Treatment Of Ship Domestic Sewage By The Coupled Process Of Magnetic Flocculation And IAMBR

As a result of the further deterioration of the marine ecological environment,the IMO?International Maritime Organization?had formulated more stringent emission standards for ship domestic sewage.At the sixty-fourth meeting of MEPC?Maritime Environment Protection Committee?,TP and TN were strictly regulated for the first time in the standard of ship domestic sewage discharge.MBR?Membrane Bio-Reactor?had many advantages in the treatment of ship domestic sewage,such as less land occupation,strong degradation capacity of pollutants,etc.But there were many problems about MBR,such as poor removal of nitrogen and phosphorus and membrane fouling.Therefore,the intermittent aeration and the adding of magnetic powder and flocculant to the reactor were of great significance for strengthening the effect of nitrogen and phosphorus removal and slowing down the membrane fouling of MBR.In this paper,the coupled process magnetic flocculation and IAMBR?Intermittent Aeration MBR?was applied to treat ship domestic sewage.The characteristics of removal of pollutants and the membrane fouling status of the reactor were studied.The main study contents were summarized as follows:1.The beaker experiment was used to analyze the removal characteristics of COD_Cr,ammonia nitrogen,TN and TP by flocculation-adsorption and to determine the best type and dosage of flocculant and the dosage of magnetic particle when magnetic flocculation process was applied to ship domestic sewage.2.The removal characteristics of COD_Cr,ammonia nitrogen,TN and TP by the reactor was investigated when MBR was running for a long time.IAMBR was continuously operated under different operation conditions.The removal characteristics of COD_Cr,ammonia nitrogen,TN and TP under different operation conditions were investigated respectively,and the best intermittent aeration operation condition was obtained.The results showed that the removal efficiency of TN was very obvious under the intermittent aeration operation.And compared with the continuous aeration operation,the average removal rate of TN increased by 58.09%under the intermittent aeration operation,but almost no effect on TP removal.3.The experiment for getting the best dosage was carried out when the coupled process Magnetic flocculation and IAMBR was used to treat ship domestic sewage.The effect of removal of COD_Cr,ammonia nitrogen,TN and TP by the addition of flocculant and magnetic powder in the IAMBR was analyzed.The effect of TMP growth rate and sludge activity was also analyzed.Through the above analysis,the best dosage of flocculant and magnetic powder was determined.At last,the magnetic flocculation coupled IAMBR reactor was running for a long time under the optimal dosage condition.The removal efficiency of COD_Cr,ammonia nitrogen,TN and TP was investigated.The results showed that the magnetic powder and flocculant can significantly improve the removal efficiency of TP,the average removal rate of TP increased by 75.89%,and the removal efficiency of COD_Cr,ammonia nitrogen and TN also have increased,but the increase amplitude was smaller.4.The membrane fouling of IAMBR and magnetic flocculation coupled with IAMBR was investigated.The test results showed that the membrane fouling rate of IAMBR was the highest when the aerating 30min/stoping aerating 90min,and the addition of PAC and magnetic powder could effectively delay the membrane fouling of MBR.Finally,through the analysis of TMP,SMP,EPS and SEM,the reasons for the reduction of membrane pollution were obtained by adding PAC and magnetic powder.After analysis,PAC could reduce the content of SMPc in sludge mixture by adsorption,slow down the rate of membrane fouling,and the magnetic powder was mainly through the enhancement of microbial activity in the sludge,reduced the secretion of EPS and SMP in the sludge microorganism,so that the rate of membrane fouling mitigation.