Environmental and economic assessment of proposed on-site wastewater management system in multi-storey residential building Snehal V. Dewalkar and Sameer S. Shastri ABSTRACT In the present study, the concept of ‘environmental floors’ in the multi-storeyed building is proposed, where separate treatment of greywater by gravity-governed stabilization tank and blackwater by underground Malaprabha digester of the DOSIWAM (Decentralized On-Site Integrated WAste Management) system is carried out. The study evaluates the feasibility of the non-mechanised DOSIWAM system by comparing it with the mechanised activated sludge process (ASP) with the life cycle and cost assessment (LCA and LCCA) method. The LCA was carried out with the SimaPro software using the impact 2002þ method. Both systems served a multi-storeyed (G þ 30) building with 890 population equivalent. The LCA results reveal that the non-mechanised DOSIWAM system has three to six times reduced environmental impacts than the ASP system in almost all impact categories. Although DOSIWAMS’ weaker removal efficiency dominates in the results of aquatic eutrophication and acidification impact, the latter comparative economical assessment showed to be the most cost-effective alternative due to reduced land use cost, O&M cost, and benefits achieved with energy recovery in the form of biogas. The electricity and chemical consumption in the operation phase caused the highest environmental impact for the ASP system, whereas the production of clinker and steel are responsible for a detrimental impact in the construction phase of the DOSIWAM system. Key words | activated sludge process, decentralised on-site integrated waste management, impact 2002 þ , life cycle assessment, life cycle cost assessment HIGHLIGHTS • An innovative approach of wastewater management. • Concept of multi-storeyed building with environmental floors. • Separate treatment of greywater and blackwater, where every drop of liquid and every grain of solid is treated hygienically. • Land occupation and harmful environmental impacts can be well eliminated by decentralised on-site integrated waste management. • Cost effective treatment with biogas recovery. Snehal V. Dewalkar (corresponding author) Department of Civil Engineering, Sinhgad College of Engineering, Vadgaon (Budruk), Savitribai Phule Pune University, Pune, Maharashtra 411048, India E-mail: svdewalkar.sae@sinhgad.edu Sameer S. Shastri Department of Civil Engineering, Sinhgad College of Engineering, Vadgaon (Budruk), Savitribai Phule Pune University, Pune, Maharashtra 411041, India INTRODUCTION Indian metro-cities have major downsides of inadequate infrastructural facilities and land unavailability for constructing a wastewater treatment plant (WWTP). Ever- increasing wastewater quantities give rise to major environmental and health problems. As against this, the treatment facilities provided are inadequate and nearly 50% of them have outdated infrastructure (CPCB ). A centralized approach for wastewater treatment is a costly affair, comes to 10 million Rs. per million litres daily (MLD) for infrastructure development and additional oper- ation and maintenance (O&M) costs, which becomes challenging to the government day by day (CPCB ). 3003 © IWA Publishing 2020 Water Science & Technology | 82.12 | 2020 doi: 10.2166/wst.2020.548 Downloaded from http://iwaponline.com/wst/article-pdf/82/12/3003/803853/wst082123003.pdf by guest on 11 January 2021