Tudy Of Pretreating Print And Dyeing Wastewater By Ferrate

Print and dyeing wastewater is difficult to treat because of its strong chroma,complicated component, and high concentration of COD. Coagulation is an effective way to treat it. But its shortcoming is substantial dosage using in reagent, bulky sludge production. To fond a sort of simple, economical, and efficient reagent that can solve those problems is a breakthrough.Ferrate, a new reagent that has manifold functions such as oxidation, coagulation, and so on, is much potential in wastewater treatment. Many researchers have done a lot of work by using it in wastewater treatment. It is of pioneering magnificent by using ferrate in print and dyeing wastewater. And it will also expand wastewater-treating scope. Experiment testified that it is feasible by using ferrate as a pretreatment reagent in treating print and dyeing wastewater.In this paper various conditions were experimented in preparation of ferrate by hypochlorite, Based on which a better preparation method, chemical oxidation and electrolysis, was brought forth. With comparison, the conclude was that chemical oxidation and electrolysis was much better than chlor-oxidation for its high productivity, high purity in products, and economical, and less pollution.The research indicated that ferrate can reduce a part of COD. Some giant molecule, especially those which were difficult to reduce, could be decomposed into small molecule, thus reduce the concentration of COD. Generally speaking, the more dosage the ferrate was put in, the better effect we could get..As to the chroma, ferrate could break off double bonds of chroma-molecules in soluble state. At the same time it could cut short the bonds combining hydraulics parts and chroma, which could buildup alie-hydraulics so that to be coagulated easily in next step. The production of ferrate was Fe3+ which hydrolyze quite easily. The outcome of hydrolyze is flocculent that could remove alie-hydraulics and giant molecule effectively by sedimentation.Preoxidation by ferrate could enhance coagulation effect. In the experiment,much higher results could be achieved by using ferrate as a coagulation-aiding reagent for alum than using ferrate or alum alone in the same strength.Finally, we did the study of feasibility of pretreatment by ferrate in print and dyeing wastewater. Because it will not impact the biology system, but be able to remove parts of heavy metal, produce less sludge, and more economical than other reagents, it is feasibility.Ma Junmei (environmental engineering) Superbised by: Wang Yonghui Xue Gang...