Zero Emissions Research On Key Technologies Of Processing Of Cashmere Dyeing Wastewater

The study on decolorization of dyeing and printing waste water,removal of turbidity,reduction of COD was carried out.This paper studied the ozone oxidation decoloration reaction kinetics in unisol red B-B dye wastewater and factory wastewater in the range of temperature change of 10～70℃,the phenomenon of reaction rate crossover at different temperatures was found and explained,the characteristic color（concentration）of dyes was quantitatively analyzed by UV visible spectrophotometry,treatment of wastewater by ozonation combined flocculation and filtration,the comparison of ozone decolorization by a bubbling bed,a packed bed and a rapid gas-liquid mixing reactor was conducted.A recycling process of recycled water and corresponding water quality indexes were recommended.The following results were obtained:（1）Ozone decolorization has two color change points,the first one is dye characteristic color vanishing point,and the second is colorless change point（non dye characteristic color vanishing point）.The apparent reaction kinetics accorded with the first order kinetics at different water samples and different temperatures.The reaction rate constant is 0.00526s^-1 at 40℃.（2）"Baseline uplift"phenomenon caused by diffuse scattering was found when using ultraviolet visible spectrophotometry to analyze the ozonation of plant wastewater.Ozone oxidation combining flocculation and filtration can be used to remove coloured material between two color changing points,including substances that cause diffuse scattering.（3）The fast gas-liquid mixing reactor is more suitable for ozonation.Using the relationship between the increase of gas-liquid mixed surface energy and the decline of reactor pressure,the mass transfer area of the reactor is estimated to be 10⁵ m²/m³ order of magnitude,the average bubble size is 10¹ micron orders of magnitude.The gas-liquid volume ratio is 4 for ozone decolorization of conventional sewage（air source）,the gas-liquid ratio of high concentration sewage can reach 9.5.For the conventional mixing wastewater of the factory at 40℃,when the gas-liquid volume ratio is more than 4,the chroma、turbidity and suspended substance of sewage are close to fresh water by flocculation and filtration,increasing activated carbon adsorption treatment of residual COD,zero discharge of sewage recycling is possible.