Microbial and Heavy Metal Contamination of Treated Hospital Wastewater in Thailand
Somwang Danchaivijitr MD*, Wichai Wongchanapai MD**, Susan Assanasen MD*, Duangporn Jintanothaitavorn MSc***
Affiliation : *Department of Medicine, **Department of Forensic Medicine, ***Center for Nosocomial Infection Control, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok.
Objectives : To determine the microbial and heavy metal contamination of treated hospital wastewater.
Materials and Methods : Methods of treating wastewater were acquired by questionnaires. Chlorine concen-
tration, pH, bacteria and parasites in treated wastewater were tested in the individual hospitals. Heavy metal
concentrations were measured by atomic absorption spectrophotometry.
Results : In 2002, 72 hospitals were included in the present study. The common methods of treating wastewater
were activated sludge and oxidation ditch. Bacteria exceeded standard numbers, pathogenic bacteria and
parasites were found in two-thirds of the hospitals. Heavy metals, namely lead, chromium and cadmium, in the
hospital effluent did not exceed standard concentrations.
Conclusion : Micro-organisms exceeding standard levels were found in treated wastewater in two-thirds of
the hospitals. Lead, chromium and cadmium levels in hospital effluent were in an acceptable range.
Keywords : Contamination, Microbial, Heavy metal, Wastewater, Hospital
