Development of Community Sewage Treatment System Consisting of UASB and the Third Generation DHS (Down Flow Hanging Sponge) Reactor for Developing Countries
Issue: Vol.4 No.2
Authors:
Hariom Sharma (Manav Rachna International University, Faridabad)
B.B. Arora (Manav Rachna International University, Faridabad)
Rakesh Bhardwaj (Dyal Singh College, Karnal)
H. Harada (Tohoku University, Japan)
Keywords: DHS reactor, Post treatment; sewage treatment; UASB reactor.
Abstract:
Downflow handing sponge reactor (DHS) is a novel aerobic post treatment system originally developed by our research group in search of appropriate sewage treatment technology for developing countries. The principle of DHS process is similar to that of trickling filter, but suing polyurethane- made sponge material as a medium to support bacterial growth. There is no need of external forced aeration, because the sponge material is exposed to ambient air. This paper presents process performance of the combined system of UASB and DHS G3 and evaluates the potential of the proposed combination of UASB and DHS as a sewage treatment system, especially for developing countries. A third generation Downflow Hanging (DHS) reactor has been developed and proposed as an improved variant of post treatment system of UASB treating waste water. A pilot scale UASB and DHS was installed in a municipal sewage treatment site and constantly monitored for one year. UASB was operated at an HRT of 6h corresponding to an organic load of 2.15kg-COD/m3 per day. Subsequently, the organic load in DHS was 2.35kg-cod/m3 per day, operated at a HRT of 2h. Organic removal by the whole system was satisfactory, accomplishing 96% of unfiltered BOD removal, However, nitrification decreased from 56% during the startup period to 28% afterwards. Investigation on DHS sludge was made by quantifying it and evaluating oxygen uptake rates with various substrates. Average concentration of trapped biomass was 26g-VSS/ L of sponge volume, increasing the SRT of the system to 100-125d. Removal of coliforms obtained was 3-4 log10 with the final count of 103 to 104 MPN/100ml in DHS effluent.
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