Immobilized cells augmented activated sludge system: Process development and applications.

摘要

An immobilized cells augmented activated sludge system (ICAAS) relies on two advanced biotechnologies, cell immobilization and bioaugmentation, for improving activated sludge process performances. The ICAAS employs the immobilized cells, which are activated and maintained for their specific treatment activity in an off-line enricher-reactor, for bioaugmentation. This research focused on the applications of this novel ICAAS scheme to enhance three types of performances of completely mixed activated sludge (CMAS): hazardous compound treatment using pentachlorophenol (PCP) as a model compound, nitrogen removal, and general treatment performances.; In the hazardous compound treatment investigation, cellulose triacetate (CA) and powder activated carbon (PAC) combined with CA (PAC + CA) were the two types of media employed for the entrapment of the PCP degrading culture. With ICAAS at 10% by volume augmentation, PCP removal of 85.6 and 86.6% was achieved for the systems with CA and PAC + CA media, respectively, while the average PCP removal in control CMAS was 48.7%. The advantage of ICAAS includes a small hazardous inducing compound requirement as results further showed that the immobilized cells retained their effective PCP degrading ability when the inducer (PCP) was fed to the enricher-reactor once every 20 days.; For the enhanced nitrogen removal experiment of ICAAS, CA was the only type of media used to coimmobilize nitrifiers and denitrifiers at a 2:1 mass ratio. ICAAS augmented with the coimmobilized cells between 5% and 20% by volume gained approximately 24+/-5% higher nitrogen removal than a control CMAS, which provided nitrogen removal of 28+/-7%. The ICAAS scheme is a viable alternative for upgrading existing CMAS systems to gain better nitrogen removal.; The general treatment performances of ICAAS studied were organic and suspended solids removal and excess sludge production. CA and PAC + CA were the two types of media employed for the entrapment of municipal activated sludge used for bioaugmentation. For both types of media, ICAAS with 1, 2.5, 5 and 10% bioaugmentation by volume achieved higher removal of dissolved organic carbon, biodegradable dissolved organic carbon, and soluble chemical oxygen demand and soluble biochemical oxygen demand at 5 days than a control CMAS system.