Study On The Biodegradation Characterristics Of Several Disperse Dyes

With the widely use of terylene, which usually be dyed by disperse dyes. The usage of disperse dyes are increasing,so with the disperse dye wastewater. The composition of disperse dye wastewater is complex and the biological method is the primary treatment to it, but it is still a main problem of wastewater treatment.In this paper, the impacts of aerobic, anaerobic and alternative anaerobic-aerobic operating conditions on the degradation of four kinds of disperse dyes, Neocron Black, Rhodamine B,Disperse Red S-BWFL, Disperse Red S-5BL had been discussed. The degradation rate and the influence of initial conditions were reflected by residual dye concentration and COD. Meanwhile,the degradation pathway was analysised based on the degradation intermediates detected by GC-MS. The findings may be a support of degrading of disperse dye or its degradation intermediates. The main results as follow:(1)The biodegradation characters of an azo disperse dye, Neocron Black(NB), were investigated in the activated sludge system under the conditions of aerobic, anaerobic and anaerobic/aerobic separately, and the biodegradation process of the dye was conjectured. The results showed that NB got the highest biodegradation rate under aerobic condition while the lowest under anaerobic condition and anaerobic/aerobic condition in between. It also proved that the increasing of NB concentration declined the dye bio-removal rate and the added biodegradable carbon source could promote its biodegradation efficiency. The optimal initial pH was at 7. By the spectrophotometry and GC-MS analysis, it testified that the luminous group of NB was biodegraded completely and the intermediate products of the dye were Benzenamine, 2,4-dinitro-;Benzonitrile, 2-amino-5-nitro-;p-Nitroaniline etc.(2)The same aerobic, anaerobic and anaerobic/aerobic activated sludge system was used to another disperse dye, Rhodamine B, and with a maximum dye Removal efficiency of 7.0%.(3)The biodegradation characters of an azo disperse dye, Disperse Red S-BWFL, were investigated in the activated sludge system under the conditions of aerobic, anaerobic and anaerobic/aerobic separately, and the biodegradation process of the dye was conjectured. The results showed that Disperse Red S-BWFL got the highest biodegradation rate under anaerobiccondition while the lowest under aerobic condition and anaerobic/aerobic condition in between. It also proved that the increasing of Disperse Red S-BWFL concentration declined the dye bio-removal rate and the added biodegradable carbon source could promote its biodegradation efficiency. The optimal initial pH was at 8. By the spectrophotometry and GC-MS analysis, it testified that the luminous group of NB was biodegraded completely and the intermediate products of the dye were phthalic acid, mono-(2-ethylhexyl) ester, p-nitroaniline and 4-nitroanisole.(4)The biodegradation characters of an azo disperse dye, Disperse Red S-5BL, were investigated in the activated sludge system under the conditions of aerobic, anaerobic and anaerobic/aerobic separately, and the biodegradation process of the dye was conjectured. The results showed that Disperse Red S-5BL got the highest biodegradation rate under anaerobic condition while the lowest under aerobic condition and anaerobic/aerobic condition in between. It also proved that the increasing of Disperse Red S-5BL concentration declined the dye bio-removal rate and the added biodegradable carbon source could promote its biodegradation efficiency. The optimal initial pH was at 8. By the spectrophotometry and GC-MS analysis, it testified that the luminous group of NB was biodegraded completely and the intermediate products of the dye were phthalic acid, mono-(2-ethylhexyl) ester and p-nitroaniline.