Abstract
To reduce the diffusion of trihalomethane precursors from livestock farm, field survey and laboratory experiments were carried out concerning 1) trihalomethane precursors concentration in livestock barn wastewater and effluent of treatment facilities, 2) potential diffusion of trihalomethane precursors from manure and compost, and 3) fate of trihalomethane precursors from composted manure in soil and aquatic environments. Median value of trihalomethane formation potential (THMFP) in wastewater from 11 livestock barn was 7,700 μg·l-1. Median value decreased to about 570 μg·l-1 by aerobic biological treatment. THMFP of the wastewater shows significant positive correlation between TOC, BOD and COD. THMFP also correlated with 260 nm absorbance of filtrate (E260). Since measurement of E260 is simple and rapid, it should he suitable for rough estimation of THMFP of the wastewater. Leachable trihalomethane concentration in swine faeces was 880 μg·g-1 dry weight. After solid composting, the concentration decreased to 130 μg·g-1 dry weight. Slurry derived from dairy cow barn contained dissolved trihalomethane precursors of 13,500 μg·l-1. After liquid composting by aeration, the concentration decreased to 4,400 μg·l-1. Immediately after mixing of the solid and liquid compost with soil, leachable trihalomethane precursors decreased drastically probably due to adsorption of the precursors to soil particles. However, only slight decrease of leachable trihalomethane precursors occurred afterward. Soluble trihalomethane precursors of the solid and liquid compost were decreased only slightly during incubation after mixed with spring water. These results suggest that trihalomethane precursors diffused from solid and liquid composts are persistent against microbiological degradation in soil and aquatic environment.
