Resource Recovery From Quickly Alkaline Fermentation Liquid By Activated Wasted Sludge

Resource recovery is one of quite attractvie scopes in environmental topics.Due to abundant organic components stored in wasted activated sludge (WAS),protein and carbohydrate were always recovered by anaerobic fermentation afte rfeasible pretreatments. Generally, the mixture of sludge and fermentation liquidwere adopted. However, this approach would increase hydraulic retention time.Thus, in this study, quickly alkaline pretreatment technic was applied, and abundantof protein and carbohydrate was sobulized after24h. And, the resource recoverywas proceeded after centrifuge.Due to high content of nitrogen and phosphorus, struvite precipitation wasintroduce to reclaim the NH4+-N and PO43--P. This study introduced L9(34)orthogonal test to discuss the optimal conditions for struvite precipitation process.The results revealed that the pH was the most sensitive factor, while the time wasthe last sensitive. Then, optimal single factor tests were introduced, and the optimalconditions are as follow: pH10.0, Mg/P1.8, P/N1.6, and the time is5min. At thissituation, the concentration PO43--P of decreased from104.8mg/L to6.2mg/L, therecovery efficiency was94.1%. The concentration NH4+-N of decreased from379.6mg/to142.9mg/L, the recovery efficiency was62.3%. Thus, it has been provedthat the struvite precipitation was feasible for recovery of nitrogen and phorphorusin fermentaion liquid.This study applied the fermentation liquid containing principally proteins andcarbohydrates as influent to enrich PHA （polyhydroxyalkanoates)-producingmicroorganis m. Two aerobic SBRs were used in this study. And, acetate sodium andfermentation liquid were used as inffluent, respectively. The results suggested thatthe fermentation liquid can be successfully used to enrich PHA-producingmicroorganis m. The maxmium PHA yield by fermentation liquid was420.5mg/gDS, which was82.6mg/g DS higher than acetate sodium. The results of singlecycles indicated that substrace degeradation and PHA synthesis were basicallycompoleted at12h, and73mg/g DS higher than acetate sodium as carbon source.The PCR-DGGE results showed the changes of bacterial population. As the processcarring on, the predominant community was changed into PHA-producing bacteria, such as: Alcaligenes sp., Pseudomonas sp. and so on. Simultaneously, acid formingbacteria Clostridiales sp. was appeared in this system, which was in accordancewith process efficiency.At lase, this study discussed the hydrogen producing feasibility offermentation liquid after quickly alkaline pretreatment. The hydrogen-producingsludge was used as seed sludge, batch tests were introduced to study the effects oforiginal pH on hydrogen yie ld. The results revealed that original pH11.0was theoptimal condition, which24.4mL/g DS hydrogen was yield. The H2was mainlygenerated from deamination and decarboxylation of amino acids. The PCR-DGGEresults analyzed the predominant community, such as Clostridium sp., Enterococcusdurans, Mesorhizobium sp., Pseudomonas sp., Eubacterium sp.. And, Eubacteriumsp. might be the functional microorganism for fermentaion of protein andcarbohydrate.