A short-term investigation using In-situ ammonia monitoring at a WWT, M Keown Severn Trent Water
Two separate inlet streams are received for treatment at this works, one being predominantly domestic in origin and the other being predominantly industrial, arising from a local dye works. Their treatment is kept completely separate with municipal stream being subject to preliminary treatment, primary settlement, and secondary treatment in surface aerated activated sludge basins and final clarification.
The consent to discharge from this stream includes an ammonia level of 10 mg/l. It has been noted over an appreciable period that although this was complied with the majority if the time, nitrification would be lost during holiday periods.
No satisfactory explanation has been found for these phenomena up to now and hence it was decided to study the effluent Ammonia concentration in greater detail over the Easter period of 2000.
To accomplish this it was necessary to install a continuous measurement Ammonia monitor on very short notice. For the majority of available Ammonia monitors this would not have been possible, requiring pumped delivery systems, weather proof housings and same pre-treatment.
Envitech, one of the water companies suppliers, offered a system manufactured by Isc-Stip for a trial period over the Holiday period, which could be rapidly installed and deployed.
This gave the customer an opportunity to carry out both an instrument performance assessment and a process investigation at the same time.