The Responses Of Aerobic Granular Sludge To Insecticide Thiamethoxam

Insecticide thiamethoxam (TMX) achieves good results since put on the market as the second kind of neonicotinoid insecticides. So it is used in great quantities. Research shows that, this will cause big damage to the environment. The aerobic granular sludge with good settling performance and perfect treatment, processing, widely used in the treatment of toxic and harmful substances.This study successfully cultivates aerobic granular sludge by the sequencing batch reactor (SBR).There are three reactors called R1 treating synthetic wastewater by aerobic granular sludge, R2 treating wastewater containing TMX by aerobic granular sludge and R3 treating synthetic wastewater by activated floc sludge.Getting the following conclusions:1, With the particles gradually mature, the ability of removing organics is increasing gradually, In the 50 d, the COD removal of R1 and R2 system is maintained at 93%, the removal of NH4+-N rate is maintained at 90%, R3 reactor is maintained at about 83%. When adding TMX into R2, COD and NH4+-N removal rate appeare decline. With the adaptation to the environment, COD and NE4+-N removal rate improve in the later period.2, The removal rate of TMX increased from the original 46.81% to 77.56%, it shows that aerobic granular sludge has been gradually adapt to TMX wastewater and achieved a good removal effect.3, The ratio of PN/PS of extracellular polymeric substances (EPS) increased up to 2 times in the formation of aerobic granular sludge. When adding TMX, relevant characteristics of granular sludge changed, at the same time, PN/PS ratio decreased. It may because that aerobic granular sludge change the secretion of EPS to adapt the external environment. With the adaptation of the reactor, it gradually returnes to the original value.4, PN materials is a key group in the formation of aerobic granular sludge. The change of selection pressure can stimulate the secretion of EPS. When adding TMX, the secretion of EPS changes. PeakA of representing fulvic and PeakE of representing Hu Min acid appeared to resist the toxic action of TMX.5, According to species identification results, the correlation bacterium group of degradation of TMX is Acinetobacte sp.in the reactor with TMX.