Abstract:
To study the effects of ballasting agent types and sizes on settling velocity in activated sludge process. Three types of ballasting agent with 4 average sizes, talc (2, 5, 10, 18 μm) powder activated carbon (PAC) (5, 10, 24, 99 μm) and crumb rubber (110, 242, 656, 848 μm) were tested in lab scale activated process. The initial settling velocity (ISV) was used to demonstrate the sludge settling efficiency. While COD removal used to demonstrate the treatment efficiency and floc formation between sludge and the ballasting agents observe by microscope and electron microscope. The results showed that, in term of COD removal, three agents could effectively removal of COD close to blank controller set. Moreover, three types and sizes could increase an initial settling velocity efficiency, 17.64, 13.91, 13.74 m/h for talc, PAC, crumb rubber respectively and the ISV of three agents were better than blank controller have the ISV is 2.81 m/h. From the study with microscope and electron microscope, illustrated the floc formation between sludge and the ballasting agents from electron microscope Talc, PAC and Crumb rubber were compatible with bacteria. Moreover, the ballasting agent can touch sludge in 3 types, were covered, enameled and adhered. So, these three agents were considered as a proper ballasting agent to improve the AS process in term of sludge settling and COD removal. Furthermore, in the case of using crumb rubber in AS process is alternative choice to reuse material.