The impact of inadequate wastewater treatment on the receiving water bodies – Case study: Buffalo City and Nkokonbe Municipalities of the Eastern Cape Province

Abstract

The performance of four wastewater treatment plants that serve the Buffalo City (Dimbaza, East London) and Nkokonbe (Alice, Fort Beaufort) Municipal areas in the Eastern Cape Province of South Africa was investigated for the removal of microbial and chemical contaminants. Statistical evidence showed a relationship between the quality of the final effluent and that of the receiving water body and the relationship was such that the better the quality of the final effluent, the better the quality of the receiving water body. The quality of both the effluents and the receiving water bodies was acceptable with respect to the temperature (mean range: 16.52 to 23.33‹C), pH (mean range: 7.79 to 8.97), chemical oxygen demand (COD) (mean range: 7 to 20 mg/.) and total suspended solids (TSS) (mean range: 161.43 to 215.67 mg/.). However, in terms of the nutrients (orthophosphate - mean range: 3.70 to 11.58 mg/. and total nitrogen - mean range: 2.90 to 6.90 mg/.) the effluents and the receiving water bodies were eutrophic. The dissolved oxygen (DO) (mean range: 3.26 to 4.57 mg/.) and the biological oxygen demand (BOD) (mean range: 14 to 24 mg/.) did not comply with the EU guidelines for the protection of the aquatic ecosystems. The general microbiological quality of the effluents discharged from all the plants did not comply with the limits set by the South African authorities in respect of pathogens such as Salmonella, Shigella, Vibrio cholera and coliphages. The effluents discharged from the Dimbaza, East London, Alice and Fort Beaufort wastewater treatment plants were identified as pollution point sources into their respective receiving water bodies (Tembisa Dam, the Nahoon and Eastern Beach which are part of the Indian Ocean; the Tyume River and the Kat River).