Efficiency evaluation of sewage treatment plants with different technologies in Delhi (India) Priyanka Jamwal & Atul K. Mittal & Jean-Marie Mouchel Received: 11 November 2007 / Accepted: 14 April 2008 / Published online: 25 June 2008 # Springer Science + Business Media B.V. 2008 Abstract Physical, chemical and microbiological effi- ciencies of Sewage Treatment Plants (STPs) located in Delhi’ s watershed in context of different treatment technologies employed in these plants have been determined. There were in all seventeen STPs treating domestic wastewater which were studied over a period of 12 months. These STPs were based on Conven- tional Activated sludge process (ASP), Extended aeration (Ex. Aeration), physical, chemical and biolog- ical removal treatment (BIOFORE) and oxidation pond treatment process. Results suggests that except “Mehrauli” STP which was based on Extended aeration process and “Oxidation pond”, effluents from all other STPs exceeded FC standard of 10 3 MPN/ 100 ml for unrestricted irrigation criteria set by National river conservation directorate (NRCD). Actual inte- grated efficiency (IE a ) of each STP was evaluated and compared with the standard integrated efficiency (IE s ) based upon physical, biological and microbiological removal efficiencies depending upon influent sewage characteristics. The best results were obtained for STPs employing extended aeration, BIOFORE and oxidation pond treatment process thus can be safely used for irrigation purposes. Keywords Wastewater treatment plants . Efficiency . Activated sludge process . Fecal coliform . Fecal streptococcus Introduction River Yamuna, which drains an area of approximately 1483 km 2 , is the main watercourse through Delhi. The river has instigated deterioration in its water quality through the course of time. To improve the quality of river water, government of Delhi in 1993, started Yamuna action plan (YAP 2006a), under which number of Sewage Treatment Plants (STPs), aerobic as well as anaerobic were upgraded and constructed. Design of STPs was based upon TSS (Total suspended solids) and BOD 5 (Biochemical oxygen demand) removal, whereas the removal of Fecal Coliforms (FC) and pathogens was not considered. Based upon these parameters sixteen up-flow anaer- obic sludge blanket reactors (UASBR) were con- Environ Monit Assess (2009) 153:293–305 DOI 10.1007/s10661-008-0356-9 P. Jamwal Environmental Engineering Laboratory, Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India A. K. Mittal (*) Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India e-mail: akmittal@civil.iitd.ac.in J.-M. Mouchel Cereve, Ecole Nationale des Ponts et Chaussées, Champs sur Marne, Marne la vallée, Paris 77455, France