| Water supply in Chongqing mountainous rural areas are of poor water quality,and it's operation and management are lack of technology and capital,ultrafiltration water purification technology has good effluent water quality,it is convenient to operate and manage,and has a low cost of investment and operation as well as great application advantages in rural safe water supply.But,the popularization and application of ultrafiltration technology is restricted by the membrane fouling,the operation method of non-fouling flux can effectively control membrane fouling,ensure the long-term stable operation of ultrafiltration waterworks,has a important value of study and application in rural safe water supply.This paper introduced the general situation of ultrafiltration demonstration project in waterworks of Chongqing,the water was prepared in laboratory to sinulate raw water quality of waterworks in Chongqing,the non-fouling flux of direct-ultrafiltration process under this water quality condition was determined,the removal efficiency of pollutant and membrane fouling of ultrafiltration membrane under the operation of non-fouling flux was investigated,impact of different pollutants on non-fouling flux of ultrafiltration membrane was studied;according to the experimental results,the ultrafiltration waterworks choosed a suitable membrane flux,the operation evaluation of ultrafiltration demonstration project was carried out,including water purification efficiency evaluation,non-fouling flux operation and membrane fouling evaluation and engineering economic analysis.The main conclusions of this study are as follows:The non-fouling flux of direct-ultrafiltration was 27.5 L/(m~2·h)under the raw waer quality of Lonquan waterworks by the flux-step-adding method in laboratory.The ultrafiltration membrane has a good operation efficiency with non-fouling flux,the effluent turbidity was below 0.1NTU,the effluent CODMn was between 2.4 mg/L and2.9 mg/L,the colony count and total coliform group can be 100% removed,the 4indexes met the requirements of standards for drinking water quality(GB5749-2006);the trasmembrane pressure of ultrafiltration almost didn't increase with the flux of 27.5 L/(m~2·h),the “non-fouling” operation can be achieved.Impact of turbidity and UV254 on non-fouling flux of ultrafiltration membrane was investigated.When the raw water only exists turbidity,the turbidity had little effect on the non-fouling flux of ultrafiltration membrane;when the raw water only exists organic matter,the non-fouling flux was decreased with the increase of organic matter concentration.Impact of interaction between turbidity and organic matter on non-fouling flux of ultrafiltration membrane was more complex: when the organic matter concentration was low,the non-fouling flux can be improved with the increase of the turbidity;when the organic matter concentration was higher,the non-fouling flux decreased with the increase of the turbidity;no matter the turbidity was high or low,the increase of organic matter concentration can reduce the non-fouling flux of ultrafiltration membrane.Direct-ultrafiltration process of waterworks had a good purification efficiency,the106 effluent indexes met the requirements of standards for drinking water quality(GB5749-2006),the problem of variation raw water quality had been solved.During the period from August to December of 2015,the average operation membrane flux was 9.7 L/(m~2·h),and the average transmembrane pressure was-6.4kPa,which accounted for only 6.4% of the operation pressure,ultrafiltration membrane was with good condition,there is no chemical washing during operation period,achieved a long-term on-fouling flux operation mode.After prolonged filtration cycle,the water production rare,gas water ratio and power consumption of single filtration work was93.7%,0.12:1 and 0.0048 yuan/m~3;the estimation result of water producing cost by ultrafiltration process is 0.21 yuan/m~3,which is low and meet the development requirements of rural areas. |
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