Application Study On Advanced Treatment Of Textile Wastewater By Integrated Ozonation-biological Aerated Filter Process

A large number of water would be used by the dye-printing textile industry, at the sametime it should be a potential water resources. Nowadays, Face of the stringent emissionstandards, a growing shortage of water resources and vast market space, how cost-effectiveachieved advanced treatment and reuse of textile wastewater has become a new opportunityand challenge for the dye-printing textile industry.A textile company of Guangdong decided to upgrade their wastewater treatment facilityin response to the call for development of clean production of “12th Five-Year Plan”,5,000m³/d of wastewater would be advanced treated and reused after the upgrading. For thecharacteristics of higher color, less suspended solids and poor biodegradability of secondarybiological treatment textile wastewater, using “integrated of ozone-biological aerated filter（O₃-BAF）and biological aerated filter （BAF）” combined processes as the advancedtreatment and reuse process. The effluent could be reused after subsequent and the densephase water of follow-up treatment could still be directly discharged.Raising the microbe in the filter and starting the system, exploring the optimumoperating parameters of the combined process. During the start-up phase, it was found that thesecondary BAF had a poor treatment effect to the wastewater, so it was changed intointegrated of ozone-biological aerated filter through argumentation. After transformation, theremoval rate of CODcr increased by9.4%, removal rate of color increased by33.4%, theeffluent CODcr less than40mg/L, color less than4times and the secondary effluent couldmeet the post-processing requirements. The operating parameters of two O₃-BAF system:total ozone dosage of20mg/L, dosing proportion of3:1; the hydraulic loading of firstO23-BAF1.05m³/m h, gas-water ratio of5; the hydraulic loading of secondary O₃-BAF1.68m³/m²h, gas-water ratio of3.During stability operation of the water reuse pretreatment system, the average CODcr ofinfluent92.8mg/L, color37times, the average CODcr of effluent can be reduced to35.6mg/L, color3times after pre-treatment system, the average removal rates were61.2%and89.9%. The study showed that the secondary effluent could meet the RO processingrequirements after pretreatment system. At the same time, the average CODcr of follow-upsystem concentrate could meet local emissions standards which is88.4mg/LThe running costs of water reuse pretreatment system were0.68yuan/m³wastewater,the total operating cost lower than the average price of local industrial water. The mainadvantage of this system: small footprint, strong anti-shock loading capability, no secondary pollution and simple day-to-day operation. Practice has proved that this process has strongapplicability and economic advantages. The project is the first large-scale application ofintegrated device of ozone-biological aerated filters; it has exemplary significance because itwas a breakthrough and innovation of industrial wastewater advanced treatment and reusetechnology.