Abstract
In this study waste activated sludge (WAS) was sonicated to release bacteria-sized volatile solids (VS) from flocs, after initial pH adjustment to 10 for higher energy efficiency. The released VS supported growth of phagotrophic alga Ochromonas danica. Initial-rate growth experiments confirmed the Monod-type kinetics but the specific cell growth rate, μ, correlated with the prey-to-predator ratio, i.e., the ratio of (fed VS concentration)-to-(initial O. danica concentration), significantly better than with the VS alone, as the typical Monod dependency on soluble substrates. The best-fit kinetics had the following parameters: μmax = 0.198 h−1 and KM = 1.056 (g-VS/g-algae). Post-sonication reflocculation could render particles too large to ingest by O. danica; therefore, pH and VS effects on reflocculation were investigated. Batch cultivations were then conducted in fermentors at pH 5, under nonsterile conditions. Algae number reached 8.86 × 1010 L−1 after 20 h, corresponding to ∼2.3 g/L dry-weight and volumetric algae productivity of 2.8 g/L-day. VS reduction was 38%, giving an O. danica VS yield of 44.5%. The ultrasonication-algae process can be used to produce algae while achieving at least partial WAS treatment.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
