Study On The Treatment Of Low Concentration Sewage In Small Towns With The Multipolar Biofilm Reactor

The object of the article is to study and exploit high efficiency,low energy consumption treating technology suitable for the low concentration wastewater of small towns, aiming at the quality characteristics of low concentration sewage, continuous multipolar biofilm reactor has been developped accordingly, nitrogen removal technics process is simplified and shortened by the means of constructing simultaneous nitration/denitration environment of microorganisms, at the same time, the critical parameters and control condition for high efficiency SND has been obtained. The biological TP removal performance of the reactor is intensified and improved by intermittent aeration and discharging sludge in good time; the stability of TP removal in low temperature can be guaranteed by adopting the combination of biological removal and physical removal by medium. Discussing the influence of organic loading rate,nitrogen loading rate,influent mode,DO,temperature on the nitrogen removal performance of the reactor, the condition parameters for treating low concentration sewage of small towns are ascertained consequently, especially for the low temperature operation in winter. Compared with the congener biofilm technologies, the referred reactor has the advantages of high performance, low investment, low running cost and convenient management. The main conclusions are described as follows:①Experiment of loading rate expresses: when the temperature is 25℃, Nv≤1.44kgCOD/(m3?d), nitrogen loading rate≤0.36kgN/(m3?d), DO = 4.0mg/L, HRT=2.0h, biofilm density=30%, the low concentration sewage of small towns in which influent COD=120mg/L,NH4+-N=27mg/L,TN=30.0mg/L can be reduced to NH4+-N=0.6～6.4mg/L,TN=10.8～19.2mg/L in the effluent, the removal rate of NH4+-N and TN is 73.3%～97.8% and 31.4%～67.1% respectively, which can achieve the acquired standard. The reactor has preferable capability for the SND.②Experiment of influent mode expresses: when the Nv≤0.36 kgCOD/(m3?d), nitrogen loading rate≤0.09 kgN/(m3?d), the respective-point influent mode should be adopted, which can advance the using rate of carbon.③Experiment of DO expresses: the optimal range of DO is 4.0 mg/L～6mg/L, the optimal DO is different with distinct loading rate and temperature.④Experiment of nitrogen removal in winter expresses: when the temperature is 5～8℃, Nv=0.48kgCOD/(m3?d), nitrogen loading rate=0.12kgN/(m3?d), DO=6.0mg/L,...