| Printing and dyeing wastewater contained high concentration of pollutant, high chromaticity and complex component. And its quality and quantity changes frequently. So it is a kind of organic industrial wastewater which is difficult to treat. In this paper, hydrolytic acidification-biological contact oxidation-Fenton’s reagent oxidation processes were used to treat printing and dyeing wastewater in the laboratory. The effective design and control parameters of the processes were found out by analyzing the removal efficencies, variation of COD and chromaticity in the processes.Firstly, the experiment on hydrolytic acidification-biological contact oxidation processes to treat printing and dyeing wastewater was carried out. Hydrolytic acidification cell in the first part was used to improve biodegradability of the wastewater and reduces chromaticity, which was benefical for subsequent treatment. Two subsequent biological contact oxidation stages was aimed mainly to reduce COD and BOD5.Hydrolytic acidification-biological contact oxidation processes were started up to treat two kinds of printing and dyeing wastewater, i.e. reactive brilliant blue KN-R dye wastewater and mixed dyes wastewater which contained reactive brilliant red K-2BP, reactive brilliant orange X-GN and direct scarlet4BS. The results showed that the system run well, and the effluent qualities respectively meet standard I and standard Ⅱ of 《Discharge standard of water pollutants for dyeing and finishing of textile industry(GB4287-92)》By orthogonal tests the impacts of reactor effect factors such as influent flow (hydraulic retention time), gas water ratio of the first and the secondary bio-contact oxidation column were analyzed. The final results showed that influent flow is the most prominent effect factor, followed by gas water ratio of the first bio-contact oxidation column and gas water ratio of the secondary bio-contact oxidation column.Selecting the removal rate of COD and color as evaluation indexes, multi-index problem was transformed into a single index problem by the index overlay method. The best operation conditions of the reactor to treat reactive brilliant blue KN-R dye wastewater were obtained, which are:influent flow=10L/h (hydraulic retention time =30h), gas water ratio of the first bio-contact oxidation column=8:1, and gas water ratio of the secondary bio-contact oxidation column=7.2:1. The best operation conditions of the reactor to treat mixed dyes wastewater are:influent flow=5L/h (hydraulic retention time=60h), gas water ratio of the first bio-contact oxidation column=11:1. gas water ratio of the secondary bio-contact oxidation column=9:1.Secondly, the experiment on hydrolytic acidification-biological contact oxidation-Fenton’s reagent oxidation processes to treat azocarmine G wastewater was carried out. The results showed it was a feasible process for treating azocarmine G wastewater, with effluent COD and chromaticity of less than50mg/L and30, respectively. The effluent qualities not only meet standard I of 《Discharge standard of water pollutants for dyeing and finishing of textile industry(GB4287-92)》, but also meet two more stringent local discharge standard of water pollutants for dyeing and finishing of textile industry standards of Jiangsu Province and Shandong Province.According to the Monod equation, when the single reaction cell in the hydrolytic acidification-biological contact oxidation processes to treat azocarmine G waste water was assumed as a completely mixed steady-state reactor, its kinetic equation was derived and the relevant parameters of the equation were determined by experimental measurements and linear regression equations. The kinetic equation of biochemical reaction in the hydrolytic acidification cell was v=0.3096(Le-0.4238)(d-1). The kinetic equation of biochemical reaction in the first biological contact oxidation cell was v=0.4532(Le-0.0647)(d-1). The kinetic equation of biochemical reaction in the secondary biological contact oxidation cell was v=0.2882(Le-0.0647)(d-1).When temperature remained unchanged, the influencing factors of Fenton oxidative degradation of azocarmine G are:initial pH, initial dye concentration, initial concentration of ferrous ions and initial concentration of hydrogen peroxide. When initial pH remained unchanged, the apparent kinetic model of Fenton oxidative degradation of azocarmine G was derived. Then the parameters of the model were calculated by measuring the dye concentrations in different time when the reaction of Fenton oxidative degradation of azocarmine G was conducted. The kinetic equation of reaction of Fenton oxidative degradation of azocarmine G was v=-dC/dt=0.0228C0.9050R0.5150S0.3478(mg L-1min-1)。... |
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