Construction Of Salt-tolerant Aerobic Granular Sludge By Mycelial Pellets And Its Application In High-salt Organic Wastewater

Polycyclic aromatic hydrocarbons(PAHs)are common refractory pollutants in highsalinity organic wastewater,mainly found in petroleum and coal chemical wastewater.Salttolerant aerobic granular sludge(SAGS)has good treatment efficiency for PAHs in highsalinity wastewater due to its dense structure and high tolerance.Mycelial pellets have strong aggregation ability and can be used as biomass carriers to promote the formation of aerobic granular sludge(AGS),but their application in SAGS granulation is rarely studied.This paper explores the effect of exogenous addition of mycelial pellets on the construction of SAGS system and removal of PAHs.Based on the previous study of the research group on the enhanced degradation of salt-tolerant organic pollutants by coupling Martelella sp.AD-3 moderately halophilic bacteria and activated sludge,the study investigates the effect of exogenous addition of mycelial pellets on the SAGS system and the removal of PAHs.The results show that a salt-tolerant fungus Penicillium sp.L22 was screened from intertidal sludge of Hangzhou Bay with glucose and phenanthrene as carbon sources.By optimizing the growth and degradation conditions,the optimal conditions for the growth and degradation performance of mycelial pellets were found to be pH 7 and 3%salinity,where efficient mycelial pellet formation was achieved.The addition of mycelial pellets to the Martelella sp.AD-3 bacteria and activated sludge enhanced system showed a slower granulation rate and smaller particle size(average particle size decreased by 19.3%)compared to the control group(without mycelial pellets),but the formed granular structure was more compact and stable,with a higher reactor biomass(VSS increased by 3.2 times)and better sludge settling performance(SVI5 decreased by 24.4%).The addition of mycelial pellets increased the extracellular polymeric substances(EPS)content in the sludge,which promoted sludge aggregation.In terms of organic pollutant degradation,the mycelial pellet experimental group showed a 20.5%increase in COD removal rate and a 53.1%increase in representative model pollutant phenanthrene degradation activity in the third stage compared to the control group.High-throughput sequencing analysis showed that in the third stage,the number of AD3 bacteria OTUs in the mycelial pellet experimental group was 78.5 times higher than that in the group without mycelial pellets,and the relative abundance of Martelella genus was significantly positively correlated with the specific degradation activity of the sludge,indicating that the addition of mycelial pellets may enhance the degradation of PAHs by strengthening the retention of AD-3 bacteria(Martelella genus).In addition,the degradation of Penicillium genus and PHE also showed a significant positive correlation.This study reveals the community succession characteristics of mycelial pellets in enhancing the SAGS system and provides technical support and theoretical basis for the enhanced treatment of high-salinity organic wastewater.