Decentralised wastewater management ─ New concepts and innovative technological feasibility for developing countries
Sustain. Environ. Res., 22(1), 39-44 (2012)
AUTHOR(S)
Murugesan Dhinadhayalan and Arvind Kumar Nema
KEY WORDS
Black water treatment, blending, grey water, water short habitations, socio-techno, economic, septic tank, upflow filter
ABSTRACT
On-site disposal methods (mostly septic tanks or pit latrines) are in use for addressing wastewater management in most of the developing countries particularly in rural, small towns and periphery areas of larger cities. The effluent from septic tank disposed without adequate treatment is violating the discharge standards thus contaminating the ground and surface water resources. Water supply in most of the small and periphery areas of large cities in developing countries is low. Generally, the water supply rate in small and periphery areas of large cities is ranging from 70 to 125 L per day person which equates to a raw sewage BOD (biochemical oxygen demand) of 560 to 800 mg L-1 (considering 80% water supply) for which conventional underground sewerage system is not feasible and there is no conventional technologies to reduce the BOD to the permissible standards. Therefore, there is a need to evolve an alternate sanitation system that would be sustainable from socio-techno-economic and environmental perspectives.
This paper documents the performance of a unique decentralized sanitation system installed in a Tsunami rehabilitation colony under such scenario. The authors present results from experiments on the treatment of black water from toilet by septic tank with upflow filter and subsequent treatment of blended wastewater by waste stabilization pond systems. The data show that the septic tank with upflow filter that treat black water, has the average COD (chemical oxygen demand) removal efficiency of 61%, BOD of 69% and that of suspended solids (SS) 85%. The data also show that the comprehensive system has the COD removal efficiency of 95%, BOD 98% and SS 99%. This paper also documents the socio-techno-economic and environmental benefits for adoptability of the system in developing countries so that this alternative can meet a sustainable wastewater management requirement especially for countries like India, where the water and sanitation issues are becoming a more and more important issue and are under new period of infrastructure development.
