LIFE CYCLE COST ASSESSMENT OF DIFFERENT SEWAGE TREATMENT TECHNOLOGIES: A CASE STUDY

摘要

The need for the present study arouse due to the increased demand for application of higher treatment technologies for reuse/recycle of sewage meeting water demand to maintain green stretch in urban areas. In this study a comparative Life Cycle Cost (LCC) analysis of secondary treatment methods such as ASP, MBBR and SBR has been carried out for a period of 20 years at different rates of interest by assessing some treatment plants of each technology. LCC of ASP plants was found to be lower as compared to the MBBR and SBR plants. LCC analysis of five disinfection treatments was also carried out for five options, namely, chlorination, ozonation, ultraviolet (UV) irradiation, hybrid disinfection A (Cl_2/O_3) and hybrid disinfection B Cl_2/UV). Chlorine disinfection process is found to be most cost effective compared to others. Both ozone and UV have a benefit that no residuals are left after treatment, hence do not pose any toxicity risk to aquatic organisms of the receiving waters. However, due to their relatively higher cost as compared to chlorine, these processes need optimization. Hybrid disinfection A (Cl_2/O_3) and hybrid disinfection B (Cl_2/UV) strategies were evolved to avoid high doses of chlorine by adopting a two-step treatment. LCC of hybrid disinfection strategies was found to be lower as compared to Ozonation and UV treatment for 20 years at different rates of interest. On combining LCC cost of secondary and tertiary treatment, it was found that LCC of ASP followed by five disinfection strategies was more cost effective compared to similar combination with SBR and MBBR. These data would help in decision making for choosing appropriate technology for sewage treatment and reuse in the changing scenario.