| At present, there is a series of vanadium smelting pollution problems. the emissionstandard in China for vanadium smelting enterprises are more and more stringent. In orderto better regulate vanadium industrial production and pollution control, Our CountryEnacted the "vanadium industrial pollutant discharge standards"(GB26452-2011) in2011,and all industrial enterprises implemented vanadium water pollutant emissions limits fornew enterprises since January1,2013. This standard not only reduced pollutant emissionlimits, especially for chloride ion emission limit requirements, but also the basis of per unitof product made more stringent requirements displacement. Therefore it is inevitable thatdepth study of vanadium smelting wastewater treatment and reuse. Membrane technologyhas unique advantages, along with the film unit cost of continuous improvement andcontinuous development of membrane materials and technologies mature, membranetechnology is play to a huge role in waste water treatment and reuse, and other fields. Thispaper analyzes the current situation of vanadium smelting wastewater treatment and the"low sodium baking-flooding out-ion exchange resin purification," a production ofvanadium vanadium smelting process wastewater quality characteristics in a companyfrom Western Hunan. In this study, an integration technology including "Coagulation-sand filtration-activated carbon filter-microfiltration-reverse osmosis" was provided,Meanwhile, various factors for the operation of membrane were also studied, eachprocessing stage water quality were monitored and analysised in three months, equipmentcleaning cycle and its treatment effect of recovery after cleaning were inspected,and thecost per ton of waste treatment were briefly calculated.The research contents and results are as follows:(1).The main water quality indicators of the enterprise vanadium smelting waste water:pH was7.8to9.0, turbidity was18NTU~45NTU, suspension was153mg/L~419mg/L,chloride ion was25200mg/L~32700mg/L, V was15mg/L~21mg/L, total chromiumwas47mg/L~55mg/L, hexavalent chromium was30mg/L~37mg/L, COD was120mg/L~400mg/L, the conductivity was47800μS/cm~58600μS/cm.(2). Optimum conditions for coagulation and sedimentation: The dosage of PAC was600mg/L, pH was greater than9, optimal retention time was1.5h. This phase of the totalvanadium and total chromium removal rate reached about80%, hexavalent chromiumremoval rate reached about87%, COD removal rate reached about31%, suspended solidsand turbidity removal efficiency of about90%. (3). Various factors for the operation of membrane were also studied, including theoperating pressure, time and pH. The run effect of membrane was determined by the waterflux and salt rejection membrane. Operating pressure and water flux were substantiallypositive linear correlative, the desalination rate sharply increases with the elevatedpressure,when the pressure were3MPa, the removal rate have reached99.4%, due to themaximum pressure of the membrane was3.5MPa, the working pressure was considered3MPa. After the membrane system was stable, water flux and salt rejection were relativelystable, the run time had little effect on the water flux and salt rejection. Low or high pHvalue of water had little effect on the water flux membranes, however,with the increase ofthe pH value, desalination rate first decreased and then increased.With pH value being8to9,desalination rate have reached a maximum, which matched exactly with pH optimumof the coagulation and sedimentation, the step of adjusting the pH value into the reverseosmosis membrane can be omitted.(4). The results showed that the COD in wastewater after reverse osmosis was20.7mg/L, the chlorine concentration was176mg/L, the conductivity was387μS/cm, and thedesalination rate was99.4%. The removal efficiency of heavy metals such as totalchromium, Cr(VI) and total vanadium was more than99%, and the content of heavy metalsin water were much lower than the emission standard in China. This water could be reusedfor most of the production process. And the concentrate was also applied for the ballingprocess and flue gas treatment. Zero emissions of wastewater in the Vanadium smeltingwastewater was obtained in this process.(5). Under conditions of optimum parameters remain unchanged, the effluent treatmentprocess carried out in various stages of three months on-site monitoring and inspectionequipment cleaning cycle. the water flux of RO averaged38.4L.m-2.h-1after chemicalcleaning, which compared with31.2Lm-2h-1reverse osmosis before cleaning, improvedby18.8%; just the reverse osmosis unit beginning of the run40.5Lm-2h-1as compared toreturn to the original95%.(6). There was a brief estimates for the cost per tonne of vanadium smeltingwastewater treatment,it was about4.29yuan.The results showed that an integration technology including "Coagulation-sandfiltration-activated carbon filter-microfiltration-reverse osmosis" to deal with thevanadium smelting waste was feasible,it can be used for engineering applications, And wasin line with concept of circular economy. therefore it will provide considerable economicvalue and broader applications. |
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