The Research On EM-Vermiculite Media Biological Aerated Filter For Dealing With Wastewater From The City District

Wastewater from the city district is one of the main sources of the water body pollution. With the rapid development of the urbanization process, the wastewater emissions has increased year by year. A great deal of this kind of sewage which has not been treated or without reaching the sewage discharge standard directly drains into natural water body, which causes water environmental quality more and more worse. Therefore, according to the national conditions of our country, researching and developing small-scale integrated sewage disposal system which is high efficiency and low consumption to deal with district sewage on the spot has positive and realistic meanings.This paper aims at developing the new-type media, combining the mode of starting with the effective micro-organisms (EM).The performance of vermiculite media biological aerated filter for dealing with wastewater in the city district is studied and evaluated systematically. On the basis of the performance of this starting-up experiment, the effect of this reactor treating this kind of wastewater is investigated in different operation conditions, the function mechanism of this vermiculite media is analyzed, the technological parameter correlated to the reactor is selected and the dynamics equation of organic matter degradation is derived out.The results are as follows:(1) During the course of this starting-up, the reactor shows satisfied removal efficiency, the average removal rate of COD was above 75%. On the initial stage of this starting-up, the removal efficiency of TP and NH₄⁺ -N is 91% and 93% respectively. During the middle and later periods, the removal rate of NH₄⁺ -N reduces to some extent, the removal effect of TP is relatively bad.(2) By means of seeding EM to the reactor, the removal efficiency of NH₄⁺ -N improves notably. After the starting-up, the average removal rate of COD and NH₄⁺ -N is 85%and82% respectively.(3) The vermiculite media biological aerated filter has stronger adaptability to the changes of hydraulic loading, organic loading and ammonia nitrogen loading, especially in getting rid of NH₄⁺ -N, even if COD loading rises to 5.62 kg C0D/(m3. d), the removal rate of NH₄⁺ -N still have 72%. The main reason is that the vermiculite media possesses better absorption and ion exchange capacity for its sandwich structure. Among many Influencefactors, DO content has great effect on the removal of COD and NH/-N.(4) The layer of vermiculite media presents different function zones along the wastewater flowing direction. It is most obvious to remove COD in the vermiculite media layer of section 0-80cm, and the removal of NH4+-N mainly lies in media layer of section 40-100cm.(5) Considering results of the single factor experiments and the orthogonal experiment synthetically, when the corresponding influent organic loading and ammonia nitrogen loading are below 4.6kgCOD/(m3.d) and 1.06kg NH4+-N/(m3.d) respectively, under the conditions of HRT = 1.3h and gas/liquid = 6:1, the influent COD and NH4+-N concentration meet the first grade discharge standard.(6) At the same time, the dynamic model of the aerated biofilter treating organicmatter according to the experimental data is deduced. The model is:156.01Se U = 1885.34+SeBased on this model, HRT could be forecasted.