Performance evaluation of a sensor-based anaerobic bio-decentralised sewage treatment system for sustainable wastewater management

Decentralised wastewater treatment systems are gaining increasing attention as sustainable alternatives to conventional centralised sewage treatment plants (STPs), particularly for small to medium-scale applications. Conventional STPs as well as advanced systems such as Moving Bed Biofilm Reactors (MBBR) often involve high energy consumption, skilled manpower, complex mechanical components, and substantial operational and maintenance costs. This study presents the design, implementation, and pilot-scale evaluation of a sensor-based, fully automated anaerobic Bio-Decentralised Sewage Treatment Plant (Bio-DSTP) with a treatment capacity of 10 m³/day (10 KLD). The proposed system operates without aeration or chemical dosing and integrates anaerobic biological treatment with compact post-treatment units, including sand filtration, activated carbon filtration, and ozonation for final disinfection. A 30-day pilot-scale investigation was conducted under realistic domestic wastewater conditions, accounting for diurnal variations in flow during peak and non-peak hours. Treatment performance was assessed using key water quality parameters, namely biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The system consistently achieved significant reductions in organic pollutants and suspended solids while maintaining stable hydraulic and treatment performance, producing treated effluent that complied with the applicable Central Pollution Control Board (CPCB) standards for the monitored parameters and was suitable for non-potable reuse. Techno-economic analysis indicated approximately 90% lower operational and maintenance costs than conventional STP technologies, primarily due to the elimination of aeration, minimal sludge generation, reduced energy demand, and negligible manpower requirements. The findings demonstrate that the proposed Bio-DSTP is a compact, energy-efficient, cost-effective, and sustainable solution for decentralised wastewater treatment and water reuse.