| With the development of economy and the acceleration of urbanization, the contradiction between supply and demand of urban water is rising. To realize the reuse of wastewater and reclaimed water, it is very necessary to further develop the urban sewage and proper dispose surplus sludge. And it is of great strategic significance for ensuring safety of city water and sustainable use of environmental resources. In recent years, A2/O (Anoxic/Anaerobic/Oxic) technology has been widely used in the urban sewage treatment. However, as a secondary unit of urban sewage treatment, A2/O process still faced with some problems like removal performance instability of nitrogen (N) and phosphorus (P), carbon source deficiency and disposal difficulty of excess sludge.This study simulated and developed pilot test of A2/O process to treatment urban wastewater according to China’s urban sewage treatment plants feed water quality characteristics. The influence on the performance of N and P removal process and measures were studied and optimized, like operation parameters of adjustment process, dosing carbon sources and auxiliary chemicals, etc. Following to these treatments, the effluent of A2/O were post further processed by high efficiency fibrous filter chamber and UV disinfection measure, and the process parameters of these treatments were discussed. A scheme of integration and optimization of further improvement technology of municipal sewage treatment plant water quality was proposed and applied to guide practical test and operation process. In addition, the urban sewage treatment plants surplus sludge was used to prepare bacterial manure. And the influence factors of sludge compost were investigated, like sludge characteristics, raw material composition, and ratio of biological strains and dosing of functional bacteria. While the application effects were considered, the feasibility to prepare bacterial manure by active sludge was discussed theoretically. The main works are as follows:(1) Optimization of process parameters of A2/O and investigation the performance to N and P removal of adding carbon sources and auxiliary chemicals①The hydraulic retention time (HRT) and inner recycling ratio have greater influence to N and P removal than organics removal process. Prolonging HRT and increasing reflux ratio contribute to improve nitrification efficiency and N/P removal effect to some extent. It is shown that under the optimum parameter conditions:HRT is10h, inner recycling ratio is200%, the effect of pollutants removal is the best. In addition, the process could achieve high COD removal efficiency in a relatively short period of HRT (6h) and small reflux ratio (100%), which reflects the strong resistance to organic load capacity.②Dosing methanol could improve removal effect of N and P while it has little influence to the removal performance of COD and NH3-N. The results indicate that, the efficiency of N and P removal process is not apparent, tending to be stable when the dosing quantity of methanol is more than40mg/L. And the optimum dosing range of methanol is20-40mg/L. Study on the influence of nitrate N to P removal effect of P enrichment bacteria in anaerobic zone indicates that the release P characteristic P of enrichment bacteria will be obviously inhibited when nitrate N concentrations is more than2mg/L in anaerobic zone. The influence on dosing methanol to the performance of release P of P enrichment bacteria is not obvious.③Three kinds of chemicals, polyaluminium chloride (PAC), polymeric aluminum ferric chloride (PAFC) and polyaluminium sulfate (PAS), could strengthen P removal function of treatment process. And the effluent quality can meet the first class of A standard while the optimum dosing quantity of chemicals is40mg/L PAC in the front of secondary sedimentation tank.(2) Study on the treatment effect and process parameters of high efficiency fibrous filter chamber to effluent of A2/O①The filter water turbidity could be reduced to1NTU or less in4min when the initial speed of fibrous filter chamber are10m/h,20m/h,30m/h,40m/h. In addition, the effluent turbidities from fibrous filter chamber are all below1NTU in different turbidities and initial filter speeds, and there are long running period and get a good result in backwashing.②The optimum operation parameters were obtained with the filter speed of20m/h and filtration cycle22h. The periodic quantity of water produce is440m3/m2and water consumption rate of backwashing is about3%.③The COD removal rate of suspended substances is above56%by fibrous filter chamber in the optimum operating conditions, while it does not work with the dissolution of COD.(3) Commissioning and operation of field process①The pilot plant test results indicate that the optimum operating condition of Guangda water resources Jinan Co., Ltd Plant2is HRT10-12h, inner and external recycling ratio150-200%and100%and sludge age20d.②The effluent of A2/O were added chemicals, post further processed by high efficiency fibrous filter chamber and UV disinfection measure. And the final effluent water quality could reach the first class of A standard.③Compared with the influent quality before transformation, a significant change was discovered in Guangda water resources Jinan Co., Ltd Plant2, under the influence of South-to-North Water Transfer Project and municipal water supply network construction in Jinan City. At present, carbon source could meet the need of process.(4) Preparation technology of bacterial manure by active sludge①The analysis of sludge properties of Guangda water resources Jinan Co., Ltd indicate that the sludge are rich in organic matter and plant nutrition ingredient while the heavy metals concentrations was low, which can meet the requirements of farmland application.②The composting effect, fermentation time and temperature of the fertilizer composition of sludge, rice husk and mushroom residue are much better than the composition of sludge, rice husk, peat and fly ash. And the most feasible conditions to prepare bacterial manure are the ratio of dewatered sludge, rice husk and mushroom residue is57.25:16.20:24.50.③It is beneficial to high efficient fermentative material for dosing compound bacteria with0.2%-0.3%during the composting process. And it could provide a suitable micro-ecological environment for crops adding beneficial bacteria.④It could improve fertilizer efficiency of bacterial manure, enhance the crops’ resistance to disease and the final product could reach the national standard of biological organic fertilizer (NY884-2004), adding bacillus subtilis after the material fermentation. |
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