Abstract
This study investigates the influence of pipe characteristics on the bacteriological composition of material mobilised from a drinking water distribution system (DWDS) and the impact of biofilm removal on water quality.Hydrants in a single UK Distribution Management Area (DMA) with both polyethylene and cast iron pipe sections were subjected to incremental increases in flow to mobilise material from the pipe walls. Turbidity was monitored during these operations and water samples were collected for physico-chemical and bacteriological analysis. DNA was extracted from the material mobilised into the bulk water before and during flushing. Bacterial tag-encoded 454 pyrosequencing was then used to characterize the bacterial communities present in this material.Turbidity values were high in the samples from cast iron pipes. Iron, aluminium, manganese and phosphate concentrations were found to correlate to observed turbidity. The bacterial community composition of the material mobilised from the pipes was significantly different between plastic and cast iron pipe sections (p < 0.5). High relative abundances of Alphaproteobacteria (23.3%), Clostridia (10.3%) and Actinobacteria (10.3%) were detected in the material removed from plastic pipes. Sequences related to Alphaproteobacteria (22.8%), Bacilli (16.6%), and Gammaproteobacteria (1.4%) were predominant in the samples obtained from cast iron pipes. The highest species richness and diversity were found in the samples from material mobilised from plastic pipes. Spirochaeta spp., Methylobacterium spp. Clostridium spp. and Desulfobacterium spp., were the most represented genera in the material obtained prior to and during the flushing of the plastic pipes. In cast iron pipes a high relative abundance of bacteria able to utilise different iron and manganese compounds were found such as Lysinibacillus spp., Geobacillus spp. and Magnetobacterium spp.
Highlights
Drinking Water Distribution Systems (DWDS) are complicated engineering systems consisting of pipes, storage vessels, fittings, valves, etc. made of a variety of different materials such as cast iron, PVC and polyethylene that interact with the bulk water
Viruses and protozoa are inhabitants of DWDS, we have focused our study on the characterization of bacteria since these microorganisms are dominant in drinking water biofilms due to their enhanced ability for producing extracellular polymeric substances, rapid growth and adaptability (Chaves Simoes and Simoes, 2013)
All conditions were not identical such as daily regime and pipe diameter the high relative abundance of iron and manganese bacteria in the samples obtained from the iron pipe and the correlation of the relative abundance of some of these bacteria with the concentration of iron suggests that pipe material was the main factor in driving bacterial community structure
Summary
Drinking Water Distribution Systems (DWDS) are complicated engineering systems consisting of pipes, storage vessels, fittings, valves, etc. made of a variety of different materials such as cast iron, PVC and polyethylene that interact with the bulk water. Drinking Water Distribution Systems (DWDS) are complicated engineering systems consisting of pipes, storage vessels, fittings, valves, etc. The water that consumers drink at the tap has travelled potentially large distances taking significant durations through the distribution network and it is accepted that from leaving the treatment plant deterioration in quality might occur. This deterioration in water quality will be influenced by factors such as decay of disinfectant residual, temperature, hydraulic regime, water residence time and bacterial regrowth (Machell et al, 2010; Ramos et al, 2010)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
