Efficiency Regulation About The Treatment Of Brackish Water In Kashgar By Nanofiltration Combined Process

Faced with the development of social economy in recent years,the requirement of drinking water quality has been improved constantly.The scarce surface water has been polluted by industrial and urban domestic wastewater in Kashgar,causing the water quality will be hard to reach the requirement.Thus the deep groundwater became the major drinking water source,while its total dissolved solids and hardness exceeded the standard and limited the purification effect of conventional water treatment process.Nanofiltration combined process shows technological advantages in decentralized water supply and desalination of brackish water.In this project,the author will study the efficiency of nanofiltration combined process for treating brackish water in Kashgar,optimize the process operation parameters,summary the operation management experience of nanofiltration combined process for treating brackish water,and establish the emergency pollution response mechanism.Firstly,we investigated the water quality of Kashgar to analyze its local characteristics risk.Based on the report,the simulated water quality was determined and the experimental study of ultrafiltration and nanofiltration were carried out.The results shows the optimal operation pressure of ultrafiltration is 0.04 MPa,and the optimal operation pressure and cross flow rate of nanofiltration are 0.75 MPa and 0.1 m/s.It was also pointed out that the effect of decommissioning on the filtration efficiency of nanofiltration membrane should be more significant than that of different membrane types and background components.Secondly,this paper analyzed the operation efficiency,condition adjustment and cost accounting of two sets of devices in Kashgar.The efficiency analysis showed they were keeping in normal running,but the improper addition of scale inhibitor caused problems lately.After adjusting the recovery rate,scale inhibitor,pressure and other working conditions on,and carrying out chemical cleaning,the devices performance obviously recovered.According to the field data,the cost of nanofiltration combined process is nearly 1.74 yuan/m³.Based on the investigation of water quality and the analysis of drinking water safety risk factors,the experimental study on the emergency pollution of organics and heavy metals were carried out.The results revealed the pollution of organic matter was mainly reversible cake layer pollution,which has little effect on the water quality;the pollution of heavy metal Cu²⁺ had little effect on the specific flux of membrane,but it could promote the irreversible resistance.And there was a hidden danger of water safety when the load was higher than 5 mg/L.Chemical cleaning could alleviate organic pollution,and the life of nanofiltration membrane could be maintained for 4 years under the impact of continuous organic load.The experimental results showed the adsorption capacity of zeolite to Cu²⁺ was 3.03 mg/g in static state and 2.11 mg/g in dynamic state,and the adsorption can effectively alleviate the irreversible resistance（> 75%）.