Feasibility study of nitrogen removal with the mecellulose wasted liquor as an external carbon source in the two-stage denitrification process.

The utilization of mecellulose wasted liquor (MWL) as an external carbon source was investigated to find an alternative for methanol in the two-stage denitrification pilot process. The pilot plant was supplied with the raw water from the J-Municipal Sewage Treatment Plant (J-MSTP) in Korea. The raw water of J-Municipal Sewage Treatment Plant contains low and high concentration of biodegradable organics and nitrogen source, respectively, due to the inflow of industrial wastewater and landfill leachate. Methanol was fed to provide external carbon source for high concentration of nitrogen source removal by denitrification in this J-Municipal Sewage Treatment Plant, and thus this study was performed to test effects to the effluent quality and efficiencies of nitrogen source removal with an alternative carbon source for the cost reduction. The 6.5mg 1(-1) and 5.7mg l(-1) of total nitrogen (TN) concentration in the effluent were achieved with mecellulose and methanol, whereas mecellulose and methanol were fed to give the same ratio of gCODgNO,-N(-1), respectively. The 60% of COD in mecellulose wasted liquor was used as a carbon source for denitrification and the stable denitrification rate was earned when one half of the required total carbon source for denitrification was fed to pre-anoxic tank in the pilot plant. The required gCODgNO,-N(-1) ratio with mecellulose wasted liquor was 1.4 times higher than with methanol. Mecellulose wasted liquor is feasible to be used as external carbon source for organic loading, nitrogen and phosphorus removal. If mecellulose wasted liquor is considered as an alternative external carbon source to substitute methanol 26-28m3 mecellulose wasted liquor per 1 m3 methanol will be required. However, to meet with the effluent standard (10 mg BOD l(-1)) for J-Municipal Sewage Treatment Plant, the feed concentration of mecellulose wasted liquor should be recommended to be lower than 200 mgl(-1).