Performance Evaluation of a Common Effluent Treatment Plant Treating Mixed Industrial Effluents in Western India Using the Wastewater Quality Index and Statistical Analysis

In India, micro, small, and medium enterprises can send their effluent to common effluent treatment plants (CETPs) after preliminary and primary treatment. Most studies reporting the performance of a CETP or a wastewater treatment plant have considered only a few basic wastewater quality parameters. In this study, performance evaluation of a CETP receiving wastewater from diverse industries is conducted using 11 wastewater quality parameters. The wastewater quality of samples collected after primary and secondary treatment was compared with that of the equalized influent to estimate removal efficiency. Except for occasional samples collected in summer (April/May), the CETP could meet the discharge norms for all parameters, except ammoniacal nitrogen (NH4+-N) and total Kjeldahl nitrogen (TKN). Principal component analysis revealed that the first three principal components could explain 83.3% and 85.7% of the variance in the data for equalized influent and secondary treated effluent, respectively. This indicates that a few wastewater quality parameters have a strong influence on the overall wastewater quality. Pearson correlation analysis revealed a strong correlation among NH4+-N, TKN, sulfate, and total organic carbon in the influent and treated effluent. In this work, the wastewater quality index (WWQI) was applied for the first time for determining improvement in wastewater quality as a result of treatment in the CETP. The WWQI revealed the quality of influent as poor and that of the treated effluent as regular across most of the sampling events.