On Wednesday 15th January, Class 3 headed off to the Didcot Sewage Treatment Works as part of our Geography topic looking at the resources of the UK and how they are managed. We started in the education centre where we learned that sewage arrives at the works as a result of gravity, so houses that are at a lower altitude than the works have to have septic tanks.
We learned that Thames Water is happy for us to put the four ‘p’s into the system: poo, pee, puke and paper. Anything else is a problem and we found out about the specific problem of putting wipes into the system. We carried out an experiment that showed us that even ‘flushable’ wipes aren’t a good idea.
After this, we put on plenty of Personal Protective Equipment and headed out on site. We gazed at the raw sewage arriving at the inlet and then saw the four overflow storm tanks nearly completely full due to the recent heavy rain. We made our way around the rest of the site and learned how raw sewage in turned into stream water by the simple processes of filtration and using bacteria which eat many of the harmful particles. Finally, we saw clean water flowing into the stream on the edge of the site. We also learned that fertiliser and methane are by-products of the treatment process and the methane is used on site to generate electricity.
Back in the education centre, we created our own filters to see who could make the cleanest water from our made-up ‘sewage’ of water, hot chocolate, lentils, soap etc.
It was a fascinating trip and we learned a lot, as shown in the process diagrams created back at school.