Case study on evaluation of the performance of waste stabilization pond system of Jodhpur, Rajasthan, India

Abstract

The objective of this study is to find out physico-chemical and microbiological characteristics of influent and effluent generated by the sewage treatment plant of Jodhpur city. The treatment plant was constructed in the year 2003–2004 and based on waste stabilization pond (WSP) system. The treatment capacity of the plant is 45 ML/d. Relationship between different physico-chemical and microbiological parameters were studied. After the treatment of wastewater in WSP, average removal of BOD, COD, TSS and TKN were 84.1, 53.4, 79.7 and 61.7% respectively. Average removal of Total Coliforms (TC), Fecal Coliforms (FC), E. coli and Fecal Streptococci (FS) were 2.79 logs, 2.47 logs, 1.65 logs and 1.58 logs respectively. Maximum efficiency of fecal bacteria removal was found during the summers (2.7 to 4.0 log units) and minimum in winters (1 to 1.8 log unit). Further correlation of temperature, pH and biological oxygen demand with TC, FC, E. coli and FS were studied. Among all these parameters temperature shows highest correlation with microbiological parameters as follows: TC (−0.85), FC (−0.62), E. coli (−0.65) and FS (−0.75). High ambient temperature, long photoperiod and high intensity of light can be considered as the major factor for the removal of fecal indicators during the sewage treatment. After treatment pH, BOD, COD, TSS and TKN were found within the permissible limit of Central Pollution Control Board, India. The observed values of fecal indicator organisms are higher than the permissible limit of World Health Organization (WHO). There are no maturation ponds in the treatment plant; construction of maturation ponds will provide better removal of fecal coliforms.