The Application Study Of Treatment On Dyeing And Printing Wastewater By Combination Of ABR-A~2/O-BAF-F Process

According to china’s environmental requirement, the COD concentration of thedyeing wastewater from printing and dyeing companies along the Tai Lake should beless than60.0mg/l. However, the current treatment processes most printing and dyeingcompanies have employed fail to meet the standard above. On one hand, somecompanies have applied physicochemical treatment to decolorize before biochemicaltreatment. The problem associated with decolorization is that the coagulatingsedimentation, due to the reaction from ferrous sulfate, as the decolorizer, and lime,can generate large amount of sludge, leading to high labor intensity. Even worse,calcium hydroxide from physicochemical treatment would cause scaling in thepipelines, and therefore threat the normal operation. It is worth mentioning that theiron ion in the effluent will impair the reuse of recycled water as well. On the otherhand, there are a number of companies which have employed hydrolytic acidificationtogether with aerobic treatment. In this method, the effluent from the secondarysedimentation tank is discharged after coagulant polymeric aluminium is used todecolorize. Even so, this technology can only reduce COD concentration to80.0mg/l.Considering the fact that Zhejiang province makes such requirement that the CODconcentration less than60mg/l must be met by all companies along the Tai Lake or theQiantang River, all printing and dyeing companies, therefore, are looking forward to asound dyeing wastewater treatment technology which is low invest, low cost, technicalreliable and easy to operate.The project is aiming to figure out a practical dyeing wastewater treatmentprocess, through identifying the current problems existing in dyeing industry, combingwith actual projects and doing experimental researches. Such treatment process wouldbe universally compatible around this industry. What this project features is as follows:1. Biochemical treatment is employed to the raw wastewater after PH adjustment.Since biochemical treatment avoids the physicochemical step, it reduced theproduction of the sludge and therefore lower the sludge treatment cost.2. Anaerobic Baffled Reactor (ABR) in the combined process is adopted to bringthe wastewater treatment cost down and improve the treatment efficiency. Thistechnology can help to further improve the biodegradability while getting rid of thepollutan. 3. Anaerobic/Anoxic/Oxic (AAO) includes build-it suspended filter to increase theamount of microorganisms. This sludge-membrane process has higher treatmentefficiency than regular activated sludge process; meanwhile it reduces the amount ofsludge production abundantly.4. Biological Aerated Filter (BAF) is used for advanced treatment, in considerationof the stability of the entire system. BAF in advanced treatment can avoid the foulingproblems of filters when they are in the biochemical treatment.