| Phenoliccompounds are characteristic pollutants of cokingwastewater.Traditional biological process could not completely degrade phenoliccompounds and may increase chromaticitydue to the intermediate generated by theprocess of degradation of phenolic compounds. Therefore, in this paper, actualcoking wastewater was used, andvolatile phenol and COD was used as indicators oforganic matter. The removing effect of organic matterin coking wastewater byozone/activated carbon system was studied seriously, and compared with separateozone system.At the same time, the factors that affect oxidationand the main role ofactivated carbon in ozone/activated carbon system were discussed. The dynamicsanalysis of degradationwas also carried on. All these were to provide scientific basisand technical support for setting up treatment technology of coking wastewater byozone/activated carbon system. The main research results and conclusions of thispaper were as follows:1) Ozone had an degradation effect on organic compounds in cokingwastewater. At the end of the reaction(60min), the removal ratio of phenol (about80percent) was higher than COD, which could only reach30percent.2) pH and temperature had a great influence on the removal of organic matterin coking wastewater,but ozone dosagehad little effect like above two factors. Withthe increase of pH, the removal ratio of phenol and COD were obviouslyimproved.pH rised from6to12, the phenol removal ratio could rise30percentandCOD removal ratio could increase20percent.As temperatures rised, phenol removalratio changed little, but the removal ratio of COD obviouslydropped by about10%.With the increase of ozone dosage, the removal ratio of phenol and COD havesmall increases, but the effect was limited and unstable.3) In the same process conditions, the COD removal rate in theozone/activated carbon system was higher than single ozone system by about20%, showed that activated carbon obviously improve the mineralization degree oforganic matter.4) In the ozone/activated carbon system, phenol removal ratio was improved,with the increase of additive amount of activated carbon. The COD removal ratio hasincreased significantly at60min.The additive amount of activated carbon for10g/L,COD removal ratio is about40%, while the additive amount of active carbonincreased to25g/L, COD removal ratio increased to70%. Wastewater pH fluctuatedfrom6to10, had little effect on phenol and COD removal rate.This is different fromozone system, suggestedthat the role of activated carbon may also includedtheinfluence on the change oforganic matter degradation pathways.5) The adsorption effect of activated carbon in the ozone/activated carbonsystem did not lead to removeorganic matter finally.By adding sodium carbonateinto the ozone (pH=10) and ozone/activated carbon system, the removal ratio ofphenol and COD significantly reduced. This fact illustratiod hydroxyl radicalsgeneratiod by ozone have played an important role in removing organic matter.6) Activated carbon can be repeated use in catalytic system, and the catalyticeffect did not decrease significantly.7) The bigger the specific surface area and total pore volumn the activatedcarbon had, the better catalytic effect could reach. The content of and acidic oralkaline groups of surface oc activated carbon has little effect on the catalytic effect.With grannular activated carbon, the smaller the particle size was, the better catalyticeffect was.8) The ozone system could obtain good fitting effect under the condition ofdifferent dosing quantity and low pH. The high pH in ozone system and high dosageactivated carbon in ozone/activated carbon system had a poor fitting on the firstorder kinetics. The lifetime method was uesd to ascertain the reaction order, and partof the reaction kinetics order was found that tended to second. The second orderkinetics fitting was made for above two situations obtained good fitting effect. |
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