Dyeing And Finishing Wastewater Treatment By Hybrid Hydrolytic Acidification And Anoxic/Aerobic Alternative SBR Process

Dyeing and finishing wastewater is characterized by high discharge amount and complicated composition(such as high-strength organics,poor biodegradability,high chroma,high proportion of organic nitrogen,etc.).It is difficult to meet the discharge standard consistently via traditional activated sludge process.In this study,a hybrid hydrolytic acidification and anoxic/aerobic alternative SBR process with synchronous chemical phosphorus removal was employed to treat real dyeing and finishing wastewater.Pollutants removal under different operation parameters during hydrolytic acidification SBR,anoxic/aerobic SBR and chemical phosphorus removal were systematically investigated to explore the optimal operation parameters,under which the treated effluent can meet the current direct discharge standard of dyeing and finishing wastewater in China(GB4287-2012).The main outcomes were achieved as follows:After the optimization and debugging,the real dyeing and finshing wastewater was treated by hydrolytic acidification SBR under the conditions of reaction time of 10 h,temperature of 30? and no p H control.After hydrolysis and acidification,the average effluent COD and COD removal was 736 mg/L and 32%,respectively.The average effluent ammonia nitrogen was 19.5 mg/L,10 mg/L higher than influent,which derived from the conversion of organic nitrogen into ammonia nitrogen.The average effluent acetic acid was55.6 mg/L,24.3 mg/L higher than influent.The average effluent pentanoic acid was 8.5 mg/L,4.3 mg/L lower than influent.The average effluent total VFAs was 64 mg/L,20 mg/L higher than influent.The better performance of organic nitrogen conversion into ammonia nitrogen and VFAs accumulation could enhance the following biological nitrogen removal via nitrificantion and dentrification.After the optimization and debugging,the hydrolytic acidified effluent was treated by anoxic/aerobic alternative SBR under the conditions of reaction time of 12 h,room temperature of 25?30?,p H of 7?8 and SRT of 15 d.Performance of anoxic/aerobic alternative SBR was the best under stage III with 800 ml: 200 ml influent distribution ratio.In stage III,the average effluent COD and COD removal was 94 mg/L and 86.9%,respectively.The effluent ammonia nitrogen and ammonia nitrogen removal was less than 0.1 mg/L and close to 100%,respectively.The average effluent total nitrogen and total nitrogen removal was 13.5 mg/L and 62.8%,respectively.The average effluent total phosphorus and total phosphorus removal was 2.63 mg/L and 24.5%,respectively.The average effluent aniline and aniline removal was 0.45 mg/L and 66%,respectively.The average effluent chroma and chroma removal was 58(dilution times)and 51.7%,respectively.The average effluent suspended solids was 31 mg/L.The effluent ammonia nitrogen,total nitrogen,aniline and suspended solids meet the direct discharge standard of dyeing and finshing wastewater,achieving good biological nitrogen removal.The experiment for chemical phosphorus removal was conducted in stage III of anoxic/aerobic alternative SBR.Coagulant for phosphorus removal was added into the reactor at the end of reaction time.When the molar ratio of polyferric sulfate versus targeted removed phosphorus was 6,the COD(77 mg/L),ammonia nitrogen(less than 0.1 mg/L),total nitrogen(14 mg/L),total phosphorus(0.42 mg/L),aniline(0.38 mg/L),chroma(35 times)and suspended solids(19 mg/L)of the effluent from anoxic/aerobic alternative SBR could meet the direct discharge standard of dyeing and finishing wastewater,achieving the research target of this study.