Wastewater treatment plants (WWTP) involve several complex physical, biological and chemical processes. Often these processes exhibit non-linear behavior that is difficult to describe by classical mathematical models. Safer operation and control of a WWTP can be achieved by developing a modeling tool for predicting the plant performance. In the last decade, many studies were realized in wastewater treatment based on intelligent methods which are related to modeling WWTP. These studies are about predictions of WWTP parameters, process control of WWTP, estimating WWTP output parameters characteristics. In many studies, neural network models were used to model chemical and physical attributes in the flow rate. In this Thesis, a data-driven approach for analyzing water quality is introduced. Improvements in the data collection of information system allow collection of large volumes of data. Although improvements in data collection systems have given researchers sufficient information about various systems, they must be used in conjunction with novel data-mining algorithms to build models and recognize patterns in large data sets. Since the mid 1990's, data mining has been successfully used for model extraction and describing various phenomena of interest.

The project involved the study of 12 Victorian municipal wastewater treatment plant discharges. These included lagoon-based plants and those with activated sludge based processes. Permission was obtained from all the relevant water authorities to collect samples of final effluent at point of discharge to the environment, whether that was to a creek, a river, the ocean, or the land. Samples were collected in November 2003, and then again in April and June 2004, and subjected to a number of biological and chemical analyses, including toxicity tests, measurement of hormonal (estrogenic) activity using yeast-based bioassays, and the measurement of specific hormonal concentrations (17-estradiol) using enzyme-linked immunosorbent assays (ELISA). Almost all of the effluents examined showed estrogenic activity, to a greater or lesser extent (no response to 55 ng/L 17β-estradiol equivalents). On the whole, the levels of estrogenic activity observed were to the lower end of the range observed overseas in the northern hemisphere, and comparable with that recently reported in Australia and New Zealand using similar, human-estrogen receptor based assays (no response to ~ 10 ng/L 17β-estradiol equivalents). The reassuring low/no assay response is bolstered by the chemical assessment of estradiol concentrations by ELISA, which returned concentrations of these compounds for the most part in the range 2-5 ng/L. From an aquatic environmental perspective, it is difficult to say with any certainty what the potential risk to aquatic organisms in waters receiving these effluents will be. Typically, in environmental risk assessment one first looks to agreed national or international guideline or trigger values for the type of waters being assessed. In this case, there are as yet no guideline values. Without guideline values to drive the assessment, then one compares a chemical’s concentration in a sample (in this case a WWTP effluent) with data obtained from toxicological experiments in which the concentration known to elicit a specific effect has been determined. In this case, levels of 17β-estradiol were typically between the lowest reported level to induce the production of Female-indicative proteins in male fish (plasma vitellogen; 1 ng/L), and the lowest concentration of known to induce intersex in fish (8 ng/L). Consequently, such levels in a WWTP discharge are likely to be an environmental risk if there is little or no dilution of the discharge by the receiving water, i.e. discharge represents major component of stream flow. In short, to truly assess the risk (hormonal impact) of these WWTP effluents, in vivo testing needs to be undertaken, ideally with a representative native species but failing that with a ‘standard’ species such as the fathead minnow. When this programme began, the ‘watching brief’, being held in Australia on the topic of endocrine disrupting chemicals and their potential effects on aquatic wildlife was considered too passive by many. It still is, by some. Despite the assurance the results may provide (of minimal impact in most cases if there is significant dilution), there is still a need for further extensive on-ground, reassurance research to provide data for higher-level risk assessment by industry and government agencies.

<p>Hedesunda reningsverk är beläget i södra delen av Gävle kommun och hanterar avloppsvatten från Hedesunda samhälle och ett fåtal närbelägna byar. Antalet anslutna personer är strax över 1500. Reningsverket byggdes på 1960-talet och byggdes om i slutet av 1990-talet. Vid ombyggnaden anlades torkbäddar för avvattning av det slam som produceras vid reningsverket. Inledningsvis fungerade dessa torkbäddar bra men sedan 2005 har slammet i bäddarna inte avvattnats i önskad omfattning.</p><p> </p><p>Syftet med detta examensarbete var att utreda hur slamavvattningen i Hedesunda ska se ut i framtiden. Utgångspunkten var att den nuvarande lösningen är otillräcklig och att en förändring är nödvändig. Inledningsvis delades frågeställningen upp i två separata delar: avvattning av slammet och avsättning för avvattnat slam. Fokus låg på ekonomiska och miljömässiga aspekter av slamhantering och en sammanvägning av dessa gjordes där så var möjligt.</p><p> </p><p>Frågan om hur avvattningen bör se ut undersöktes genom att en enkät skickades ut till nio olika företag som levererar avvattningsutrustning. Dessa fick svara på 17 frågor om vilken lösning de ansåg vara bäst lämpad för reningsverket i Hedesunda. Sammanlagt samlades sex olika svar in. Utöver dessa undersöktes även alternativet att restaurera de befintliga torkbäddarna närmare. Detta skedde bland annat genom provtagning och analys av slammet i bäddarna. De olika alternativen för slamavvattning sammanställdes och jämfördes genom att varje undersökt parameter delades in i intervall som gav olika betyg. De tre alternativ som enligt denna undersökning ansågs bäst lämpade var att restaurera de befintliga bäddarna, att anlägga vassbäddar eller att installera en mindre silbandpress.</p><p> </p><p>Då slammet avvattnats återstår frågan kring hur det avvattnade slammet ska hanteras. Detta undersöktes genom att två alternativ studerades närmare. Dessa var att fortsätta med den nuvarande hanteringen som är kompostering och tillverkning av anläggningsjord eller att certifiera slammet genom REVAQ och sprida det på åkermark. Ett försök till att skatta kostnaden för de båda alternativen gjordes, bland annat genom att frågor ställdes till de kommuner/driftbolag som idag är certifierade enligt REVAQ. Kostnaden för certifiering och spridning på jordbruksmark är betydligt mycket högre än kostnaden för kompostering. Certifieringsalternativet innebär dock en större måluppfyllelse i och med att fosfor återförs till produktiv mark.   </p><p> </p><p>Resultatet av studien är ett konkret förslag på hur slamavvattning och avsättning för slam vid Hedesunda reningsverk kan skötas i framtiden. Detta förslag innebär att de nuvarande torkbäddarna restaureras och att möjligheterna att certifiera flera delar av Gästrike Vatten AB:s verksamhet utreds närmare. Att enbart certifiera slam från Hedesunda reningsverk anses ekonomiskt orimligt.</p> / <p>Hedesunda wastewater treatment plant (wwtp) is located in the southern part of Gävle municipality in Sweden. The wwtp treats wastewater from Hedesunda community and a few nearby villages. All in all there are approximately 1500 persons connected to the plant. Hedesunda wwtp was originally built in the 1960’s and was restored in the late 1990’s. At the restoration sludge drying beds were built on the site for sludge dewatering. Initially, these beds worked fine but since 2005 the dewatering result has not been satisfactory.</p><p> </p><p>The objective of this master thesis has been to investigate different alternatives for a more effective sludge handling at Hedesunda wwtp in the future. Initially the sludge handling process was divided into two different parts: sludge dewatering and management of dewatered sludge. The focus has been on economical and environmental aspects of sludge handling and where it’s been possible these factors have been weight together.</p><p> </p><p>The question of how a more effective dewatering of sludge could be achieved was answered by a questionnaire that was sent to different companies that supply dewatering equipment to the Swedish market. Altogether six answers were collected. Besides these answers the option of restoring the existing sludge drying beds was also considered. The latter was done by sampling and analyzing sludge in the existing beds, among other things. The different options for dewatering were compiled and compared in a matrix where every parameter was split up in intervals and assigned grades. Three options that received the highest total grade were considered the best options. These were: restoring the sludge drying beds, reed beds and a small belt filter press.</p><p> </p><p>The matter of how to handle the dewatered sludge was simplified to a study of only two alternatives. These were to continue the present handling or to certify the sludge according to REVAQ and use it as fertilizer. Attempts to estimate the cost for the two alternatives were made. The cost for certification is higher than the cost for composting, but to certify the sludge will lead to a higher target achievement.</p><p> </p><p>The study resulted in concrete suggestions for how the sludge at Hedesunda wwtp can be handled in the future. This suggestion states that the existing sludge drying beds should be restored and that the possibility to certify several wwtp:s within Gästrike Vatten AB should be investigated. It is not considered economically plausible to certify sludge from Hedesunda wwtp alone.</p>

This study investigated the microbiota in ten different drinking water treatment pools, particles in the Biological Activated Carbon Filtration (BACF) bed, and two mimic columns in the Cheng-Ching Lake Water Treatment Plant. Assimilable organic carbon (AOC) is one of the main nutrition sources for microbes to survive in tap water. Over growing microbes not only decrease the water quality, but also contaminate the water treatment system and distribution system. In this study, we used two molecular biology techniques, the polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE), to analyze the dynamic microbial communities and biodiversities in the drinking water cleaning system and the micorbiota that exist in the BAC and anthracite filtration pellets. The bacterial 16S rDNA sequences resulted from PCR-DGGE were compared with the data in the Ribosomal Database Project Bank to construct a phylogenetic tree which allowed us to understand the microbial communities and biodiversities in the drinking water treatment pools and the filtration pellets. The total bacterial count and PCR-DGGE profiles showed that the drinking water quality had been improved during the treating processes and most of the microbes in raw water were removed. The scanning electron microscopy clearly indicated the biofilms were developed on the pellet surface. From the mimic column studies, the PCR-DGGE profiles suggested that various microbial communities were present on different depth of the columns samples. In comparing the 16S rDNA sequences with Gene Bank, many are new category bacteria were found and most of them are unculturable. Most of these microbes belong to the beta-proteobacterium. Although many bacteria were located on the surface of the filtration pellet, the BAC and anthracite could still absorb AOC efficiently to enhance the bacteria growth. The over growing bacteria might release out and contaminate the drinking water. Therefore, we suggest that it is important to backwash the filter bed frequently in order to diminish microbes of the filtration pellet and avoid re-contaminate the drinking water.

Idag fokuserar företag mer och mer på att energieffektivisera sina verksamheter då det finns både ekonomiska och miljömässiga vinster i detta. För att minska energiförbrukningen i samhället är det bra att börja med dess infrastruktur. För att funktionen hos ett avloppsreningsverk ska vara god samtidigt som energikostnaderna hålls nere är bland annat valet av rätt pumpar och blåsmaskiner för den aktuella driftsituationen av största vikt. Att hitta balansen mellan funktion och energieffektivitet hos en kombination av maskiner är dock ett tidskrävande arbete. Genom två fallstudier och matematisk modellering var syftet med detta examensarbete att bestämma huruvida det är möjligt att grovt uppskatta livscykelkostnaden hos olika kombinationer av pumpar och blåsmaskiner i varierande driftsituationer. En sådan modell skulle hjälpa projektören att uteslutande undersöka de kombinationer av maskiner som är mest troliga att ha den lägsta livscykelkostnaden. Det har visats att det krävs en förmåga att mycket noggrant kunna förutsäga verkningsgraden hos de individuella maskinerna för att det ska vara möjligt att bestämma livscykelkostnaden så pass väl att resultatet är användbart. Sannolikt är det dock inte möjligt att finna en modell som är tillräckligt noggrann. Detta beror huvudsakligen på att mycket små förändringar av verkningsgraden ger en kraftig påverkan av livscykelkostnaden samt att verkningsgraden beror av många faktorer som är svåra att generalisera. Däribland att verkningsgraden inte förändras proportionellt till en varierande belastning på maskinen samtidigt som påverkan inte heller är densamma mellan olika maskinmodeller. Projektet har däremot mynnat ut i en ekvation för det flöde en blåsmaskin behöver generera i en given driftsituation samt ett beräkningsverktyg som underlättar undersökandet av de ingående parametrarnas inverkan på detta flödesbehov och därmed i förlängningen på livscykelkostnaden. Utöver detta slår rapporten fast att det i många fall är möjligt att sänka livscykelkostnaden med hjälp av icke frekvensstyrda maskiner. / Today companies tend to focus more and more on energy efficiency as there are both economical and environmental benefits to be gained. From a society’s point of view a good start to save energy is in its infrastructure. When designing wastewater treatment plants and their pumps and blowers choosing the right machines for the right operational circumstances is crucial to make it all work together and lower the energy cost at the same time. But to weigh the function against the energy efficiency of a combination of machines is a time consuming effort. Through two case studies and mathematical modeling this thesis project aimed to determine whether it is possible to roughly predetermine the life cycle cost of different combinations of pumps and blowers in variable operational circumstances. This would help the process engineers to focus their time and effort on the combinations of machines that are the most probable to have the lowest life cycle cost. The results show that the ability to accurately predetermine the efficiency of the individual machine is crucial to determine the life cycle cost to a usable degree. Unfortunately it doesn't seem feasible to find a model that will be accurate enough to be of practical use. This is due to the fact that slight changes to the efficiency cause great changes to the life cycle cost and that the efficiency depends on several factors that are hard to predict including the fact that it does not change proportionally to a variable load.

Hedesunda reningsverk är beläget i södra delen av Gävle kommun och hanterar avloppsvatten från Hedesunda samhälle och ett fåtal närbelägna byar. Antalet anslutna personer är strax över 1500. Reningsverket byggdes på 1960-talet och byggdes om i slutet av 1990-talet. Vid ombyggnaden anlades torkbäddar för avvattning av det slam som produceras vid reningsverket. Inledningsvis fungerade dessa torkbäddar bra men sedan 2005 har slammet i bäddarna inte avvattnats i önskad omfattning.   Syftet med detta examensarbete var att utreda hur slamavvattningen i Hedesunda ska se ut i framtiden. Utgångspunkten var att den nuvarande lösningen är otillräcklig och att en förändring är nödvändig. Inledningsvis delades frågeställningen upp i två separata delar: avvattning av slammet och avsättning för avvattnat slam. Fokus låg på ekonomiska och miljömässiga aspekter av slamhantering och en sammanvägning av dessa gjordes där så var möjligt.   Frågan om hur avvattningen bör se ut undersöktes genom att en enkät skickades ut till nio olika företag som levererar avvattningsutrustning. Dessa fick svara på 17 frågor om vilken lösning de ansåg vara bäst lämpad för reningsverket i Hedesunda. Sammanlagt samlades sex olika svar in. Utöver dessa undersöktes även alternativet att restaurera de befintliga torkbäddarna närmare. Detta skedde bland annat genom provtagning och analys av slammet i bäddarna. De olika alternativen för slamavvattning sammanställdes och jämfördes genom att varje undersökt parameter delades in i intervall som gav olika betyg. De tre alternativ som enligt denna undersökning ansågs bäst lämpade var att restaurera de befintliga bäddarna, att anlägga vassbäddar eller att installera en mindre silbandpress.   Då slammet avvattnats återstår frågan kring hur det avvattnade slammet ska hanteras. Detta undersöktes genom att två alternativ studerades närmare. Dessa var att fortsätta med den nuvarande hanteringen som är kompostering och tillverkning av anläggningsjord eller att certifiera slammet genom REVAQ och sprida det på åkermark. Ett försök till att skatta kostnaden för de båda alternativen gjordes, bland annat genom att frågor ställdes till de kommuner/driftbolag som idag är certifierade enligt REVAQ. Kostnaden för certifiering och spridning på jordbruksmark är betydligt mycket högre än kostnaden för kompostering. Certifieringsalternativet innebär dock en större måluppfyllelse i och med att fosfor återförs till produktiv mark.      Resultatet av studien är ett konkret förslag på hur slamavvattning och avsättning för slam vid Hedesunda reningsverk kan skötas i framtiden. Detta förslag innebär att de nuvarande torkbäddarna restaureras och att möjligheterna att certifiera flera delar av Gästrike Vatten AB:s verksamhet utreds närmare. Att enbart certifiera slam från Hedesunda reningsverk anses ekonomiskt orimligt. / Hedesunda wastewater treatment plant (wwtp) is located in the southern part of Gävle municipality in Sweden. The wwtp treats wastewater from Hedesunda community and a few nearby villages. All in all there are approximately 1500 persons connected to the plant. Hedesunda wwtp was originally built in the 1960’s and was restored in the late 1990’s. At the restoration sludge drying beds were built on the site for sludge dewatering. Initially, these beds worked fine but since 2005 the dewatering result has not been satisfactory.   The objective of this master thesis has been to investigate different alternatives for a more effective sludge handling at Hedesunda wwtp in the future. Initially the sludge handling process was divided into two different parts: sludge dewatering and management of dewatered sludge. The focus has been on economical and environmental aspects of sludge handling and where it’s been possible these factors have been weight together.   The question of how a more effective dewatering of sludge could be achieved was answered by a questionnaire that was sent to different companies that supply dewatering equipment to the Swedish market. Altogether six answers were collected. Besides these answers the option of restoring the existing sludge drying beds was also considered. The latter was done by sampling and analyzing sludge in the existing beds, among other things. The different options for dewatering were compiled and compared in a matrix where every parameter was split up in intervals and assigned grades. Three options that received the highest total grade were considered the best options. These were: restoring the sludge drying beds, reed beds and a small belt filter press.   The matter of how to handle the dewatered sludge was simplified to a study of only two alternatives. These were to continue the present handling or to certify the sludge according to REVAQ and use it as fertilizer. Attempts to estimate the cost for the two alternatives were made. The cost for certification is higher than the cost for composting, but to certify the sludge will lead to a higher target achievement.   The study resulted in concrete suggestions for how the sludge at Hedesunda wwtp can be handled in the future. This suggestion states that the existing sludge drying beds should be restored and that the possibility to certify several wwtp:s within Gästrike Vatten AB should be investigated. It is not considered economically plausible to certify sludge from Hedesunda wwtp alone.

Most of wastewater treatment plants (WWTP) are operated under low loading both in water quality and water capacity (flow rate) in Taiwan. Because various treatment methods used in WWTP would cause different power consumptions. In general, the flow rate of wastewater treated is proportional to the power consumption. The purpose of this study is simulating water quality and water capacity with a case of municipal wastewater treatment plant, using standard activated sludge method. In this work we will investigate the feasibility of save power using operation and parameters adjustment in wastewater system. A further step is to conduct the save energy in current WWTP under normal wastewater treatment capacity and national effluent standard. Results showed the major save energy was at inflow pump and aeration system of biological treatment stage. Both power consumptions of two were about 60 ~70 % of total power consumption in the plant. Thus we should focus the operating conditions to plan the save energy project, and calculate the total power system and energy consumption of all unit facilities before we are going to improve the energy save in WWTP. Important note is firstly to select units and facilities having high energy consumption for evaluating the possibility of energy save. Secondly is develop and using a good management system to attain the goal of save energy.

Cheng-Ching Lake water treatment plant (CCLWTP), the largest water treatment plant in southern Taiwan serving the Kaoping region, uses the Kaoping River water as the source water. The plant has encountered both technical and managerial challenges to implement advanced water treatment system since 2004 in order to provide high quality drinking water to the residents living in the Kaoping metropolitan area and to meet future stringent drinking water standards. Granular activated carbon (GAC), derived from wood, bituminous coal, lignite, or other carbon-containing materials, and is the most widely utilized adsorbent for treating water and wastewater. It is usually used after the sand filtration process in water or wastewater treatment plant; the exhausted GAC is re-activated by a combustion process. Moreover, biological activated carbon (BAC) filtration (biofiltration) has become one of the advanced treatment techniques applied in the water treatment plant. In general, BAC offers a large internal surface area for the adsorption of taste, odor, and color compounds, excess chlorine, toxic and mutagenic substances (e.g., bromide, chlorinated organic compounds, including trihalomethanes), trihalomethane precursors, pesticides, phenolic compounds, dyes, toxic metals, and substances that cause biological after growth. After the biofiltration process, a final disinfection is necessary to ensure the microbial quality of the treated water. Because biofiltration is usually not capable of removing biorefractory substances, pre-oxidation with ozone is usually applied for oxidizing the most biorefractory organic matters and also improving their biodegradability before the water is treated in the BAC process. Hence, using ozone pre-oxidation will greatly enhances the effectiveness of the subsequent BAC process. The CCLWTP effluent meets the current drinking water quality established by Taiwan Environmental Protection Administration (TEPA). However, the microbial regrowth due to the residual minute quantity of organic carbons causes pipe corrosion, and the formation of disinfectant by-products (DBPs) in the distribution system leading to potential contaminations of the clean water after it enters into the distribution system. Thus, monitoring the water quality in water distribution systems necessity to develop appropriate strategies for managing both the treatment plant and following distribution systems. Chlorine is often used in municipal water treatment plant for disinfecting drinking water; it can react with naturally occurring organic matter to form trihalomethanes (THMs), e.g. chloroform, bromodichloromethane, chlorodibromomethane and bromoform that causes long-term health hazards to consumers through oral ingestion, dermal absorption and inhalation. The lifetime cancer risk and the hazard index of THMs through oral ingestion, dermal absorption, and inhalation exposure from tap water in 9 districts in Kaohsiung City are estimated. In the first part of this study, water samples were periodically collected from each treatment process of Cheng-Ching Lake Water Treatment Plant (CCLWTP) to assess the AOC (assimilable organic carbon) removal. In the second part of this study, the role of BAC filtration used in advanced water treatment plant and its capability to remove pollutants (AOC, bromide, bromate, and iron) were evaluated. Additionally, the efficiency of biofiltration process using GAC and anthracite as the fillers was also assessed with a bench-scale GAC adsorption column. In third part of the study, the distribution system of CCLWTP was selected for conducting the case study for understanding the fate and transport of water quality indicators in the distribution system. The last part of the study concentrated on undertaking multipathway exposure assessment based on the concentrations of various THMs found in the water samples collected at various locations of Kaohsiung City water supply system. The AOC removal efficiency of the advanced water treatment processes of the CCL was assessed using data collected in the field during the first phase of this study. However, the effect of two different filling materials on the efficiency of biofiltration process was evaluated using a laboratory bench-scale column study. Results of both laboratory study and field investigation show that a significant AOC removal efficiency was achieved by the BAC system implemented in CCLWTP. Conclusions of this study are summarized as follows: 1. Significant AOC removal efficiency was achieved in CCLWTP and the AOC concentrations in the effluent could meet the current established standards. 2. The increased AOC concentrations after the treatment of preozonation and chlorination may be caused by the oxidation of organic matters to more biodegradable and assimilable products. 3. The removal of AOC is correlated with the decrease in concentrations of other drinking water indicators, e.g., coliform, TPC, TDS, and particle counts). 4. The addition of sodium thiosulfate in water samples could enhance the performance of the AOC analysis (the accuracy and reliability). 5. The BAC filtration has been demonstrated to play an important role in the removal of the trace AOC. Thus, the application of BAC for AOC removal is feasible and should be included as a required treatment unit in the advanced WTP. The field study completed in the second part assessed the removal efficiencies of AOC and other water quality indicators in CCLWTP, while the effects of using two different filling materials on the efficiency of biofiltration process and microorganisms growing were evaluated using a laboratory bench-scale column study. Conclusions of this study include the following: 1. The BAC filtration system is capable of removing trace pollutants including organics and metals. 2. Significant overall treatment efficiency can be achieved in the CCLWTP, and concentrations of the water quality indicators in the effluent will meet the drinking water standards established by TEPA. 3. The increased AOC concentrations after ozonation and chlorination processes may be caused by the oxidation of organic matters into more biodegradable and assimilable organic products. 4. GAC is a more appropriate filling material than anthracite in the biofiltration system for the removal of AOC. 5. More microorganisms were observed in GAC column than in BAF column. This may be due to the effect that GAC has more specific surface area than anthracite. Additionally, more microbial growth was observed at depth of 5 cm than 0 and 40 cm in both columns indicating that 5 cm below the column surface is rich in both dissolved oxygen and biodegradable that causes higher microbial populations. 6. The BAC filtration plays an important role in the removal of the trace AOC; it should be included as a required treatment unit in future advanced WTP. Additionally, the BAF filtration column filled with anthracite is not as effective as the GAC-filled column in removing AOC. Thus, GAC should be used for the proposed BAF filtration unit. 7. The oxidation process using ozone will increase the amount of carbonyl group organics in the oxidized water leading to poor biological stability. Therefore, the oxidation should be combined with a subsequent GAC or biological process to minimize the AOC formation potential. The third study, Using the oxidation/reduction potential (ORP) along with other water quality parameters to indicate the water quality in the CCLWTP distribution systems was assessed and focused. Behavior of water quality parameters by monitor and investigate was made a replacement of corrosive pipe line. The results reveal that the treated water leaving CCLWTP (clear water) meets the drinking water standards in Taiwan. However, the water is re-contaminated by a number of factors including the corrosion of old pipes while it is flowing in the distribution system. Major conclusions of this study are summarized in the following sections: 1. The free residual chlorine concentration in CCLWTP distribution system is adequate to meet the drinking water standards established by TEPA. 2. The residual AOC concentration is well correlated with the TOC concentration in the samples collected at various sites in different administrative areas. 3. Ratios of AOC/TOC in six administrative areas were higher than 9%, indicating that the biofilms were fall and increased organic matter of tap water distribution systems. 4. The average AOC concentrations were increased with followed variations of UV-254 value. 5. A number of factors (AOC, pH, redox potential, TOC, UV-254, and chlorine residual) control the growth of microorganisms on pipe surfaces. 6. DO have a negative relationship between THMs and HAAs concentrations. Because that oxygen have higher electronegative than chlorine and bromine, and apt utilization of organic carbon. 7. Results were shown of pH, DO and ORP had a positive relationship (Need to be more specific about the correlationship. 8. Major chemical reactions in the distribution system involve both electrons and protons transfers; they are pH- and Eh (ORP)-dependent. Therefore, chemical reactions in pipe net often can be characterized by pH and Eh together with the activity of dissolved chemical species. 9. The results reveal that the non-scaling water in LSI of distribution systems of CCL close to saturation (LSI = 0) (Cannot be understood). As show the other results, located K and M1 areas in LSI¡@were -0.002 and -0.012, respectively. The appearance of the pipe in K and M1 areas were corrosion and undersaturated with CaCO3 (needs to be re-written). 10. The RSI value was between 7.0 and 7.5 showing potential corrosion and prioritizes replacement of the pipe. 11. The DO value has a correlation with the reverse in Fe and Fe3+ concentrations. 12. High oxidation conditions and elevated Fe3+ concentrations of exist inside the corrosion scales of the corroded water distribution pipes. 13. The Fe concentrations in the samples collected in various administrative areas exceed the TEPA drinking water standards. 14. The appearance of CCL distribution system of shows severe corrosive and oxidized conditions. The last part of this study concentrated on evaluating the association between trihalomethanes (THMs) exposure through three different pathways and long-term health risks. The results show that the consumer has a higher risk of cancer through Inhalation route. This is different from the results reported by other research. Because most residents living in Taiwan are accustomed to drinking boiled water, the lifetime cancer risks through oral ingestion of water-borne CHBrCl2, and CHBr2Cl in tap water in all 9 districts were higher than 10-6. By oral ingestion the lifetime cancer risk for total THMs was highest in the 7th district, while the lowest lifetime cancer risk for total THMs was in the 4th district. Chloroform poses a higher cancer risk to Kaohsiung City residents through dermal exposure than the other three THMs. This study showed that residents in 7th district had the highest cancer risk through inhalation of chloroform among the 9 districts, and the residents in 6th district had the least cancer risk. Residents in 7th district has the highest risk of cancer due to exposure of THMs during showering and bathing as compared with residents in 4th district Males have a higher cancer risk than females through dermal absorption when exposed to THMs. The results of noncarcinogenic risk assessment for THMs indicate that if the main pathways are through oral ingestion and dermal absorption, 7th district has the highest hazard index of the four chemicals, while 4th district has the lowest hazard index. According to the above results, the quality of drinking water in Kaohsiung City is in general in accordance with the guidelines for drinking water quality as recommended by the World Health Organization. A better drinking water quality can be achieved by reducing the quantity of disinfection by-products (DBPs) through the removal of DBP precursors using modified treatment practices. Coagulation, granular activated carbon, membranes and ozone-biofiltration can all remove natural organic matter. Additionally, source water protection and control are effective non-treatment alternatives to control water-borne precursors. Optimized applications of disinfectants as primary and secondary disinfectants can further be implemented to control DBPs. Although research efforts continue to develop new treatment methods that will reduce the levels of DBPs during disinfection, it is generally accepted that risks to health caused by water-borne DBPs in drinking water are relative small in comparison with risks associated with water-borne diseases due to inadequate disinfection. Thus, it is important that the disinfection process should not be compromised in attempting to control water borne DBPs. The predominant DBPs group has been shown to be THMs, with chloroform and BDCM as the most dominant THMs. Although THMs are only one subgroup of the many DBPs formed during chlorination, they are useful as indicators of the overall DBP formation. It is concluded that, given the current state of knowledge, a risk assessment based on THMs would provide the greatest level of confidence regarding the ability of a drinking water guideline to protect against risks of cancer and other long-term health hazards. In conclusion, in order to reduce the cancer risk and hazard as indexed by THM concentrations in the drinking water, some methods could be used including controlling to reduce THMs precursors and microbial contaminants in raw water, and aged pipeline, optimizing all treatment processes to ensure that concentrations of disinfectant are adequate, using alternative disinfectants and reducing water age in distribution system. The potential human risks associated with drinking water disinfection are largely unknown, even though some information is available from toxicological and epidemiological studies. More research is needed to determine the risks associated with DBPs. The next progress will facilitate a more realistic assessment of risk due to drinking water contaminants without increasing the levels of uncertainty in risk estimates.

In natural waters, high concentrations of ammonia are toxic to fish, and the oxidation of ammonia to nitrate (NO₃-) consumes large quantities of dissolved oxygen. The influent to municipal wastewater treatment plants in the United States typically contains approximately 40 mg/L of ammonia nitrogen (NH₃₋ N). Almost all of this ammonia must be removed in a wastewater treatment process before the effluent is discharged to the natural environment. This dramatic decrease is accomplished by the aerobic biological process of nitrification, in which ammonia is oxidized to nitrate Biological denitrification is an anoxic biological process in which nitrate (NO₃-) is reduced to nitrogen gas (N₂). Denitrification can increase the alkalinity in activated sludge aeration basins and decrease the concentration of filamentous organisms. The staff at the City of Austin Water Utility decided to implement a denitrification system at Walnut Creek Wastewater Treatment Plant to control filamentous organisms and increase the alkalinity within the aeration basins. The denitrification configuration that the staff implemented was unconventional because no structural changes were made to the aeration basins to encourage denitrification. However, the system functioned well and allowed operators to turn off one of the two air blowers, which saves the plant a significant amount of energy. The current operation has occasional problems, where the alkalinity in the aeration basin decreases or the effluent ammonia increases. When the alkalinity decreases to the point where the pH drops to near 6.0, operators are forced to add chemicals to increase the alkalinity. When the effluent ammonia increases to near the permitted concentration (2.0 mg NH₃-N/L),operators are forced to turn back on the second blower which eliminates the anoxic zone. These problems occur most often during the winter, when the wastewater is the coldest. The wastewater temperature at Walnut Creek varies from a high of 30°C during the summer to a low of 18°C during the winter. The goal of this research was the identification of ways to make the operation more robust which would prevent the need for chemical addition and minimize the use of the second blower. Laboratory-scale reactors were operated to assess possible improvements that could be made to the operation and configuration of the denitrification system at Walnut Creek. The data observed in the laboratory scale experiments showed that the population of denitrifying bacteria limits denitrification and is especially important during the winter. Increasing the solids retention time to 20 days appeared to be the best way to increase the population of denitrifying bacteria and improve denitrification. Improvements can also be made by increasing the volume of the anoxic zone. Increasing the volume of wastewater and biomass recycled will most likely not benefit denitrification until other improvements have been made. Recommendations to the City of Austin Water Utility include the following: 1) increase the solids retention time at Walnut Creek, 2) Increase the volume of the anoxic zone, 3) Separate the anoxic zone from the aerobic section of each aeration basin, 4) During the winter, operate the flow equalization basins to reduce the dissolved oxygen entering the anoxic zone, 5) Continually mix some of the effluent from the aeration basins with the primary effluent in the flow equalization basins. / text

Water treatment residues (WTRs), which are by-products from the production of potable water, are chemically benign, inorganic materials which are suitable for disposal by land application. Their high phosphorus (P) sorption capacities have, however, generated some concern in an agronomic context where P is recognised as a growth limiting plant nutrient. The extent to which labile P pools are reduced or enhanced by WTR amendments is, therefore, a central issue with respect to their disposal by land application. Therefore, the aim of this study was, through the use of empirical adsorption isotherm equations and chemical fractionation of P within the residues, to investigate the chemical processes responsible for the retention and release of P from 15 South African WTRs. Chemical characterisation revealed considerable variation in residue properties relevant to P sorption-desorption processes. pH, exchangeable Ca and organic carbon content ranged from 4.77 to 8.37, 238 to 8 980 mg kg-1 and 0.50 to 11.6 %, respectively. Dithionate, oxalate and pyrophosphate extractable Al fractions ranged from 741 to 96 375, 1 980 to 82 947 and 130 to 37 200 mg kg-1, respectively. Dithionate, oxalate and pyrophosphate extractable Fe ranged from 441 to 15 288, 3 865 to 140 569 and 230 to 90 000 mg kg-1 respectively. Therefore mechanisms of retention were hypothesised to be residue specific, being dependent on the unique chemical properties of the sorbent. Elevated Ca and amorphous Al and Fe concentrations did, nevertheless, suggest that all residues had the capacity to adsorb high amounts of P and to retain this P in forms unavailable for plant uptake. These arguments were confirmed by the sorption study where labile P was, for all residues, found to constitute a small fraction of total applied P even at high application concentrations (128 mg P L-1). Sequential P fractionation revealed that most of the inherent P (which ranged from 1 149 to 1 727 mg P kg-1) and applied P were retained in highly resistant mineral phases or fixed within the organic component. Thus P replenishment capacities were restricted even though residual P concentrations were often within adequate ranges for plant growth. Phosphorus adsorption data was described by four empirical adsorption isotherm equations in an effort to determine possible mechanisms of retention. Sorption data was, for most of the WTRs, described by the Temkin isotherm while the Freundlich and linear models fitted data for two residues each. A key finding was that the distribution coefficient (Kd) tended to increase with the quantity of P adsorbed (S) as opposed to decrease or remain constant in accordance with model assumptions. Therefore, the models could not be used for mechanistic interpretation, even though they provided excellent descriptions of the data. The direct relationship between Kd and S suggested a mechanism of retention involving the activation of sorption sites. This notion was supported by the fractionation study which showed that P addition results in the transfer of an increasing quantity of organically bound P to resistant residual forms. Model affinity parameters were strongly correlated to dithionate and pyrophosphate extractable Al and Fe which suggested that P was adsorbed primarily through ligand exchange mechanisms. The mobility of P bound to organic fractions did indicate that P was retained through weaker forces of attraction such as monodentate ligand exchange, charge neutralisation or proton transfer. Evidence to support the notion that P is immobilised through the formation of Ca phosphates was lacking. Based on P fractionation data, it was suggested that strong chemisorption mechanisms and the diffusion of P into WTR micropores were largely responsible for the minimal quantity of P desorbed by disequilibria desorption processes. A greater quantity of P was desorbed in the presence of oxalate and citrate which suggested that plants may increase bio-available pools through the release of organic ligands. Phosphorus desorbed in the presence of these ligands did, however, decline with P addition which confirmed that the affinity of the WTR surface for P increases with P application. Therefore, it was concluded that the application of P to WTRs is an uneconomical process unless sorption sites are already saturated or immobilisation processes are inhibited. In light of these findings, it was suggested that the absence of plant P deficiencies under the field application of WTRs is due primarily to inhibited sorption. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.