| At present, high energy costs in aeration and sludge disposal are serious problems for common municipal wastewater treatment technologies. These problems significantly affect the construction and operation of urban sewage treatment plants in China. The cleaner production of urban wastewater treatment plant has not been given enough attention. Excess sludge, order and standard attainment wastewater are also discharged from the sewage treatment plants. The living environmental of mankind is damaged seriously by all these problems. To solve these problems, this study focused on treating wastewater through synchronous controlling of wastewater & sludge of high efficiency hydrolytic acidification process, synchronous controlling of wastewater & odor of biotrickling filter, and strengthening nitrogen and phosphorus removal of composite flow constructed rapid infiltration, which were low energy cost.Through abundant experiments in laboratory and pilot scale project, the results showed as follows:The mass and heat transfer efficiency of hydrolytic acidification was improved significantly by using composite anaerobic reactor. The wastewater treatment time and sludge hydrolization time were reduced to 4 hours and 24 hours, respectively. The maximum hydraulic load was 2.4 kgCODCr/(m3?d). The maximum excess sludge load was 9 kgCODCr/(m3?d). The SS and CODCr removal efficiency were 94% and 44% for actual domestic wastewater, respectively. The SS and CODCr removal efficiency were 94% and 44% for excess sludge, respectively. The process could be used as pretreatment to reduce load for post treatment. The SS and CODCr removal efficiency were 96% and 75% for mixed liquid of actual domestic wastewater and sludge, respectively. It could achieve synchronous controlling of wastewater & sludge very well. Hydrolytic acidification fluid could be used as organic carbon source for nitrogen removal and the effect was better than input wastewater used as carbon source. The process could solve the problem of insufficient carbon source for denitrification in urban sewage treatment plants.The biotrickling filter included both aerobic zone and anoxic zone. Aeration and oxygen supply were strengthened by holes in the upper part. Adding solid-phase organic carbon source in the lower part. Thus, the nitrogen removal efficiency was improve for the process. In static test, the phosphate removal efficiency was beyond 80% by the modified biological ceramic which was added into the biotrickling filter. The optimal hydraulic load was 2m3/(m2·d). The CODCr, NH3-N, TN and TP removal efficiency were 74.8%, 70.9%, 37.4% and 57.8%, respectively. The optimum of C/N was 4 when removing nitrogen and the TN removal efficiency reached 80%. The walnut shell was chosen as solid carbon. Odor was collected by the gas-collecting hood and injected into the equipment by the air diffusion tube, which was set up in thickened sand and gravel layer. It could be avoid for being blocked of air diffusion holes by biofilm and filler. The relative humidity of air exceeded 90% and it could provide optimum environment for filler bed. Mass transfer of solid-liquid-gas was strengthened by gas disturbance. Thus, the treatment effect was improved. When the hydraulic load was 2m3/(m2?d), liquid gas ratio was 1:5 and C/N was 4, the H2 S, NH3-N, TN and TP removal efficiency were 86.4%, 84.6%, 79.2% and 55.2%, respectively. It achieved synchronous controlling of wastewater & odor during municipal wastewater treatment process.It was easy start up and steady operation for composite flow constructed rapid infiltration. The nitrate removal effect was strengthened by selecting filler and effluent recirculation. The filler of nitrate removal pond were zeolite and corn cob. The filler of phosphate removal pond were anthracite and modified ceramic. The filler of rapid infiltration pond ceramic and local soil, which was used as substrates for canna and lythraceae. Compared with traditional rapid infiltration, the treatment effect was improved significantly. The optimum operation conditions were: 25% of reflux ratio, 1.0m/d of hydraulic load and 8h/24 h for ratio of wetting-drying-time. The CODCr, NH3-N, TN and TP removal efficiency were 80%, 90%, 80%, and 90%, respectively. The quality of effluent could meet the standard A of first class in “Discharge standard of pollutants for municipal wastewater treatment plant”(GB 18918-2002).On the basis of three key treatment processes, further study of pilot scale production was investigated in wastewater treatment plant of Xiedao resort in Beijing. The results showed that: the effluent of composite flow constructed rapid infiltration and composite biotrickling filter could meet the standard A and B of first class in “Discharge standard of pollutants for municipal wastewater treatment plant”(GB 18918-2002), respectively. The odor from anaerobic unit could be treated by composite biotrickling filter. The effluent could meet the standard of GB14554-1993. Two systems were operated without power consumption of blasting aeration and without excess sludge. Thus, the treatment cost was reduced significantly. The calculating operating cost of composite biotrickling filter and composite flow constructed rapid infiltration was 0.20~0.25RMB/t and 0.15~0.20RMB/t. Compared with traditional treatment technology, the system has a significant advantage. It could solve the bottleneck for municipal wastewater treatment, full realize the cleaner production of wastewater treatment, and form a positive environmental benefits. The results of this study could meet the imperative requirement of energy saving and emission reduction. |
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