cirrhosis, fatty liver disease, and post chemotherapy fibrosis. From this work the use of pre-coagulation with methods and device developed was shown to be safe and effective for reducing the amount of blood loss and transection time during liver resections.

碩士
國立成功大學
環境工程學系碩博士班
98
English Abstract Eutrophication in reservoir leads to algal blooms during spring and summer days. After death, algae release organic compounds and reducing materials such as iron and manganese. These chemical in the reservoir may cause turbidity, odor, and color increasing, resulting in consuming more coagulant and pre-oxidants 、the higher turbidity of outflow of sedimentation tank and increasing frequency of filter backwash. This study take Baoshan water treatment factory, which converge Baoshan Reservoir and Baoshan second Reservoir water as the main source of raw water, as research object to discuss the effect of raw water treatment efficiency after different dosage and different types of pre-oxidant、coagulant treatment by laboratory test and model test. The results showed that using chlorine as pre-oxidants can reduce the turbidity without coagulant treatment. However, manganese dioxide produced by using potassium permanganate as pre-oxidants would increase water turbidity. Taking alum as a coagulant, it has positive effects whether chlorine or potassium permanganate as pre-oxidants in the removal of turbidity and particles. However, taking ferric chloride to replace the alum as coagulant, chlorine as pre-oxidant can easily make flocs formation decrease, resulting in more residual particles in the outflow of sedimentation tank than without pre-oxidants treatment. Compare the effect of different coagulants, we can see that using ferric chloride as coagulant is better than alum in the removal of turbidity and particles. In the removal of organic compound-- NPDOC, it has no significant difference with low-dosage pre-oxidants treatment. The efficiency of Permanganate - ferric chloride process is higher than no pre-oxidation treatment, or chlorine- ferric chloride process for the removal of NPDOC. However, either potassium permanganate or chlorine as pre-oxidants in high-dose treatment would lead to NPDOC significantly increased. Taking disinfection byproducts formation potential : THMFP7days, as an example, the main sources of disinfection by-product is soluble organic compounds.Particulate and organic compounds seldom cause disinfection by-product formation. Process of using ferric chloride as coagulant and potassium permanganate as pre-oxidant generated good removal efficiency than alum in the formation potential of disinfection by-products

ABSTRACT With an increasing population density throughout the world and the current drive to provide fresh water to as many people as possible, innovative methods of providing safe drinking water are in very high demand. In 2002, the United Nations stated in their millennium declaration that one of their priority goals was “to halve, by the year 2015, the proportion of people who are unable to reach or to afford safe drinking water” (UNESCO, 2000). This goal was set with high standards, and will require a great deal of water treatment related research in the short coming years. Over the past two decades, drinking water treatment via membrane filtration has been widely accepted as a feasible alternative to conventional drinking water treatment. Membrane processes are used in environmental, chemical, food, beverage, pharmaceutical, and various other industries for separation applications. Since the early 1990’s, there has been rapid growth in the use of low-pressure hollow fibre membrane processes for the production of drinking water. These membrane systems are increasingly being accepted as feasible technologies for drinking water treatment. Like with any innovative process, it has limitations; the primary limitation being membrane fouling, which is an accumulation of particles on the surface and inside the pores of the membrane surface. Membrane fouling has the ability to reduce the flux, in doing so, requiring a higher pumping intensity to maintain a consistent volume of water being treated. This project investigated chemical coagulation as a pre-treatment to membrane ultra-filtration, with the goal of mitigating fouling impact in order to maintain a consistent permeate flux, while monitoring several water quality parameters before and after treatment such as turbidity, alkalinity, pH and total organic carbon (TOC). Two different raw water sources were studied: Grand River water taken from the Hidden Valley intake, located in Kitchener, ON, and Lake Ontario water taken from the Woodward Water Treatment Plant in Hamilton, ON. The evaluated coagulants include alum and ferric chloride, which are widely used hydrolyzing metal salt (HMS) coagulants; and three polyaluminum chloride (PACl) products, which are pre-hydrolyzed coagulants formed by the controlled neutralization of aluminum chloride solution. Phase 1 of the project involved the coagulation of water using various aluminum and iron-based coagulants. Synthetic water was used at the outset, followed by the use of raw water obtained from two water treatment plants: one on the Grand River and one on Lake Ontario. A series of jar test trials was conducted to determine optimum coagulant dosages for the removal of NOM. These doses were then used as a baseline for subsequent membrane trials in phase 2 of this project. Phase 2 involved the treatment of raw and coagulated waters with a hollow fibre bench scale UF unit (Zenon Environmental Inc.®, ZeeWeed-1). Membrane trials were performed with the coagulants applied at optimal and sub optimal dosages in order to evaluate the integrated process for mitigation of organic fouling. As all trials were conducted at a constant flowrate, membrane fouling was evaluated by monitoring trans-membrane pressure (TMP) over time. The raw and treated water were fractionated to obtain quantitative information on the size components of NOM contributing most to fouling. Results will be presented comparing how the different coagulants affected the concentration of each NOM MW fraction in the raw and treated waters. Collectively, results showed that all four coagulants substantially decreased the rate of TMP increase, particularly with the Grand River water which contained much higher turbidity and TOC concentrations than the Lake Ontario water. During the trials conducted with Grand River, alum performed best, reducing the TMP by 57 % over a 3-day period. The PACl coagulants performed best at reducing the TMP during the Lake Ontario membrane trials; reducing the TMP by 21 % and 19 % for SP 70 and SP respectively. The system’s ability to maintain a permeate turbidity level of 0.1 NTU or lower was met, and TOC removals varied a small amount across the four coagulants, ranging from 45-65 % and 15-35 % for the Grand River and Lake Ontario trials, respectively.

碩士
國立成功大學
環境工程學系碩博士班
100
Eutrophication is becoming a serious problem for reservoirs today. Natural organic matter (NOM) may cause fouling when using UF (Ultrafiltration) membrane to treat eutrophicated source water. Fouling phenomena can be varied with the organic contents in the feed water, membrane material, and pore size, etc. In this study, the effect of coagulation pretreatment and the material of hollow-fiber UF membrane on NOM fouling was studied. The source water from an eutrophic reservoir in souther Taiwan was collected. As this study was focused on the dissolved organic part, the source water was firstly filtered by 0.45 μm membrane filter. Secondly, the filtrate was subjected to coagulation by laboratory-prepared polyaluminum chloride (PACl), with different basicity (B value). Then the filtrated and the caogulation-treated water were filtered through bench-scale hollow-fiber UF membrane unit under constant pressure. Two kind of UF membranes with different material were tested, namely polyvinyl chloride (PVC) and cellulose acetate (CA). The coagulation results show that at high dosage PACl0 (B = 0) had high dissolved organic removal that of PACl20 (B = 2). The explanation is: the dominant aluminum species in PACl0 are monomeric aluminum species (Ala), while those in PACl20 are polymeric aluminium species (Alb). At higher dosage, the hydrolysis of PACl0 to form polymeric aluminum species, would consume alkalinity, and drop the pH to lower value, around 6.3. At this pH value, large amount of Al(OH)3(s) could form, and facilitate the DOC removal via adsorption. Coagulation pretreatment was found to improve the performance of both PVC and CA based UF membrane filtration by reducing flux decline rate. Based on SEM images, it can be noticed that cake layer structure on fouled membranes were different between those from feed water with and without precoagulation. Apparently, coagulation altered the cake layer, probably made it more porous. Based on the results from HPSEC (High Performance Size Exclusion Chromatography), the PVC membrane was found to remove only the microorganism-related extracellular polymer substance (EPS) fraction of NOM, while the CA membrane removed portion of low-molecular weight acids (LMW acids), in addition to EPS fraction. LMW acids could be removed because it was hydrophilic, and tented to be adsorbed by hydrophilic CA membranes. Further, the flux decline rate of PVC membrane was found to be reduced with increasing PACl dosage of precoagulation. As the EPS removal during coagulation was also increased with increasing coagulant dosage, it is speculated that EPS were the main foulant of PVC membrane. For CA membrane, the flux decline rate curve of the un-precoagulated feed water showed two stages type, with a fast decline first stage, and a low second decline stage after that. It was speculated that the initial fast flux decline was caused by pore blocking, as the molecular weight of large amount of EPS in the un-precoagulated feed water was closed to the pore size of CA membrane. Further, the effect of PACl dosage on CA membrane flux decline was not as obvious as that of PVC membrane. This is probably due to the lower coagulation removal efficiency of LMW acids, which may cause membrane fouling by adsorption inside the pore.

碩士
國立臺灣大學
環境工程學研究所
96
Due to the characteristics of high concentrations of dissolved organic carbon (DOC), low turbidity and low alkalinity in the Tai-Lake source water in Kinmen, the DOC is difficult to remove by conventional treatment processes. However, the introduction of the enhanced coagulation based on disinfectant/disinfection by-product Rule (D/DBP Rule) again would result in the formation of high trihalomethanes beyond the drinking water quality standard (80μg/L) in Taiwan. As a result, the purpose of this study was intended to evaluate the effect of pre-ozonation on the performance of coagulation and formation of trihalomethanes, to separate the hydrophobic and hydrophilic fractions of natural organic matters (NOMs), and to develop at DOC removal model in enhanced coagulation. The results of this investigation reveal that the ozone doses and pH levels would influence the coagulation performance significantly. The pH levels and ozone doses were held at 9 and 0.45 mgO3/mgDOC, respectively. The removal efficiency of THMFP was about 60%. In addition, the results of the DAX-8 resin separation process indicate that the specific THMFP for hydrophobic and hydrophilic organics are 57.3 and 98.7 ugTHMFP/mgDOC, respectively. This suggests that hydrophilic organics are significant precursors of THMs. The introduction of pre-ozonation have a positive effect on hydrophobic organic removal, but an insignificant on hydrophilic organics. In the comparison of competitive and non-competitive adsorption models for the hydrophilic and hydrophobic organics, the non-competitive adsorption models could successfully predict the hydrophilic and hydrophobic DOCs removal in the enhanced coagulation process.

碩士
國立中央大學
環境工程研究所
100
Due to extreme high turbidity during typhoons or heavy rains, which resulted in difficulties in potable water treatment, the water intake well to draw water from upper levels of the reservoir was built in the Shihmen reservoir. After drawing water from the intake well, it was found that there were bubbles or foams on the surface in slow mixing tank and filter during backwash in Pingjan water treatment plant. Moreoever, the run time of filtration was significantly reduced and the filter was severely clogged. In this research, two source waters were taken from Shihmen reservoir: one was the surface water at the water intake well, the other was from Pinghan water treatment plant while switched to intake water from the mid-point of the intake well, which locates at water level 228 m. Removal of turbidity, TOC, and DOC by pre-chlorination and coagulation were investigated. The effects of types of coagulants were also examined by using PACl, ferric chloride, and aluminum sulfate. Forwater taking from the reservoir, it was found that pre-chlorination promoted the removal of turbidity. Also, aluminum sulfate can effectively reduce the ratio of DOC, which suggests that Al-DOC complex were formed, and therefore, the residual turbidity was the highest. When the water was taking from the intake well (from Pingjan water treatment plant), it was found that only PACl was effective in the removal of turbidity. After pre-chlorination, the settling of ferric flocs became worse.

碩士
雲林科技大學
環境與安全工程系碩士班
96
A large amount of nano-particles were stability state in backside grinder wastewater. Therefore, it caused high turbidity and decreased the efficiency of treatment. Although there is no restriction effluent standard for turbidity at present, but turbidity will cause the water quality to be muddy.It is not only influence the sighted , but also relatively higher degree in colorness. Amount of medicine added difficult control, power consumption improvement by a wide margin, retrieve result to be apparent to raise, increase issues such as the cost,etc. Does not accord with the economic benefits and unable to control effectively. Research this deal with, carry on brilliant recovery to carry waste water and utilize research that deal with to coagulant, pretreat coagulant to the brilliant influence which carries the waste water treatment result. Mix and congeal different mechanism''s factors with coagulant to carry on discussion analysis to chemistry. Expect to carry on feasibility research by the association of different conditions, finding out the magnetization effect will mix the relevance which congeals the mechanism to chemistry. Pre-Magnetized on Coagulation cause coagulant pH drop, temperature rise, electric conduction degree rises, pH of FeCl2 after magnetization 1600G, 8 hours is dropped from 2.67 to 2.4, that temperature rises to 44℃, the electric conduction degree rises from 1130 μs/cm to 3140 μs/cm. After chemistry mixes the procedure of congealing, the turbid degree of waste water increases with FeCl2 magnetization time, turbid degree drops with FeCl2 (800G, 4 hours) And the speech is the best, turbidity drops to 16.7 NTU, has not magnetized turbid degree (31.6 NTU) of FeCl2 Reduce by 400%. And magnetize FeCl2 and also reach and change already existingly and add the medicine amount bestly in advance, drop to 40 mg/L (1200G, 4 hours) from original 80 mg/L And the speech is the best. But the speech of and the speed precipitated of congealing in drifting along, can demonstrate from studying in the intensity of low magnetic field, can accelerate precipitating the speed and connecting and shortening and precipitating original 1/3/2 of time, is used in the reducible volume of precipitating the pool in the real field; In the high magnetization intensity, its influence may cause the influence of reverse side.

碩士
逢甲大學
環境工程與科學所
91
This thesis is to study the effect of pre-oxidant, ClO2 to the removal efficiency of organic matter by coagulation/sedimentation. Four coagulants； Al(SO4)3•14H2O(alum )、Poly Aluminium Chloride（PACl）、Ferric Chloride （FeCl3）and Polyferric Sulfate（PFS）were used as coagulants to test the coagulation performance for the effluent of pilot-scale bio-filter in Feng-Shan water treatment facility. The results of jar-test shown that the organic matter removal with FeCl3 and FPS were better than that with PACl. The floc of Fe(OH)3 produced from Fe salt coagulants were more denser than from Alum salts and the low residual turbidity also observed with the high coagulant dose addition. As pre-oxidation was added, Cl2 presented the best enhancement for the turbidity removal on the following coagulation operation. There were less significant influences with application of ClO2 or KMnO4. To the organic matter removal for raw water and bio-filter water, the combination of ClO2 pre-oxidation and alum coagulation can decrease UV254 , however did not provide significant decrease on DOC. From the result of DOC and UV254 for ClO2 was to destroy the high molecular weight matter into a low molecular weigh . With addition of ClO2, particle size distribution of water would not change by ClO2, but particle would produce micro-flocculation reaction to enhance coagulation efficiency. With the measurement of molecular weight analysis, ClO2 oxide the 0.45μm~10K organic matters into 1~10K of raw water and 1~10K into<1K of bio-filter water. Most of high molecular weight matters were removed by the coagulation.

碩士
國立雲林科技大學
環境與安全工程系碩士班
95
The study was conducted to observe the effect of glass polish wastewater treatment on condition that pre-microwaved PAC(Poly Aluminum Chloride ) was added to the targeted wastepaper from a TFT-CCD glass baseboard factory. In particular, some properties of treated glass polish wastewater were studied: its precipitation time, turbidity, conductivity, temperature and the size of floc aggregates formation. In it, separate parts of PAC which had been microwaved for different time limits were separately added to the wastewater in order to ruin the stabilities of those charged particles and then the treated wastewater was left to form floc aggregates. The separate heating time limits of PAC are 0,10,20,30,40,50seconds, and then added to the wastewater for coagulation. After that, its supernatant liquor was sampled at different time point of precipitation in order to measure and analyze the effect of microwaved PAC on the variation of wastewater turbidity. The result had shown that the most obvious effectiveness of precipitation appeared on condition that the targeted wastewater was mixes with PAC which reached the temperature(50-52℃) after treated with 20 seconds’ heating(800w 2450MHz). The wastewater mixed with the PAC treated with 20 seconds’ heating was left to precipitate for 3 minute . Its average turbidity was 93.4 NYU, which could occur only after 10 ~20 minutes’ precipitation of the wastewater mixed with unheated PAC. The result showed that the addition of microwaved PAC to wastewater which occurred before the cougulation of the mixed wastewater contributed to the precipitation of floc and thus positively enhances the effectiveness of the recycling of water resources for reuse.

碩士
逢甲大學
環境工程與科學所
93
The objective of this research was to characterize the effects of chlorine dioxide on organic matter removal, coagulation/sedimentation efficiency, and disinfection by-products (DBP) formation in raw water from the Cheng-Kong reservoir. The tests were processed under the coagulation with the condition of pH=5.5 and 7.0 or the enhance coagulation combined the pre-oxidation by chlorine dioxide with different dosage and reaction time. The removal of DOC and A254 are insignificantly enhanced in raw waters with the addition of chlorine dioxide as the pre-oxidation. The results showed that changing coagulation conditions provides greater removal efficiency of organic matters than adding chlorine dioxide. The organic matter removal efficiencies of various processes set are listed in descending order: traditional coagulation at pH 5.5 > enhanced coagulation at pH 6.3 > traditional coagulation at pH 7.0. The chlorine dioxide pre-oxidation is able to breakdown large molecules (0.45μm ~10 K) into small molecules (< 1K). From the fluorescence intensity measurements, it is indicated that the most of oxidized large molecules is the humic acid. According to the Zeta potential measurement, the chlorine dioxide is play as the coagulant aid to decrease the amount of THMFP and the formation of ClO2- and ClO3- with the low pH condition. For the raw water with the hydrophilic organic matter only, because of the low reactivity between chlorine dioxide and hydrophilic organic compounds, an insignificant DOC and A254 removal is found. Furthermore, chlorine dioxide is not able to alter the molecular weight distribution of organic matter and THMFP/DOC are decrease with dosage. However, the decreasing of ClO2- and ClO3- formation is also found in the process of ClO2 pre-oxidation with combination of coagulation. Because of the high content of bromide in the water of the Cheng-Kong reservoir, all of the bromine species of THMFP is significantly measured.

The combination of moving bed biofilm reactors and membrane bioreactors (MBBR-MR) can compensate for the drawbacks of both of these systems and further increase their acceptance and application in wastewater treatment industries. Despite the potential benefits of a MBBR-MR technology there has only been limited study of this configuration. The present study consisted of an overall assessment of the performance of a combined MBBR-MR system under high and low loading rates. Since colloidal matter in mixed liquor suspended solid (MLSS) is considered as one of the important contributors to membrane fouling, pre-treatment of membrane feed by coagulation was investigated for improving membrane performance. The performance of the MBBR-MR was assessed based on its chemical oxygen demand (COD) removal efficiency and membrane fouling mechanisms. The study was carried out using pilot-scale MBBR and bench-scale batch membrane filtration setups (Millipore Inc. Bedford, MA). The pilot MBBR had a working volume of 1.8 m3 and a 30% carrier fill fraction. The MBBR was operated with loading rates of 160 ± 44 g/m2/d (hydraulic residence time (HRT) of 4.6 h) and 223 g/m2/d (HRT of 2.6 h). The MBBR feed was obtained from a starch recovery line in a potato chip processing factory. The carriers were mixed by coarse bubble aeration and the dissolved oxygen (DO) was maintained above 2 mg/l. Preliminary jar test trials (based on turbidity removal) were performed in order to obtain an optimal dosage of coagulants for subsequent ultrafiltration (UF) tests. The efficiency of three coagulants (alum, ferric chloride and a blend of polyaluminum chloride and polyamine) was evaluated. The membranes were composed of polyethersulfone (PES) and had a pore size of 0.05 microns. The results of this study indicate that the combination of MBBR with membrane filtration can be operated at relatively high loading rates to yield a constant high quality permeate that is suitable for water reuse purposes. Fouling of the membrane by the wastewater was found to be substantially reduced by treatment with the MBBR. The reversible and irreversible fouling of the MBBR effluent were 56 and 63%, respectively, of that observed with the raw wastewater. The MBBR Loading-rate was found to affect treatment efficiency of the MBBR-MR and membrane performance. Operation under the elevated loading-rate conditions HRT = 2.6 hours) resulted in an increase in the irreversible fouling of the membranes (60% on average). The addition of all the coagulants in this study was found to decrease the fouling of the membrane. However, the extent of the pre-coagulation effect on membrane fouling was found to strongly depend on the type and dosage of the coagulant and the MBBR effluent characteristics. All the coagulants were effective in decreasing membrane fouling at their optimal dosages which was determined in preliminary jar tests. Ferric chloride performed the best as a pretreatment coagulant compared to alum (Aluminum sulfate) and the coagulant blend with reductions in both reversible and irreversible fouling (43-86% and 51-71%, respectively) and increased consistency (in decreasing fouling) as compared to the other coagulants. Alum had no effect on irreversible fouling and the coagulant blend significantly increased irreversible fouling in some trials (up to 196% or by a factor of 3 when overdosed). Additionally, alum and the blend were, on average, 29% and 7%, less effective than ferric chloride in reducing reversible fouling under the conditions and dosages tested.