Which form of activated sludge is better at handling shock or toxic loads?

The complete mix form of activated sludge is particularly effective at handling shock or toxic loads because it maintains a uniform concentration of microorganisms throughout the reactor. This consistent mixing allows the biomass to quickly adapt to sudden changes in influent characteristics, such as increased concentrations of toxic substances or unexpected spikes in organic loading.

In a complete mix system, the continual circulation and blending of influent and effluent ensure that the microorganisms are evenly distributed and can digest fluctuating organic materials superbly. This system can mitigate the impact of toxicity by ensuring that only a fraction of the microbial population is exposed to high concentrations of toxic substances at any given time, allowing others to continue functioning and maintaining system efficiency.

Other forms of activated sludge, like contact stabilization or sequencing batch reactors, may be less effective under sudden shock loads due to their operational characteristics and design, which may not provide the same level of immediate adaptability or uniformity as the complete mix system.