THE PRE-DESIGN OF BERENPLAAT WATER-TREATMENT WORKS, ROTTERDAM - ADDITIONAL PROCESSES TO ACHIEVE BIOLOGICALLY STABLE WATER

Biological regrowth in a water distribution system can be avoided by e ither maintaining a free chlorine residual to suppress growth or contr olling conditions which may support growth, or by a combination of bot h. Micro-organisms will grow in water only if nutrients are present in sufficient amounts; conversely the reduction of biodegradable nutrien ts in water is vitally important in controlling the regrowth of micro- organisms and zooplankton in the distribution system. The measurement of assimilable organic carbon has been developed as a way of evaluatin g the concentration of biodegradable material which is available to su pport such biological growth. This paper describes the pilot-plant and full-scale studies carried out at the Berenplant water-treatment work s, Rotterdam to (a) improve disinfection, (b) eliminate the formation of trihalomethanes and other halogenated compounds formed by chlorinat ion, and (c) reduce the final water assimilable organic carbon concent rations to very low levels, so that a high degree of biological stabil ity can be maintained in the distribution system.