Successful Final Effluent Monitoring Trial

Engineers at Intellitect Water (UK) have developed a version of the company’s innovative multiparameter water quality monitoring sonde, the ’Intellisonde FE™’ that can continuously monitor final effluent without the need for chemicals or frequent maintenance and calibration.

A unit has been installed on the final effluent of Wessex Water’s Holdenhurst wastewater treatment plant in Bournemouth since January 2010 and initial results indicate that this new technology could bring the advantages of online monitoring to a much larger proportion of wastewater treatment plants.

The Intellisonde FE™ is a very small multiparameter monitor that is able to run unattended for weeks. Low capital and operational costs will mean that it will become possible to install continuous monitors at plants for which the costs were previously considered prohibitive.

The Bournemouth trial was conducted adjacent to traditional online monitoring instruments and Wessex Water’s Regional Waste Scientist Mike Robinson, says: "The trial is proceeding very well, with the Intellisonde FE™ producing measurements that closely mirror data from our other monitors and from manual tests. For example, we employ traditional online single parameter monitoring instruments at the outfall and we also utilise portable instruments to measure parameters such as clarity and ammonium."

The Intellisonde FE™ is located in a flow-through chamber which is fed by a submerged sampling pump located in a sump. A level gauge ensures that the sump does not pump dry. The trial unit has been fitted with a small strainer to prevent any possible accumulation of dirt in the measurement chamber. However, it has only been necessary to occasionally remove small stones and snails, although these did not have any effect on the measurements.

Inside the sonde head, tiny solid-state sensors continuously monitor conductivity, pH, temperature, turbidity and ammonium. The unit can log at intervals between one minute and one hour on all parameters simultaneously. Measurements are retained on an internal datalogger, however data is transmitted via GPRS to a dedicated server which feeds a web site to enable 24/7 access to (almost) live water quality information. The units are also able to provide an analogue output that could interface with a water company’s regional telemetry system, providing a closed-loop system for data protection.