Development And Application Of Sludge Biolysis Multiple Species Inoculants For Dewaterability Enhancement

The sewage industry of China pays attention to water only while ignoring sludge,and municipal sludge treatment and disposal has become a technical bottleneck all over the world.were applied for excess waste sludge biolysis pretreatment and dewaterability enhancement.This study based on Bdellovibrio-and-like organisms(BALOs),a group of predatory bacteria with a high biolysis capacity,and mainly focused on the development and application of sludge biolysis multiple species inoculants.The mechanisms of sludge structure and properties bacterial community variations were investigatedto reveal the key technologies of enhancement of sludge dewatering ability and BALOs-dependent sludge reduction.Furthermore,a self-designed sludge biolysis and reduction reactor was designed to expand the the field test.This study will provide a new environmentally friendly ecological solution for alleviation of increasingly serious pressure of excess sludge treatment and disposal.16 indigenous predatory BALOs strains were firstly isolated and screened from the activated sludge in a municipal WWTP,and 4 strains of BALOs with high biolsis activity were screened out.The high-efficiency biolysis strain D15 which has been fully studied was combined with other high-efficiency strains to analyze the sludge dewatering performance and community structure change during biolysis treatment.The D15 and D18 compound inoculants had the highest dewater performance optimization performance,and the CST decline rate was(53.9±3.5)%.The abundance of the dominant strains was significantly reduced after biolysis tratemt of D15 and DG1 compound inoculants,biological diversity was the lowest,and the synergistic cracking effect was exhibited,which expanded the range of the composite bacteria.By further optimizing the composition of the bacteria and the ratio of the bacteria,and considering simplifying the practical application operation and controlling the process cost,it is finally determined that the high-efficiency sludge biolysis multiple species inoculants is D15,D18 and DG1(2:1:2).In view of the engineering application requirements of BALOs-dependent sludge biolysis,this study was expanded and cultured BALOs by BALOs microbial fermentation system.The concentration of BALOs in fermentation broth was 86.0 times that of flask culture,which could greatly improve the utilization rate of bacteria liquid and reduce the transportation and application cost.At the same time,the combined process of BALOs-dependent biolysis and mechanical dehydration is proposed.Under the condition of no chemical injection and ordinary dehydration pressure(0.4 MPa),the moisture content of the sludge cake is≤80%after the biolysis of single D15 strain,.According to the requirements of external transportation,the sludge after the biolysis of the biolysis multiple species inoculants meets the requirements of sludge landfill(≤60%).At the same time,the single D15 strain and the biolysis multiple species inoculants have a wide applicability to different process sludges(oxidation ditch,A~2O,CAST process),and have a high engineering application prospect.BALOs-dependent sludge biolysis can promote the release of bound water retained by intracellular water and extracellular polymer(EPS)by destroying the microbial cell wall integrity of sludge and the stability of sludge floc structure,improving sludge dewatering performance and biodegrading.Furthermore,It can promote the release of organic matter in intracellular and bound EPS into the liquid phase,accelerate the degradation of sludge organic matter,and facilitate the sludge reduction and stabilization.At the same time,the sludge biolysis multiple species inoculants can enhance the biological lysis effect and expand the biolysis than the single strain.The scope of action strengthens the destruction of sludge cell and sludge floc structure and further improves sludge dewatering performance.The regrowth of viable microorganisms in the sludge,the re-stabilization of the sludge floc structure,and the anti-predation mechanism between the BALOs and predator bacteria are the main reasons for the deterioration of the sludge dehydration ability in the later stage of the biolysis treatment.