Engineering Design Of Printing And Dyeing Wastewater And Experimental Study On Antimony Removal

The production of waste water in textile printing and dyeing industry in China was always in the forefront of the industry.In recent years,with the continuous development of printing and dyeing technology,raw materials and chemical auxiliary reagents used in printing and dyeing were becoming more and more complex,which leads to the difficulty in the treatment of waste water discharged from the printing and dyeing enterprises.In addition,the removal of metal antimony（Antimony,Sb）in printing and dyeing waste water was required in the new standards for pollutant discharge.The traditional waste water treatment system has been difficult to meet the water quality requirements.Although there are many new technologies and new methods for the treatment of printing and dyeing waste water containing antimony,most of them are still in the laboratory simulation stage or need to be improved.Therefore,the design of stable,efficient and economical technology for printing and dyeing wastewater treatment and antimony removal has become co-urgent demand of the environment and enterprises,which will be beneficial to the realization of the healthy and sustainable development of dyeing and finishing of textile industry in China.This design is planed for the treatment on the waste water from 6 printing and dyeing enterprises in Economic Development Zone in Changshu.By drawing on similar engineering cases,combining the geographical location of the sewage plant and the actual development situation of the park,a set of printing and dyeing waste water treatment process is designed.The design aimed at obtainning abilities including stable effluent,strong anti impact and convenient management operation.At the same time,the test for a new method of antimony removal are carried out in order to introduce this method to be used in design.According to the approved water consumption volume of each entry area,and considering the fluctuation of water quality and quantity of printing and dyeing production,the design scale of the project is about 15000 m³/d.In order to ensure the normal operation of the sewage treatment plant and the transportation pipeline of the wastewater,the necessary pre-treatment facilities are set up in the factory.The printing and dyeing enterprises are not allowed to use nitrogen containing substances such as urea and other printing processes.The water quality of this project is determined as follows:p H=10-12,COD_Cr=600 mg/L,BOD₅=150 mg/L,total Sb=700μg/L,NH3-N=15 mg/L,SS=250 mg/L,and chroma is 500.The process consisted of the regulating pool-coagulating sedimentation tank-hydrolytic acidification-CAST biological pool-Fenton oxidation-FMBO antimony removal-Thunip’s rotary fibre disk filtration system.The effluent from the process was required to meet the water quality of"Discharge standards of water pollutants for dyeing and finishing of textile industry"（GB42 87-2012）and its following the revised list for antimony removal.Surplus sludge were concentrated and dehydrated through sludge thickener,plate and frame filter press and dewatering machine for furthur disposal.Some stinky structures,such as grille,regulating pool,hydrolytic acidification pool,sludge thickening pool and sludge conditioning pool,are covered and the waste gas from these pools were collected through biological filter for deodorization.The factory boundary index was required to reach the second standard of"Discharge standard of pollutants for municipal wastewater treatment plant"（GB18918-2002）.A new T20 antimony removal agent（mainly composed of iron and manganese oxide,FMBO）is selected for wastewater treatment from printing and dyeing industry.A static beaker test is carried out in lab.According to the result of the beaker test,the optimum dosage of the dosage is 1500mg/L,the optimum p H range is 4.5-5.5,the fast stirring speed of the stirring device is 500r/min,and the slow stirring speed is 80r/min.In order to verify the best treatment condition of the agent and the best effect of antimony removal in practice.The agent was used in Zhouhang Xinzhou sewage treatment plant in Changshu（which contains antimony pollution factor is more typical）.The results of the production test show that the antimony removal efficiency of FMBO is about 90%and the antimony in the wastewater was completely tranformed into Sb（V）in effluent.The effect of antimony removal is remarkable,and it can reach the standard.It can be used in the treatment engineering of antimony printing and dyeing waste water.The total investment of the project（15000m³/d）was estimated about 61.4546million.The operation cost of sewage treatment plant engineering unit is 2.39 yuan/m³,and the average value of total cost is 3 yuan/m³.The implementation of this project can make wastewaer from the six printing and dyeing enterprises in Economic Development Zone of Changshou to be treated together with the advantage of the scale advantages and energy-saving and emission reduction.Operation of the project would meet govemment’s requirment for strengthening the prevention and control of sewage pollution and has a positive contribution to the pollution control of water body in Changshu.