An assessment of the quality of effluent discharged from several wastewater treatment plants into the Crocodile River of Mpumalanga, South Africa

Abstract

The effluents from the South African wastewater treatment plant systems have a detrimental effect on the country's water resources and public health. Municipal wastewater services are often considered inadequate when compared to national standards and inter-national benchmarks. The objective of this study was to evaluate the quality of wastewater effluent discharged from multiple sewage treatment facilities throughout the Crocodile River catchment area in the Lowveld. The quality of wastewater effluent was tested at nine wastewater discharge stations along the Crocodile River. Samples were collected monthly during the eight-month duration of 2021. Samples were analyzed by the South African National Accreditation System (SANAS) laboratory and statistical analysis was conducted using the Seaborn program. The results indicated that almost all the sampling sites had very high suspended solid concentrations in their effluent discharges; the highest was recorded at Kanyamazane site with 26,20 mg/L, and the lowest at Kabokweni with 7,2 mg/L. High levels chemical oxygen demand (COD) were recorded, which increased nitrate levels. High COD is an indication of water treatment system inefficiency. In most cases, the levels of E. coli were within the legal required limits, except for Kabokweni (192425)/100 mL) and Hectorspruit (1183/100 mL). R2= 0.83 showed a strong association between suspended particles and ammonia nitrogen (NH3-N). Pollution of the Crocodile River is mostly due to wastewater treatment facility failure; therefore, the South African government should invest in wastewater treatment and sludge management technology. Funds should be utilized efficiently for infrastructure development and maintenance.