| Water resources of the Central Shaanxi Plain are scarce,and the water consumption of farmland irrigation amounts to a considerable proportion of water resources.With the development of urbanization,the amount of sewage water discharges is increasing,while the majority of villages are far away from the surface water,sewage discharges through the irrigation channel,and there is some problems of Rural sewage treatment including less investment,operating costs are difficult to guarantee,weak management and others,According to the characteristics of the Central Shaanxi Plain and the bottleneck of rural sewage treatment,this paper puts forward the processing mode by weakening the nitrogen and phosphorus removal,transforming resource utilization,recharging farmland,studied on effects of intermittent aeration process design and operating parameters on the removal efficiency of pollutants,Proposing optimized design and operating parameters.The operation mode is not only beneficial to remove organic matter,but also beneficial to eliminate stench and retain nitrogen and phosphorus,and recycling agricultural irrigation to reduce fertilizer and water resources consumption,The operation mode of the intermittent aeration save energy consumption of aeration,and reduce operating expenses,are of practical significance to solve the current problem of rural water environment in the Central Shaanxi Plain.In this research,actual domestic sewage was used as the treatment object,and the common activated sludge was used as inoculated sludge.The continuous flow reactor was started and realized the operation of the continuous flow-intermittent aeration reactor at room temperature.On this basis,To study the operating parameters,such as sludge load;aeration time;aeration frequency?Aerobic-anaerobic alternating frequency?and so on,impact on removal efficiency of COD?TN?NH4+-N?NO3--N?NO2--N and TP.Obtained the removal characteristics of N,P and COD in continuous flow-intermittent aeration system,and further proposed the engineering design and operating parameters with the purpose of recycling agricultural irrigation after treatment?To achieve good COD removal efficiency at the same time,weaken the nitrogen and phosphorus removal efficiency?,Which is intended to provide a basis for the immediate use of sewage in rural areas of the Central Shaanxi Plain.The main results are as follows:?1?To study the effects of different sludge load on the removal efficiency of COD,TN,NH4+-N,NO3--N?NO2--N and TP in continuous intermittent aeration system.As the sludge load from 0.1 kg COD/?kg sludge ·d?up to 0.8 kg COD/?kg sludge ·d?,the removal efficiency of COD of intermittent aeration conditions decreased to 72% from 82%,the removal efficiency of NH4+-N decreased to 17% from 75%,the removal efficiency of TN increased to 41% from 12%,the removal efficiency of TP increased to 32% from 20%.The results showed that COD removal rate and NH4+-N removal rate decreased with the increase of sludge load,TN removal rate and TP removal rate increased with the increase of sludge load.The nitrification was weakened and the denitrification was strengthened under the operation mode of intermittent aeration.The operation mode of Intermittent aeration was helpful to sludge settling and inhibit sludge bulking problem.?2?To study the effects of different intermittent aeration conditions on the removal efficiency of COD,TN,NH4+-N,NO3--N?NO2--N and TP in continuous intermittent aeration system.As the aeration time from 8 h up to 24 h,the removal efficiency of COD increased to 92% from 82%,the removal efficiency of TP increased to 34.9% from 29.6%,the removal efficiency of TN decreased to 23.2% from 55.8%;The change of the aeration frequency affected the DO concentration in the reactor mixture.The results showed that COD removal rate and TP removal rate increased with the increase of aeration time,the DO concentration in the reactor mixture increased with the increase of aeration frequency,so COD removal rate increased,but this condition was not helpful to remove TP,TP removal rate decreased.?3?The study of denitrification rate?NUR?showed that,in the denitrification process,the lower temperature and higher DO concentration will inhibit the denitrifying bacteria activity,resulting in reducing denitrification rate;The longer the time to stop aeration period is more favorable for the complete progress of the denitrification reaction,and the denitrification rate?NUR?was positively correlated with the concentration of NO3--N at the beginning of anoxic phase.?4?The sludge load is 0.3 kg COD/?kg sludge ·d?,the aeration time is 16 h and the high aeration frequency?stop aeration period-aeration period was 1.33-2.67?,the removal efficiency of COD,TN,and TP was up to 89.9%?28.4%?30.7%,achieving good COD removal efficiency and weaken the nitrogen and phosphorus removal efficiency,can be used as the design and operating parameters of the actual engineering application. |
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