Microbial and heavy metal contamination of treated hospital wastewater in Thailand.

ABSTRACT

OBJECTIVES: To determine the microbial and heavy metal contamination of treated hospital wastewater MATERIAL AND METHOD: Methods of treating wastewater were acquired by questionnaires. Chlorine concentration, 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.