GENeco (a division of Wessex water) looked to improve the treatment process at their water recycling centre at Avonmouth by analysing how to maintain pipes for optimum performance. They observed that solid deposits gradually formed around the internal circumference of the pipes. In order to solve this problem GENeco enlisted the help of the research facilities team to determine what the major deposit consisted of in order to guide the appropriate action to de-clog the pipe.

X-ray diffraction

Powder X-Ray Diffraction (PXRD) is a powerful analytical tool to determine the phase of a crystalline material. Every crystalline compound has its own unique PXRD pattern, much like humans have their own characteristic set of fingerprints. The research facilities team ran a finely ground powder sample of the deposits on our state-of-the-art X-ray diffractometer and compared the diffraction pattern to a database containing thousands of compounds from around the globe. The result came back as a 100% match to Struvite.

The struvite nuisance

Struvite is a good fertiliser with chemical formula (NH4)Mg[PO4]·6H2O that was first described in the 1850s after it was discovered in the excavation sites of medieval waste dumps of Hamburg, Germany. The “struvite nuisance” is well known amongst waste water treatment plants, and is especially common if the organic sludge has been hydrolysed before digestion due to the release of calcium, magnesium, nitrogen and phosphorous during this process. If the sludge is hydrolysed above a pH of 7 deposits of calcium phosphates and struvite readily form.

Now that the deposits have been identified as struvite, GENeco are taking the appropriate measures for maintaining the performance of the pipework at Avonmouth.