Tsutomu OKUBO

Development of an energy efficient novel sewage treatment system with a combination of UASB + DHS (Downflow Hanging Sponge) reactor for developing countries -Real scale experience in India-

Hideki HARADA, Akiyoshi OHASHI


A demonstration plant of a novel aerobic biofilm reactor, which is called DHS, was constructed for polishing up the effluent from an UASB plant treating municipal sewage under YAP at a 40 MLD sewage treatment plant site in Karnal, India.

The DHS was fed daily with 1000m3 of the UASB-effluent at 0.75h HRT on the basis of sponge volume (31.1m3). The wastewater is sprinkled from a distributor arm. Each module with 2m of vertical length consists of 38-43 of series-connected hanging sponge cubes were put on two steps inside a concrete-made column.

The final effluent from DHS showed superior quality, i.e., on average, 5 mg/L for BOD and 10 mg/L for SS, respectively, which satisfactorily achieved the effluent standards in India. Removal of fecal coliform by UASB+DHS system was 1.9log. Although this result showed that our proposed system exhibits an excellent performance that is almost equivalent to that of conventional ASP, in some cases the final effluent may need further disinfection.