Research articles
ScienceAsia 50 (2024):ID 2024026 1-9 |doi:
10.2306/scienceasia1513-1874.2024.026
Reduction and regrowth of total coliform bacteria, fecal
coliform bacteria, and E. coli after chlorine and peracetic acid
disinfection in the hospital effluent
Supavita Suwannasina, Siranee Sreesaia,b,*, Chaowalit Warodomrungsimuna,b, Chatchawal Singhakanta,b, Wannee Magunc
ABSTRACT: Hospital wastewater is an important source of pollutants resulting from medical activities. It has a high
vulnerability towards the outbreak of several diseases. The aim of the study was to investigate the disinfection efficiency
of different dosages and contact times of chlorine and peracetic acid (PAA) to reduce the contaminated microbes.
The consequences after treatments such as regrowth capacity, disinfection by-products, and water quality were also
observed. The result showed that in all fourth-time samplings of effluent, its physical, chemical, and biological
characteristics exceeded the standard requirement and needed further treatment before discharge. The disinfection
experiments were run in parallel among 3 chlorine dosages (1.388, 1.588, and 1.988 mg/l) and 3 PAA dosages (5, 10,
15 mg/l) at contact times of 15 and 30 min. PAA performed faster than chlorine from the beginning, after that, they
all provided similar microbial reduction around 2.38?4.47 log 10 MPN/100 ml. Chlorine provided higher efficiency in
reducing total coliform while PAA was greater for E. coli. The efficiencies increased as contact time was increased. PAA
exhibited higher physical and chemical treating capacities than those of chlorine. The study suggested that chlorine
at 1.528 mg/l and/or PAA at 5 mg/l, at a contact time of 15 min, are suitable microbial treatments for this effluent.
These suggested conditions could improve all water quality parameters to meet the standard requirement and inhibit
regrowth of microbes during the three-day incubation period. The stakeholders should also continue to monitor effluent
characteristic variation and treatment conditions regarding the application of these infectants.
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a |
Department of Environmental Health Science, Faculty of Public Health, Mahidol University,
Bangkok 10400 Thailand |
b |
Center of Excellence on Environmental Health and Toxicology (EHT), OPS, MHESI, Bangkok 10400 Thailand |
c |
Research and Laboratory Development Center, Department of Health, Ministry of Public Health,
Nonthaburi 11000 Thailand
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* Corresponding author, E-mail: siranee.sre@mahidol.ac.th
Received 1 May 2023, Accepted 3 Dec 2023
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