United Utilities Compliance Management

The water and sewerage sectors in the UK have to comply with national and European legislation to ensure over 50 million household and non-household consumers receive good quality water, sanitation and drainage services, as well as to protect the surrounding environment. One of our trials at United Utilities is specifically centred on compliance, to ensure the case study site in question is well within strict regulatory compliance. SENTRY is being used as an early warning system of varying loads, such as toxic shock events and predicting periods where additional sludge filtrate could be added.

“SENTRY is quick and easy to install and boasts an intuitive dashboard to display its graphical representation of real-time data. This has provided us with a whole new level of insight into our site performance, which our graduate team are utilising to study efficiencies in our activated sludge process.”
United Utilities Business Manager

SENTRY Installation

Installation at this United Utilities facility consisted of three probes and a control panel. A SIM card was used to transmit data from the control panel to the SENTRY dashboard, for Innovation and Operations to monitor the output. Following installation, no calibration or maintenance was required. Reliable and robust data was produced with very limited signal drift.

The SENTRY platform was set to record a reading every minute with 1,440 Microbial Electron Transfer (MET) readings in a 24-hour period. The MET readings were displayed on an on-line dashboard with a signal also sent to the on-site SCADA system to integrate with other data being collected at the facility.

Project Objectives

• Monitor incoming wastewater conditions and identify key biological imbalance triggers
• Validate correlations between biological activity and organic loading to the facility
• Develop historical data sets that show the weekly and daily biological activity trends for influent wastewater
• Use the generated microbial activity data sets to predict periods where additional sludge filtrate could be added

SENTRY Identifying Toxic Shock Events

Microorganisms are key to keeping a wastewater treatment plant operational. The real-time bio-electrode data from SENTRY allows the operators to monitor the microbial health of the treatment plant. For example, imbalance or toxic shock events can be identified the instant they begin to impact microbial activity. Figure 1 shows an example where the microbial activity has dramatically decreased. When incidences such as these occur, operators can take immediate action to reduce the negative impacts on system performance.

SENTRY sensors were installed at key influent and aerobic basin locations with real-time data going to a web-based dashboard. Since the SENTRY dashboard can be accessed anywhere in the world, operators can even be working from home and have the knowledge that the site capacity is at normal levels.

SENTRY found that the case study treatment facility was able to handle the additional organic load received from other treatment facilities. The sludge centrate increased microbial activity in the wastewater prior to ASP (activated sludge process) but had a modest impact on MET in the ASP effluent. Organic loading continues to be increased gradually while SENTRY MET alerts provide operations with real-time monitoring of performance.

SENTRY Detecting Opportunities for Process Optimisation

Historical data sets were generated and provided aggregated weekly trending insights. A visual output shows that there is a clear daily and weekly pattern generated at the influent monitoring location. The influent sees significantly higher sustained microbial activity from Sunday night into Tuesday with a much lower MET on Saturday (Figure 2). Periods of lower activity could be a source of opportunity for adding additional sludge filtrate.

Through investigation, it was found that large precipitation events greatly reduced the influent microbial performance. This is due to infiltration and inflow into the collection system reducing organic strength. The ASP effluent was not found to be strongly influenced by such events to date, suggesting the system had ample retention time and good hydraulic characteristics.

However, it was noted that there was concern regarding first flush events, when a long dry period is followed by a period of heavy rain. When this situation was occurring, ammonia was increasing. In this situation, SENTRY was acting as an early warning system for the ammonia. This was one period where receiving additional sludge filtrate should be done with caution.

SENTRY for Compliance Management

SENTRY found that the case study treatment facility was able to remain compliant despite the additional organic load received from other treatment facilities. Based on the SENTRY results, the load on site will gradually increase and the real time monitoring will ensure the plant performance to act as a process optimisation strategy for the ASP system at this site.

2/2/2026