Experimental Study On Slightly Polluted Cellar Water Treatment By Combined Enhanced Electrocoagulation And Ultrafiltration

Water resources are extremely short in arid and semi-arid areas of northwest China,and rainwater is an indispensable and highly valuable water resource,and even the only water source in some serious water shortages areas.A series of rainwater utilization project aimed at solving people drink distress problems have been constructed in China.Though problems like the shortage of water supply are solved,the water quality problem remains.Rainwater is susceptible to contamination during the process of collecting and storing,resulting in a number of water quality indicators in the rainwater harvesting pits.The long-term consumption of untreated pits can cause great harm to the health of the local residents.Therefore,it is necessary to conduct research on cellar water treatment technology.To provide reliable technical guidance and experimental support in this paper,the micro-polluted rainwater cellar water is taken as the research object,and use enhanced electroplating combined with ultrafiltration technology to deal with rainwater cellar water for the purification of the pit water.The effect of the main factors on the electrocoagulation effect such as plate spacing,current density and electrolysis time are analyzed.The optimum operating conditions are concluded firstly.Secondly,in order to strengthen the effect of electrocoagulation,the pre-ozone enhanced electrocoagulation experiment was carried out.The effects of different dosage of ozone on the effect of electrocoagulation were investigated,and the most suitable dosage was selected.Finally,ultrafiltration experiments were carried out to investigate the effect of ultrafiltration,flotation combined with ultrafiltration,pre-ozone enhanced electroplating combined with ultrafiltration on the removal of contaminants in raw water,and the ultrafiltration Membrane flux changes.During the experiment of electroplating cellar water,the effect of electrode spacing,current density and reaction time on the removal effect of electrocoagulation was studied by using aluminum,aluminum and titanium as the anode and cathode respectively.The optimum operating conditions for electrocoagulation are: plate spacing 10 mm,current density 26.76 A / m²,electrolysis time 15 min.Under these conditions,the maximum removal rates of turbidity,CODMn,UV254 and NH₃-N were 94.03%,53.84%,74.71% and 53.31% respectively.The titer of turbo,CODMn,UV254,The maximum removal rates of NH₃-N are 91.97%,51.24%,73.08% and 49.69% respectively.The maximum removal rates of turbidity,CODMn,UV254 and NH₃-N are 90.63%,47.41% and 69.23%,44.01%.In addition,under the optimum operating conditions,the flocs are characterized by 1.23,1.21 and 1.20,respectively,and the zeta potential of the three kinds of electrodes of aluminum-aluminum,aluminum-titanium and aluminum-stainless steel was 1.27 mV increased to-1.76 mV,-2.25 mV,-3.91 mV,respectively.By comparing the effect of the electrocoagulation of the three electrode materials on the removal of pollutants in the cellar under the same conditions and the analysis of the combined dimension and Zeta potential,it is concluded that the effect of using the aluminum-aluminum electrode to treat the micro-Aluminum-titanium and aluminum-stainless steel electrodes are good,so in the subsequent joint experiments are used aluminum-aluminum electrode.During the pre-ozone enhanced electrocoagulation experiment,the experimental results show that the organic matter with water molecular weight greater than 50 KDa is less than the pre-ozone treatment,and the organic matter with molecular weight less than 3KDa becomes more and the structure of the organic matter becomes simple,which is beneficial to the subsequent electrocoagulation treatment The The removal rate of CODMn,UV254 and NH₃-N in the raw water was 59.74%,79.59% and 53.91% respectively,and the flocculation of CODMn,UV254 and NH₃-N in the raw water was higher than that of the other Treatment increased by 9.72%,11.22%,4.43%,indicating that pre-ozone can play the effect of enhanced electric flocculation.In the experiment of pre-ozone-enhanced electroplating combined with ultrafiltration,the removal efficiency of pollutants in raw water was compared with that of ultrafiltration,flotation combined with ultrafiltration,ozone enhanced electroplating combined with ultrafiltration,and the effect of each process after treatment of raw water ultrafiltration membrane flux changes,can be obtained alone after ultrafiltration treatment of raw water,the water turbidity significantly reduced,while the ultrafiltration membrane adsorption and retention of raw water in the CODMn,UV254,NH₃-N.A certain removal effect,the removal rate was 20.96%,14.20%,13.38%,but the water quality is not up to standard.In addition,the pre-ozone can make the particles in the water destabilized,also can improve the effect of electrocoagulation treatment,so that the water quality to further improve the use of pre-ozone enhanced electroplating combined with ultrafiltration process on raw water.The removal rates of CODMn,UV254 and NH₃-N were 64.92%,83.67% and 56.13%,respectively,and increased by 7.95%,10.20% and 4.45%,respectively,when compared with the ultrafiltration process.The raw water is percolated by pre-ozone and then passed through the ultrafiltration membrane.At the end of the four filtration cycles,the membrane flux became 79.3% of the initial flux,which is much higher than that of the ultrafiltration and flotation.Using pre-ozone enhanced electroplating combined with ultrafiltration process on the pit water treatment,the indicators of the drinking water can reach the drinking water health standards.