Bacteria Community Attached to Iron Pipe Wall in Drinking Water Distribution System of Jinan
|Keywords||Drink water distribution system PCR-DGGE bacteria attached to pipewall iron corrosion AOC|
Deterioration of drinking water quality in distribution pipes remains to be a serious problem for drinking water supply. Cast iron pipes have been common used in water distribution systems, e.g., in China, about50%of water distribution pipes are iron pipes because of economic and historical reason. Most water distribution pipelines have a buildup of iron corrosion products inside the iron pipes, and corrosion scales not only restrict the flow of water, but also degrade the water quality. This study has focused on iron pipes of the drinking water distribution system in Jinan.Firstly, the bacteria community of corrosion products was investigated in distribution system and colored tap water using culture-based method and PCR-DGGE method. Three dominant groups-Bacilli, Actinobacteria, and Proteobacteria (α,β, y-Proteobacteria), including Rhizobium, Pseudomonas, Lactococcus, Brevundimonas, Rheinheimera, Arthrobacter, Bacillus, and Herbaspirillum-were detected by PCR-DGGE method. XRF analysis indicated that the composition of elements in iron corrosion products and colored tap water were similar, and the most frequently detected element was Fe. X-ray diffraction analysis showed that the crystallographic composition of corrosion products were goethite (a-FeOOH), magnetite (Fe3O4) and CaCO3. The retentate of colored tap water was non-crystalline material. It indicated that the occurrence of colored water was not driven by hydraulic scour. Iron release will cause the intrusion of bacteria from corrosion products into the bulk water, which leads to pollution.Secondly, in this study, the effect of AOC on the re-growth of bacteria in distribution pipes we studied using the tap water in Shandong University with the addition of appropriate amount of acetic acid carbon. With biofilm annular reactors (BARs), the relationship between suspended bacteria and biofilm growth was tested in different AOC conditions. At the same time, detection of microbial species in the reactor under the conditions of different AOC level was performed. The results showed that high AOC favored growth of diverse bacterial species, including Sphingomonas sp., Pseudomonas sp., Flavobacterium sp., Acinetobacter sp., Hydrogenophaga sp., and Leptothrix sp. But in low AOC reactor, there were only Sphingomonas sp. and Pseudomonas sp. growing on slides.