Study On The Property Of Fixed Biofilm SND System In Coke Plant Wastewater Treatment

With the Wastewater discharging standards getting increasingly stricter, many new and effective Wastewater treatment processes were studied, especially in the biological denitrification field. In recent years, a lot of researchers have investigated the SND (simultaneous nitrification and denitrification) phenomena. In this paper, a fixed biofilm SND system was studied, and also the properties of biological degradation reaction rate of nitrogen removal.With a brief review on the status of Wastewater treatment process, the SND process was found to be an efficient system. Till now, however, the mechanism of SND process is not clear. A lab-scale biological reactor, in which microbe carrier packed, was studied, and the hydraulic properties of the reactor accorded the plug-flow model approximately. The experimental results showed that, for the studied process, dissolved oxygen was the most important factors for the effluent quality. Changing the operating way from non- to fully aeration, the efficiencies for the organic removal varied with 54.62%, and the optimal DO level near the inlet was 3.5-4.0mg/L. The influential degrees of the other operating parameters was, in turn, pH>HRT> COD concentration in influent. In the orthogonal test, the influence of the influent NH₄⁺ —N concentration on COD removal was relatively small; the extreme difference was 4.38%. With the optimal condition based on the orthogonal test, the average COD removal rate was about 92.44%, and the performance was stable.With regard to ammonia nitrogen removal, the results showed that the HRT should be controlled between 40.1h-56.3h in order to make the effluent concentration meet the discharge standard (<15mg/L). The removal efficiencies for COD and NH₄⁺-N were 93% and 95% respectively with the HRT around 48.4h. For coke plant Wastewater, the carbon source was usually insufficient. By adding extra methanol to the influent, the effluent total nitrogen (TN) was put down obviously. The results showed, for the Wastewater with low C/N, the extra carbon source was important, or else the biological nitrogen removal process could not be finished. The...