The effect of clay addition on the settling ability of activated sludge as a proposed method to control filamentous bulking

摘要

Filamentous bulking is a problem that has long plagued activated sludge (AS) wastewater treatment plants (WWTPs). Much research has looked at its prevention and control but there is still no solution. The sludge microbiological community is very complex and there are many factors that can affect bulking. Clay addition in scaled-down activated sludge systems was investigated at concentrations of 0.4, 2.0 and 5.0 g/L along with sequencing batch reactor (SBR) parameters when run with a synthetic wastewater (SWW). The 5.0g/L concentration exhibited positive results on settling in the form of modified SVI but appeared to cause no reduction in filament length. These preliminary investigations indicate that clay may help improve sludge settling but make no difference in the abundance of filamentous microorganisms. The SBRs exhibited trends in regards to running systems with a synthetic wastewater. A loss of volatile suspended solids (VSS), coupled with increase in sludge volume index (SVI), suggested a link between lack of non-VSS and settling ability. This has implications in the importance of non-VSS such as grit or clay in research performed using SWWs.