Study On The Extracellular Polymer Substance And The Settle Ability Of Activated Sludge

Activated sludge process is the mainstream technology of urban wastewater treatment,and the biggest weakness is sludge settling property.Sludge bulking is one of the serious problems,making it hard to operation management of sewage treatment system and reducing the sewage treatment efficiency.In this research,continuous sludge samples were collected from urban sewage treatment plant and lab SBR reactor.We studied the relationship between sludge Extracellular Polymeric Substance(EPS)and the sludge settling property,through analyzing EPS content,3D-EEM,FTIR,and molecular weight of protein.Thus providing theoretical basis support for effective control of sludge bulking.The main results of this paper are as follows:(1)Aerobatic sludge of sewage treatment plant polysaccharide and protein content of TB-EPS are higher than that of in S-EPS and LB-EPS.Anaerobic sludge S-EPS,LB-EPS contents are more than that of aerobatic sludge of the same sewage treatment plant?The results showed that with the increase of total EPS,the Sludge Volume Index(SVI)also increased,r=0.543.There are correlation between the polysaccharide content and SVI in S-EPS,LB-EPS,and TB-EPS of aerobatic sludge.The r are 0.712,0.741,and 0.571 respectively.With the increasing of the EPS polysaccharide content,the SVI also increased.There are correlation between SVI and protein content in LB-EPS and TB-EPS,and the r are-0.127 and 0.484 respectively.Protein content in S-EPS and in LB-EPS is good for sludge settling.On the contrary,TB-EPS protein is bad for sludge settling.(2)It is showed that EPS occurred accumulation under low temperature.With the temperature decreasing,the polysaccharide increased.Water temperature increased from 13.4?to 24.5?,and SVI decreased from 274 m L/g to 159 m L/g.With the increasing of the temperature,the SVI reduced yet.(3)Analyzing three-dimension excitation emission matrix fluorescence spectrum detection showed that there are mainly peak A and peak T1 in LB-EPS of sewage treatment plant sludge,and their fluorescence intensity increased along with the SVI decreased.There is mainly peak C in the TB-EPS,and peak C fluorescence intensity increased with the SVI increasing.(4)FTIR functional group analyze showed that EPS of activated sludge of sewage treatment plant contain protein and polysaccharide?Adsorption frequency of TB-EPS is the richest,next is LB-EPS adsorption frequency,and adsorption frequency of S-EPS is the least.(5)HPLC showed the molecular weight of EPS from aerobic and anaerobic sludge of sewage treatment plant.The bigger molecular weight protein and the better sludge settling ability.(6)Functional characteristics results of activated sludge in SBR reactor:(1)With the increasing of polysaccharide content of S-EPS,LB-EPS,and TB-EPS,the SVI also increased in SBR reactor sludge.With the increasing of protein content of TB-EPS and total-EPS,the SVI also increased.But S-PN and LB-PN are negative correlation with SVI,which the same rule with sewage treatment plant sludge.(2)When the COD load ranging from 0.10 to 0.35 kg COD/(kg MLSS·d),the COD date displayed that with increasing of COD load,EPS Ctotal polysaccharide and protein are increased.(7)Comparing EPS of activated sludge from sewage treatment plant and SBR reactor,total-EPS content of reactor sludge is higher than sewage treatment plant;total S-EPS and LB-EPS from Sewage treatment plant sludge are higher than that from reactor sludge;Total TB-EPS content from reactor sludge is higher than sewage treatment plant sludge.