Livestock excretions containing high concentration of nutrient, pig liquid fertilizer, and cattle manure were applied to agricultural land. The characteristics of nutrient transport were examined in surface runoff and groundwater by an artificial rainfall event at real scale field site. Also, the effects of the artificial rainfall event on the characteristics of residual soil after the rainfall and phosphorus adsorption capacity were evaluated in the lab.

In this study a single-well, “push–pull” test method is adapted for determination of in situ denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push–pull tests. The method consists of the controlled injection of a prepared test solution (“push”) into an aquifer followed by the extraction of the test solution/ground water mixture (“pull”) from the same location. The injected test solution consists of ground water containing a nonreactive tracer and one or more biologically reactive solutes. Reaction rate coefficients are computed from the mass of reactant consumed and/or product formed. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). Extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifying microorganisms and consisted of injection of site ground water containing fumarate and nitrate. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate > nitrite > nitrous oxide. The series of push–pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification in nitrate-contaminated aquifers.

Groundwater contaminated by nitrates occurs frequently. In this research, fumarate, acetate, formate, lactate, propionate, ethanol, and methane were evaluated as a potential electron donor and carbon source by comparing the denitrification rate for the in situ bioremediation of nitrate contaminated groundwater. The denitrification rate for each substance was the quickest in the order of: fumarate > hydrogen > formate/Lactate > ethanol > propionate > methanol > acetate. Microcosm studies were performed with fumarates and acetates. When fumarates were used as a substrate, nitrates were removed completely at a rate of 0.66 mmol/day, while the conversion rate from nitrate to nitrogen gas and other by-products was 87%. For the microcosm test, 42 mg of fumarates were needed to remove 30 mg of NO(3)--N/L. When using acetate as a sole carbon source, 31% of nitrates were removed during the initial adjustment period. Among the removed fractions, however, 83% of the nitrates were removed by the cell growth. Overall, the nitrate removal rate was 0.37 mmol/day when acetate was used as a sole carbon source. The acetate showed longer lag time before denitrification occurred, which implied that fumarate would have been a better carbon source compared to acetate as more amounts were utilized for nitrate removal than cell growth.

Swine wastewater effluent is a key source of water contamination since it contains high levels of nutrients, including nitrogen and phosphorus, as well as nitrates and refractory organic matter (ROM). ROM refers to organic compounds that are usually resistant to microbial degradation. When swine wastewater effluent containing high levels of ROM is subsequently discharged into rivers and streams without being adequately treated, purification costs for drinking water increase and there remains a possibility for harmful substances to enter the human body. In this study, we introduce new methods for setting total organic carbon (TOC) water quality standards for discharging swine wastewater effluent containing high levels of ROM after treatment. To set the TOC water quality standards, various analysis methods based on statistics, technology, and experience based on operational data of livestock-manure treatment facilities were applied. In addition, the achievability of the proposed TOC standards in livestock-manure treatment facilities and the financial burden of their implementation on livestock farms were also reviewed. Here, we set tentative values that include all of our results derived from each methodology and set the TOC standards to levels that can be achieved through the normal operation of swine-wastewater treatment facilities (60 mg/L for public treatment facilities and 140 mg/L for treatment facilities operated by individual farms). When setting TOC standards, both single and combined methodologies should be considered and employed after comprehensively assessing livestock management policies, regional conditions, and the burden on stakeholders.