Study On The Treatment Of Rural Domestic Wastewater By TF-CW Technology And Its Application

The eutrophic degree of Lake Taihu has descended after the effectual treatment of industry effluence point pollution in the recent years.But the non-point pollution in Taihu Lake area has been the most important one for the pollution contribution with the serious pollution of nitrogen and phosphorus.So the disposition of water circumstance in Taihu Lake area has become the most imperative thing that will be done. This full-scale experimental study belongs to the subject about technology and demonstrative engineering for rural domestic wastewater treatment which is one part of the 863 tasks. Combined with the rural fact complexion,the advanced treatment progress and technology which can treat rural domestic sewage in Taihu Lake area effectively will be provided.With the experimental data,the optimal running conditions are obtained which can provide the experiences for continued treatment tasks.Based on these,the trickling filter-constructed wetland combined processes for treating rural domestic wastewater are designed.The following conclusions can be arrived at during the practice:1.The DO concentration in trickling filter has correlation to both the exterior air temperature and sewage temperature,the sewage temperature effects the DO in TF effluent remarkably while the gap between the air and water temperature has almost no effect to the DO in TF effluent.2.The loads of process,hydraulic load and circumfluence ratio influence the treatment effect of TF,the best treatment effect can be obtained at the following level:COD cubage load≤0.5kgCOD/m3·d, hydraulic load is 4.0m~3/m~2·d, circumfluence ratio is 200%.The nitration action has close correlation to the water temperature,and the low temperature can bring out the cumulation of nitrite.3.The analysis through the microorganisms inside TF indicate that bacteria data in TF is at 1012cells/g biofilm level and the delamination distribution cases which reduced first while increased later.The nitrosomonases and nitrobacters are distributing equably within the whole TF.The effect of nitration in TF has a positive correlation with the amounts of nitrifying bacterias in the middle and nether parts within TF.4.The data regression done according to the simple model for TF through the full-scale test indicate that the reaction velocity constant k20 is 1.354 d-1,constant n is 0.77, temperature coeffifientθis 1.021 when using COD as the organic matter concentration and the condition is that the filtration mediums are perlite slags as well as the height of which is 2.5 metres.5.The constructed wetland has perfect effect for removal of COD and NH4+-N.The main mechanism of nitrogen in wetland systems is the action of microorganisms,while the removal efficiency will increase with the protraction of HRT(hydraulic resort time)in wetland,and also the action has a close relationship with the alternant changes of DO formed by the undee flowing.The main mechanism of phosphorus removal is the adsorption and sedimentation by the reaction of wetland bed medium with phosphate in wastewater,and the debasement of pH along the length of wetland will make against the action of phosphate'reaction with the gypsum.