| Based on the characteristics of rural domestic sewage dispersion and the current status of rural domestic wastewater treatment,this article puts forward the concept of bio-ecological combination process named "biological filter/artificial wetland" to treat rural domestic sewage,using three-dimensional mesh material instead of the traditional biological trickling filter fillers.To figure out the best working conditions of the improvement of biological trickling filter/artificial wetland combined process though a series of experiments.Effects of system optimization on the removal of contaminants in combination process were discussed.The main work and results are as follows:(1)The three-dimensional mesh material has good advantages of large specific surface area,high porosity and light material,and it is also easy to be loaded and disassembled in an integrated manner,which can solve the trouble of flushing of the traditional biological trickling filter.The main factors influencing the bio-trickling filter film hanging start;Factors affecting the removal of pollutants in biotrickling filter,such as hydraulic load,reflux ratio,volume loading of organic matter,etc.Based on the experimental results,the optimal operating parameters such as water flow load,reflux ratio and volume loading of organic matter were determined.The nitrogen conversion regularity in the reactor was studied.The system turn outs to be good carbonation,nitrification and amination efficiency.(2)The improved biological trickling filter achieved the most perfect treatment effect when the hydraulic loading was 3.44m3/m2d,the reflux ratio was 200%,and the organic volume loading was less than 1.1 kgCOD/m3·d.The average removal rates of CODcr and NH4+-N were 75.75%and 86.08%in this case.The average effluent concentration was 57mg/L and 2.27mg/L.The effluent of NH4+-N is satisfied with grade A standard of?Pollutant Discharge Standard of Urban Wastewater Treatment Plant?(GB18918-2002).(3)The artificial wetland has great removal effect on CODcr?NH4+-N and TN,the removal efficiencies is 71.08%,97.78%and 52.09%,respectively.The average effluent concentrations of the three pollutants all meet?Pollutant Discharge Standard for Urban Wastewater Treatment Plant?(GB18918-2002)level A standard.Wetland phosphorus removal mainly rely on matrix adsorption precipitation,microbial phosphorus absorption and plant growth absorption.When the ratio of gas to water reached to 8:1,the removal rate of TP increased to 77.29%and the average concentration of effluent was 0.88mg/L,which met the first grade B standard.(4)Through the continuous operation of system testing,the removal rate of CODcr,NH4+-N,TN and TP were 92,53%,99.55%,62.26%,63.82%,the average water concentrations were 17.4 mg/L,0.57 mg/L,11.95 mg/L,1.41 mg/L.CODcr,NH4+-N,TN the water reached the "urban sewage treatment plant pollutant discharge standard"(GB 18918-2002)level of A standard.The results show:the improvements of bio-trickling filter/artificial wetland combined process is a new combined breakout of biologic and ecological technology with better treatment effect on rural domestic sewage. |
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