| Phosphorus is a kind of non renewable resources.Because of the excessive harvesting of phosphate rock,the phosphorus resource is gradually exhausted.At the same time,a large number of phosphorus containing wastewater directly discharged into natural water bodies will cause serious environmental problems such as eutrophication of water bodies.So,exploring the new sewage treatment craft,recovery and utilization of phosphorus resources in wastewater can not only solve the problem of phosphorus pollution,but also can effectively alleviate the shortage of phosphorus resources.MAP(Magnesium Ammonium Phosphate)crystallization method can effectively remove and recover phosphorus in wastewater,but the crystallization reaction conditions are harsh,especially when the phosphorus concentration is very low,it is difficult to achieve phosphorus recovery.Ultrasonic technology has a good effect on the removal of refractory organic matter,and can promote the crystallization reaction.Therefore,this paper intends to give full play to the role of ultrasonic phosphate crystal,ultrasound enhanced and A/O alternating biofilter process organically,investigated the combined process of synergistic phosphorus removal efficiency and process characteristics,to provide theoretical support and technical reference for the removal and recovery of phosphorus wastewater.Based on the A / O alternate biofilter technology researched in the early stage,this paper investigates the single-cell start-up and alternate operation of A / O alternately running biological filter.By adjusting the aeration time(asynchronous water / aeration),optimize the effluent mode of anaerobic tank and change the cycle time of alternating operation,etc.,this research has focused on the anaerobic phosphorus release law in A / O alternative biofilterr.Combined with the removal rule of pollutants along the space between the different operating cycles,the best anaerobic release curve has been gotten.In addition,this research proposed the A / O alternative biofilter optimized operation mode for producing anaerobic pool with high efficiency,stable phosphorus release and inspection removal effect of A / O alternative biofilter in the optimized operation mode.Based on the water quality of A / O alternate biofilter,the reaction characteristics and phosphorus removal efficiency of the supplemental magnesium source and the application of ultrasonic enhanced MAP crystallization were studied.The optimum conditions of MAP crystallization reaction were obtained.Based on this study,the two-stage biofilter and the center-enhanced MAP crystallization device were run and the effects of pollutant synergistic treatment and phosphorus recovery were investigated.In conclusion,we can get the following main conclusions as follows:When the influent COD concentration was 265~350mg/L,HRT=2h,DO=2~4mg/L,T=22~28 single cell C,the TP concentration of the influent ammonia concentration was 9~12mg/L,38~42mg/ conditions,single stage biofilter takes 15 days to complete the start-up operation,after stable operation,the effluent COD concentration is 36mg/L,ammonia nitrogen below 0.5mg/L,and the average removal rate of phosphorus only about 30%;48.2% In the same water condition,aerobic anaerobic pond aeration pool DO=2~4mg/L,stop,two 48 hours A/O alternate operation,the average removal rate of COD can reach more than 85%,the average ammonia nitrogen removal rate was above 99%,the effluent phosphorus concentration was 2~6mg/L,and the average removal rate was 48.2%;In the alternating cycle,the anaerobic phosphorus release curve showed the change law of rising,stable and decreasing.The peak of phosphorus release was 29.5mg/L,and the anaerobic duration was about 32 h.It was found that the A/O alternating biofilter had a good effect on the anaerobic release of A/O alternating biofilter compared with the intermittent 12 h operation at the intermittent period of 48 h.The two-stage A/O alternate biofilter was operated at the interval of 48 h alternately 48 h,the average COD concentration was below 50mg/L,the ammonia nitrogen was below 0.5mg/L,the phosphorus removal rate was 30% ~ 60% The duration of release of phosphorus and phosphorus was about 44 h,the peak value of phosphorus release was 28mg/L,and the phosphorus release rate was stable and the phosphorus release curve was gentle.The intermittent time of A / O alternate biofilter is 8h and the alternating period is 48 h,in the anaerobic filter multi-point running conditions,the system showes good ammonia nitrogen and COD removal capacity,the removal rate of ammonia nitrogen is above 99%,the average concentration of effluent COD is 34.6mg / L,the average removal rate of phosphorus is 50.3%?In the alternating cycle,the concentration of anaerobic effluent phosphorus is more stable,and the peak of anaerobic release is 29.5mg / L.The release of phosphorus in the anaerobic filter is more stable and the phosphorus release curve is more stable.Under this condition,the effect of anaerobic phosphorus release was better than that of 8h intermittent 48 h alternating two-stage biofilter.In a certain range,with the increase of pH and Mg / P,the MAP induction period became shorter and the crystallization rate was accelerated;Ultrasound has an important effect on the induction period of MAP.With the increase of the power of ultrasound,the MAP induction period is shortened and then prolonged;In a certain range,the increase of ultrasonic power is helpful to the removal of phosphorus;Increasing the ultrasonic power can reduce the supersaturation of the MAP crystallization reaction and the requirement of pH,the crystal morphology is cluttered and prone to bifurcation?The reaction conditions of ultrasonic enhanced MAP crystallization were as follows: ultrasonic intensity was 2.37 w / cm2,the action time was 20 min.Only over-cast magnesium source for MAP enhanced phosphorus can achieve better phosphorus recovery effect,anaerobic process phosphorus release stability,indicating that excessive application of magnesium source of biological phosphorus removal process has no effect;The excessive application of magnesium has a negative effect on the removal of ammonia nitrogen and COD in the two stage biological aerated filter system,but it is helpful to the anaerobic removal of ammonia nitrogen;In practice,it should be considered to reduce the dosage of magnesium source.Compared with the addition of only magnesium source,the centralized enhanced MAP Crystallization can effectively improve the treatment of ammonia nitrogen and COD,and the average concentration of ammonia nitrogen and COD is 1.17mg/L and 44.9mg/L.After the centralized enhanced MAP Crystallization,the phosphorus removal capacity of the combined process system was greatly enhanced,and the final effluent phosphorus concentration decreased from 5.4mg / L to 0.98 mg / L,indicating that ultrasound had a significant effect on the crystallization of phosphorus removal;The results of SEM and EDS characterization of the crystal products show that the main component of the product was a mixture of magnesium ammonium phosphate and other crystals,but the crystal grain size was small. |
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