Summer’s coming – Andrew Kendall of United Utilities explains how his team prepares Windermere treatment works ready for the extra visitors

Our operational teams are always out and about every day to make sure our treatment works are performing to the highest standards. A key time for us is the run up to the summer months when we see more visitors flock to Windermere. Our wastewater treatment works are sized to treat the sewage from maximum population numbers at peak times, but we have to gradually get them ready so that the treatment processes are constantly running at top performance.

Wastewater treatment plants include a living process so, a bit like brewing beer or making cheese, sewage engineers also harness the power of certain types of bugs and bacteria to help us do our work. We provide these “Good Bugs” with the ideal conditions to thrive – that’s oxygen, and the nutrients in the sewage – and they eat the nutrients and clean the sewage. We just need to give these bugs a bit of an extra workout to acclimatise them before all of the visitors arrive.

So how do we do it? Our preparations start around eight weeks before Easter at which point we slowly add ammonium sulphate into our treatment process. Adding this helps the microorganisms in the process adapt to increased levels of ammonia before the extra visitors arrive.

With specific conditions these bugs grow and multiply, removing ammonia and treating the wastewater. The more bugs we have cleaning the water, the quicker we can send the wastewater to the next stage of the treatment process which involves removing phosphorus to the lowest achievable limits (0.25 milligrams per litre) and then it is finished off with a blast of Ultra-Violet light. This zaps the cleaned sewage with light energy (similar to natural sunlight) with kills any harmful bacteria before the water is released into the lake.

This final UV stage is an important factor which helps the four Windermere bathing waters maintain their highest Excellent rating every year