Study On Combined Triple Circle Technology

According to wastewater treatment in middle or small cities and towns, CTCT(Combined Triple Circle Technology) is invented. This technology has many characteristics, such as highly efficient, energy-saving, simplely running, and so on.The effect of biological denitrification and phosphorus removal is studied in the small-scale experiment. DO(Dissovled Oxygen), HRT(Hydraulic Retention Time)and SRT(Sludge Rentention Time) are the three control factors. Each factor has three levels and the experiment is planned by orthoganal table. All kinds of factors, especially DO, HRT and SRT, are analyzed which affect denitrification and phosphorus removal. The results show that in the condition of low carbon source, the three DO levels don't affect notably, HRT has some effects and SRT affects notably. Because of high water temperature in summer, the effect of nitration is very good and the average of effluent ammonia is no more than 1mg/L. Anti-nitration is affected by high influent total nitrogen and lack of carbon source. As a result, the rate of denitrification is 50% approximately. Meanwhile, elimination of phosphorus is affected by low ratio of C/N and C/P. Therefore, the best of phosphorus removal is 30% approximately. For the experimental model, in the condition of defined influent water quality, the optimal control parameters are that DO equals to 1mg/L, SRT equals to 13 days and HRT of aerobic area equals to 8 hours.The separator is the core device of CTCT. The experimental results show that the arc inboard separator is better than the arc outboard separator in the effect which solid separates from liquid. Through observation and analysis of the fluid state inside the separator, it is found that there are several states about the flow of mixing liquid. Mixing liquid flows into the separator in the front of the separator. Mixing liquid flows out in the end of it. In the middle of it, there are low horizental velocity and sludge turbulence among the inclined boards. The special fluid state results in sludge deposit in the middle of the separator.One of energy-saving measures about CTCT is the return of sludge and mixing liquid without pump. There are two reasons for the automatic return of mixing liquid. One is the velocity of flow difference between outboard current and inboard current of annular channels. The other is that negative pressure which is caused by underwater propeller.