Investigation of algal cultivation and anaerobic co-digestion of sewage sludge and algae at wastewater treatment plant (WWTP)

摘要

Micractinium and Chlorella, harvested from local WWTP, were cultivated in primaryrneffluent, sludge centrate, and their combination. Continuous light condition (24hr light)rnand periodic light (16hr light/8hr dark) were provided to investigate the behavior of theserntwo algal species in different growth media. Primary effluent supported better growth ofrnboth algal species, and also led to higher soluble nitrogen (84-92%) and phosphorous (59-rn74%) removal. The specific growth rates in all media were low due to the phosphorouslimitedrncondition. Microalgae posed different growth characteristics in real wastewaterrnand resulted in different amount of extracellular polymeric substances (EPS). Highrnamount of EPS helps algal aggregation. Co-digestion study showed that addition ofrnmicroalgae did not bring negative effects on anaerobic digestion of sewage sludge. Thesernresults indicated that microalgae-based process has potential to decrease nutrient loadsrnalong with bioenergy production by coupling algae cultivation into wastewater treatmentrnsystems with anaerobic digesters.