Study On The Removal Of COD In Coal Coking Wastewater With Microorganism And Nontronite

Coal coking wastewater consists of many complex organic contaminants,and the organic contaminants are stable,toxicity and carcinogenicity.The COD of coal coking wastewater usually is very high,but BOD/COD is very low,which means that it's hard to be degraded by microorganisms.Hence,coal coking wastewater belongs to typical difficult to governance and toxic waste water.Quinoline,as the highest concentration of organic compounds in coking wastewater,has potential carcinogenicity and low biodegradability,and it is currently one of the difficult to remove in wastewater.Clay mineral is widely distributed in nature,and has many excellent properties,such as the huge surface areas,strong adsorption ability and strong cation exchange capacity.So it was studied by many experts as an environmental modification material.In the experiment we firstly considered quinoline as target contaminant,and isolated quinoline-degrading bacteria from coking wastewater.And then we isolated a deep quinoline-degrading strain,which can utilize the production of quinoline biodegradation and reduce the COD of coking wastewater.In addition,we use iron clay minerals under aerobic conditions to produce hydroxyl radicals,which can unselectively oxidate the organic pollutants in coking wastewater to reduce the effluent COD.We use the clay minerals and microorganisms in the coking wastewater,for example: 1.firstly microorganisms and then clay minerals.2.firstly clay minerals and then microorganisms.In this study,a quinoline-degrading strain was isolated from coking wastewater and identified as Alcaligenes faecalis.A deep quinoline-degrading strain,which can utilize the production of quinoline biodegradation by Alcaligenes faecalis,was also isolated from coking wastewater and identified as Mesorhizobium sp.The optimum conditions for degradation were 30 ?,salinity 0.3%,pH 8.0.And it can completely degrade 500mg/L quinoline and have a strong ability to degrade phenol.During the biodegradation process,the quinoline-N was released as ammonium.We quantifiedthe initial intermediate of the biodegradation,2-hydroxyquinoline.According the analysis by LC-MS,quinoline can be degraded in two pathways at the same time by Alcaligenes faecalis and Mesorhizobium sp.In the first pathway,the benzene ring was degraded earlier than the pyridine moiety of quinoline.In the second pathway,the N-heterocyclic was degraded earlier than the benzene ring of quinoline.The above results showed that Alcaligenes faecalis could coexist with Mesorhizobium sp.,which made further biodegradation quinoline.We use the clay minerals and microorganisms in the coking wastewater.Compared with biodegradation,chemical reduced clay minerals for coking wastewater removal rate of COD is higher,removal effect is better.In the microorganism-clay mineral model and clay mineral-microorganism model,the removal rates of COD almost are same.But in the earlier stage the effect of biodegradation is better.So we choose microorganism-clay mineral model as the best method to remove COD in the coking wastewater.