Microbial contamination in distributed drinking water purifiers induced by water stagnation
Xiao Chen1, Yi Wang1, Weiying Li2
1College of Defense Engineering, The Army Engineering University of PLA, Nanjing, 210007, China.
Environmental Research
|June 8, 2020
Summary
Water stagnation in small-scale distributed water purifiers (SSDWPs) rapidly increases bacterial counts and pathogenic risks. Terminal disinfection is strongly advised to ensure safe drinking water from these popular home and public devices.
Area of Science:
- Environmental Microbiology
- Water Treatment Technology
- Public Health
Background:
- Small-scale distributed water purifiers (SSDWPs) are widely used for improved drinking water quality.
- Non-continuous operation can lead to water stagnation and microbial contamination, a poorly understood issue in SSDWPs.
- Existing research on microbial contamination dynamics in SSDWPs during stagnation is scarce.
Purpose of the Study:
- To investigate microbial changes in an SSDWP (sand filtration, granular activated carbon, ultrafiltration) due to water stagnation.
- To analyze bacterial counts, cell integrity, microbial size, microbiome composition, and pathogenic communities.
- To assess the impact of stagnation time and nutrient levels on microbial contamination and pathogenic risks.
Main Methods:
- Establishment of a multi-stage SSDWP (SF, GAC, UF) for experimental analysis.
- Monitoring bacterial counts and cell integrity using flow cytometry.
- Characterization of microbiome and pathogenic communities through sequencing.
- Comparison of microbial dynamics in SSDWPs versus drinking water distribution systems (DWDS) under stagnation.
Main Results:
- Bacterial counts in SSDWPs exceeded 500 cfu/mL after 2.5 hours of stagnation, significantly faster than in DWDS.
- Microbial size decreased, while the proportion of intact cells increased with stagnation time.
- Microbiome evolution in SSDWPs followed an isolated island model with higher biodiversity compared to DWDS.
- Mycobacterium and Acinetobacter were identified as dominant pathogenic genera in different SSDWP units, with risks increasing upon stagnation.
Conclusions:
- Water stagnation in SSDWPs significantly alters microbial communities, increasing bacterial loads and pathogenic potential.
- Spatial differences within the SSDWP units had a greater impact on microbiome dissimilarity than temporal differences.
- Terminal disinfection is crucial for mitigating microbial contamination and ensuring the safety of water from SSDWPs.
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