Research Publications (Water and Wastewater Technology)

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Application of radio-immunoassays to assess the fate of estrogen EDCs in full scale wastewater treatment plants
(Taylor and Francis, 2013) Bux, Faizal; Surujlal-Naicker, Swastika
Wastewater effluents have been documented as major contributors of hormone endocrine disrupting compounds (EDCs) in to the aquatic ecosystem. The need for rapid, simple and cost effective methods to detect these EDCs has increased. The use of Radio-immunoassays (RIA) were assessed to determine the fate of estradiol in a laboratory batch test and the three natural estrogens (estrone (E1), estradiol (E2) and estriol (E3)) in wastewater treatment plants (WWTPs) with different types of configurations. Precision of the RIAs were done using intra-assay and inter-assay validations. The E2 intra-assay variation was <8% and inter-assay variation was <11% for standards 1 to 6. E1 RIA showed less than 8% for both the intra-assay and inter-assay variations. E3 RIA showed extremely good variations with both the intra and inter-assay variations being below <8% for all standards. The lab scale investigation showed a 94% reduction in E2 after 5 h and after 10 h both E2 and E1 were no longer detected. The simple activated sludge process, the biological nutrient removal (BNR) activated sludge process and the oxidation pond had final effluent concentrations of 10.75, 5.96 and 25.48 pg E2/mL respectively; 20.80, 9.30 and 46.55 pg E1/mL, respectively, and 0.12, 0.07 and 0.17 ng E3/mL, respectively. Thus far findings indicated that the RIA can be employed as a rapid technique for detection of natural estrogens in water. Results indicate that these potential problematic hormone EDCs are still present in final wastewater effluents that are discharged in to South African aquatic sources.
Assessment of brewery effluent composition from a beer producing industry in KwaZulu-Natal, South Africa
(PSP, 2014) Enitan, Abimbola Motunrayo; Swalaha, Feroz Mahomed; Adeyemo, Josiah; Bux, Faizal
The objective of the study was to assess the physico-chemical composition and process variations of the effluent from a brewery industry located in KwaZulu - Natal, South Africa during the months of September 2011 to May 2012. The parameters monitored for the quantitative analysis of brewery wastewater include the total and soluble chemical oxygen demand (TCOD and SCOD), biological oxygen demand (BOD5), total solids (TS), volatile solids (VS), total suspended solids (TSS), volatile suspended solids (TSS), pH, ammonia (NH3), total oxidized nitrogen, nitrate, nitrite, phosphorus, electrical conductivity (EC), crude protein and alkalinity content. On the average, the TCOD and SCOD concentrations of the brewery effluent were 5340.97 and 3902.24 mg/L, respectively, with average pH values of 4.0 to 6.7. The BOD and the solids content of the effluent from the brewery industry were high indicating that the effluent is of biodegradable type. This suggests that the effluent is very rich in organics, and its discharge into the water bodies or the municipal treatment plant can cause environmental pollution or damage the treatment plant. In addition, there were variations in the effluent composition throughout the period of monitoring which might be due to the activities that take place during the production process and the effects of peak periods of beer production. Thus, there is a need for an on-site effluent treatment plant in order to reduce the high pollution of the effluent prior to its discharge to the municipal wastewater treatment plants.
A probabilistic assessment of the contribution of wastewater-irrigated lettuce to Escherichia coli O157:H7 infection risk and disease burden in Kumasi, Ghana
(IWA Publishing, 2015-03) Seidu, Razak; Abubakari, Amina; Amoah, Isaac Dennis; Heistad, Arve; Stenström, Thor-Axel; Larbi, John A.; Abaidoo, Robert Clement
Wastewater use for vegetable production is widespread across the cities of many developing countries. Studies on the microbial health risks associated with the practice have largely depended on faecal indicator organisms with potential underestimation or overestimation of the microbial health risks and disease burdens. This study assessed the Escherichia coli O157:H7 infection risk and diarrhoeal disease burden measured in disability-adjusted life years (DALYs) associated with the consumption of wastewater-irrigated lettuce in Kumasi, Ghana using data on E. coli O157:H7 in ready-to-harvest, wastewater-irrigated lettuce. Two exposure scenarios – best case and worst case – associated with a single consumption of wastewater-irrigated lettuce were assessed. The assessment revealed wastewater-irrigated lettuce is contributing to the transmission of E. coli O157:H7 in Kumasi, Ghana. The mean E. coli O157:H7 infection risk and DALYs in the wet and dry seasons, irrespective of the exposure scenario, were above the World Health Organization tolerable daily infection risk of 2.7 × 10−7 per person per day and 10−6 DALYs per person per year. It is recommended that legislation with clear monitoring indicators and penalties is implemented to ensure that farmers and food sellers fully implement risk mitigating measures.
Uptake of inorganic and organic nutrient species during cultivation of a Chlorella Isolate in Anaerobically digested dairy waste
(American Institute of Chemical Engineers, 2016-06-23) Wahal, Shantanu; Viamajala, Sridhar
A natural assemblage of microalgae from a facultative lagoon system treating municipal wastewater was enriched for growth in the efﬂuents of an anaerobic digester processing dairy waste. A green microalga with close resemblance to Chlorella sp. was found to be dominant after multiple cycles of sub-culturing. Subsequently, the strain (designated as LLAI) was isolated and cultivated in 203 diluted digester efﬂuents under various incident light intensities (255–1,100 mmoles m22 s21) to systematically assess growth and nutrient utilization. Our results showed that LLAI production increased with increasing incident light and a maximum productivity of 0.34 g L21 d21 was attained when the incident irradiance was 1,100 mmoles m22 s21. Lack of growth in the absence of light indicated that the cul-tures did not grow heterotrophically on the organic compounds present in the medium. How-ever, the cultures were able to uptake organic N and P under phototrophic conditions and our calculations suggest that the carbon associated with these organic nutrients contributed signiﬁcantly to the production of biomass. Overall, under high light conditions, LLAI cul-tures utilized half of the soluble organic nitrogen and >90% of the ammonium, orthophos-phate, and dissolved organic phosphorus present in the diluted waste. Strain LLAI was also found to accumulate triacylglycerides (TAG) even before the onset of nutrient limitation and a lipid productivity of 37 mg-TAG L21 d21 was measured in cultures incubated at an inci-dent irradiance of 1,100 mmoles m22 s21. The results of this study suggest that microalgae isolates from natural environments are well-suited for nutrient remediation and biomass pro-duction from wastewater containing diverse inorganic and organic nutrient species
Water quality modelling to assess sources and transport of pathogens within uMsunduzi catchment, South Africa
(2022-05) Ngubane, Zesizwe; Bergion, Viktor; Dzwairo, Bloodless; Troell, Karin; Amoah, Isaac; Stenström, Thor Axel; Sokolova, Ekaterina
Water quality modelling is essential to integrated water resources management and decision-making, as it improves the understanding of the spatial and temporal dynamics of chemical and microbial pollution in a river system. Understanding of the spatio-temporal dynamics of pollution and accurate prediction of its pollution hotspots are vital to improving the microbial quality of surface water. South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among rivers with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Escherichia coli (E. coli) and Cryptosporidium, chosen to represent bacteria and protozoan parasites respectively, this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT) model. SWAT uses a combination of empirical and physically based equations that use readily available inputs and enables users to study long term impacts. Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R² of 0.64 and 0.58, respectively. The SWAT module for predicting microorganism loads and concentrations in the river was used. The main faecal sources in the uMsunduzi catchment can be summarised as: wastewater treatment plant (WWTP), broken sewers in the urban area, and faecal droppings from grazing livestock. The microorganism loads from these sources were described in SWAT using data from different local water authorities and stakeholders. With respect to E. coli, the output from SWAT was compared to observed data from four points within the catchment representing upper rural, upper urban, lower urban, and lower rural parts. The output from the SWAT model showed slightly low variability, however, the trend in the SWAT model simulations followed the observed data patterns in most subbasins. The trend with Cryptosporidium was such that concentrations are higher downstream the WWTP than upstream, though insufficient data exists to compare the model Cryptosporidium output with observed data. Overall, the model microbial output showed that in rural areas, animals contribute more to pathogen loads than human sources. Human sources were more prominent in urban areas owing to the major contributions from wastewater infrastructure. The microbial output data from the SWAT model were used as input for quantitative microbial risk assessment (QMRA). Considering that not all E. coli are pathogenic, 8% of E. coli was assumed as pathogenic following various studies. The exposure routes investigated were direct ingestion of the uMsunduzi River water during recreational swimming, canoeing training, and drinking. The exposed population was categorised as children (<18 years old) and adults (>18 years old). The probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines and by the World Health Organisation (WHO).
The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.