Dissertations / Theses on the topic 'Sand filter wash water'

The purpose of this study is to evaluate the convenience and effectiveness of using a disc filter to treat washing water from the sand filters at Sundet wastewater treatment plant. The disc filter is used aiming for the reduction of suspended solids and phosphorus. The study was divided in two main experimental stages. During the first stage laboratory jar-tests were performed in order to identify which flocculation aid was more suitable, this was further on used to improve the water treatment. Based on the laboratory trials results, two different polymers (1 and 2) were chosen to be tested at pilot scale. The second stage involved the pilot filter operation itself; this period was as well divided in two sub-stages where filter cloths with two different pore openings were tested. During the first sub-stage the pilot operated with an 18 μm pore opening filters cloth and both polymers. At the end of the first half polymer 1 showed to be more efficient and so it was further used throughout the second sub-stage in combination with a 10μm pore opening filter cloth. As from theoretical knowledge the phosphorus and suspended solid removal were expected to be between 75% and 90%, results which were achieved during both laboratory trials and pilot filter. The best results were observed with the 10μm pore opening filter cloth and polymer 1. Also, additional results from pilot trials performed at Sundet after the study period are presented.

Process water is used for cooling and for transporting material in all kinds of industries. To clean the water for reuse, various types of filters can be used. Many conventional process water treatment plants incorporate sand filters, which readily clean the water from suspended matters. However, at some circumstances the sand filters do not remove high enough concentrations of metals. This master thesis compares the water treatment abilities of activated cork, produced by Spikes & Cogs AB, to those of the sand filters used at steel making company Ovako Hofors AB in Hofors. As an on-site pilot study, the thesis investigates the cleaning capacity of three types of activated cork filters: Fats, Oils and Solvents (FOSS) filter, Fast Acting Digesting Enzymes (FADE) filter, and Metal Adsorption and Concentration (MAAC) filter. The cork filters were compared to the sand filters during normal operation and, because of previous problems with the stability of the sand filter performance, during stress tests. The results show that the cleaning capacity of the sand filters is higher than the cleaning capacity of the cork filters at normal operation. At the conditions of the stress tests, at which the sand filters do not function, the cleaning capacity of the cork filters was somewhat lowered but was still well within acceptable limits. An important result from the experiments is that the cork filters neutralize the pH. The sand filters are sensitive to changes in the pH, meaning that the cork filters could function as a buffering unit prior to the sand filters.

Diarrheal diseases are a global public health burden, killing 1.8 million people annually. Diarrhea disproportionately affects children and those in poverty. Most diarrheal cases can be prevented through safe drinking water, basic hygiene and/or sanitation measures, with drinking water interventions having the most impact on reducing diarrheal disease. There is no generally agreed-upon field method for determining biosand water filter effectiveness that is usable in low-resource communities. A pilot study was conducted of potential field use indicators, including the Colilert coliform presence/absence (P/A) test, hydrogen sulfide, alkalinity, hardness, pH, and fluorescently labeled latex microspheres. The study included both laboratory and field testing. The Colilert P/A test had the highest correlation to the United States Environmental Protection Agency standard method (IDEXX Quanti-trays), but more data are needed before making a recommendation. This study adds to understanding about evaluation of biosand water filters and provides preliminary data to address the need for a field use indicator for biosand water filters.

An activated unsaturated sand filter (AUSF) is one of only a few of the filtration technologies utilized to treat waters and wastewaters that use unsaturated filter media. AUSF employs sand coated with potassium permanganate and operates with an open chamber allowing free air flow into the column of sand. The AUSF also benefits from operation without the need for a sedimentation unit. Previous studies have demonstrated the efficient removal of iron and manganese using an AUSF, however, to date there are still very limited studies available that use AUSF technology for the removal of metals from waters and wastewaters. Thus, there is an urgent need and opportunity to exploit this technology further. This research was conducted in order to develop and study the characteristics and subsequent operational performance of a novel AUSF media. The study focuses on the removal of copper, manganese, zinc and nickel from a synthetic wastewater and extends current knowledge to a passive aeration process rather than the active aeration used in the previous study by Lee et. al. (2004). The characterisation involved the use of sieving, Brunauer- Fmmett-Teller (BET) analysis, water evaporation studies and scanning electron microscopy (SEM) for structural analysis such as particle size, surface area, porosity and topography. Energy dispersive X-ray analysis (EDX), acid/alkali resistance, isoelectric point determination and acid digestion analysis were used to determine the chemical constituency, chemical stability, electrical charge properties and the binding efficiency of the media. Finally, tracer studies were employed to determine the flow characteristics through the particle media. The manganese coated sand was proven effective for the removal of copper in both agitated tank batch studies and continuous column studies. The batch studies showed that the equilibrium sorption of copper followed a Langmuir isotherm and the sorption rate was best modelled using the pseudo-second-order kinetic model. This suggests that adsorption is taking place as a single homogeneous layer on the surface of the sand particle via the chemisorption method. The Weber-Morris and Bangham models were used to determine the rate-controlling mechanism and this was found to be predominantly intra-particle diffusion. This was confirmed for column studies using the Bohart-Adams model that demonstrated that liquid-film mass transfer was not significant. Several mechanisms of metal removal are proposed and these include precipitation, electrostatic attraction, adsorption, ion exchange and complex ion formation. The column studies demonstrated that dispersion was low under the operating conditions and plug flow performance could be inferred, thus justifying the use of the AUSF model employed. Copper was best removed when operating as an unsaturated particle bed and the removal capacity was increased by approximately 100% when compared to a saturated particle bed. Moreover, the pH increase that occurs on exposure of the process water to the unsaturated column further improves removal capacity. Thus, there is no requirement for an expensive pH adjustment as a pre-treatment process prior to this unit operation. In addition, the removal capacity of the AUSF was demonstrated to increase with lower metal concentrations, lower water flow rates, smaller sand particles, an increase in manganese to sand ratio and an increase in particle bed height. The AUSF performance in removing metals followed the order Cu > Mn > Zn > Ni for individual and mixed component solutions and Cu > Ni > Zn > Mn for a synthetic wastewater typical of the electroplating industries. In conclusion, the novel manganese coated AUSF developed is effective in the removal of metals from solution and offers the potential of a sustainable low cost treatment method for the purification of waters and wastewaters.

Diarrheal diseases are a global public health burden, killing 1.8 million people annually. Diarrhea disproportionately affects children and those in poverty. Most diarrheal cases can be prevented through safe drinking water, basic hygiene and/or sanitation measures, with drinking water interventions having the most impact on reducing diarrheal disease. There is no generally agreed-upon field method for determining biosand water filter effectiveness that is usable in low-resource communities. A pilot study was conducted of potential field use indicators, including the Colilert coliform presence/absence (P/A) test, hydrogen sulfide, alkalinity, hardness, pH, and fluorescently labeled latex microspheres. The study included both laboratory and field testing. The Colilert P/A test had the highest correlation to the United States Environmental Protection Agency standard method (IDEXX Quanti-trays), but more data are needed before making a recommendation. This study adds to understanding about evaluation of biosand water filters and provides preliminary data to address the need for a field use indicator for biosand water filters.

The objective of this research project was to investigate the influence of the principal design and operational parameters on the quality of the filtrate from a slow sand filter. These parameters are sand effectivc size, depth of sand bed, rate of filtration, water temperature and influent quality. Attempts were then made to establish relationships between the variables employed by means of regression analyses of the experimental data. To carry out the investigation three laboratory scale filter columns were constructed each measuring 150 mm in diameter and 3010 mm height. The filtration medium in each column consisted of a 1.2 m depth of sand on a 0.3 m depth of gravel. For the three individual columns three different sand sizes were employed. These were 0.17 mm effective size (ES), 0.35 mm ES and 0.45 mm ES. Water to be filtered was abstracted from the Burleigh Brook, adjacent to the Civil Engineering laboratories. As required small amounts of settled sewage, obtained from the Loughborough Water Reclamation Works, were added to increase both the turbidity and the count of indicator bacteria. The filters were operated at five different filtration rates at three different temperatures. These temperatures were 25 degrees C, 15 degrees C, 5 degrees C and the filtration rates repeated for each temperature were 0.1, 0.2, 0.3, 0.4, 0.5 m/h. The filters were operated for not less than one month at each filtration rate. In order to assess the efficiency of the filters water samples were taken and analysed from the influent and from the filtrate and also from a series of sampling taps positioned at various depth down the sand media. These water samples were tested for total coliform bacteria, for faecal coliform bacteria, suspended solids and turbidity. Regression analyses were then carried out on the data obtained and regression models were developped for 100 mm and 1200 mm sand depths of each filter for each period. Occasional tests (i. e. at least once for each flow rate) were also carried out for nitrate and ammoniacal nitrogen, colour, pH, conductivity, total organic carbon (TOC) and dissolved oxygen. Following the completion of the filtration operation at three temperatures and five filtration rates the sands of the filtration media were also examined. Sand samples were taken for examination from 0, 50, 100, 150, 200, 300, 400, 600, 800, 1000 and 1200 mm below the sand surface of each filter. Then in order to assess both the penetration of the removed solids into the filter bed and to investigate the concentration of the biological film developed within the sand bed, sand samples were analysed for suspended solids, turbidity, standard plate count bacteria and particulate organic carbon. Regression analyses were also carried out on these data and variation of each parameter against each filter bed was modelled. The solid and biological deposits on the sand samples were also viewed with a Scanning Electron Microscope.

Cationic proteins from the seeds of the Moringa oleifera tree are of interest as sustainable coagulants for drinking water treatment in regions with poor access to potable water in tropical and subtropical regions of the world. They have been shown to reduce turbidity in natural water sources as well as in various model freshwaters. To identify the active components in the seed extract, high performance liquid chromatography was employed. Eight M. oleifera cationic protein fractions were isolated and characterized using gel electrophoresis, dynamic light scattering, and circular dichroism. Coagulation performance experiments were conducted using a micro-coagulation assay that was validated by comparison to a standard jar test. Fraction coagulation performances were compared individually and in various combinations against kaolin clay suspensions in model freshwaters of varying hardness. The unfractionated protein extract was found to be effective across a broad range of protein dosages. Coagulation activity for this extract was further investigated against humic acid and mixtures of kaolin clay and humic acid in model freshwaters of varying hardness. The coagulation mechanism of Moringa oleifera proteins was demonstrated to be adsorption and charge neutralization. Adsorption isotherms were measured using ellipsometry to investigate the effects of water hardness, fractionation, and fatty acid extraction on protein adsorption to silica surfaces. The zeta potentials of the resulting protein-decorated surfaces were measured by the rotating disk streaming potential method. Sands can be effectively modified with M. oleifera proteins using small amounts of seed extract under various local water hardness conditions. Gravity sand filters packed with Moringa oleifera modified sand were constructed and shown to be effective against kaolin and humic acid. Protein layer coverage and composition did not affect filter performance. These studies may aid in the design of a simple, effective, and sustainable water purification device for developing nations.

The availability to clean drinking water is something a lot of people take for granted today. Daily, there are about 1.8 billion people around the world that drinks water from a contaminated water source. Unfortunately, the deficiency is a fact, and about 361 000 children under the age of five die each year because of diarrheal disease (WHO, 2016a).  Earlier studies show that a biosand filter is an easy and efficient water purification method that cleans the water both physically, biologically and chemically. A biosand filter is often built using local material and is filled with sand, which makes the construction cheap and easy to repair is needed. Earlier studies have shown that this purification method can reduce waterborne disease by 99,9% with the help of a biofilm layer which develop in the top layer of the sand if the conditions are meet (CAWST, 2009). The purpose with this study was to build and evaluate a biosand filter as a water treatment method in Ghana. In total, three biosand filters was built with local material, each with different sand heights. The evaluation was done by studying the waters physical, biological and chemical properties before and after the filtration, which then was compared to the water quality standards from the World Health Organization (WHO) and Sweden. The results show that none of the three filters could produce water which met the standards for drinking water, which might be caused by the high flow of water through the filter which prevented the biofilm to grow. With the help from the results in Ghana, a new design of a water filter has been made to reduce the flow of water through the filter. Which gave a new biosand filter design with a diameter of 42 cm that, sand height of 80 cm and gravel height of 15 cm.
Tillgången till rent dricksvatten är idag något som många tar som en självklarhet. I dagsläget är det omkring 1.8 miljarder människor i världen som dagligen dricker vatten från en kontaminerad vattenkälla. Dessvärre är bristen på rent dricksvatten ett faktum, vilket gör att det årligen dör cirka 361 000 barn under fem års ålder på grund av diarrésjukdomar världen över (WHO, 2016a).  Tidigare studier har visat på att biosandfilter är en enkel och effektiv vattenreningsmetod för att rena vatten både fysiskt, biologiskt och kemiskt. Ett biosandfilter är ofta byggt med lokala material och fylld med sand, vilket gör konstruktionen billig och enkel att reparera vid behov. Tidigare studier har visat på att vattenreningsmetoden kan reducera vattenburna sjukdomar med upp till 99.9% med hjälp av ett biofilmslager som utvecklas i sandlagrets övre skikt om förhållandena är gynnsamma (CAWST, 2009).  Syftet med denna studie var att bygga och utvärdera biosandfilter som vattenreningsmetod i Ghana. Totalt byggdes tre biosandfilter av lokala material med olika sandhöjder. Utvärderingen gjordes utifrån att studera vattnets fysiska, kemiska och biologiska egenskaper före och efter filtrationen, som sedan jämfördes med vattenkvalitetsstandarder från World Health Organization (WHO) och Sverige. Resultaten visade på att ingen av de tre sandfiltret kunde producera vatten med en drickvattenstandard, detta tros bero på det höga flödet genom filtret som hindrat biofilmstillväxten. Med hjälp av resultat från Ghana har en ny design av ett biosandfilter tagits fram för att minska flödet genom filtret. Vilket gav en filterdiameter som är ungefär 42 cm som sedan är fylld med 80 cm sand och 15 cm grus.

In this research, a household water treatment system was built and evaluated as a trial for improving the drinking water quality of the Nile River for the low-income communities. The system consisted of household-scale slow sand filters, and transparent polyethylene terephthalate-bottles for solar disinfection. The evaluation of the system depended on the removal/inactivation of some surrogates for the reference pathogens, and turbidity. The reference pathogens are pathogens specified by the World Health Organization to evaluate the efficiency of the household water treatment options. They were chosen to represent the classes of pathogens in water (bacteria, viruses, protozoa). The surrogates used in the evaluation of the system are Escherichia coli (E.coli), Clostridium perfringens and Escherichia coli bacteriophage (MS2). The candidate surrogates are also specified by the World Health Organization. The designed household-scale slow sand filter was very efficient in removing the different turbidity levels to ≤0.4NTU. The evaluated system is classified as highly protective because it was able to achieve higher than 4 log removal for E.coli and Clostridium perfringens, and higher than 5 log removal for MS2.

Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xxi, 187 p.; also includes graphic (some col.). Includes abstract and vita. Advisor: Karen M. Mancl, Dept. of Food, Agricultural, and Biological Engineering. Includes bibliographical references (p. 169-178).

This project investigated the bacteria in water entering and leaving the slow sand filters at Ringsjö Water Works using flow cytometry. The purpose was to explore the possibility of utilising flow cytometry as a monitoring method for optimising water production using slow sand filters. Data describing the bacterial community in water was collected over seven weeks and analysed with FlowJo, flow cytometric image comparison and Minitab. The total cell count, intact cell count and the percentage of high nucleic acid bacteria were analysed. These parameters were highly dependent on scraping events, water entering the filters and season. The results indicated that flow cytometry has great potential for use as a monitoring method, although more data should be collected to establish expected trends and secure baseline values for routine comparisons.

Fördröjning av publikation fram till 31 december 2020.

Östby waterworks in the community of Kramfors has since 2003 had problems of fast clogging of the slow sand filters. As the clogging appears more often, they must be cleaned more frequently which has made the drinking water preparation difficult. Wintertime it has sometimes been impossible to clean the filters which has led to their closing and this has influenced the water quality negatively.

The waterworks is a surface waterworks which takes its raw water from the lake Sjöbysjön. The water is flocculated and filtered in a contact filter with the flocculent EKOFLOCK 91. Thereafter it is alkalinized before it reaches the outdoors placed slow sand filters. After the filters the water is alkalinized and disinfected before it reaches the customers.

This thesis work has looked into which factors influence the clogging and trials have been made in order to optimize the waterworks and thereby reduce the clogging. The raw water has been studied with aspect to biology and chemistry, the filtered water has been studied with aspect to chemistry and also the pressures in the slow sand filters have been studied.

The colour of the raw water from Sjöbysjön and its catchment area has increased since the beginning of the 90-ies and also the bio volume has increased in the lake.

The contents of aluminium before the slow sand filters are far higher than the contents after, which leads to the conclusion that aluminium is accumulated in the filters. The differential pressure over the sand bed increases with time after a cleaning. This indicates an accumulation of particles which increases with the load. Observations of the filter surface before cleaning showed that it was covered by a brown, jelly-like film. The internal resistance in the filter beds increases successively after a cleaning and one month after cleaning it is highest in the upper part of the sand bed. All this points to that flocculated aluminium is gathered in the slow sand filters, on the surface, causing clogging.

While the thesis work has been going on a process of alkalinizing before the contact filters has been reengaged and this has influenced the flocking of organic materials. When raising the pH the dose of flocculent was increased and this combined increased the amount of flocculated material. The contact filters could not bear this increased amount of flock load but showed instead a breakthrough.

In a few lab scale trials the flocking pH was varied as well as the dose flocculent to the raw water and after this the water was filtrated. A tendency was seen that the separation of aluminium, colour and turbidity increased with increasing pH and dose flocculent. At the pH 6.2 and the chemical dose of 60 g/m3 the content of aluminium, the colour and the turbidity showed the lowest values in the filtrate.

Vattenverket i Östby, Kramfors kommun, har sedan 2003 haft problem med för snabba igensättningar i långsamfiltren. Ju oftare de sätter igen desto mer frekvent måste de rensas vilket har försvårat dricksvattenberedningen. Vintertid har rensningar ibland inte kunnat utföras och långsamfiltren har därför stängts av vilket har påverkat vattenkvaliteten negativt.

Verket är ett ytvattenverk som tar sitt råvatten från Sjöbysjön. Vattnet flockas och filtreras i kontaktfilter med fällningskemikalien EKOFLOCK 91. Därefter mellanalkaliniseras det innan det går till de utomhus placerade långsamfiltren. Efter långsamfiltren efteralkaliniseras och desinficeras det innan det når konsumenterna.

I detta examensarbete har faktorer som påverkar igensättningarna undersökts och försök har också gjorts för att optimera driften och därmed minska igensättningarna. Råvattnet har undersökts avseende dess biologi och kemi, filtraten i verken har undersökts med avseende på deras kemi och tryckbildningar i långsamfiltren har studerats.

Färgtalet i råvattentäkten Sjöbysjön och dess tillrinningsområde har ökat sedan början av 90- talet och dessutom har biovolymen i sjön ökat.

Halterna aluminium före långsamfiltren är mycket högre än halterna efter, vilket antyder att aluminium ansamlas i filtren. Differentialtrycket över sandbädden ökar med tiden efter en rensning. Detta tyder på en ansamling av partiklar som ökar med belastningen. Observationer av filterytan innan rensning visade att den täcktes av en brun geléaktig hinna. Motståndet i filtren ökar successivt efter en rensning och är en månad efter rensning störst i den övre delen av sandbädden. Allt detta pekar på att aluminiumflock ansamlas i långsamfiltren, på ytan, och orsakar igensättningarna.

Under examensarbetets gång har en föralkalinisering återinförts i vattenverkets process och den har påverkat fällningen av det organiska materialet. Då pH höjts har också dosen fällningskemikalie ökats vilket har ökat mängden flock. Denna ökade flockmängd har kontaktfiltren inte kunnat bära utan istället släppt igenom.

I några försök i labbskala varierades fällnings-pH och dos fällningskemikalie till råvatten med en efterföljande filtrering. Tendenser som kunde ses var att avskiljningen av aluminium, färg och turbiditet ökade med ökat pH och ökad dos fällningskemikalie. Vid pH 6,2 och kemikaliedos på 60 g/m3 var aluminiumhalterna, färgen och turbiditeten som minst i filtratet.

Ett avloppsvatten innehåller olika föroreningar som påverkar recipientens vattenkvalitet. En förorening somreningsverken inte är optimerade för att reducera är mikroorganismer, som i recipienten påverkar bland annatbadvattenkvalitén. Syftet med examensarbetet var att ta reda på hur utvalda processteg i ett reningsverkpåverkar utgående halter av mikroorganismer, hur utsläppen av mikroorganismer kan övervakas och hur mikroorganismernapåverkar recipientens badvattenkvalitet. Examensarbetet har uppfyllt syftet genom att undersökahur biologiska reningssteg reducerar indikatororganismerna E.coli och intestinala enterokocker jämfört medslutreningsalternativen kontinuerligt sandfilter samt skivfilter. Provtagning genomfördes på två reningsverk ochresultatet analyserades för att besvara frågan. Andra kvalitetsparametrar i avloppsvattnet samt flöde, lufttemperaturoch nederbörd har jämförts med utgående koncentration av indikatororganismerna från reningsverk föratt undersöka om det finns några samband som går att använda för att uppskatta det mikrobiologiska utsläppet.För undersökningen har de statistiska metoderna Kendalls Tau och Partial Least Squares använts. En litteraturstudiepå hur implementering av läkemedelsrening med ozon kan desinficera avloppsvattnet, vilken doseringsom krävs och vad den bör baseras på har genomförts. Efter avloppsutsläpp i en recipient sprids mikroorganismernamed vattnets strömmar och mikroorganismerna dör normalt av med tiden. Denna avdödandeprocesskan beskrivas med en ekvation av första ordningens kinetik. Ekvationens känslighet för variation i variablernasolinstrålning, temperatur, siktdjup och tid har undersökts. Ekvationen har även använts för en fallstudie av avloppsutsläppvid bräddning och hur det påverkar en badplats nedströms. För fallstudien fanns information omflödestid, utspädning och nedbrytningsvariablerna att tillgå. Undersökningen visar att biologisk rening med biobädd reducerar indikatororganismerna effektivast av de undersöktareningsstegen. Sandfiltrets reduktionsförmåga var god men skivfiltret presterade sämre. Från provtagningenframkom också att koncentrationen av E.coli är konsekvent högre och reduceringen sämre än motsvarandeför intestinala enterokocker. Indikatororganismernas koncentration i utgående avloppsvatten är enligtkorrelationsanalysen slumpmässig och inget signifikant och starkt samband fanns till de undersökta parametrarna. På grund av detta är uppskattning av mikrobiologiska utsläpp med hjälp av mätning av andra parametrarinte tillförlitlig. Den genomförda litteraturgranskningen av ozondosering visar att dosen som krävs för desinfektionav avloppsvatten behöver anpassas för varje reningsverk samt att resultat från forskningen går isär omhur doseringen bör optimeras. I recipienten har siktdjupet störst betydelse för nedbrytningen och recipientensegenskaper är viktigare än utsläppets storlek för vattenkvalitén enligt den modell som använts. Fallstudien visadeatt även vid bräddning på reningsverket hinner mikroorganismerna spädas ut och brytas ner tillräckligt föratt badvattenkvalitén inte ska klassas som otjänlig vid närliggande badplats.
Depending on the efficiency of the processes used in a wastewater treatment plant, the recipient receives watercontaining various concentrations of microorganisms. These microorganisms might infect people using therecipient for recreational purposes. The thesis aims to investigate how some process choices affect the concentrationsof microorganisms in sewage and how the concentration can be monitored with the use of other waterquality measurements. Lastly the microbial degradation after discharge in a lake was investigated. Process choiceswere evaluated through sampling before and after two biological treatment steps, one sand filter facilityand one disc filter facility. The obtained results demonstrate that among the investigated alternatives, a biologicalstep using biofilm is the most efficient for removing microorganisms, followed by sand filtration and leastefficient with high variability was disc filtration. The literature review suggests that the use of ozonation forreducing pharmaceutical residues could be efficient in reducing microorganisms, but the required dosage is notuniformly established in previous research. Statistical analysis on water quality measurements with Kendall’sTau and Partial Least Squares did not appear to be a good substitute to use for monitoring and prediction ofbacterial concentrations. The water quality of the recipient, especially the transparency for UV-light, is moreimportant for maintaining good bathing water quality than the outflow concentration of microorganisms in thesewage. In a small case study, it was shown that an official bathing site is not at risk for acute microbiologicalcontamination even when extreme rainfalls causes overflow in the upstream waste water treatment plant.

Eighty percent of the 780 million people worldwide that access water from an unimproved source live in rural areas. In rural areas, water systems are often managed by community based organizations and many of these systems do not provide service at the designed levels. The Sustainability Analysis Tool developed in Chapter 2 can inform decision making, characterize specific needs of rural communities in the management of their water systems, and identify weaknesses in training regimes or support mechanisms. The framework was tested on 61 statistically representative geographically stratified sample communities with rural water systems in the Dominican Republic. The results demonstrated the impact that long term support by outside groups to support community management activities can improve sustainability indicators, including financial sustainability which is a significant issue throughout the world. When analyzing the financial sustainability of water systems, it is important to consider all life-cycle costs including the expenditures made by households. Chapter 3 analyzes financial and economic expenditures on water services in 9 rural and peri-urban communities in Burkina Faso. Data from household and water point surveys were used to determine: socio-economic status, financial and economic expenditures, and service levels received by each household. In Burkina Faso recurrent financial and economic expenditures on water service ranged between US$5 and US$9.5 per person per year, with cumulative costs approximately US$19.5 per person per year. The average expenditures on water in Burkina Faso were well above the affordability threshold used by World Bank demonstrating the need to improve subsidies in the water sector. The sustainability of water supply systems and the ability to ensure the health benefits of these systems is also influenced by the deficiencies in sanitation infrastructure. Unimproved sanitation can be a source of water contamination and a risk factor in water related disease. Furthermore, the effective management of community water supply infrastructure is not a sufficient condition for ensuring water quality and eliminating health risks to consumers. As a result water treatment technologies, such as ceramic water filters (CWFs), implemented and managed at the household level and combined with safe storage practices are proposed as a means of reducing these risks. The performance of CWFs in laboratory settings has differed significantly from field studies with regard to microbial treatment efficacy and also hydraulic efficiency. Chapter 4 presents a 14 month field study of two locally manufactured CWFs conducted in a rural community in the Dominican Republic. Each of the 59 households in the community received one filter. The CWFs in this study performed poorly with regard to water quality and hydraulic performance. Focus group meetings and household survey suggests that flow rate is a major issue for user acceptability. To address the user concerns Chapter 5 presents two mathematical models for improving the hydraulic performance for the frustum and paraboloid designs. The models can be used to predict how changes in user behavior or filter geometry affects the volume of water produced and therefore can be used as tools to help optimize filter performance.

Small on-site sanitation systems for wastewater collection and treatment are prevalent in suburban and rural areas in many countries. However, these systems often underperform, causing potential impact to the receiving waters and increasing the risks to public health, thus hindering the overall sustainability of the systems. Understanding the different sustainability dimensions and trade-offs between assessment indicators can support the planning of sustainable on-site sanitation systems for a specific context. The overall aim of this thesis was to evaluate the sustainability and function of on-site sanitation systems by defining a set of indicators to assess on-site sanitation options and estimating them for different scenarios, and by investigating the treatment efficiency of on-site facilities for domestic wastewater treatment in a field study. Particular attention was given to the removal of phosphorus (P) and indicator bacteria due to their relevance in terms of eutrophication risk and public-health concern. In a multi-criteria approach, twelve indicators were defined to assess nine on-site sanitation systems. A reference group representing stakeholders’ views assigned weights to express the relative importance of each indicator. The reference group assigned the highest weights to the indicators robustness, risk of pathogen discharge and nutrient removal. Assessing the robustness proved to be challenging, as there is a gap between how the sanitation systems are expected to perform based on their design, and how they actually perform in practice, mainly due to incorrect construction, operation and maintenance. The discriminating power of the indicators was calculated using the entropy method, which showed that the indicators energy recovery and capital cost had little impact in the final ranking of the alternatives. A sustainability ranking was obtained by using the method ELECTRE III. A scenario analysis based on different settings of interest based on socio-economic and geographical factors was done to evaluate the changes in the ranking of alternatives. Overall, the greywater–blackwater separation system ranked the highest in the baseline scenario and when nutrient-related indicators were important (Scenario 2), together with the urine diversion system. The sand filter and drain field were the most sustainable options when nutrient removal and recycling was not important (Scenario 1), and (in combination with chemical P-removal) when the indicators related to energy and climate change had the highest weights (Scenario 3). In terms of P-removal, chemical removal outranked the alkaline P-filter. In a field study, the effluent wastewater from twelve on-site wastewater treatment facilities with sand and alkaline P-filters was evaluated in terms of removal and discharge of organic content, total and dissolved phosphorus, and indicator bacteria (E. coli, total coliforms, intestinal enterococci and C.perfringens). The results showed that the investigated sand filters generally had low P-removal capacity and sometimes exceeded the criteria for excellent water quality set by the EU bathing water directive with regard to intestinal enterococci and E. coli. Only one sand filter of eight was confirmed to remove P according to the Swedish guidelines for areas with non-sensitive receiving waters with a tot-P effluent concentration below 3 mg L−1. This indicates that a downstream treatment step is needed to meet the guidelines regarding P discharge concentrations. Alkaline P-filters generally removed P efficiently. Despite high effluent pH, the collected data did not generally confirm a further reduction of the bacterial content of the wastewater in the P-filters, as had been previously hypothesized. However, effluent concentrations of indicator bacteria showed moderate positive correlations with effluent concentrations of P and organic matter, indicating the potential of the P-filters to serve as a polishing step also for bacteria.
Små lokala avloppssystem för insamling och rening av avloppsvatten är vanligt förekommande i omvandlings- och landsbygdsområden i många länder. Dessa system fungerar ofta sämre än förväntat vilket kan leda till effekter på recipienter, ökad risk för folkhälsan och begränsa systemens hållbarhet. En djupare förståelse för hållbarhetsdimensioner och avvägningar mellan olika indikatorer kan stödja planering och implementering av hållbara lokala avloppsystem för specifika sammanhang. Det övergripande syftet med denna uppsats var att utvärdera hållbarhet och funktion av enskilda avloppssystem. Detta utfördes genom att först definiera en uppsättning indikatorer för bedömning av ett antal enskilda avloppsalternativ och sedan utvärdera dem för olika scenarier. Vidare var syftet att undersöka några systems prestanda för rening av hushållsavloppsvatten i en fältstudie. Särskilt fokus lades på reduktion av fosfor (P) och indikatorbakterier på grund av deras relevans i relation till övergödningsrisk och folkhälsoperspektiv. I en multikriteriestudie definierades tolv indikatorer för att bedöma nio typer av enskilda avloppssystem. En referensgrupp som representerade olika intressenter viktade indikatorerna för att uttrycka den relativa betydelsen av varje indikator. Referensgruppen gav systemens robusthet, risk för utsläpp av patogener, och näringsreduktion störst vikt. Att bedöma robusthet var en utmaning i studien, eftersom det finns ett gap mellan hur systemen förväntas fungera, och hur de faktiskt fungerar i praktiken, mestadels på grund av felaktig konstruktion, drift och underhåll. Indikatorernas diskriminerande effekt räknades ut med entropimetoden, som visade att indikatorerna energiåtervinning och kapitalkostnad hade liten inverkan på alternativens slutgiltiga rangordning. En scenarioanalys genomfördes baserad på socioekonomiska och geografiska faktorer. En hållbarhetsrankning erhölls genom att använda ELECTRE III-metoden. Överlag rankades system som separerar gråvatten – svartvatten samt urinseparerande system högst i basfallsscenariot och när näringsrelaterade indikatorer var viktiga (scenario 2). Markbäddar och infiltrationsanläggningar var de mest hållbara alternativen när rening och återvinning av näringsämnen inte var viktigt (scenario 1) och (i kombination med kemisk P-rening) när indikatorer relaterade till energi och klimatförändringar viktades högst (scenario 3). När det gäller P-rening, gav system med kemisk rening ett bättre utfall än de med alkaliska P-filter. I en fältstudie utvärderades tolv enskilda avloppsanläggningar med markbaserade system och alkaliska P-filter med avseende på rening och utsläpp av organiskt innehåll, totalt och löst P och indikatorbakterier (E.coli, totala koliformer, intestinala enterokocker och C.perfringens). Resultaten visade att de markbaserade systemen generellt hade låg P-reningskapacitet och ofta överskreds kriterierna för utmärkt vattenkvalitet enligt EUs badvattendirektiv avseende intestinala enterokocker och C. perfringens. Endast ett markbaserat system av åtta uppvisade en P-rening som låg under de svenska riktlinjerna för områden med normal skyddsnivå, med en utsläppskoncentration på under 3 mg L-1 tot-P. Detta indikerade att markbäddar behöver nedströms placerade reningssteg för att uppfylla nuvarande riktlinjer för utsläpp av P. Alkaliska P-filter avskilde generellt P effektivt. Trots högt pH-värde kunde ingen ytterligare minskning av bakterieinnehåll i avloppsvattnet från P-filtren påvisas statistiskt. Utsläppen av indikatorbakterier uppvisade emellertid måttliga positiva korrelationer med utsläpp av P och organiskt material, vilket visar på en viss potential att P-filtren kan fungera som ett ytterligare poleringssteg även för bakterier.

Orientadores: Bruno Coraucci Filho, Roberto Feijo de Figueiredo
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-11T03:44:49Z (GMT). No. of bitstreams: 1 Tonetti_AdrianoLuiz_D.pdf: 1722600 bytes, checksum: e50780c638866b2c1f1ca142ed978993 (MD5) Previous issue date: 2008
Resumo: Nesta pesquisa estudou-se um sistema para o tratamento de esgotos de pequenas comunidades composto pela combinação de filtro anaeróbio com filtro de areia e reator de desnitrificação. Para isso foi avaliada a partida e a operação de três filtros anaeróbios com recheio de bambu operados com tempo de detenção hidráulica nominal de 9 horas, sendo o efluente gerado disposto sobre os leitos de quatro filtros de areia em distintas taxas de aplicações. No primeiro filtro de areia aplicaram-se 50 Lm-2 uma vez por dia. No segundo, terceiro e quarto filtro, esta mesma carga foi disposta em dois, três e quatro horários, espaçadas entre as 9 horas e às 16 horas, correspondendo às taxas de 100, 150 e 200 Lm2dia. Cada filtro de areia era seguido por um reator de desnitrificação em que se buscou um meio propício à remoção do nitrogênio, objetivando adequar o efluente ao lançamento em um corpo hídrico e como água de reúso. O sistema foi avaliado quanto a parâmetros físicos, químicos e biológicos. Como resultado, o efluente atendeu a legislação de Minas Gerais e São Paulo quanto a DQO e DBO e, após a correção do pH e adição de efluente anaeróbio como fonte de carbono, obteve-se uma remoção de 43,5% de N-total no reator em que se aplicou 50 Lm-2dia-1, passando a ter um grau moderado para a prática agrícola. Palavras-chave: esgoto, filtro de areia, tratamento, desnitrificação, reúso
Abstract: The main objective of this research was to study an onsite system to treat the wastewater from small villages. The system was constituted by the combination of an upflow anaerobic filter followed by a sand filter and a denitrification reactor. The start up and the operation of three upflow anaerobic filters filled with bamboo rings were evaluated. These filters were operated with hydraulic detention time of 9 hours. The produced effluent was disposed over four sand filters in different frequencies of application. On the first sand filter, 50 Lm-2 were applied once a day. On the second, the third and the fourth filters, the same load was disposed in twice, three and four times a day, distributed between 9 am and 4 pm. Each sand filter was followed by a denitrification reactor aiming at the removal of total nitrogen, thus making appropriate the effluent for discharge or water reuse. Weekly, the system was evaluated by analyses including physical, chemical and biological parameters. As a result, the effluent was suitable for the COD and BOD legislation and, after the pH correction and the addition of external carbon source, a removal of 43,5% from total-N was reached in the reactor which received a load of 50 Lm-2dia-1, consequently the effluent was ready to be used within a slight to moderate degree of restriction. Keywords: wastewater, sand filter, treatment, denitrification, reuse
Doutorado
Saneamento e Ambiente
Doutor em Engenharia Civil

This thesis explores the posibility of using of foundry filter ash for production of inorganic composite materials, that could be used primary in the construction industry. The thesis is divided into theoretical and experimental section, where theoretical section contain literature review of used materials and the experimental section summarizes the results of laboratory tests performed on tested mixture based on portland and alumina cement with various content of foundry filter ash. For comparison was also used another foundry waste - foundry sand. Prepared test bodies with dimension of 40 x 40x 160 mm was subjected to mechanical strength tests and the influence of amount of foundry waste on the strenght of the prepared mixtures was monitored. Next the thesis deals with possibilities of alkaline activation of foundry waste, where sodium water glass, sodium hydroxide and commercially supplied baucis L 160 component B were used as alkaline activator. These test mixtures were also subjected to mechanical strenght tests and the influence of amount of foundry waste on the strenght was observed too. The analysis of input materials were performed by XRF, TG – DTA – EGA and XRD powder diffraction methods. All strength tests were tested by testing equipment desttest 4310.

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Made available in DSpace on 2018-07-13T21:59:51Z (GMT). No. of bitstreams: 1 Uso de efluentes dom?sticos tratados na cultura do girassol (Helianthus annus L.).pdf: 2283233 bytes, checksum: 421fa4a09cacb2392028081a3186d138 (MD5) Previous issue date: 2018-03-15
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
Agricultural reutilization is an important tool in water demand reduction required by irrigation. The lack of proper management on irrigation generates large environmental degradation, mainly to water resources, therefore it?s indispensable the reduction of these impacts. The use of domestic wastewater in agricultural crops may support the search for alternative water sources to supply the irrigation demand even as provide essential nutrients to the crops, and also reducing the impact of the chemical fertilizers application. This dissertation aims to evaluate the use of treated domestic wastewater on sunflower irrigation (Helianthus annuus L.) cultivate ?Garden Gnome?, using treatments by sand strainer (SS), organic filter (OF), septic tank (ST) and well water (WW) applied in different levels (50, 75, 100, and 125% of evapotranspiration of daily crop). The experiment was conducted with buckets of 20 L with one plant per bucket in experimental design of 4 by 4 with 5 parcels, adding up to 80 experimental units. Physicochemical analyses on the soil were realized after application, and in the wastewater, additionally, microbiologic analyses were realized during the experiment. With the plants were realized biometric analyses: stem diameter, plant height, leaves number and phytomasses: dry and fresh phytomass from the aerial part, from the pseudostem, and from the roots. It can be conclude that the use of different irrigation sources didn?t produced significant effect in biometric evaluation and of sunflower phytomass, being possible the use of all the studied sources, without losses to the plant development. The sand filtration provided considerable efficiency, being a simple and cheap solution to the domestic wastewater treatment
O re?so agr?cola ? uma importante ferramenta na redu??o da demanda h?drica requerida pela irriga??o. A falta de manejo adequado na irriga??o provoca grande degrada??o ambiental, principalmente aos recursos h?dricos, sendo assim, se torna imprescind?vel a redu??o desses impactos. A utiliza??o de efluentes dom?sticos em cultivos agr?colas pode favorecer a busca por fontes alternativas de ?gua para suprimento das demandas de irriga??o assim como fornecer nutrientes essenciais aos cultivos, reduzindo o impacto tamb?m na aplica??o de fertilizantes qu?micos. O trabalho teve como objetivo avaliar o uso de efluentes dom?sticos tratados na irriga??o do girassol (Helianthus annuus L.) cultivar An?o de Jardim, utilizando tratamentos por filtro de areia, filtro org?nico, fossa s?ptica, e ?gua de po?o em diferentes l?minas de irriga??o aplicadas (50, 75, 100 e 125% da evapotranspira??o da cultura di?ria). O experimento foi conduzido em baldes de 20 L com uma planta por balde em delineamento experimental 4x4 com 5 parcelas, totalizando 80 unidades experimentais. Foram realizadas an?lises f?sico-qu?micas no solo ap?s aplica??o e nos efluentes adicionalmente, foram realizadas an?lises microbiol?gicas durante o experimento. Nas plantas foram realizadasan?lises biom?tricas: di?metro do caule, altura da planta e n?mero de folhas e de fitomassas: fitomassas fresca e seca da parte a?rea, do cap?tulo e da raiz. Pode-se concluir que a utiliza??o de diferentes fontes de irriga??o n?o produziu efeito significativo nas avalia??es biom?tricas e de fitomassa do girassol, sendo poss?vel a utiliza??o de todas as fontes estudadas sem preju?zo ao desenvolvimento da planta. A filtra??o de areia proporcionou efici?ncia consider?vel, sendo uma solu??o simples e barata para o tratamento de efluentes dom?sticos

Foi pesquisada a aplicação de métodos, em nível de laboratório, através dos quais é possível otimizar, tratar e dispor resíduos de lavagem de filtros de estações de tratamento de água (Caso ETA do rio Descoberto - ETA-RD Brasília). Na clarificação da água de lavagem dos filtros, observou-se o efeito favorável da adição de polímero para melhorar a separação líquido-sólido é, portanto, as eficiências de remoção de turbidez, cor aparente, sólidos suspensos e coliformes totais. Observou-se melhor sedimentabilidade do lodo a ser desaguado. Os ensaios de centrifugação, em escala de bancada, mostraram que o método aplicado auxilia na determinação da dosagem a ser usada numa centrífuga em escala real. Foram avaliados três métodos de disposição do lodo adensado da ETA-RD em ETE: 1) sedimentação com esgoto sanitário e posterior digestão anaeróbia do lodo; 2) Digestão anaeróbia e 3) digestão aeróbia. Os melhores resultados foram obtidos com a digestão anaeróbia. Os estudos realizados mostraram que há diversas alternativas de tratamento e disposição desses resíduos, mas é necessário, sempre que possível, a avaliação das diferentes alternativas para selecionar a(s) mais apropriada(s) a cada caso em particular, pois fatores como custos e disponibilidade de de sistemas ou equipamentos, definirão a aplicabilidade ou não de determinado método.
It was researched the application of methods on laboratory bench scale to optimize the reuse, treatment and disposal of wastes from filter backwash of Water Treatment Plant - WTP (WTP-RD Descoberto River, Brasília case). In the clarification process of this waste, favorable effect of addition of polymer for best liquid-solid separation and, thus, better removal efficiencies of turbidity, apparent color, suspended solids and total coliforms was observed. Better sedimentability of the sludge occurred. The centrifugation tests showed that the applied method help on determination of dosagem to be used in full scale. Three methods to dispose thickened sludge of WTP-RD on wastewater treatment Plants - WWTP were evaluated: 1) Sedimentation with domestic sewage and anaerobic digestion of sludge; 2) Anaerobic digestion and 3) Aerobic digestion. Best results were obtained with anaerobic digestion. The results showed that there are alternatives of treatment and disposal of wastes of WTP, but is necessary, if possible, to make the evaluation of this alternatives to select the most appropriate(s) in each case because factors as costs, systems or equipments availability, will define the applicability or not of a particular method.

Ce travail s'inscrit dans le cadre de la mise au point de procédés de traitement des eaux usées peu coûteux et adaptés aux conditions tropicales. Il s'agit d'évaluer l'intérêt de plantes aquatiques pour l'élimination des polluants et des microorganismes pathogènes. La recherche a été conduite en 4 phases. La première concerne l'étude de l'évapotranspiration en présence de macrophytes comme Pistia stratiotes et Typha australis se développant sur des eaux usées. La deuxième est réservée à la construction et la mise au point d'un distillateur solaire couplé avec la culture de Typha australis. Une station expérimentale d'épuration des eaux usées a été construite dans un troisième temps afin d'étudier les abattements des paramètres physico-chimiques et bactériologiques. Le dispositif comporte trois systèmes d'épuration tertiaire en parallèle: 2 lagunages à macrophytes (Salvinia molesta, Lemna paucicostata + Ceratophyllum demersum) et un filtre à sable à macrophytes enracinés suivi d'une électrolyse. Enfin, la quatrième phase concerne la valorisation de la biomasse produite, par compostage ou en tant qu'aliment pour volailles. Les résultats montrent que la présence de macrophytes augmente l'évaporation par rapport à une surface d'eau nue. Le distillateur solaire à macrophytes a presenté des performances peu convaincantes en raison de la faible possibilité de monter en température et de difficultés à refroidir le condenseur. Les macrophytes augmentent l'abattement des paramètres physico-chimiques dans le traitement secondaire et bactériologiques dans le traitement tertiaire. La biomasse végétale produite peut être compostée seule ou en mélange. Elle peut être aussi utilisée comme aliment pour l'élevage avicole. En conclusion, l'utilisation de macrophytes dans le lagunage montre une voie adaptée pour le traitement des eaux usées en milieu tropical en raison des performances obtenues et des possibilités de valorisations de la biomasse et de l'eau épurée

碩士
國立成功大學
地球科學系碩博士班
95
After the 921Chi-Chi Earthquake, The earth materials of mountain area in Taiwan were loosened and rock weakened. With steep slope and weakened rocks, debris of rocks and soils will fall into the water during typhoon or raining season; thus cause the turbidity of water body to jump up. Most reservoirs in Taiwan are in-basin reservoirs. Debris of rocks and soils from upstream regions can easily be flashed into the reservoirs; namely, water treatment plant of public water supply system was frequently forced to close down due to the high water turbidity. Water treatment plant of Shihmen Reservoir was closed down due to the high water turbidity during the typhoon season has been the most well known incident in 2005. It had widely affected the public water supply in southern Taoyuan region. Purpose of this work was set to quickly lower the turbidity of intake water in order to match the capability of water treatment plant; namely to obtain a stable water supply even during the extreme weather season that may highly increase the turbidity of the water body. A sand filter system was adopted to evaluate its efficiency on removal of water turbidity. Water of different turbidities was made by using the earth materials from Gutingkeng formation mudstone of Kaohsiung area, Taiwan. The turbidity removal efficiency due on the different grain size sand filter layer and different infiltration flow rates was evaluated, in respectively. Results of the experiments showed that a 40% efficiency of turbidity removal can be obtained by using 0.425~0.710 mm grain size sand filter layers under the designated infiltration flow rate.

碩士
國立中興大學
環境工程學系所
98
Although the average annual rainfall in Taiwan is as high as 2000 mm, water resources in Taiwan are still significantly insufficient because of the unequal distribution of rainfall in terms of time and space. According to the United Nations’ investigation of global water distribution, Taiwan was ranked 18th as a water-scarce region. Based on these results, the annual average water consumption in Taiwan area of each person is only one seventh of the world average. It is essential to construct water reservoirs in order to ensure stable quality and quantity of water supply. At the moment the illegal discharge of industry and livestock wastewater into the river or into the reservoir in combination with insufficient rainfall, which is caused by global climate change, changed the water quality and reduced its quantity. This forced the water supply plant to improve its adaptability and to set an operational cutoff point in order to resolve the unexpected problem as soon as possible. Li Yu Tan reservoir, which is located in Miaoli county, has the function of electric power generation, irrigation and water supply for Miaoli county and Taichung city area. Recently a large amount of algae has been found at specific periods (2008.11~12、2009.03). Meanwhile the rapid sand filter of water supply plant has been blocked, so the filter run has been shortened and the backwash frequency has to be increased. In this study, two rapid sand filter modules to simulate different operation conditions were constructed. One of the modules was set up in the Li Yu Tan drinking water supply plant in order to determine the plant operational state. The other module, smaller than the former, was set up in laboratory and used to simulate the situation when influent contains large quantities of algae. According to the investigation result (2009.08~2010.04), the algae found in Li Yu Tan reservoir were Dinoflagellates, Green algae, Cyanobacteria and Diatoms. The most abundant algae appear to be diatoms, including Cycotella sp., Achnanthes sp. and Synedra sp.. In the larger rapid sand filter module, experiments were conducted under various operating conditions including packed depth (70 and 65 cm), media characteristics (sand and anthracite) and different media diameters (0.6 and 0.85 mm) in order to observe the effect of effluent water quality. At the second test, under the influent (total precipitation water) of high turbidity (average 2.55 NTU) condition, the filter module was still able to maintain effluent turbidity of lower than 0.2 NTU. The average removal rate of 90 ~ 94% showed excellent efficiency. In the laboratory module test, the influent was added with different algae species including environment samples, Anabaena sp.、Chlorella sp. and Desmodesmus sp.（Scenedesmus sp.）. The results showed that the filter packed with coarse filter media could not block most of the algae at the initial stage; even at the late stage the algae might breakthough the filter bed.

When Biosand filters cannot be constructed with crushed quarry rock due to resource limitations, a suitable alternative filter media is needed. In this research, two crushed quarry rock alternatives were examined. Three bench-scale Biosand filters with crushed rock, beach sand, and heat-treated beach sand media were simultaneously dosed with Willamette River water seeded with K-12 E. coli for 31 days. Influent and effluent filtrate was analyzed for E. coli using 3M Petrifilm E. coli/Coliform plate counts; influent and effluent pH, conductivity, turbidity, dissolved oxygen, and temperature were monitored. All three filters achieved stable E. coli removal efficiencies of 99% or greater after filter maturation, suggesting that it is possible to effectively use beach sand and heat-treated beach sand in Biosand filters for pathogenic bacteria removal. Mean effluent E. coli concentrations for crushed rock, beach sand, and heat-treated beach sand filters were 12, 29, and 30 CFU/mL respectively. Crushed rock filter effluent was significantly lower in mean effluent E. coli concentration than beach sand (P < 0.001) and heat-treated beach sand (P < 0.001) filter effluents, suggesting that beach sand and heat-treated beach sand media should only be used as a secondary option to crushed rock media due to potentially greater exposure risk to pathogenic bacteria.
Graduation date: 2013

碩士
國立中興大學
環境工程學系所
99
Although the average rainfall in Taiwan is higher than lots of country, water resources in Taiwan are still significantly insufficient because of the landform and climate. To solve this problem, our government built reservoirs to supply sufficient water resource. Human activity caused serious eutrophication in our reservoirs and lots of algae growth rapidly in short-term, Algae were impacted the water treatment processes and reduced the quality of drinking water. Recently a large amount of algae has been found at specific periods (2008.11~12、2009.03)was set up in Li Yu Tan reservoir. Serious algae bloom accompanied rapid sand filter of water supply plant has been clogged. So water company has to raise the backwash frequency to assured the quality of effluent in water treatment processes. In this study, two rapid sand filter modules to simulate different operation conditions were constructed. The large module in Li Yu Tan water supply plant in order to simulate the operation of filtration processes. The small module was set up in laboratory and used to simulate the situation when influent contains large number of algae. In this investigation (2010.04~2011.04),The maximum concentration of algae was observed in October. The diatom was the predominant species in the reservoir. In different season, algae species change significantly with weather and temperature. In large rapid sand filter module, experiments were conducted under five operating conditions. The average removal efficiency of turbidity was higher than 80% in each case. Raising media diameter can reduce the head lost in the operational term. Other experiments determined that decreasing packed depth may reduce the turbidity removal rate. Isolation of predominant species in the reservoir is difficult because diatom growth slower than other green algae. In this study, four kind of algae were isolated. There were Cycotella sp.、Chlorella sp.、Oscillatoria sp. and Scenedesmus sp.. In small rapid sand filter module, The Oscillatoria sp. formed serious clogging in surface of filters and accumulated highest head lost about 53 cm in 8 hr. The Chlorella sp. accumulated lowest head lost about 40 cm in 8 hr and it is most easiest to breakthrough the filters into filtrate.