Release of organic matter in a discontinuously chlorinated drinking water network.
The effects of discontinuous chlorination on the characteristics of the water in a pilot drinking water distribution network were investigated. The release or consumption of organic matter (as dissolved organic carbon, DOC) following chlorination and non-chlorination periods were estimated, as were changes in bacterial cell production. In each unchlorinated network 0.3 mg DOCl(-1) was consumed and the average cell production was approximately 1.3 x 10(5) cells ml(-1). In discontinously chlorinated networks (chlorine treatment: 3.3 mg Cl2l(-1), chlorine residual: 0.1 mg Cl2l(-1)) the DOC release (DOCout-DOCin) was between 0.1 and 0.2 mg Cl(-1). Biomass production (cells(out)-cells(in)) during this chlorination period was lower (approximately 2 x 10(4) cells ml(-1)). The delay before DOC was released in chlorinated networks appeared to be less than 24 h, which corresponds to one hydraulic residence time. Likewise, when chlorination was stopped, 24 h or less were required before an efficient DOC removal was resumed. When chlorination was prolonged the observed release of DOC was progressively reduced from 0.2 mg l(-1) to zero, thus after 6 weeks of continuous chlorination the DOCin was equivalent to the DOCout.
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Boualam
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Gauthier
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Gatel
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Cavard
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Benabdallah
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Lahoussine
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D018441:Biofilms; D002244:Carbon / Q000032:analysis*; D017606:Chlorine Compounds / Q000032:analysis / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis; D014872:Water Movements; D018508:Water Purification; D014881:Water Supply
D017606:Chlorine Compounds; D009930:Organic Chemicals; D002244:Carbon