Experimental Study On Treatment Of Rural Domestic Sewage By Rotaring Biological Contactor Process

With the acceleration of urban-rural integration,rural domestic sewage has become a major body of water pollution.In order to protect water resources,people are exploring and researching the treatment technology of rural domestic sewage.RBC is a membrane treatment technology.With its unique structural advantages,it does not need aeration and sludge reflux in operation,and has a good effect of removing organic matter,nitrogen and phosphorus.It is simple to operate and saves resources.It is very suitable for treating small-scale rural domestic sewage.Through the experimental study of simulated rural domestic sewage with three-stage aerobic RBC,the following conclusions can be drawn:1.In the aspect of organic matter degradation:1)When the organic loading range of aerobic biological turntable treatment was 12-18 g/（m²·d）,the removal efficiency of organic matter was better with the increase of the loading.2)The removal rate of organic matter by aerobic RBC decreases with the excessive increase of hydraulic load.3)In spring,autumn and winter,the removal efficiency of organic matter by aerobic RBC decreased in turn.The experiment span was three quarters.It can be seen that the color of biofilm of aerobic bio-rotating disc changed from light yellow to black,which shows that air temperature is an important factor determining the treatment effect of RBC.4)Five groups of different reflux ratios were set up.It was found that the system had the best treatment effect when the reflux ratio was 1.0.When the reflux ratio was too high,the dissolved oxygen carried in the reflux would destroy the anaerobic environment of the denitrification tank.2.In terms of denitrification:1)The average removal rate of ammonia nitrogen was higher in summer than in winter,and the removal rate of ammonia nitrogen was the worst in winter.2)In the absence of reflux,the removal efficiency of total nitrogen from wastewater is poor,which indicates that the aerobic RBC biofilm is not suitable for forming anaerobic environment and is not conducive to the growth of denitrifying bacteria.3)Additional reflux system improves the denitrification capacity of RBC,but has no effect on the nitrification capacity of the system.4)When the reflux ratio is 1.0,the system has the best denitrification effect.When the reflux ratio is too high,the dissolved oxygen carried in the reflux will destroy the anaerobic environment of the denitrification tank.3.In the aspect of phosphorus removal:1)The function of phosphorus enrichment by aerobic RBC biofilm is not obvious,and the removal of total phosphorus is poor.2)Experiments were conducted to investigate the effect of PAC on the removal of wastewater in the whole system.The positions of PAC were effluent tank,denitrification barrel and the first biological turntable inlet.The results showed that the effect of PAC on phosphorus removal was the same in three different places,and the phosphorus index could reach the standard.When the feeding position is in the denitrification box and the first biological turntable,the biofilm of the biological turntable will grow slowly because of the lack of phosphorus,resulting in the reduction of ammonia nitrogen removal rate.Therefore,the good feeding position of the phosphorus removal agent is at the end of the system.4.In terms of kinetics:1)According to the experimental data analysis,the COD degradation order of the aerobic RBC turntable is 1,which shows a linear relationship.The rate constant of organic matter degradation is 0.3537h^-1,and the kinetic equation of organic matter degradation of the RBC turntable is C_t=298.1e^-0.3537t.2)The nitrification reaction order of the aerobic RBC turntable is 1,which shows a linear relationship.The nitrification reaction rate constant K₁ is 0.2714h^-1,and the kinetic equation of ammonia nitrogen degradation in RBC turntable is C_t=20.8e^-0.2714t.