Study On The Falling Water Driving Packing-type Rotating-cage Optimization In Bioecological Combination Process Of The Decentralized Waste-water

The characters of rural sewage are that the amount of water is small,while the overall water quality coefficient is high.The features of China’s rural areas are vast,scattered,and large population.So the treatment model of rural sewage is much more suitable for using the the decentralized sewage treatment mode for the geographical and economic factors.The "anaerobic pool-anoxic pool-water dropping －artificial wetland" was established,which combined the advantages of biological treatment and ecological treatment.What’s more,the process were energy conservation and commercial value creation.In this paper,the oxgeneration capacity and treatment efficiency of the falling water driving rotating-cage bioreactor was studies.What’s more,the the substrate degradation models of the falling water driving rotating-cage bioreactor were established.And the effects of the biological treatment was also researched.The main results are as follows:(1)The start-up of anaerobic-hypoxia tank lasted 54 days.The HRT has a great effect on the degradation of COD in anaerobic tanks.And with the increase of HRT,the removal rate of COD in the anaerobic pool was gradually increased when the water temperature was 17.8～21.3 ℃.When the HRT was 48 h,the removal rate of COD was 70.33%.The reflux ratio had a certain effect on the removal of TN for the anoxic pool.When the reflux ratio was 200%,the removal rate of TN in anaerobic-anoxic pool was the highest,reached 48.81%.Suggested that the best operation conditions of anaerobic-anoxic pool were that HRT was 48 h of ananerbic pool,and reflux ratio was 200%.(2)It was concluded that water flow of 440ml/min,water height of 0.7 m,immersion height of 105 mm were the best operating conditions in the water oxygenation test of the falling water driving rotating-cage bioreactor.And the KLa was 0.03423 min-1,and the oxygenation efficiency was 69.58%at that conditions.The sponge filler and filt filler were choosed to research the properties of the falling water driving rotating-cage bioreactor.And the highest specific oxygen uptake rate of rotating-cage were 0.00461 mgO2/(mgVSS h),0.00415 mgO2/(mgVSS·h),and 0.00376 mgO2/(mgVSS·h)at all levels in sponge filler.In addtion,the nitrification rate were 0.00400 mg/(mgMLVSS·h),0.00524 mg/(mgMLVSS·h),0.00472 mg/(mgMLVSS h)at all levels of the reactor.The results showed that the biofilm-forming time of sponge filler was shorter than that of felt filler.What’s more,the microbial activity of sponge was more stronger.The HRT and the immersion height of the rotating-cage influnced the treatment efficiency of the falling water driving rotating-cage bioreactor.When HRT was 2.5 h,the removal rate of NH4+-N and COD were 55.57%and 69.64%,respectively.And when the immersion height was 95 mm,the removal rates of COD and NI4+-N were 64.08%and 79.24%,respectively.Suggested that the best operation condtions of the falling water driving rotating-cage bioreactor were that HRT was 2.5 h and immersion height was 95 mm.(3)The COD degradation models and the NH4+-N degradation models of the the falling water driving rotating-cage bioreactor were constructed on the basis of material balance and Monod equation,which could reflect the degradation of COD and NH4+-N of the falling water driving rotating-cage bioreactor.In addition,the substrate degradation model had a mathematical relationship with the saturation constant,biofilm thickness and biomass concentration.And the model of substrate degradation could also be used in the calculation of the the falling water driving rotating-cage bioreactor’s microbial parameters such as surface area.Dissolved oxygen concentration was an important factor influencing the operation of the falling water driving rotating-cage bioreactor.And studied on the influence of different factors on the oxygenation performance of the rotating-cage could optimized the design of the rotating-cage.Filler was the main part of the rotating-cage for wastewater treatment,so selected the appropriate filler was conducive to improving the efficiency of the treatment of the cage.In addition,the establishment of substrate degradation model provided a theoretical basis for the study of the falling water driving rotating-cage bioreactor.