Study On Discolorant Treatment For Reclaimed Water

At present, deep processing technology are widely used in reclaimed watertreatment field. But high colored raw reclaimed water can produce high coloredtreatment water which can’t meet GB/T19923-2005, GB/T18920-2002and othernational standards’ requirements. Use the orthogonal experiments to prepare a kind offlocculating decoloring agent, and to determine the optimal parameter values offlocculating decoloring agent used with ozone, make sure that the color of treatmentwater can meet the national standards’requirements.(1) Select three kinds of dye to simulate high colored raw reclaimed water. Usespectrophotometric method to ascertain concentration and absorbance standard curveto calculate discoloring rate.(2) Use the orthogonal experments to determine the optimal parameter values ofconstituent parts of flocculating decoloring agent. Get two kinds of flocculatingdecoloring agents named TH-1and TH-2, which can get good decolorizing effects inview of high colored raw reclaimed water. The constituent parts of flocculatingdecoloring agents include dicyandiamide, urea, formaldehyde, ammonium chloride,calcium chloride, EDTA, etc. Formula is as follows:TH-1dicyandiamide: urea is3:1, dicyandiamide: formaldehyde is1:2.4,(dicyandiamide+urea): ammonium chloride is1:0.8,70℃constant temperature forthree hours, EDTA solution scales up along with dicyandiamide.TH-2dicyandiamide: formaldehyde is1:2.5, dicyandiamide: ammonium chlorideis1:1,65℃constant temperature for three hours, calcium chloride solution scale upalong with dicyandiamide.Use infrared scanning spectrum analizes ingredients of TH-1and TH-2, andindicates the mechanism of flocculating decoloring agents.(3) After determining the optimal running parameter values of flocculatingdecoloring agents, ozone, PAC, ozone exposure time and the order of treatmentprocess, employ orthogonal experiment to determine the optimal values of the aboveparameters when flocculation-ozone process are used to high colored water and rawreclaimed water. Results show that under the condition of the optimal parameters itcan get low turbidity and decolorization rate for two kinds of experimental water, and the variable quantity of pH is in manageable.(4) Use medium scale experiments to validat the decolored effects of flocculatingdecoloring agent and the optimal parameters of coagulation–ozone process under thecondition of the low temperature (16.8℃) and high temperature (22.4℃). Resultsshow that to raw reclaimed water, decolorization rate of TH-1is54.5%, of TH-2is45.4%, the efficacy of TH-1is better than TH-2under the condition of hightemperature, TH-1can be dropped to0.08mL/L, the TH-2to0.1mL/L; under thecondition of low temperrture, the effects of two drugs is worse than effects under thecondition of high temperature, it’s recommended to use TH-1, dosage is0.1mL/L.Calculates the cost of drugs under the condition of medium scale experiment.