Process Optimization, Energy Savings, Quality Assurance, by Control of Bowers
Process optimization by on-line measurement of dissolved oxygen in the aeration stage with the O2X ensures that the right amount of air is supplied in the aerated zones. The microorganisms are given the right environment to reduce BOD and also to oxidize ammonia to nitrate. In activated sludge plants that run nutrient reduction in anoxic zones, the O2X ensures oxygen free environment to get full de-nitrification.
To achieve good energy efficiency in the active sludge stage, on-line measurement with the O2X in multiple points enables good control of the oxygen level resulting in considerable economical savings as the blowers is one of the major energy consumers in a plant.
Measurement and control of the dissolved oxygen level ensures an even and safe process which will contribute to assure the quality of the effluent and sludge.
Control of Mass Balance and SRT (Sludge Retention Time)
Process Optimization, Sludge Quality and Control of the Active Sludge Stage.
Good quality of the sludge in the active sludge stage is dependent of many parameters. One significant factor is the Sludge Retention Time (SRT). iIf nutrification is dersired, the SRT is one of two key factors. The degree of nitrification is primarily dependent of the SRT and will be higher with longer SRT. The other key is the temperature; higher temperature gives higher nitrification rate. The SRT indicates the relation between biomass and sludge production.
One easy way to achieve process optimization and make sure the SRT is kept reasonably constant is on-line measurement of MLSS in the aeration and return activated sludge (RAS). Also the TSS in the secondary clarifier outfall could be measured to ensure that eventual sludge wash out is taken into consideration. The measurements are used to control the SRT level according to the well known formula for the SRT.
The goal is to control the wasted activated sludge (WAS) according to the growth of MLSS in the aeration. So instead to calculate the SRT we put the desired SRT in the formula and calculate how much WAS should be taken out to keep the desired SRT.
Cerlic provides an Excel sheet that may be used for calculatioon of how much WAS that should be taken out to keep the SRT at desired length at your plant.
