Research Of Nitrogen Removal From Urban Sewage Treatment Plant Effluent Using Denitrification Filter Filled With Bamboo Charcoal

In this research,one of wheat straw,reed,corncob is choosen as carbon source and adsorption material bamboo charcoal is choosen as the media of denitrification filter for advanced nitrogen removal from urban sewage treatment plant effluent.And denitrification characteristics of corncobs are studied.The experimental results are as follows:(1)COD release rules of wheat straw, reed, corncob all accord to double reciprocal relationship with the simulated equation 1/c=0.0207/t+0.0239, 1/c=0.3498/t+0.1435, 1/c=0.0595/t+0.0129,respectively. Corncob is an excellent material for carbon source with great potential and sustained release of COD.(2)It is feasible to hang membrane in denitrification filter filled with bamboo charcoal by way of inflow continuously according to the design load. The results showed that when C/N=4~5, HRT=2h, room temperature maintained at 20℃, the biological membrane can mature after 13 days, average NO3--N removal rate was over 80%.(3)The treatment effect was determined with different parameter values of amount of corncobs, hydraulic retention time, volume loads conditions of COD and NO3--N when artificial wastewater was used as inflow,corncob vessel and bamboo charcoa denitrification filter in series was used as reactor.When COD influent concentration is 20~60mg/L, NO3--N influent concentration is 15~30mg/L, hydraulic retention time is 1~4h, the reactor effluent nitrogen concentration is below the limit of the level of 15 mgL. Under stable operation condition, the reactor’s maximum volume loading of total nitrogen was 0.585 kg/(m3?d).(4)According to COD and NO3--N balance of in series reactor, 4.77 g corncob is demanded to remove 1g NO3--N and 2.01 g corncob is demanded to release 1g COD. The biofilm’s morphology of corncob and bamboo charcoal were characterized by scanning electron microscopy.It is found that coccus and shortrod bacteria spreaded closely on corncob’s biofilm while filamentous coccus and shortrod bacteria spreaded on bamboo charcoal’s biofilm. Presumably, coccus and shortrod bacteria observed are Micrococcus, Pseudomonas, Chromobacterium that of denitrificans.(5)Microorganisms and NO3--N both have a positive effect on corncob’s TOC release rate, and the release is related to NO3--N concentration. Optimal temperature and pH for corncob’s denitrification are 30 ℃ and 7.8,respectively.The maximum denitrification rate is 5.80 mgNO3--N/(gSS?h) when corncob acts as the solid carbon source and the biofilm carrier.