Advances in Water Treatment and Enviromental Management

126 WATER TREATMENT6. DiscussionFrom the previous two sections, it is clear that there is little commonality betweenthe technologies used in the chemical/pharmaceutical industries and waste watertreatment. Even where similar are employed (e.g. submerged turbine aerators),their application tends to’be very different. Whilst, undeniably, many of thedifferences arise from the fundamentally different requirements outlined in Section3, the inevitable question is: can the industries improve their processes (andprofitability) learning more from each other?Technology transfer at the manufacturer level is good: for example, Mixing EquipmentCompany (Lightnin) are market leaders in both industries. However, evidence fromthe chemical process industries has proven that there is great benefit in theequipment end users themselves improving their knowledge of processes: the successof process industry related research club projects, such as FMP and HILINE atBHR Group and others (e.g. HTFS, SPS etc) is a good example.Looking at two recent conferences related to mixing provides some enlightenment.A conference of “Bioreactor Fluid Dynamics”, Ref. 7, attracted no papers and nodelegates from the water industry; yet what is an activated sludge treatment plant,if not a bioreactor? The most recent European Conference on Mixing, Ref. 8, attractedonly 2 papers as waste water applications out of a total of 77. Equally, recentconferences related to wastwater treatment probably attracted few delegates fromthe chemical industry. Process industry research clubs have had little success inrecruiting members from the water industry, although FMP and HILINE have recentlyboth recruited members (Yorkshire Water and C.G.E. respectively).A detailed analysis of the pros and cons of the technologies will not be tackled, but,speaking from expertise relating to the chemical industry, the following observationsare made on water processing techniques:1. Many water treatment tanks appear to be designed totally around civilengineering considerations, resulting in square or rectangular, relativelyshallow tanks with flat bases. Mixers are introduced as an “add on extra”.Could more effort be placed in designing a combined tank/agitator system,closer to the geometries developed and optimised for the chemical industry?This may result in higher civil costs, but would the improved/reducedprocessing cost compensate?2. Aeration techniques such as ejectors and the fixed head aerator employlocal, rapid mass transfer with jet mixing to keep tanks well mixed. Theoriginal technology for liquid jet mixing actually comes from the waterindustry (mixing in reservoirs), but has since been greatly advanced forapplications such as oil storage tanks. Have the latest data, e.g. Ref. 9,been transferred back to the water industry to aid designers?