• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.69-75
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• 2009

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution. A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhood children. Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation. It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of ground-water and reclaimed secondary wastewater irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.67-74
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• 2011

The objectives of this study were to assess the rice yields and evaluate fertilizer reduction effect of reclaimed wastewater irrigation in paddy fields using the Decision Support System for Agrotechnology Transfer (DSSAT) v4.5 model. The experimental plots were designed, which was located near the Suwon wastewater treatment plant in Gyeonggi-do, Korea. The rice yield, irrigation amount, irrigation water quality and soil data were monitored and collected between 2006 and 2009. The DSSAT model was calibrated and validated with observed data. The methods that were used to evaluate this model were the root mean square error (RMSE), normalized root mean square error (nRMSE), and index of agreement (d). The values of RMSE, nRMSE, and d ranged from 145 to $789\;kg\;ha^{-1}$, 3.0 to 13.3 %, and 0.90 to 0.95 for the calibration period, respectively and represented from 91 to $538\;kg\;ha^{-1}$, 2.0 to 10.4 %, 0.94 to 0.98 for the validation period, respectively. Overall, this model showed good agreement with observed data of rice yields irrigated with reclaimed wastewater. The fertilizer reduction effect in paddy field of reclaimed wastewater irrigation was assessed about 60 % in 2008 and 40 % in 2009.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.59-65
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• 2011

The purpose of this study was to analyze the water quality change when wastewater applied to study paddy fields. CREAMS-PADDY (Chemical, Runoff and Erosion from Agricultural Management System) model was used to estimate the field-scale water quality. Simulated results were compared with observed data monitored from Byeongjeom study paddy fields which is located near the Suwon sewage treatment plant in Gyeonggi-do. Significance analysis was performed for the three different irrigation water quality level and five fertilizer reduction scenarios using LSD (Least Significant Difference) and DMRT (Duncan's Multiple Range Test). Total nitrogen was found to be significant for both irrigation water quality level and fertilizer reduction while total phosphorus was not. Annual drainage load for total nitrogen was reduced by 66~92 % compared to irrigation load when treated wastewater irrigated to study paddy fields from 2002 to 2007. Total phosphorus was reduced by 70~86 %.

• KCID journal
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• v.11 no.1
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• pp.57-63
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• 2004

This study is established to investigate reusable wastewater resources and their applications for agricultural uses, and far drought mitigation purposes that may be applied for agricultural reuse, and develop a GIS database 1) to survey the responses of f

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.53-63
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• 2012

The objectives of this study were to develop a linked watershed-waterbody modeling system and to assess the impacts of indirect wastewater reuse on irrigation water quality. The Osan stream watershed within Gyeonggi-do of South Korea was selected for this study. The linked modeling system was composed of the SWAT (Soil and water assessment tool) and QUALKO2 models. The SWAT model was calibrated and validated using the stream discharge and water quality data from 2010 to 2011. Runoff and non-point source pollutants from each subbasin and stream discharge from 1980 to 2009 were simulated by the SWAT model and applied to the QUALKO2 model. The QUALKO2 model was calibrated and validated under the conditions of low water and normal discharges, respectively. Finally, The 10-day irrigation water quality from April to September was simulated. The statistical measures of coefficient of determination ($R^2$), reliability index (RI), and efficiency index (EI) were used to evaluate the system performance. The $R^2$, RI and EI values ranged from 0.5 to 1.0, 1.03 to 1.92, and -35.03 to 0.95, respectively. The 10-day irrigation water quality showed the concentrations of BOD and coliform exceeded the water quality guidelines for wastewater reuse. The linked modeling system can be a useful tool to estimate non-point source pollutant loads in watershed and to control the water quality of effluent from a wastewater treatment plant and irrigation water in the downstream waterbody.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.643-648
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• 2005

The objective of this paper is to analyze the environmental effects by the fertilizer change with wastewater reuse for agriculture. For this research, Lysimeter tests are being implemented to cultivate rice with different levels of fertilizer applications with wastewater irrigation., and to analyze the nutrient loading by wastwater reuse in paddy fields was examined the CREAMS-PADDY model. CREAMS-PADDY model is modified from CREAMS model for considering the hydrologic cycles in paddy field. As a result, in the lysimeter treated by irrigation with wastewater and chemical fertilizer with half of the conventional amount showed generally similar tendency to the control plot. This may require the modifications of standard cultural practices for rice in terms of fertilizer and pesticide applications. However, high concentration of sodium in wastewater might cause damage to physico-chemical properties of paddy soil. And the wastewater reuse effects on nutrient loads were quantitatively analyzed and this results provide the reasonable management for agricultural reuse.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.1
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• pp.27-32
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• 2009

The objective of this study is to assess the feasibility of wastewater reuse for the vegetable farming. The study region, about 250 ha in size, is located on the west coast of Jejudo, Korea. Major agricultural products of the study area are the cabbage, broccoli, garlic and onion. To confirm the feasibility of wastewater reuse, the drought duration and the water requirement analysis were conducted respectively. The average annual precipitation of the study region (1,121 mm) was smaller than that of Jeju island (1,975 mm). The drought duration for a ten-year return period in October through November was more than 20 days. The water requirement for irrigation was calculated by the FAQ Penman-Monteith method which took into account the cultivated crops, planting system, and meteorological conditions of the study region. The water requirement for a ten-year return period was estimated 4.7 mm/day and the water demand for irrigation was $4,584\;m^3/day$. As a result, the irrigation water for the crops was insufficient during their breeding season, especially in October through November. Thus, the result indicated that the study region required the alternative water supply such as wastewater reuse during the non-rainy season. As drought continues to place considerable stress on the availability of fresh water supplies in the study region, irrigation with reclaimed wastewater will play an important role in helping to meet future water demands.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.192-196
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• 2003

Objective of this study was to investigate the influences of harvest index and percolation water quality as irrigated the discharge waters from an industrial and a municipal wastewater treatment plants and seawater (1:5 seawater: tap water) as alternative water resources during tillering stage for drought stress. There were four different treatments such as the discharge water from an industrial (textile dyeing manufacture plant) wastewater treatment plant (DIWT), discharge water from the municipal wastewater treatment plant (DMWT), seawater (1:5) and groundwater as a control. For the initial chemical compositions of alternative waters, it appeared that higher concentrations of COD, $Mn^{2+}$, and $Ni^+$ in DIWT were observed than reused criteria of other country for irrigation, and concentrations of $EC_i$, Cl, and $SO_4$ in seawater were higher than that for irrigation. Harvest index was not significantly different between DIWT and DMWT with different irrigation periods in two soil types, but that of seawater (1:5) is decreased with irrigation periods in clay loam soil and not different between 10 days and 20 days of irrigation periods in sandy loam soil. For percolation water qualities, values of sodium adsorption ratio (SAR) are increased with prolonging the irrigation periods of seawater (1:5) and DIWT, but those of DMWT were almost constant through the cultivation periods regardless of the irrigation period in both soil types. EG of percolation waters is eventually increased with prolonging days after irrigation regardless of irrigation periods in both soil types. Therefore, it might be concluded that there was potentially safe to irrigate the discharge water from municipal wastewater treatment plant relative to harvest index, SAR and $EC_i$ values of the ground water through the rice cultivation period at tillering stage for drought period.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.401-404
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• 2002

Two irrigation districts, Maekok and Byungjum 1 which are irrigated with polluted stream flow, and one control district Kichun, that is supplied from a reservoir complying with the water quality standard are selected for water quality monitoring to identify the effects of polluted irrigation on crop yields, environments, and health hazards for farmers. The water quality at Maekok and Byungjum 1 districts are worse than the control district, and continuous water quality monitoring are needed for the wastewater reuse for agriculture.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.91-104
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• 2013

The objectives of this study were to monitor and assess the environmental impacts of indirect wastewater reuse on water quality and soil in paddy fields. Yongin monitoring site (YI) irrigated from agricultural reservoir and Osan monitoring site (OS) irrigated with treated wastewater diluted with stream water were selected as control and treatment, respectively. Monitoring results for irrigation water quality showed a significant statistical difference in salinity, exchangeable cation and nutrients. Pond water quality showed a similar tendency with irrigation water except for the decreased difference in nutrients due to the fertilization impact. Soil chemical properties mainly influenced by fertilization activity such as T-N, T-P, and $P_2O_5$ were changed similarly in soil profiles of both monitoring sites, while the properties, EC, Ca, Mg, and Na, mainly effected by irrigation water quality showed a considerable change with time and soil depth in treatment plots. Heavy metal contents in paddy soil of both control and treatment did not exceed the soil contamination warning standards. This study could contribute to suggest the irrigation water quality standards and proper agricultural practices including fertilization for indirect wastewater reuse, although long-term monitoring is needed to get more scientific results.