Our method is to maintain certain levels of biomass and dissolved oxygen in the aeration tank by manipulating waste sludge flow, return sludge flow and aeration capacity. Such strategies are based on measurements of the concentrations of mixed liquor suspended solids and dissolved oxygen.
The respiration rate of activated sludge is an essential part of our control, since it is an essential variable in the activated sludge process and provides information on activity and concentration of the biomass, influent waste concentration, toxicity and concentration of biodegradable matter in the effluent. Therefore, these effects have been used to manipulate the respiration rate by control systems. This is due to adequate measurement techniques and partly to a high level of respiratory-based control.