Alkali Reduction Treatment Of Dyeing Wastewater

In this paper,the resource and the water quality and quantity of alkali-minimization printing and dyeing from Xiaoshan New Ninotex Industrial Co.,LTD, Hangzhou, were investigated. The characteristics of the wastewater were high COD, strong alkalinity and high chromaticity color,and alkali-minimization with the wastewater of printing and dyeing which made the traditional technology was incapable in the wastewater treatment.Compared with the treatment methods of alkali-minimization printing and dyeing industry wastewater,a kind treatment method of reasonability, maturity and novelty was brought:The physical-chemical pretreatment-micro-electrolysis multistage-biological contact oxidation method.In the physical-chemical process, single-factor experiment was employed.The first was alkali-minimization,and the effects of different factors such as neutralizing acid,pH, lime amount,and The optimal reaction conditions:sulfuric acid,neutralizating pH3.5,lime amount 2.0 kg/m3,COD removed rate 80.0% about.The second was composite wastewater, and effects of different factors such as flocculating agent, muti-function iron amount, and flocculating pH. The optimal reaction conditions:muti-function iron and it's amount 1.26 kg/m3.COD removed rate, colourity and turbidity were 29.4%,56.7% and 81.2% respectively. The wastewater being treated:COD1000～1300mg/L, colourity700～900 times,turbidity 90～130 degree.In the biolochemical process, the effects of different factors suchas the dissolved oxygen (DO), hydraulic detention time (HRT),calium superphosphate amount, optimal biological temperature and pH. The optimal reaction conditions:DO3～4mg/L, HRT 9h,calium superphosphate amount 0.1kg/m3,temperature 20～30℃,optimal pH 5.5～6.5.The average removed rates of COD, colourity and turbidity were 43.8%,74.2%, and 53.5% respectively. The wastewater being treated:COD560～730mg/L, colourity180～240 times, turbidity40～65 degree, which didn't reach the standard. For the disadvantages of TA which made COD could't reach the standard and was hard degradated in the traditional biolochemical process, the combined process of micro-electrolysis-biochemical process was employed,and the single different factors method were studied.The effects of different factors such as materials, Fe/C(mass),pH, etc.The optimal reaction conditions:micro-electrolysis materials were ironchip and coke, Fe/C(mass)5:1,pH 5.5～6.5,HRT 9h, calium superphosphate amount 0.1kg/m3, DO 3～4mg/L.In the biochemical process,The average removed rate of COD,colourity and turbidity were 67.5%,91.3%,and 70.7% respectively. The wastewater being treated:COD300～500mg/L, colourity50-70 times, turbidity20～40 degree.Then the mechanism of micro-electrolysis was initially dicussed.The combined industrialized process was studied.The process: alkali-minimization wastewater could be reclaimed by acidation,then the wastewater,being adjusted pH, and printing-dyeing wastewater were mixed to be further treated by micro-electrolysis multistage-biological contact oxidation method.The process possessed the characteristies of small investment, simple procedure and small floor area,and the process could be fit for dealing with the alkali-minimization printing and dyeing industry wastewater of high concentration.The wastewater being treated: COD<500mg/L, colourity<50 times, turbidity<40 degree. COD reached the third grade discharge standard of "Water Pollutants for Dyeing and Finishing of Textile Industry"(GB4287-92) and colourity and turbidity reached the require of the company.