Assessing the Physiochemical Parameters and Reduction Efficiency from Two Typical Wastewater Treatment Plants in the Vhembe District in South Africa

The primary sources of widespread pollution in most river catchments are improperly treated final effluents from various wastewater treatment plants (WWTPs), affecting the physicochemical characteristics of the receiving water bodies. Wastewater discharge must be monitored regularly to ensure compliance with national and municipal water quality regulatory/standard restrictions. This study monitored the physicochemical parameters of two typical WWTPs (WWTP A = a peri-urban plant and WWTP B = a rural plant) for 5 months. The physicochemical parameters that were assessed included pH, temperature, total dissolved solids (TDSs), turbidity, chemical oxygen demand (COD), alkalinity, dissolved oxygen (DO), free chlorine, chloride, sulphate, phosphate, ammonium, and electrical conductivity (EC). The evaluation yielded the following results: temperature (14 to 21 °C and 14 to 23 °C), pH (7.2-8.2 and 7.3-8.4), EC (90-800 μs/cm and 80-750 μs/cm), TDSs (65-440 and 55-410 mg/L), alkalinity (2.6-20.9 mg/L), nitrate (0.24-26.5 mg/L), nitrite (0.01-90 mg/L), phosphate (0.0-18.0 mg/L and 0.0-21 mg/L), ammonia (0.2-75 mg/L and 0.8-70 mg/L), sulphate (0.0-18.0 mg/L and 0.0-21 mg/L), chloride (5.0-22.0 mg/L and 2.0-25 mg/L), COD (6.0-710 mg/L and 7.0-800 mg/L), and turbidity (0.4-150 NTU and 1.8-130 NTU) for wastewater treatment A and B, respectively. The results also showed that temperature, pH, TDSs, nitrite/nitrate, chloride, turbidity, alkalinity, sulphate, and free chlorine were among the parameters in the final effluent discharged that met the set guidelines. In contrast, parameters such as COD, EC, phosphate, and ammonia did not meet the guideline values for most of the sampling period for both WWTPs. Furthermore, this study found that WWTPs reduced nitrate, sulphate, phosphate, and COD pollutants by more than 90% while maintaining 60% alkalinity. Temperature, pH, TDSs, EC, Cl^-, and other parameters were less than 40% for WWTP A and roughly less than 50% for WWTP B.