The Experimental Study Of Coking Wastewater Advanced Treatment By Magnetic Flocculation Technical

The coking wastewater is a kind of industrial wastewater created during the process of high temperature coking coal, gas purification, coking products of the recovery and refined. The chemical composition of coking wastewater is complex, inorganic compounds mainly exists in the form of the ammonium salt and organic compounds in addition to phenolic, still have aromatic compounds, including ring nitrogen, oxygen, sulfur heterocyclic compounds, etc. coking wastewater is a kind of difficult biodegradable high concentration of industrial waste water. At present, the coking wastewater is treated mostly by biochemical method such as A/O, A2/O, etc, but because that the coking wastewater biochemical treatment is not easy, the wastewater still cannot meet the wastewater emission standard, the biological treated coking wastewater needs to have an advanced treatment. At present the application is more coagulation method and adsorption method. Generally, the active carbon, fly ash, etc are used as adsorbent, but its cost is higher and scraps are hard to handle. Coagulation method uses more polyferric sulphate as coagulant, which have wide range for temperature and pH value, high quality and reasonable price, significant coagulation effect.Magnetic flocculation technology in recent years is very hot emerging water treatment technology and which showed many advantages in water treatment application, dosing magnetic powder and coagulant can not only make flocculation effect strengthened, and improve the treatment effect, still can improve flocculent body structure, shorten the static sedimentation time, and magnetic powder can also recycling, magnetic flocculation technology is a kind of more promising water treatment technology. The aim of this study was to explore the application prospect of magnetic flocculation technology in coking wastewater treatment, to provide the reference to reform the coking wastewater treatment process and to meet emission standards.The experiment on the biological treated coking wastewater treatment by magnetic flocculation was studied, taking CODcr, NH3-N, the turbidity removing rates of coking wastewater as study index, first, through the single factor static test, the influences of polyferric sulphate (PFS) dosage, polyacrylamide (PAM) dosage, magnetic particle dosage, static sedimentation time and dosing way of the drug on treatment effect were discussed, then the best test conditions of various factors was found out through the orthogonal experiment, finally, the test result was checked through the parallel tests. Test results and conclusions were as follows:(1)Dosing PFS separately, the test showed that the optimal dosage of PFS was800mg/L, the static sedimentation time was30min, CODcr, NH3-N and the turbidity removal rates reached55.20%,18.12%and84.94%respectively.(2)In the experimental condition of PFS dosing for800mg/L, dosing PAM additionally, the test showed that the optimal dosage of PAM was8mg/L, the static sedimentation time was25min, CODcr, NH3-N and the turbidity removal rates reached61%,20.67%and89.76%respectively.(3) In the experimental condition of PFS dosing for800mg/L, PAM dosing for8mg/L, dosing magnetic particle additionally, the test showed that the optimal dosage of magnetic particle was400mg/L, the static sedimentation time was20min, CODcr, NH3-N and the turbidity removal rates reached62.50%,22.26%and92.17%respectively.(4) Through the investigation of the three dosing way and the order, we could draw that the magnetic particle should be put into coking wastewater before the PFS and PAM.(5)The treatment effect and mechanism of magnetic flocculation were discussed preliminarily, the conclusions were as follows:First, the magnetic flocuulation can enhance flocculation and improve water quality. The mechanism is magnetic particle rely on its own magnetic force and a larger specific surface area to Adsorbent the suspended particles, magnetic particle can also increase the chance of collision and enhance flocculation with the flocculant.Second, the magnetic flocculation can improve the structure of the flocsand to shorten the static sedimentation time. The mechanism is to form the high-density composite magnetic floc with magnetic particle as the core and increase the proportion of flocs to achieve the purpose of rapid subsidence and efficient separation.(6)By orthogonal experiment the factor order which effected the experimental effects was as follows:the PFS dosageâ†'he PAM dosageâ†'the magnetic particle dosageâ†'the static sedimentation time.(7) Through orthogonal experiment, the best test conditions were as follows:the dosage of the magnetic particle was400mg/L,the PFS was800mg/L,and the PAM was8mg/L,the static sedimentation time was20min.(8) In this experimental condition, three groups of parallel tests were used to check the test effect, CODcr, NH3-N and the turbidity average removal rates reached62.23%,22.33%and92.07%respectively.(9)The feasibility of coking wastewater advanced treatment by magnetic flocculation technical was analyzed from the technical and economic:Coking wastewater advanced treatment by magnetic flocculation technical was feasible technically. After the magnetic particle addition, the removal rates were improved, the static sedimentation time was shortened significantly, which can provide the reference to reform the coking wastewater treatment process and to meet emission standards.Coking wastewater advanced treatment by magnetic flocculation technical was feasible economically. Simply on the basis of the traditional coagulation depth processing, the cheap magnetic particle which can be reused and waste were dosed to achieve efficient flocculation and sedimentation, to lower the cost of reagents, and the shortening of the static sedimentation time can also reduce the structure size to lower the cost.