Continuing High Phosphate Levels At Wickham Market STW

Our volunteers have been monitoring the phosphate emissions from the Wickham Market sewage works for some months now and have noticed problems with the phosphate stripping process; several samples from the outfall tested over the 1.0 mg/litre permit set by the Environment Agency in 2024. We have recorded levels up to 1.5 mg/litre several times; these have been flagged with the Environment Agency and with Anglian Water.

In mid April, residents in Wickham Market reported 24/7 visits from lorries and tankers down the narrow lanes to the sewage works and in the town centre.

We were asked by residents what had happened at the sewage works to create such a problem, at the time our Anglian Water Services contact told us:

"Wickham Market WRC was struggling with elevated Phosphate levels in the final effluent. To avoid this effluent from being discharged and having an environmental impact, the decision was made to tanker all final effluent away from the site. As of this morning (Monday 20th [April]) the Phosphate levels are back under control and the tankers have been stood down. The Process Science team continue to work hard to optimise this process."

However, our test results from the beginning of May showed the Wickham Market STW plant still out of compliance with phosphate emission levels. Anglian Water have now responded to our challenge to explain what has happened and what action they are taking.

We received a response this week from our local contact at Anglian Water to our request for information on the high phosphate problems and their use of tankers to remove waste water at the WM STW in recent weeks:

“During the prolonged dry period, when we were seeing much lower flows entering the works, the phosphate precipitation performance dropped significantly at Wickham Market. To mitigate the risk of breaching compliance, we had to implement tankering while other measures were being put in place. These mitigation strategies have since been successful. We are now exploring a more sustainable, long-term solution and may need to adopt a seasonal operating approach, although we’re still working to optimise this for dry conditions.

The issues observed on site that led to the need for tankering on this occasion were compounded by a “perfect storm” of factors, including limited sludge removal due to a company-wide incident and locally agreed sludge removal windows that operate around local business requirements, alongside extremely low flows.

Investigations are ongoing within the catchment, with autosamplers deployed to better characterise influent variability. A significant level of resource is currently being directed towards isolating and identifying the root cause. The previous compliance challenges were attributed to solid-bound phosphorus; however, this is a new issue. Current evidence suggests this new issue is predominantly driven by limitations in chemical precipitation. Operational adjustments have been implemented on site to improve hydraulic and chemical mixing, with the aim of optimising acid dosing efficiency and enhancing precipitation. We have also made alterations to optimise sludge storage and removal.

This site is now fully compliant across all water quality parameters.

Please be assured that our Process Science and Operational teams are doing all they can to optimise the P removal at Wickham Market."

You can view monthly updates on the state of the river around Wickham Market, and the rest of the Deben and it's tributaries, via our Water Quality Dashboard, or look out for our monthly reports.

Thank you to all of our DCC volunteers involved in this work, enabling us to flag this "out of compliance" trend. Thanks in particular to the Wickham Market group who spotted the extensive tanker usage.

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