| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系 === 90 === Utilizing land treatment of livestock wastewater after pretreatment by secondary treatment, both advantage the water resource reuse and reduce the treatment problem of wastewater. Moreover, using the abundant amounts of nitrogen, phosphorus, and organic matter in livestock wastewater to provide crop uptake is a very important operation in resources reuse and environmental protection. The effect of irrigating livestock wastewater to plots on their surrounding environmental quality and the evaluation of suitability of irrigation site has been conducted. However, study on the effect and evaluation of long term irrigation of livestock wastewater to soil on the contents of heavy metals in related water was few. This study was thus to investigate the effect of long term irrigation of livestock wastewater to soil on the contents of heavy metal and related water quality, and especially those of Cu and Zn.
At the experimental plots in Livestock Research Institute from April, 2001 through March, 2002 and in Lutsao Farm, Nanchin Sugar Mill Factory from March, 2001 through March, 2002, the evaluation credits for the two sites irrigated with livestock wastewater were high suitability. Through the monitoring of pH, EC, and DO values, and temperature of water samples in situ, and TOC and contents of heavy metals of water samples taken from all monitoring and farmer’s wells and surface water at the experimental plots all year, the EC values and TOC contents were higher and DO values were lower of some water samples from both experimental plots. This is probably because of the effect of rainfall. The DO values of midstream and downstream of surface water samples were lower at the experiment plot in Lutsao Farm. This is because the nearby field raising ducks operation to drain off wastewater. Moreover, As concentrations of water samples from monitoring well 1 in Lutsao farm in September and October, 2001 exceeded the 2nd control standard value (0.5 mg L-1) of groundwater pollution. This probably relates to regional characteristics of soil parent material and the highest cumulative amount of rainfall in September 2001. It did not have notable correlation with the irrigation of livestock wastewater to the plots.
The experimental plots in Livestock Research Institute and Lutsao Farm were irrigated with the secondary treatment discharge water of swine wastewater in the down date of October and August 2001, respectively. Except for the described above abnormal vales, however, there was no apparent difference in some specific chemical properties and heavy metal concentrations of groundwater and related surface water samples from the treatment and control plots in Livestock Research Institute and Lutsao Farm before and after the irrigation of the secondary treatment discharge water of swine wastewater. Cu and Zn concentrations of the water samples, which are closely related to the characteristics of the secondary treatment discharge water of swine wastewater, were even lower than the 1st control standard values of groundwater pollution. This clearly indicates that the irrigation of the secondary treatment discharge water of swine wastewater to the plots in Livestock Research Institute and Lutsao Farm did not affect the correlated quality and heavy metal concentrations of groundwater and surface water in the experiment plots and their related environments.
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