Assessing nitrate contamination from WWTPs effluents and capacity of indigenous bacterial consortia for the in-situ complete denitrification

Title: Assessing nitrate contamination from WWTPs effluents and capacity of indigenous bacterial consortia for the in-situ complete denitrification

Abstract:

Rising levels of global pollution pose significant threats to water and land ecosystems [1]. Accumulation of ammonia (NH₄⁺) and nitrate (NO₃^-) in water lead to issues such as eutrophication and increased risks of colorectal cancer in humans and animals [2]. It is therefore crucial to develop effective solutions to mitigate these impacts from potential sources. Conventional wastewater treatment plants (WWTPs) often face resource limitations, which impair their ability to effectively remove nitrogen compounds like NH?? and NO??. This failure to fully treat primary contaminants, such as organic matter and nitrogen, leads to the release of secondary contaminants in effluent streams. Specifically, incomplete denitrification processes in these treatment plants result in elevated levels of ammonium (NH??) and nitrate (NO??), contributing to environmental pollution [3]. Biological denitrification processes facilitated by isolates or microbial consortia has proven to be efficient and sustainable alternatives to traditional chemical treatments [4], converting NO₃^_ into harmless nitrogen gas (N₂) [5]. The current research focuses on the evaluating the effectiveness of indigenous bacterial consortia enriched from WWTPs in achieving complete denitrification under in-situ conditions. Through comprehensive physio-chemical and molecular analysis, significant concentrations of NO₃^- in the WWTP effluents were found to be beyond the acceptable limits. Denitrifying bacterial consortia were enriched from water samples and subjected to denitrification kinetics in batch experiments. From initial concentrations of 500 mg/L of NO3-N, 100 % removal of both NO3 and NO2 were achieved within 24 hours when using glucose as a sole Carbon source. Alternative carbon source from brew waste was applied and optimized to lower the costs of application. Results obtained revealed that the waste was usable for bacterial growth but contributed to the surge of dissolved NO3 in the cultures. Data curated in this study will contributes to the development of greater project to tackle NO3 contamination form WWTPS in KZN and ultimately contributing to improving environmental and human health outcomes.

Keywords: Bacterial consortia, bioremediation, denitrification, environmental health, nitrate pollution and wastewater treatment.

Biography:

Dr Moloantoa is an environmental microbial-biotechnologist with over ten years of training and practice in industrial wastewater bioremediation using bacteria. He is experienced in microbiology, molecular biology, biotechnology and biogeochemistry where he has published 12 research articles and presented at 15 research conferences. Dr Moloantoa has been involved in various projects including development of water treatment bioreactors, water testing kits and biological control agents (BCAs) against plant pathogens. As an academic, he has been involved in teaching and learning for over ten years in different institutions till his appointment as a lecturer at the University of KwaZulu Natal in 2022.