Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: William Ritter, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2020 / The pressing state of South Africa’s freshwater resources due to pollution from the release of raw sewage or poorly treated domestic wastewater, has resulted in the urgent need for the implementation of innovative ways to mitigate this problem. A proposed solution by the Council of Science and Industrial Research (CSIR) is to introduce different cultures of algae in wastewater treatment ponds where facilities have aged and become dilapidated. In turn fish are introduced into sewage maturation pond treated with algae to reduce algal biomass. The assumption being that if fish can survive under these conditions, the nutrients assimilated will be converted into fish biomass when ingested, in an attempt to decrease aquas nutrient loads. The aim of the study was to assess the health and survival of Oreochromis mossambicus exposed to wastewater from the Motetema wastewater treatment plant (WWTP) and to establish the extent to which this species consumes micro-algae within the water column. The aim was accomplished by assessing the consumption of algae by O. mossambicus based on algal cell density counts in fish aquaria and to establish the feeding ratio of fish based on stomach content fullness as well as to monitor the survival rate of O. mossambicus exposed to various concentrations of sewage water over a 96-hour period. To establish fish survival under wastewater conditions, a 96-hour experiment was conducted in glass tanks (60 L), whereby the health and mortality of O. mossambicus exposed to different concentrations of domestic wastewater from Motetema WWTP was investigated. One set of aquariums supplied with compressed air via the use of diffusers while the other set of aquariums were void of aeration so as to simulate conditions at the treatment plant. Treatments comprising of four concentrations of 25, 50, 75 and 100% wastewater and a control of 0% were used. Water quality parameters were monitored every four hours and mortalities were recorded. Water samples were collected twice a day and sent to Capricorn Veterinary laboratory for nutrient analysis. Gill samples were also collected and sent to Onderstepoort Veterinary Institute for histological sections analysis. To assess the consumption of algae, 18 tanks (60 L) were set up in the laboratory, whereby three aquariums served as a control void of algae with the remaining tanks dosed with two algal species (Chlorella vulgaris and Chlorella protothecoides) of concentrations of 33%, 66% and 100%, over a period of ten days. Counts of algal density before and during the course of the experiments were done using a handheld flourometer. Upon mortalities and on the fifth day, fish were randomly selected from fish tanks, euthanised and stomach contents analysed. The stomach of fish was rated based on the percentage fullness and categorised as being empty, ¼ full, ½ full, ¾ full, full or gorged. When mortalities occurred, fish were dissected and their stomach contents analysed for fullness. Upon completion of the trial, two fish per treatment were euthanised and their stomach contents evaluated for algal consumption. Fish remaining at the end of the fish trial were counted and weighed to calculate the weight gain and specific growth rate. Survival rates were also determined. Water quality parameters were monitored three times a day over the duration of the trial. Water samples were collected every second day and send to Capricorn Veterinary laboratory for nutrient analysis. All mortalities were recorded over the duration of the trial period. In exposure and survival trials, physico-chemical parameters of water from the experimental tanks were within the acceptable limit for the growth and survival of O. mossambicus, except for dissolved oxygen and ammonia concentrations. Ammonia levels and mortality rates were significantly higher (p< 0.05) in treatments with wastewater, with ammonia levels exceeding those considered toxic for O. mossambicus. High ammonia concentrations resulted in definite histopathological changes in the gills as well as fish mortalities. After exposure to wastewater moderate signs of aneurism of the gill lamella, mild epithelial lifting, focal hyperplasia and clubbing of the terminal end of the secondary lamellae were recorded. Lesions are explained as a defence mechanism where gills increase the distance between the external environment and the blood, thus serving as a barrier to the entrance of the contaminants. Furthermore, results indicated that effluent levels >25% were detrimental to the fish. Fish survival decreased when exposed to effluent water, with higher number of mortalities recorded in tanks with no aeration. A 100% survival was observed in tanks with 25% treated wastewater in both aerated and non-aerated aquariums. The presence of fish mortalities in treatments >25 domestic wastewater shows that conditions at Motetema WWTP will be unfavourable for fish. Thus, results from the study indicate that domestic wastewater would need to be diluted to less concentrated levels to ensure the survival of fish and mechanical aerators needs to be deployed to increase oxygen levels in treatment ponds. Water quality parameters for the second set of experiments fell within the recommended range for the growth and survival of fish. However, low oxygen levels were recorded from the control group with minimum values of 1.8 mg/l and maximum concentrations of 3.6 mg/l. Furthermore, temperature and pH ranges recorded during this study fell within the desired range for growth and reproduction of Chlorella vulgaris and Chlorella protothecoides. Nutrient concentration (phosphates, sulphates and nitrate) for this study were low, however ammonia and nitrite were above the acceptable level for fish growth and survival. The presence of fish resulted in increased levels of ammonia. High ammonia levels were not mitigated by algae in the tanks. However, the high ammonia levels decreased with the increasing number of fish mortalities. There were slight decreases in chlorophyll-a concentrations over the study period, from tanks comprising of algae and, tanks comprising of algae and fish. Decreases in chlorophyll-a concentrations in tanks with fish were linked to consumption of algae by the fish. This was verified by the presence of algae in the stomach of fish euthanised during and at the end of the experiment. In tanks without fish, decreases in chlorophyll-a concentrations could be attributed to plankton die offs, as aquariums had algae that had settled at the bottom of the tanks. Although, consumption of algae by fish was observed in this study, no full stomachs were recorded over the experiment period. Tanks with 66% algal concentrations had low survival rates. Better survival was observed from treatments with 33% algal concentrations. Toxic secretions could have attributed to the high mortality rate or low survival rates during the study period in tanks with 66% and 100% algal concentrations. In addition to this, ammonia and nitrite values that were above tolerable limits for fish could have also contributed to the high mortality rates (>80%). The use of fish in the tanks as a means to assimilate the algae, seemed to have an opposite effect than the desired one. As the presence of fish in tanks increased ammonia levels, therefore, the effluent would need to be further treated before it can be re-used or released into the environment. Further experiments would need to be conducted to establish whether negative influences could be neutralised, when other species such as Scenedesmus spp. are used together with Chlorella spp. for the treatment of wastewater, in order to make the environment suitable for fish survival. / DSI-NRF SARChI Chair (Ecosystem Health), Flemish Interuniversity Council (VLIR-OUS)

Wastewater treatment facilities, due to design practices and physical location, may be highly vulnerable to flooding. The implementation of flood proofing and flood damage reduction measures can reduce the economic losses and environmental impacts of a flood. Effective training and guidance is currently unavailable from the Virginia regulatory agencies. The Commonwealth of Virginia Sewerage Regulations contain the fundamental principle of avoiding construction within the 100-year flood plain. However, information is not included to discuss flood damage reduction measures or flood protective design standards. The Division of Water Programs within the Virginia Department of Health currently has an internal memorandum to govern their response to flood damaged facilities. The memorandum is general in nature with a limited discussion of assistance to wastewater treatment facilities. Specific flood damage reduction training is currently unavailable within the Virginia Department of Health. This research is intended to provide the necessary material to a) update current regulations and b) establish the basis of a training manual for use during presentations, seminars, and daily activity of regulatory engineers. / M.S.

Lime-stabilized and chemically-fixed sludges have been inadequately characterized for utilization as amendments to acid soils. Laboratory incubation studies were employed to evaluate calcium carbonate equivalence (CCE) and nitrogen (N) mineralization rates of these sludges when applied to three acid Typic Hapludults from Virginia. Greenhouse studies were conducted to evaluate the effect of increasing sludge application rates on growth of corn. The CCE of the lime-stabilized and chemically-fixed sludges were 30. 9 and 58.1%, respectively. Application of sludges to soils resulted in rapid neutralization of soil acidity. Added organic-N was mineralized at an average rate of 32% in surface soils. Based on N mineralization, application rates of lime-stabilized and chemically-fixed sludges will be limited by CCE for most soils. Corn yields on the Glenelg and Tatum soils were improved by addition of the sludges and remained within 95% of maximum at 118 and 160%, respectively, of the rate predicted to raise soil pH to 6.5. Zinc deficiencies were induced at the highest sludge application rates. Corn yields were higher when soils were amended with lime-stabilized or chemically-fixed sludges than when amended with CaC03 because the sludges contained Zn and other nutrients. Lime-stabilized and chemically-fixed sludges are good sources of lime which will supply N at the rate of approximately 32% of applied organic-N but overapplication of these sludges to meet the N needs of corn will probably result in Zn deficiency on all but the most acid soils. / M.S.

Two field sites with soil limitations, supported by column and laboratory studies, were used to evaluate spray irrigation as an alternative methodology for onsite wastewater treatment and disposal. The first site was located in Montgomery Co., VA on a Chilhowie soil (very-fine, mixed, mesic Typic Hapludalf) and the second was located in Alleghany Co., VA on a variant of the Monongahela series (fine-loamy, mixed, mesic Typic Fragiudult). Secondary pretreatment and disinfection of the effluent was performed before application through a slow rate spray irrigation system to the soil-plant system. Effluent application rates were based on the hydraulic and N assimilative capacities of the soil-plant system. Effluent applications of 1.25 and 2.5 cm wk⁻¹ were examined at both sites. After 20 months of effluent application at the Montgomery Co. site and 12 months of application at the Alleghany Co. site, adequate wastewater renovation was occurring in both sites. Water analyses at the 60 cm depth showed no potential groundwater contamination problems. Significant increases in chloride concentrations and EC measurements in the subsurface waters at both sites along with little or no increases in nitrate, ammonium, or phosphorus levels indicated that the effluent was being renovated as it percolated vertically through the soil profile. Runoff water quality measurements from the spray irrigation sites indicated no serious threat to nearby surface waters. Proper filtration of the sheet flow along with the relatively low loading rates, contributed to the good quality of runoff waters in both winter and summer seasons. Plant tissue analysis indicated that plant uptake of N was a large N sink during the growing season. Denitrification column studies examined the effect of different effluent application frequencies. There were no differences between irrigation frequencies in the amount of nitrous oxide accumulated after 24 h except in columns that were suspected to contain pockets of carbon particulates which contributed to high denitrification activity. Single daily effluent applications produced extended periods of low N₂O emissions, while more frequent effluent applications produced short periods (1-3 h) of rapid N₂O emission rates immediately after effluent applications. The denitrification capacity of the soils was shown to be limited by both C and NO₃-N. Results from the denitrification column studies suggested that there is potential for optimizing N loss in spray irrigation systems by maintaining effluent in the microbially active topsoil through proper effluent application frequencies. Both the field and column studies demonstrated that acceptable renovation of surface applied effluent by slow rate spray irrigation systems on sites with soil limitations can be obtained. / Ph. D.

A research project report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering (Civil Engineering). Vanderbijlpark, 2016 / South Africa is a semi-arid country with an average rainfall of 450 mm per annum. According to the Department of Water Affairs, the total registered water usage in 2013 met the estimated 2025 high water requirement of 17.3 billion m3/annum. Therefore, the need had arisen to reduce water consumption and increase water supply to ensure the sustainability of our nation’s water resources. Many studies show that wastewater reuse or water reclamation is an under-utilized and very viable water conservation concept in South Africa. The reuse of wastewater for direct potable or direct non-potable reuse is a highly debated topic requiring frequent engagement and investigation. Although direct reuse for potable uses is often more contentious than direct reuse for non-potable uses, it is worth investigating for possible future implementation at certain water scares areas. Hence, this study investigated the possibility of the future implementation of direct wastewater reuse at Hartbeesfontein - a selected South African community, for potable or non-potable use. The study incorporated potential users’ perceptions, the cost implications of reuse and water saving potential by means of different water balance models. The survey conducted, measuring the intention of the residents from Hartbeesfontein to accept direct wastewater reuse for potable and non-potable use, revealed the community’s overwhelming acceptance (about 70%) of a reuse system should it be implemented in the future. The community’s preference for wastewater reuse for non-potable use (75%) was higher than for potable use (67%). Hypothetically, it would be possible to reuse 85% of the community’s daily demand for potable use, if all the wastewater collected at the wastewater treatment plant could be treated. It would then mean that the municipality will only need to provide 15% of the daily water demand. The option to reuse wastewater for non-potable use (i.e. to supply an industry) could save the community 22% its daily water demand. In this study, the cost of wastewater treatment for potable use was approximately 350% higher than the cost of potable water supplied by the Midvaal Water Company. The cost of treating wastewater for non-potable use however was approximately 46% less than the cost of potable water supplied by the Midvaal Water Company. By incorporating the outcomes of the water balance, perceptions of the community and analysis of the different wastewater reuse scenario costs, it was evident from the study that direct wastewater reuse for non-potable industrial application was the most viable water reuse option for Hartbeesfontein. / MT2017

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2016 / Horizontal subsurface flow constructed wetlands (HSSF CWs) are being considered in South Africa as an alternative waste water treatment technology which is low in capital costs and typically requires less operational infrastructure when compared to conventional treatment technologies. HSSF CWs may thus be a potential solution for solving the challenge of ensuring reliable access to clean water for rural communities whose municipalities may not be able to afford the construction of a waste water treatment plant as well as not being able to supply sufficient technical expertise for the operation thereof. Proper design of HSSF CWs requires a detailed investigation into the hydraulic behaviour as it has a direct effect on the treatment performance in these systems. In this study, three available hydraulic modelling methodologies for HSSF CWs were compared and these are the impulse, step change integral and step change derivative modelling methodologies. Hydraulic data were generated from planted and unplanted pilot scale HSSF CWs using residence time distribution (RTD) studies and the modelling results using each methodology were compared. It was found that each methodology was capable of suggesting a different hydraulic behaviour for the same system being studied and since it is not possible to evaluate an analytical answer to the problem independently it was not possible to determine which modelling methodology was the most accurate. Practical limitations of the experiments used to feed hydraulic data to the respective methodologies were also highlighted. Despite a well-designed sampling regime it was not possible to capture sufficient data surrounding the peak of the impulse response curve and may have impacted negatively on the modelling results. No such difficulties were encountered with the step change tracer experiments. The mathematical techniques which each methodology employs were also critically assessed. It was found that numerical differentiation in the step change derivative modelling approach introduced noise into the RTD curve and may have affected subsequent results. Ultimately each methodology has its own associated strengths and weaknesses and choice of methodology may be dictated by other factors such as cost to set up the hydraulic experiment as well as equipment availability. Tasks two and three of this dissertation dealt with how Biomimicry can be used as a tool to develop more sustainable HSSF CW designs and hydraulic modelling processes. In task two, hydraulic data generated from the first task were used to develop estimates of the velocity profiles inside a planted HSSF CW to identify regions most prone to clogging, a phenomenon which would be a serious concern for rural communities whose sole water treatment system would be the CW. Biomimetic design principles were combined with the modelling results to develop a modular system design allowing for sections of the CW to be removed for cleaning while still allowing for continuous treatment of the waste water. Task three explored the use of heat as a hydraulic tracer. Heat is considered more environmentally friendly when compared to chemicals as tracers as the CW can equilibrate to ambient conditions post study and the effluent does not require dedicated disposal infrastructure. Heat is non-conservative in these systems and processes such as absorption by the subsurface media and loss to the surroundings distort the hydraulic response curve from which the hydraulic behaviour cannot be directly obtained. In this study a mathematical model was developed which maps a heat tracer response curve to one which would be obtained if a conservative chemical tracer were used. It was tested by conducting a combined heat-chemical tracer study on an unplanted laboratory-scale HSSF CW and the predicted chemical response curve was compared with the actual experimental response curve. The model performed satisfactorily indicated by a 5% and 6% relative difference in the Peclet number (Pe) and mean of the RTD respectively. In each of these chapters, an abstract is provided which summarizes the main findings of the study. / MT2017

Land application of industrial wastewater with high levels of nitrogen requires adequate management practices to prevent groundwater pollution by nitrates. In this study a predictive computerized model was developed for nitrate leachate concentrations resulting from land application of wastewater onto crop systems including poplars. The study included a literature review, development of a computer program that could serve this purpose, and a field investigation to test the validity of the computed predictions. The literature review focused on poplar water and nitrogen uptakes, and suggested that mature poplars could uptake up to 400 lb of nitrogen /acre/year and 2 3 million gallons of water per acre per year. The computer model, based on 10-day water and nutrient balances, takes into account a number of parameters such as wastewater quality, evapotranspiration and precipitation data, irrigation volumes, soil water holding capacities, fertilization, crop nutrient uptakes and crop coefficients. This study involves a number of assumptions selected to give conservative (i.e., worst case approach) model predictions. Attempts to validate the model were conducted through soil and groundwater sampling along with precipitation data collection in four distinct fields in Brooks, Oregon, from October 1996 to April 1997. The variations in nitrogen soil profiles from October to April helped determine the amount of nitrogen leaving the soil, and groundwater samples from 5 feet deep wells gave nitrate concentrations in groundwater below the root zone. A sensitivity analysis of the program demonstrated how important nitrogen and water uptakes values were to the model predictions. An increase of 1% in nitrogen uptake or of 0.4% in crop coefficients generated 1% decrease in nitrogen concentration of the leachate. These results are important to consider when adopting highly uncertain literature values for crop uptakes -especially with poplars. The field validation of the model showed promising results in terms of estimating average yearly leachate concentrations in nitrogen resulting from land application of wastewater, but also suggested that more groundwater wells were needed to obtain a statistically significant validation of the model. These preliminary field results indicate that the model can provide an indication of groundwater nitrogen concentration trends but needs to further verified to be used confidently as a predictive tool. / Graduation date: 1998

In Manitoba there are an estimated 200 small and 10 large wastewater treatment systems contributing nutrients to surface water when effluent is discharged. The objective of this study was to assess the sustainability and social acceptance of wastewater irrigation in the southeast Interlake region. It was concluded that sustainably irrigating forage crops would be challenging. The combination of soils with only ratings of fair for irrigability and the low quality of wastewater limits the long term sustainability of irrigation. Only one study site maintains a high potential to develop a wastewater irrigation program due to sufficient suitable land and appropriate wastewater quality. The social acceptance of wastewater irrigation is mixed with only about half the survey respondents favourable to irrigation or reuse of wastewater.

Many soils are marginally suited for installation of on-site wastewater disposal systems. With soil limitations, additional wastewater treatment prior to soil application may allow for a reduction in soil depth. Undisturbed 20-cm-diameter soil columns (fine loamy, mixed, mesic Typic Hapludult), in a factorial arrangement between depth of soil (15, 30, and 45 cm) and type of effluent (septic tank, constructed wetlands, and recirculating sand filter), were used in this study. Effluent (670 cm³/d) was applied 6 times daily. Additional treatment of septic tank effluent by a constructed wetland and a recirculating sand filter resulted in 30 and 70% higher average soil infiltration rates, 92 and 96% reduction in fecal coliforms, 34 and 44% reduction in total nitrogen, and a 60 and 94% reduction in BOD₅, respectively. Fecal coliforms were present only in soil leachate from the 15 and 30 cm soil depths receiving septic tank effluent and the 15 cm depth that received constructed wetland effluent. Average soil leachate NO₃⁻-N concentrations were 19, 10 and 14 mg/L from soil columns receiving septic tank, constructed wetland, and recirculating sand filter effluents, respectively. Soil leachate contained <5 mg/L TKN and 1.8 mg/L NH4⁺-N. Total nitrogen losses were 55, 73, and 66 for the septic tank, constructed wetland, and recirculating sand filter treatments, respectively. BOD₅ averaged less than 4 mg/L in the soil column leachate, despite a 10 fold difference among influent types. In comparing the 1993 and 1994 growing seasons, average plant tissue dry weight, percent nitrogen, and percent phosphorus were greater during the 1994 growing season. The results from this study indicate that additional treatment of septic tank effluent can be substituted for soil depth. / Master of Science