Design, development and performance evaluation of skid-mounted pilot wastewater treatment and resource recovery unit for mechanical scavenging vehicle

Abstract

The current work is an effort towards developing a sustainable solution towards the obnoxious practice of manual scavenging of the drainage pipelines and clogged pits in the developing countries. Here, a skid-mounted system has been developed and tested that works both as wastewater treatment and recovery unit and also for recovery of valuable nutrients that further has economic value. The initial bench scale work was carried out in two different approaches: the first targeting to a sequential process of separating the N, P in the form of struvite as a nutrient rich bio-cake followed by treatment and recovery of the supernatant liquid through AOP. The second approach intended to initially reduce the solid content of the effluent through coagulation followed by separating the nutrient laden liquid and treatment by AOPs to degrade the organic. Under the optimized condition of pH 9.5, Mg:P:NH₄ at 1.1:1:1 and 20 min, maximum recovery of the nutrient was achieved. The results obtained from ozone based AOP was improved by combining a venturi-based cavitation device under optimized geometric and operating condition. Both the nutrient rich bio-cake obtained from degraded sludge in a rotating hydrodynamic cavitator as well the nutrient rich water was used as the fertilizer for studying the plant growth rate and compared with commercial fertilizer. The techno-economic study indicates that $ 0.22/m³ as operational cost for treatment and recycling of sewage wastewater using the developed skid mounted device reveals techno-economic viability and self-sustainability of the process.