Activated Sludge Plant Controller Benefits Wastewater Treatment Plants

Sensors in the wastewater treatment industry rapidly lose their effectiveness due to fouling and calibration drift. The Strathkelvin Instruments’ (UK) ASP-CON has been designed to be fully self-cleaning and self-calibrating. The image shows how, after several weeks in a highly challenging aeration basin, the sensor heads remain very clean. This is mainly due to the action of the instrument’s medium pressure wipers, but also the use of a slightly acidic flush followed by a basic flush, during the auto-calibration of the sensors.

The ASP-CON is a multi-sensor instrument measuring over 16 important Wastewater treatment control parameters in one unit. Parameters include Dissolved Oxygen, Ammonium, Mixed Liquor Suspended Solids, Settlement Volume Index, Turbidity, pH, Temperature, Oxygen Uptake Rate, Specific Oxygen Uptake Rate, Nitrification, Food: Mass ratios, Toxicity and Potassium.

The ASP-CON can be installed in a number of positions within the activated sludge part of the secondary treatment process, depending upon the desired control and monitoring strategy of the WWTP. 

In a recent trial the ASP-CON was installed at around 70% of the treatment lane footprint where treatment loads varied over a 72 hour period. 3 separate measurements – namely DO, Ammonia and pH indicated that an alternative control strategy could be implemented under low loading conditions. It was estimated that by implementing alternative control strategies during the period of low loading that this plant could save in excess of $40,000 per annum. The ASP-CON has also recently been given the WEX Global Innovation Award - further proof of its success.