Research On The Treatment Of Azo Dyes With Activated Carbon Sludge Enhancement Method

Dye industry is an important industry in China's national economy.There are more than 100,000 kinds of commercial dyes,of which azo dyes account for about 70 per cent.Azo dyes are toxic to aquatic organisms and mutagenic to human body,resulting in serious environmental problems.In this study,azo dyes AO7 and RB5 were selected as characteristic pollutants.Firstly,the adsorption and biodegradation processes were analyzed in activated sludge system.Secondly,powdered activated carbon enhanced activated sludge(PAC-AS)method was established,and its treatment effect was analyzed.Then the effect of adding powdered activated carbon on the biological treatment system and its mechanism were discussed.The adsorption of AO7 and RB5 in activated sludge system mainly occurred in the early stage.And the adsorption capacity remained unchanged in a certain range.For azo dye AO7,biodegradation was dominant in the whole process.For azo dye RB5,biodegradation removal was not significant,adsorption was dominant in the whole process.In addition,it was found that the adsorption capacity of azo dyes on activated sludge increased gradually with the increase of initial concentration and temperature,and the adsorption capacity of azo dyes AO7 and RB5 was the best when pH was 3.0.The fruit shell PAC with the best-saturated adsorption capacity was selected to establish PAC-AS enhancement method from four different activated carbons.The conclusions were as follows: the optimum amount of sludge was SV=40%;the optimum dosage of PAC was 300 mg/L,and the removal effect of AO7 by PAC-AS system was the best under the condition of pH=5;the increase of temperature could not improve the overall removal rate,but could significantly accelerate the reaction rate.The addition of PAC will influence the microstructure and sedimentation performance of sludge.The PAC addition played the role of carrier of microbial aggregation and increases the area and time of contact between microbial surface andsolution in the reaction system.And with the PAC-AS system did not appear sludge floc dispersion,PAC also achieved the effect of improving sludge settling performance.In addition,the PAC-AS system greatly improved the biodegradation removal rate.In conclusion,the role of PAC in PAC-AS system is not only adsorption,but also synergistic enhancement.