Analysis of biofilm-resistance factors in Singapore drinking water distribution system

In drinking water distribution system (DWDS), biofilm offers protection of bacterial community within the extracellular polymeric substance (EPS) from outside stressors, including surrounding environment, predatory microorganisms and antibiotics. The growth of biofilm may increase cleaning and maintenance cost for the drinking water decontamination and expose high risk to human immune system. This article critically reviews current Singapore DWDS by analysing the leading and lagging performance of two stages, granulated active carbon (GAC) filtering and secondary disinfection by chloramine, which are highly relevant with the biofilm resistance. Furthermore, other extrinsic factors, such as pipe age and material, hydraulic retention time, seasonal change, primary ultraviolet disinfection, etc. are also reviewed. Finally, top-down approach to address the growth and biofilm resistance are proposed. Practices and technology methodology, e.g. good consumers' hygiene, nutrient removal, chlorine disinfection, probiotic approach, anti-biofouling coatings are discussed with their associated challenges and opportunities.