No description available.

Horizontal Roughing Filtration (HRF) is a pretreatment method used to remove excess turbidity and suspended solids of surface water fed into Slow Sand Filtration units, as these can only operate satisfactorily when the concentration suspended solids is below 25 mg/1 . A critical review and discussion of current pretreatment methods, HRF research and important filtration variables are presented together with a review of mathematical models of sand and roughing filters based on clarification and trajectory theories. A detailed historical review of head—loss theories, their development and adoption in multimedia filtration is given. I. Preliminary results from studies on a small scale HRF model suggested that: - A laboratory scale model must be over 1.2 m in length: 1.6 _in turned out to be acceptable. - An outlet chamber should be provided. — Sampling must be carried out in a two dimensional field. — Intermittent sampling is adequate. One of the main objectives of this research was to identify the Important variables affecting HRF, among velocity, temperature, particle size, particles density, arrangement of the gravel bed 'Coarse—Medium—Fine (LGF),Coarse/Fine—Fine—Coarse (SGF)§, and the bed depth. II. Experiments were conducted on a 1.6m filter scale model, using Fractional Factorial Design to identify the main variables. These were found to be particles size, velocity, and temperature. III. Further runs, using a suspension of kaolin, produced results which, upon analysis for suspended solids, turbidity, particles count, revealed that the efficiency decreases with increasing temperature and velocity and increases with increasing particles size. IV. Concentration curves along the bed enabled: — The development of the removal rate equation, — Defining the operating parts of the filter at various stages of the filtration, ' — The presence of density currents. V. Efficiency variations with the amounts of accumulated solids were monitored and revealed three main trends: a) Constant efficiency; b) Gradually decreasing efficiency; c) Increasing and then decreasing efficiency. - VI. Tracer tests showed the presence of dead zones, and - short—circuiting with either increased deposits or temperature. VII. Particles size analysis revealed that: a. The effect of velocity or temperature on the grade efficiency affects mainly suspended particles in water smaller than 10 pm and 7 pm for LGF and SGF respectively. For particles of larger diameters, an unknown repulsion phenomenon increasing with temperature rise was observed. b. The main mechanisms responsible for particles removal are sedimentation and hydrodynamic forces.

A critical review of the mechanisms of present water treatment systems including, chlorination, coagulation, filtration, granular and powdered activated carbon adsorption, ozonation and ultraviolet radiation for the removal of herbicides is presented. Rapid selective and sensitive HPLC methods were developed and rigorously validated for the analysis of the selected herbicides. Analysis of atrazine was made using Cl8 cartridges. For raw water containing interferences, extraction of the compound was made on SCX cartridges, followed by solvent exchange on C18 cartridges. A quantitative recovery of virtually 100% of the compound was achieved using C18. While the double cartridge extraction of the compound gave a recovery of about 89%. Previously developed methods for 2,4-D and MCPA were rigorously validated for the extraction and analysis of 2,4-D and MCPA. A quantitative recovery of usually greater than 90% was achieved for both compounds using Cl8 cartridges. For the extraction of paraquat different extraction systems including, reversed phase on C8 and C18, ion-paired reversed phase on C18, and cation exchange on SCX, CBA, and CN were investigated. A quantitative recovery, usually greater than 90%, of the compound was obtained using CN and CBA cartridges. The methods were then successfully used for the evaluation of the removal efficiency and establishment of mechanisms of removal of herbicides by biological filters at bench and pilot scale. Four herbicides belonging to three broad chemical categories were studied. The data presented in this study demonstrated that biological filters are very efficient in removing certain classes of herbicides. 2,4-D and MCPA were consistently removed to below a detection limit of 0.1 mug/1 for an influent concentration of 3-11 mug/1. Process variables such as flow rate, bed depth and contact time were investigated for the efficient removal of these herbicides. Seasonal variations in performance were observed and possible explanations proposed. A series of experiments was undertaken to establish .mechanisms of removal. Quantitative recovery of the herbicides from the river water proved that the processes in the filter bed as opposed to the processes in the water were responsible for removal of the herbicides. It was clear from the investigation of the adsorption of the herbicides both on the sand and organic and inorganic dirt that adsorption on these surfaces was not the main reason for removal. Filter maturation experiment showed that the presence of microorganisms in the bed is a precondition for the removal of herbicides. A depth experiment for the removal of 2,4-D showed that superficial efficient zone of removal imitates the distribution of microbial density. This evidence confirms the significance of microorganisms for the removal of herbicides by the filter bed. The ultimate proof of the biodegradation of 2,4-D by microorganisms in the filter bed was the identification of the biodegradation product 2-chlorophenol as predicted by the metabolic pathways of the compound. Filter design modifications using activated carbon were made to accommodate the removal of 'non-biodegradable' herbicides. A sandwich sand / GAC / sand filter was investigated. Filter efficiency for this arrangement was determined and short-comings were identified and a possible solution in the form of a double GAC sandwich is suggested.

The overall aim of this research was to contribute to the optimisation of aerobic wastewater treatment processes in sequencing batch reactors, by investigating the performance of the process with real and model wastewaters in order to achieve the highest possible reduction of influent COD with the minimum reactor volume and oxygen consumption. Six industrial wastewaters from the food and drink companies were treated in lab-scale aerobic sequencing batch reactors (SBRs) inoculated with soil and monitored for COD and total suspended solids (TSS) removal. The results showed high COD removal efficiencies for all the wastewaters, in the range of 64-95 %. Extended aeration tests were carried out on the reactor effluents and the results indicated that the residual soluble COD was not further biodegradable. This indicates that the soluble BOD removal in the reactors was virtually 100 %. The biodegradation efficiency was investigated over two values of the solids retention time (SRT) and the performance of the reactors was essentially unaffected by the SRT (in the range of 7-18 days considered in this study). This means that very good COD removal can be achieved at relatively lower SRT, with potential savings in capital and operating costs. The removal of TSS for the wastewaters was not satisfactory, largely due to the low food to microorganism (F/M) ratios (0.13-0.29 kg COD/kg biomass.day) in the reactors. Three batch tests at different initial substrate to biomass (So/Xo) ratios were carried out on each of the two industrial wastewaters for kinetic characterisation of the wastewaters. Oxygen uptake rate (OUR) was measured during the tests and the OUR profiles were used for the estimation of the kinetic parameters using a mathematical model consisting of substrate hydrolysis, biomass growth and endogenous metabolism. The results showed large variations with regards to the values of the parameters for each wastewater due to day-to-day variability in the biomass's response to substrate utilisation. For the two industrial wastewaters, the hydrolysis rate constant (kh) and half saturation constant for slowly biodegradable substrate (KX) were found to be in the range of 2.21-14.8 kg COD/kg biomass.day and 0.006-0.45 kg COD/kg biomass respectively. The maximum growth rate (μmax) and the half saturation rate constant for readily biodegradable substrates (KS) ranged between 1.21-7.3 day-1 and 0.004-0.89 kg COD/m3 respectively. The biomass growth yield (YX/S) and the endogenous metabolism coefficient (b) were found to be 0.3-0.57 kg biomass/kg COD and 0.001-0.41 day -1 respectively. The hydraulic retention time (HRT) and SRT were optimised in order to minimise the SBR volume and maximise the organic loading rate (OLR) of the SBR process. Two model wastewaters, glucose and ethanol, were used in the study. An experiment of eleven different SBR runs (HRT in the range of 0.25-4 days and SRT of 1-65.3 days) was carried on the glucose wastewater. Nine different SBR runs were carried out on ethanol wastewater (HRT in the range of 0.5-4 days and SRT of 1-73.6 days). The minimum HRT and SRT values for the successful operation for glucose wastewater treatment were 0.25 days and 3.1 days respectively while the minimum HRT and SRT for ethanol were 0.5 days and 4.9 days respectively. The highest corresponding OLR values from the minimum HRT and SRT which gave satisfactory process performance were 4.28 g COD/l.day and 4.14 g COD/l.day for glucose and ethanol wastewaters respectively, which are among the highest OLRs reported in the literature for aerobic conventional dispersed-growth processes. The calculated oxygen consumption and biomass production were found to depend on the SRT as well as the OLR, where in general, oxygen consumption increased while biomass production decreased at higher OLR. Batch tests were also carried out on the two model wastewaters for kinetic characterisation. The kinetic parameters for glucose wastewater were: 1.07-4.79 day -1 for μmax, 0.24-0.45 kg COD/m3 for KS, 0.04-0.1 day-1 and 0.47-0.6 kg biomass/kg COD for b and YX/S respectively. For ethanol wastewater, the kinetic parameters were: 0.99-2.3 day -1 for μmax, 0.001-0.04 kg COD/m3 for KS, 0.05-0.2 day-1 and 0.38-0.51 kg biomass/kg COD for b and YX/S respectively. A new mathematical model and procedure to calculate the periodic steady state of the SBR using a kinetic model of the biological process and values of the kinetic parameters was developed. This new procedure allows the direct calculation of the steady state profiles of biomass and substrate in the SBR without calculating the dynamics of the system from start up to steady state. The numerical accuracy of the procedure was discussed and the model was applied to show the effect of the operating parameters (SRT, HRT, length of the phases and number of cycles) on the steady state performance in terms of biomass and substrate concentrations. It was also shown how the model can be used for various applications like: optimisation of operating parameters for a minimum reactor volume; simulation of the competition between filamentous and floc-forming bacteria for bulking control; and calculation of the minimum volumetric mass-transfer coefficient required to maintain a desired oxygen concentration. In the end, the periodic steady state of the SBR was simulated for the industrial and model wastewaters at various values of the operating conditions (e.g. HRT, SRT, number of cycles) using the developed SBR model with values of kinetic parameters obtained from the various batch tests. The predicted model performance in terms of effluent quality and biomass concentration was compared with experimental results achieved during the treatment of the wastewaters. The simulation gave very good prediction of the extent of substrate removal for all the wastewaters. However, the prediction was not very accurate for biomass concentration. The study indicated that a good model prediction in terms of biomass production is strongly dependent on the values of the kinetic parameters especially b and YX/S.

This study was undertaken to examine the feasibilty of a low-cost aerobic system to treat greywater for reuse.Its purpose was to provide a system that would be easy to maintain, flexible and be affordable for households and small communities in developing countries. This thesis outlines and evaluates the key biological and chemical hazards associated with greywater reuse. It discusses the performance of a variety of wastewater treatment options in use. It presents details of the components of the greywater system,namely, an aerobic grease trap and slow sand filter. Reference is made to the evaporation and treatment bed and ultraviolet disinfection components, but these are not examined. The incorporation of vermitechnology in the preliminary stages of the system for reduction of organics in greywater is reviewed. This study takes the traditional approach to water quality assessment with the measurement of physical, chemical and biological indicators. Assessment of the system involved examining the input characteristics of the greywater, monitoring the vermiculture system and sampling the liquid discharge from the aerobic grease trap and slow sand filter for analysis of the quality indicators. The results obtained under the framework of this study have provided recommendations for further use of the aerobic grease trap and slow sand filter, while propsing an approach for an appropriate long-term monitoring program. / Master of Engineering (Hons)

Resin and fatty acids (RFA) are predominantly components of coniferous trees having the natural function of protecting against microbial damage. These compounds are released from wood during the pulping process and a fraction reaches the wastewater treatment system. RFA are acutely toxic to aquatic organisms at concentrations on the order of parts per million, and their presence has been linked to toxicity outbreaks in receiving waters following process upsets. The chronic toxicity of resin and fatty acids in complex effluent matrices is poorly understood. Furthermore, the role of hydrophobic, pulp-derived solids as a removal pathway from wastewater streams has not been comprehensively studied. The objectives of this dissertation have been to quantify the relationship between resin and fatty acid concentration and chronic toxicity and to determine the role of partitioning in the removal of these compounds from pulp mill wastewater streams. Field and laboratory studies were conducted to measure toxicity using the Microtox™ whole effluent toxicity and Ceriodaphnia dubia 7-day, survival and reproduction bioassays. One resin acid in particular, dehydroabietic acid, was found to account for a significant fraction of final effluent chronic toxicity. Dissolved and sorbed RFA concentrations were quantified by solvent extraction, methyl ester derivatization, and GC-FID analysis. Partitioning to suspended solids was found to be a major removal pathway for the RFA from the effluent treatment system. A kinetic model for flotation was applied and compared to experimental data. Flotation was found to be effective at selectively removing RFA bound to pulp-derived solids from pulp mill and bleach plant sewers at moderate to high pH.

Master of Science / Department of Biological & Agricultural Engineering / James K. Koelliker / In 2003, the EPA changed Confined Animal Feedlot Operation (CAFO) regulations to allow an alternative treatment system for feedlot runoff if a 25-year simulation can show better performance for the alternative treatment system when compared to a traditional lagoon system. A continuous computer simulation model written in C was developed to compare the release of water, nitrogen (N), phosphorous (P) and chemical oxygen demand (COD) from a Vegetated Treatment Area (VTA) system and a conventional lagoon system in Kansas. The model simulates the transport of water and constituents in a feedlot, settling basin, lagoon, and VTA. The feedlot runoff is based on NRCS unit hydrograph method for the water balance and AnnAgNPS for the constituent runoff concentrations. The settling basin is a simple water balance with sediment, organic-N, P, and COD removed with settling of the solids. The VTA is designed to calculate infiltration with Green-Ampt Equation and overland flow with Manning's Law. The VTA removes organic-N and P with the Kentucky Filtration Model. The lagoon is derived from Koelliker et al. model water balance and pumping schedule with constituent balance from Miner et al. model. VTA portion of the model was analyzed for sensitivity and calibrated with three storms. The sensitivity analysis showed that the size of the VTA and conductivity of the soil in the VTA causes the greatest variability in the release of N, P, and COD. The calibration of the release of organic-N and P for mean particle diameter showed that a diameter of 1.5 µm produced the best agreement. The model was used for a lagoon and VTA system at two sites in Kansas with 35 years of weather data. The sites were located in Ottawa and Greenwood Counties, KS. The simulated results showed that the lagoon system performed better for both sites when comparing the mean values of total-N, total-P, and COD released over the 35 years. The VTA system performance was better when median values of total-P and COD were compared at Greenwood County. This model was designed for use in Kansas, but with modifications may be useful in other areas.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Domestic rainwater harvesting (DRWH) refers to the collection and storage of rainwater for domestic purposes and in an effort to achieve the Millennium Development Goals (MGD), the South African government has started an initiative where DRWH tanks are financed in sustainable housing schemes in an aim to provide an additional water source directly to households. Although many provinces, including parts of the Eastern Cape and KwaZulu Natal, have been using harvested rainwater as a potable water source, there are a limited number of studies indicating the quality of harvested rainwater in South Africa. However, many studies, internationally, have indicated that while the practice of harvesting rainwater is gaining popularity, rainwater quality is not within potable standards (Chapter 1). During the first phase of the study, rainwater samples were collected from the Kleinmond Housing Scheme (Western Cape, South Africa). From a cluster of 411 houses, the DRWH tanks connected to 29 houses were selected for monitoring the microbial and physico-chemical properties of harvested rainwater. Drinking water guidelines stipulated by SANS 241 (2005), DWAF (1996), ADWG (NHMRC and NRMMC, 2011) and WHO (2011) were used throughout the study to monitor the quality of rainwater. Eight sampling sessions were then conducted from March to August 2012, during a high and low rainfall period. Overall, the physico-chemical parameters of the rainwater samples were within the respective drinking water guidelines. However, the microbiological analysis verified results obtained in international studies, and showed that the indicator bacteria numbers present in the DRWH samples exceeded the stipulated guidelines (Chapter 2 and 3). Species specific primers were also used to routinely screen for the virulent genes, aggR, stx, eae and ipaH found in Enteroaggregative E. coli (EAEC), Enterohaemorrhagic E. coli (EHEC), Enteropathogenic E. coli (EPEC) and Enteroinvasive E. coli (EIEC), respectively, in the rainwater samples. The virulent pathogenic E. coli genes were then detected in 3% (EPEC and EHEC) and 16% (EAEC) of the 80 rainwater samples collected routinely during the sampling period from ten DRWH tanks (Chapter 3). Bacterial isolates selected during the high rainfall period (June to August 2012), as well as PCR assays performed on total genomic DNA extraction from the rainwater samples, confirmed the presence of numerous pathogenic bacteria including Legionella spp. Klebsiella spp. and Shigella spp. Yersinia spp. were also isolated and detected for the first time in DRWH tanks (Chapter 4). Based on the results obtained in the first phase and as many studies have indicated the poor quality of rainwater, the second phase of the project was aimed at designing and monitoring point of use treatment systems. Three polyethylene DRWH tanks (2000 L) were installed at the Welgevallen Experimental farm, Stellenbosch University, South Africa. Various treatment systems, such as activated carbon and slow sand filtration, solar pasteurization and a combined activated carbon/PVA nanofibre filtration column, were then intermittently connected to the three DRWH tanks during the high rainfall period (June to October 2013). Results for slow sand filtration and activated carbon filters indicated that the biological layer that had developed on the filtration media had not matured and for this reason chemical and microbial parameters were not reduced to within drinking water guidelines. A polyvinyl (alcohol) (PVA) nanofibre membrane without activated carbon in a column filtration system was analysed and results indicated that this system was also not effective in reducing the microbial numbers to within drinking water guidelines. Lastly, by utilising a PVA nanofibre membrane with activated carbon in a column filtration system, one litre of potable water was produced and all heterotrophic bacteria, E. coli and total coliform counts were reduced to zero and were within drinking water guidelines (Chapter 5). For the solar pasteurization system (Chapter 6), at treatment temperatures of greater than 72°C, all heterotrophic bacteria, E. coli and total coliforms were reduced to zero and were within drinking water guidelines. However, PCR assays confirmed the presence of Yersinia spp., Legionella spp., and Pseudomonas spp., at temperatures greater than 72°C. Results for chemical analysis also indicated all cations were within the international and national drinking water guidelines, with the exception of iron, aluminium, lead and nickel, which were detected in the pasteurized rainwater samples and were above the respective guidelines. It is hypothesised that these elements could have leached from the stainless steel storage tanks of the pasteurization system and it is therefore recommended that the storage tank of the pasteurization system be manufactured from an alternative material, such as a high grade polymeric material, which is able to withstand the high temperatures yet will not negatively influence the quality of harvested rainwater. / AFRIKAANSE OPSOMMING: Reënwater versameling vir huishoudelike gebruik verwys na die versameling en berging van reënwater vir huishoudelike doeleindes. In 'n poging om die Millennium Ontwikkelingsdoelwitte (MOD) te bereik het die Suid-Afrikaanse regering ‘n inisiatief begin om finansiële bystand aan huishoudings te verleen vir die implementering van reënwater tenke, in ‘n poging om ‘n addisionele water bron direk aan huishoudings te verskaf. Hoewel baie provinsies, insluitend dele van die Oos-Kaap en KwaZulu-Natal, reënwater gebruik as ‘n drinkbare water bron, is daar 'n beperkte aantal studies beskikbaar oor die gehalte van versamelde reënwater in Suid-Afrika. Baie studies internasionaal het egter al aangedui dat, alhoewel die praktyk van die versameling van reënwater besig is om in gewildheid toe te neem, die kwaliteit van reënwater nie binne drinkbare standaarde is nie (Hoofstuk 1). Tydens die eerste fase van die studie is reënwater monsters geneem van die Kleinmond Behuisings Skema (Wes Kaap, Suid Afrika). Van ‘n kompleks van 411 huise, is reënwater tenke van 29 huise geselekteer vir die monitering van die mikrobiese en fisiese-chemiese eienskappe van versamelde reënwater. Drinkwater riglyne soos gestipuleer deur SANS 241 (2005), DWAF (1996), AWDG (NHMRC en NRMMC, 2011) en WHO (2011) was regdeur die studie gebruik om die kwaliteit van reënwater te monitor. Reënwater monsters is tydens agt geleenthede geneem vanaf Maart tot Augustus 2012, tydens die hoë en lae rëenval periode. Oor die algemeen was die fisiese-chemiese parameters van die reënwater monsters binne die onderskeie riglyne vir drinkwater. Mikrobiese analises het egter die resultate van internasionale studies bevestig en het aangedui dat die getal indikator bakterieë teenwoordig in the reënwater die gestipuleerde riglyne oorskry (Hoofstuk 2 en 3). Spesies spesifieke inleiers was gebruik om die virulensie gene aggR, stx, eae en ipaH, teenwoordig in onderskeidelik Entero-aggregatiewe E. coli (EAEC), Entero- hemorragiese E. coli (EHEC), Entero-patogeniese E. coli (EPEC) and Entero-indringende E. coli (EIEC), in die reënwater monsters op te spoor. Die virulente pathogeniese E. coli gene was in 3% (EPEC en EHEC) en 16% (EAEC) van die 80 reënwater monsters, geneem van 10 reënwater tenke tydens die studie, waargeneem (Hoofstuk 3). Bakteriese isolate geselekteer tydens die hoë reenval periode (Junie tot Augustus 2012), so wel as PKR (polymerase ketting reaksie) ontledings uitgevoer op genomiese DNS wat van die reënwater monsters ge-ekstraheer was, het die teenwoordingheid van verskeie patogeniese bakterieë, insluitend Legionella spp., Klebsiella spp. en Shigella spp., bevestig. Dit is ook die eerste keer wat Yersinia spp. in versamelde reënwater waargeneem is (Hoofstuk 4). Die doel van die tweede fase van die projek was om water behandeling sisteme by die punt van gebuik te ontwerp en te monitor aangesien die resultate wat gedurende die eerste fase verkry is, sowel as vele ander studies, aangedui het dat die kwaliteit van versamelde reënwater swak is. Drie poli-etileen reënwater tenke (2000 L) was geïnstalleer op die Welgevallen Eksperimentele plaas van die Universiteit van Stellenbosch, Suid Afrika. Verskeie water behandeling sisteme, soos geaktiveerde koolstof en stadige sand filters, sonkrag pasteurisasie en ‘n gekombineerde geaktiveerde koolstof/PVA nanovesel filtrasie kolom, was met tye gekonnekteer aan verskeie reënwater tenke gedurende die hoë reënval periode (Junie to Oktober 2013). Resultate van die stadige sand en geaktiveerde koolstof filters het aangedui die biologiese laag nog nie ver genoeg ontwikkeld het nie en daarom was die chemiese en mikrobiese parameters nie verminder to binne die riglyne vir drinkwater nie. ‘n Polyviniel (alkohol) nanovesel membraan sonder geaktiveerde koolstof binne ‘n kolom filtrasie sisteem, was geanaliseer en resultate het aangedui dat hierdie sisteem ook nie die mikrobiese getalle verminder het tot drinkwater standaarde nie. Laastens, deur gebruik te maak van ‘n PVA nanovesel membraan met geaktiveerde koolstof in ‘n kolom filtrasie sisteem, was een liter drinkbare water geproduseer met alle heterotrofiese bakterieë, E. coli en totale koliform getalle verminder tot nul en was binne die riglyne vir drinkwater (Hoofstuk 5). Vir die sonkrag pasteurisasie sisteem (Hoofstuk 6), by behandelings temperature van groter as 72°C, was alle heterotrofiese bakterieë, E. coli en totale koliform getalle verminder tot nul en was binne die riglyne vir drinkwater. Maar PKR ontledings het die teenwoordigheid van Yersinia spp., Legionella spp., en Pseudomonas spp. by temperature groter as 72°C bevestig. Resultate van die chemiese analises het ook aangedui dat alle katione binne die drinkwater riglyne was, met die uitsondering van yster, aluminium, lood en nikkel. Hierdie elemente was in die gepasteuriseerde reënwater monsters waargeneem met konsentrasies wat die onderskeie riglyne oorskry het. Dit word gehipoteseer dat hierdie elemente uit die vlekvrye staal van die bergings tenk van die pasteurisasie sisteem kon uitgeloog het. Daarom word dit aanbeveel dat die bergings tenk van die pasteurisasie sisteem geproduseer moet word van ‘n alternatiewe materiaal, soos ‘n hoë graad polimeriese material, wat hoë temperature kan weerstaan maar nie ‘n negatiewe invloed sal hê op die kwaliteit van versamelde reënwater nie.

6 pp. / 1. Drinking Water Wells; 2. Private Water Well Components; 3. Do Deeper Wells Mean Better Water; 4. Maintaining Your Private Well Water System; 5. Private Well Protection; 6. Well Water Testing and Understanding the Results; 7. Obtaining a Water Sample for Bacterial Analysis; 8. Microorganisms in Private Water Wells; 9. Lead in Private Water Wells; 10. Nitrate in Private Water Wells; 11.Arsenic in Private Water Wells; 12. Matching Drinking Water Quality Problems to Treatment Methods; 13. Commonly Available Home Water Treatment Systems; 14. Hard Water: To Soften or Not to Soften; 15. Shock Chlorination of Private Water Wells / This fact sheet is one in a series of fifteen for private water well owners. The one- to four-page fact sheets will be assembled into a two-pocket folder entitled Private Well Owners Guide. The titles will also be a part of the Changing Rural Landscapes project whose goal is to educate exurban, small acreage residents. The authors have made every effort to align the fact sheets with the proposed Arizona Cooperative Extension booklet An Arizona Well Owners Guide to Water Sources, Quality, Testing, Treatment, and Well Maintenance by Artiola and Uhlman. The private well owner project was funded by both the University of Arizonas Water Sustainability Program-Technology and Research Initiative Fund and the USDA-CSREES Region 9 Water Quality Program.

The design or improvement of a biological wastewater treatment system requires the characterization of influent wastewaters, the characterization of the microbial community in the system, and a knowledge of the rates of biological reactions. The wastewater treatment system of the city of Ste-Julie (Quebec) consists of four facultative aerated lagoons operating in series. Batch reactor experiments were performed with the municipal wastewater of Ste-Julie to simulate the biological processes occurring in the lagoon system. The first, second, and third lagoons were characterized in terms of soluble BOD, soluble COD, total solids, total suspended solids, volatile suspended solids, and TOC. The influent wastewater is classified as weak wastewater containing a relatively low concentration of soluble BOD compared to total BOD. The microbial communities in the first three lagoons were characterized using the BIOLOG redox technology which allows the simultaneous testing of the populations for the utilization of 95 carbon substrates. Finally, the specific initial BOD or TOC removal rates were determined for the first three lagoons. (Abstract shortened by UMI.)