A comparison of methods and models for the analysis of water distribution pipe biofilms

Abstract

The suitability of three experimental devices: biofilm reactors™ (BR), biofilm exosamplers™ (BE), and modified robbins devices (MRD), for the analysis of water distribution pipe biofilms was examined in situ within an urban water distribution system (Rouse Hill Development Area, New South Wales). Stainless steel (ss) and unplasticized polyvinyl chloride (uPVC) coupons were conditioned with biofilm in each device for a period of 70 days. Biofilm removal techniques (sonication and stomaching) were evaluated and optimized for this study. A multiparametric quantification of biofilm biomass using total protein (NanoOrange™ protein determination) and carbohydrate (phenol-sulfuric assay) content, total number of bacterial cells (BacLight™ Live/Dead® Bacterial Viability Kit) and total number of heterotrophic bacteria (R2A plate counts) is proposed. The presence of biofilm-associated faecal indicator organisms (Enterococci, E. coli, somatic, F-RNA and B40-8 bacteriophages) was assayed for each biofilm homogenate. Variability both within and between biofilm devices was observed. Notwithstanding the shortcomings of the inherent heterogeneity observed with biofilm quantification, the relatively inexpensive biofilm devices were shown to yield reliable and comparable information on biofilm growth within an urban water distribution system. Furthermore, the multiparametric measurement of biofilm biomass was shown to provide a reliable and holistic quantification of distribution pipe biofilms.