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O / A levels biological sand filtration process to treat municipal wastewater treatment plant secondary treatment effluent nitrification performance and biological characteristics of the pilot study results showed that: hanging the film success early on raw water the of COD Cr , NH 4 -N, TN average removal rate were 26.4%, 35.91%, 25.72%, biological sand filtration system of COD Cr and the NH 4 -N removal efficiency of basic stability with time of 25 days and 27 days, respectively, nitration filter column and denitrification filter column, respectively, to NH 4 -N and TN removal rate basically stable film success as hanging signs. Hydraulic loading 3.00m / h, the gas-water ratio of 2:1, and the stability of the system, the bio-sand filtration technology for each pollutant removal of: nitrification sand filtration column of COD Cr the average removal rate of 32.1%, and the average system of ammonia removal efficiency of 61.66%, 38.54% average removal rate of TN, and process systems for turbidity removal efficiency of 78.45% in average. Water temperature, hydraulic loading, gas water ratio, NH to 4 -N volumetric loading and organic volume load on the bio-sand filter nitrification performance impact when the biological sand filtration run control hydraulic loading of 3.0m / h, air-water ratio of 3:1, and the organic volume load 2.52kgCOD Cr / (the m 3 filter · d), NH < sub> 4 -N volumetric loading for 0.84kgNH 4 -N / (m 3 filter feed · d) can obtain better treatment effect. Using analytic hierarchy model AHM draw water temperature, hydraulic loading, gas and water than ammonia volume load and organic volume load weight were 0.355,0.289,0.283,0.263,0.118. Water temperature of 26 ° C, and the gas-water ratio of 3:1, hydraulic loading 3m / h, and the stability of the system under the conditions attached biofilm in the quartz sand for ultra-thin films by measuring nitrification filter column biofilm thickness 84.02μm, denitrification filter column biofilm thickness 59.08μm; biofilm increased amount along with the direction of water flow is reduced nitrification biological sand filtration, biofilm denitrification biological sand filtration columns with the direction of water flow from top down gradually reduced; With the increase of the depth of the filter column, nitrification biological sand filtration and biological denitrification biological sand filtration activity first increased and then decreased. Biological sand filtration nitrification performance dynamics model: K N 1n (N / N O ) N O -N = q N h (where the the the ammonia degradation rate q N and hydraulic loading h 'relationship q N = -1 6263h' 10.295), proven: ammonia theoretical calculations and experimental determination of the value of The largest absolute error between 0.32mg / L, the maximum relative error is 7.21%, the The nitrification performance dynamic model theoretical calculation results with the experimental measured values ??approaching. The test results show that: O / A two bio-sand filtration technology is advanced and economically reasonable, broad application prospects in the municipal wastewater treatment field.
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