Anglian Water are currently up-rating the treatment process on all their surface water sources to include ozone to aid clarification and additional GAC contact time for the removal of micropollutants such as pesticides and trihalomethanes in the water. The final disinfection for the high quality water is by either chloramination or chlorination and pumped into a distribution network containing pipes of various materials.
To investigate the effect on the distribution network of chanving from pre-chlorination to an advanced water treatment process, a pipe rig was constructed at Grafham Water Works which included sections of a 60 year old cast iron main and new plastic MDPE pipework. The work was carried out in conjunction with University College London and investigated parameters including assimilable organic carbon (AOC), total organic carbon (TOC) and temperature and monitored their effect on the biofilm growth and corrosion rates.
The biofilm growth and corrosion rates on the coupons inserted into the cast iron pipes of the rig were found to be related to their orientation on the main. Temperature had a significant effect and correlated to bacterial activity.
During the period of investigation Grafham main works also changed over from pre-chlorination to ozonation and samples were taken from the actual distribution system pre and post the process changes. The results from these findings agreed with the pipe rig model, with the overall conclusion that the change from pre-chlorination to ozonation would have little effect on the corrosion and biofilm growth in distribution.
This case study from the Civil and Environmental Engineering department of a UK university presents an educational design that uses team-based learning (TBL) to prepare students prior to undertaking a group project. Our aim is to show how the established TBL approach can be used in a novel way as a precursor to a group project to improve the achievement of learning outcomes. The purpose of the TBL was to ensure pre-reading was completed, to instil a sense of subject matter mastery, to allow students to discuss complex issues and to develop collaborative and inclusive behaviours. These skills and knowledge were necessary to successfully complete the follow-on group project and importantly for success in their future careers. Student's end of module reflective statements indicated that they positively collaborated and communicated when working on a group project.
Analysis of the biofilm on a distribution system model pipe rig gave high readings of extracellular adenosine-5′-triphosphate (ATP). The free ATP was assumed to come from dead cells at the base of the biofilm. The levels were large in proportion to the measured cellular ATP and were unstable. This resulted in errors in the calculation of cellular ATP. An enzyme Somase (0.5%) was employed to hydrolyse the free ATP. Increased accuracy of the measurement of cellular ATP was seen.
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