Study On Enhanced Coagulation Treatment Technology Of Micro-Polluted Algae-Containing Water In A Water-Plant In South China

The rapid development of industry and agriculture has caused a series of environmental pollution problems,and eutrophication of water bodies has occurred from time to time.The raw water of Tangshan Water Plant was taken from the water of Hedi Reservoir,and the mass reproduction of algae in summer brought many difficulties to the production of water plants.In this study,the current situation of the micro-polluted algae-containing water treatment in Tangshan Water Plant was firstly carried out.First,a simple coagulation test using polyaluminum chloride(PAC)and polyferric sulfate alone,a coagulation test of potassium permanganate and sodium hypochlorite pre-oxidation was carried out.Through the detection of algae concentration,turbidity,UV254,flocculation rate UV550,floc size changes before and after detection,to explore its improvement of water quality and algae removal efficiency;then computer numerical simulation of particle agglomeration process,by changing the control The variables were used to analyze the effect of flocculation factors such as turbidity and pre-oxidant dosage on the actual flocculation process.Finally,the effectiveness of pre-chlorination in the actual production operation of Tangshan Water Plant was studied.The beaker coagulation test using PAC and polyferric sulfate as flocculant showed that the treatment of raw water by PAC as flocculant was better than that of polyferric sulfate,but the addition of flocculant to algae,turbidity and organic matter.The removal effect is limited.The PAC dosage is 15mg/L,and the removal rate of algae and UV254 is only 61%and 42%.The turbidity can be controlled below 4.6NTU,and the algae is not improved.The water quality caused by reproduction deteriorates.Comparative experiments on enhanced coagulation of potassium permanganate and sodium hypochlorite showed that the treatment effect of enhanced coagulation with sodium hypochlorite was better than that of potassium permanganate.Both of them have a good removal effect on algae with a dominant population of Cyanobacteria in the water,but the effect of sodium hypochlorite intensive coagulation on turbidity and organic matter is better than that of potassium permanganate.When the prechlorination concentration reaches 3.0 mg When/L,the turbidity of the post-submerged water can be controlled below 2.6 NTU,and the removal rate of organic matter can reach 63%.Aiming at the characteristics of high turbidity and high turbidity of raw water in Tangshan Water Plant,computer numerical simulation of particle agglomeration process was carried out to realize the visualization of particle agglomeration process.By controlling the total number of initial particles and the particle adhesion distance,the effect of turbidity and pre-oxidant dosage on the actual flocculation process was analyzed.The results showed that the higher the raw water turbidity value,the more processing time would be needed.The turbidity is controlled to a prescribed value,but the flocs formed in the high turbidity raw water can have a dense structure and are more likely to precipitate,which reduces the burden on the subsequent filtration process.Through the production test of different pre-chlorination gradients,it can be determined that the optimal chlorine content in the pre-oxidation stage is 2.0 mg/L,and the production test is conducted for several consecutive days under this condition,and the water quality of the raw water and the post-submerged water is compared.Through the pre-chlorination and coagulation sedimentation process,the number of P.sinensis in the raw water can be reduced from 80 million/L to 9 million/L,and the turbidity of the post-submerged water can be controlled below 3.42 NTU.The removal rate of UV254 is between 46%and 69%,and the overall removal effect is ideal,which will not bring processing difficulty to the subsequent V-type filter,thereby ensuring the water quality of the factory.The results showed that the average number of cyanobacteria in the raw water during the experiment was 81,119,700/L.The pre-chlorination-conventional combination technology could reduce the number of cyanobacteria in the post-submerged water to about 9 million/L.The turbidity of the post-submerged water can be controlled below 3.42 NTU,and the removal rate of UV254 is between 46%and 69%,and the overall removal effect is ideal.