Trihalomethanes formation potential of shrimp farm effluents Chachoengsao province, Thailand

Abstract

Shrimp farm effluents along Bang pakong River in Chachoengsao Province were evaluated for their trihalomethane formation potential (THMFP). Samples from the river both upstream and downstream locations were also tested for their existing THMFP to allow the assessment of the impact from the river contaminated by shrimp farm effluents. The evaluation steps included the filtration through 0.45 pm filter media and the fractionation to hydrophobic and hydrophilic organic fractions using XAD-8 adsorption resin. The characteristics of shrimp farm effluents were: TOC 13.78-18.27 mg/L, DOC 12.34-13.95 mg/L, hydrophobic 3.01-4.63 mg/L, hydrophilic 8.43-10.05 mg/L. THMFP for all shrimp farm effluents were found to be in the range from 810-3300 µg/L. The hydrophilic was a more active precursor for trihalomethane (THMs) products with 700-966 µg/L THMFP obtained from these samples while only 111-363 µg/L THMFP was derived from the hydrophobic fraction. THMFP from the river samples were significantly lower than those from shrimp farm effluents. This indicated that the contamination with shrimp farm effluents might be one of the most important sources which would potentially increase the risk of exposure to high THMs level in natural water source if this water was chlorinated for further municipal/industrial usages. In addition, SUV As of the shrimp farm effluents were relatively low with values of less than 3 L/mg.m. This implied that THMs precursors were unlikely to be efficiently removed by enhanced coagulation.