Basic Research On The Treatment Of Dyeing And Printing Wastewater With Enhancement Of Activated Sludge By Magnetic Field

The dyeing and printing industry is a heavily polluting industry among the major water users in China.Due to its complex composition,difficult biodegradation and low recycling rate,it has become a key area of wastewater treatment.Moreover,the low temperature inhibits the microbial activity of the activated sludge,and the existing process is difficult to meet the requirements for the treatment of dyeing and printing wastewater by the biochemical wastewater treatment plant at low temperature,and it is difficult to meet the discharge standard.Therefore,low temperature printing and dyeing wastewater has a serious impact on the environment.In this experiment,the magnetic field and wastewater treatment technology were combined to investigate the performance of the activated sludge reactor in the treatment of dyeing and printing wastewater at low temperature.The basic analysis of COD,chromaticity,dye concentration,TTC-DHA,HPLC and microbial diversity was carried out,and the strengthening effect of magnetic field on the treatment of dyeing and printing wastewater by activated sludge at low temperature was studied.The Fenton reagent was used to pretreat the laboratory simulated dyeing and printing wastewater?Acid Red B,Reactive Red 2?to increase its biodegradability,and the optimal dosage of Fenton reagent was determined.Then,the pre-treated dyeing and printing wastewater is used as an organic carbon source of the activated sludge treatment system.It was found that the four reactors R₁,R₂,R₃ and R₄ were treated with sludge biological treatment for 24 hours respectively.The degradation rates of COD,chromaticity,dye and dye of different dye wastewaters were as follows:Acid Red?20°C?>Reactive Red?20°C?>Acid Red?5°C?>Reactive Red?5°C?;And the TTC-DHA in the Acid Red?20°C?reactor maintained high activity throughout the experimental period;the peak of HPLC scanning showed a decrease in the concentration of the substances in the four activated sludge reactors,Acid Red B and Reactive Red 2 are biodegradable at room temperature or low temperature.At low temperature,the microbial diversity in the activated sludge cultured by Acid Red B was significantly higher than that of Reactive Red 2,which is suitable as a dye for the low temperature activated sludge reaction system.Acid Red B was used as the microbial organic carbon source in the activated sludge treatment system.It was operated stably at low temperature?5°C?and applied magnetic field.The magnetic field strength was adjusted to 0,10,20,30,40 mT,respectively.The effects of the magnetic field strength of this gradient on the degradation of acid red B by activated sludge were monitored and analyzed at the same time.It is found that the degradation rate of COD,chromaticity and dye concentration of Acid Red B wastewater exposed to R₂ in the magnetic field increases with the increase of magnetic field strength and reaches the maximum value within30mT culture period.?66.30%,60.87%,61.47%,respectively?,and then began to decline.TTC-DHA in R₂ also generally increased with the increase of the magnetic field strength,and reached the maximum activity value of 9.44 mgTF/gSS at 30 mT.Compared with R₁,the HPLC peak area and peak height detection value of the R₂ reactor effluent are lower than the R₁ detection value,and the magnetic field strength has the effect of enhancing the activated sludge microbial degradation of the acid red dye wastewater.And when it is at 30mT,the peak area and peak height detection value of the effluent of the R₂ reactor are significantly reduced.30mT magnetic field was applied to the activated sludge reactor to degrade the Acid Red B wastewater.It was found that R₂ with 30mT magnetic field at low temperature has better degradation performance to Acid Red B wastewater,and the average degradation rates of COD,chromaticity and dye concentration in R₂ were 62.74%,57.30%,and 58.42%,respectively.TTC-DHA in R₂ reactor with 30 mT magnetic field maintained higher activity throughout the experimental period with an average of 8.96 mgTF/gSS.After Acid Red B wastewater was treated by R₂ reactor,the peak area and peak height of the effluent HPLC were significantly reduced.The magnetic field of 30mT at low temperature was beneficial to strengthen the activated sludge microbial activity,thereby improving the efficiency of activated sludge degradation for Acid Red B wastewater.At the same time,the total optimized sequence of activated sludge samples in the R₂ reactor is larger,and the Shannon and Simpson indices are relatively large.Therefore,the magnetic field helps to increase the microbial diversity of the activated sludge and promote the growth of activated sludge microorganisms at low temperatures.Moreover,30 mT magnetic field enriches the microbial communities in the activated sludge reactor that are effectively involved in the biodegradation of contaminants.The bacteria in the R₂ reactor that effectively participate in the degradation of pollutants by activated sludge are enriched.The dominant bacteria in the R₂ reactor are Bacteroidetes,Chloroflexi,Planctomycetes,and Acidobacteria.The dominant genus of R₂ reactor that effectively participate in the degradation of pollutants by activated sludge mainly includes Flavobacterium,Hydrogenophaga,Gemmatimonadaceae_uncultured,and Saprospiraceae_uncultured.