Impacts of effluent from different livestock farm types (pig, cow, and poultry) on surrounding water quality: a comprehensive assessment using individual parameter evaluation method and water quality indices.

Water pollution within and nearby different livestock farm types was assessed comprehensively for the first time in Vietnam. The samples of wastewater, ground water, and surface water were collected from 130 pig farms, 80 poultry farms, and 40 cow farms. Water quality was first assessed by individual parameter evaluation method in which measured values of water quality parameters were compared with the permissible limits in the national technical regulations on livestock's effluent (QCVN 62), surface water quality, and ground water quality. Subsequently, the overall quality of surface and ground water samples was evaluated by mean of water quality index (WQI). The results showed the large variations in effluent's quality, implying the considerable differences in wastewater treatment efficiency within and among farm types. Effluent from livestock farms was highly polluted by organic matters (expressed as BOD and COD) and especially by microorganisms (expressed as total coliform-CF). Almost all wastewater samples contained higher number of CF than QCVN 62 (3900 MPN/100ml), with mean concentration of CF in effluent from cow farms, pig farms, and poultry farms were 1.2e+07 ± 5.0e+07 MPN/100ml, 8.8e+04 ± 7.1e+04 MPN/100ml, 1.5e+06 ± 4.2e+06 MPN/100ml, respectively. Improperly treated livestock's waste was likely to have impacts on quality of ground water and receiving surface water bodies. High CF contamination in effluent leads to 70% of the ground water samples in cow farms and poultry farms classified as unsuitable for drinking water supply by WQI values. Although effluent from poultry farms had smaller quantity and better quality, their receiving surface water bodies exhibited the worst quality, with average WQI of 37.5 ± 16.2 compared to 49.9 ± 12 of pig farms and 50.3 ± 20.8 of cow farms. This result suggests that livestock's effluent was not only pollution source of surface water bodies nearby livestock farms.