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Wastewater Reuse
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Water Management and Conservation Research

Reuse of Treated Municipal Waste Water for Irrigation

Project Summary

Irrigated agriculture in the United States produces 60% of crop market value on less than 20% of cropped lands.  Irrigation is essential to the most highly productive, intensely managed, and internationally competitive sectors of our agricultural economy.  Yet, irrigated agriculture is subject to growing competition for water resources.  The decreasing supply of fresh water for irrigation, coupled with the increase of effluents from urban areas, leads to the opportunity for increased water supply through effluent reuse for irrigation.  Safe use of these waters requires new knowledge of the fate, transport and control of emerging contaminants and pathogens, as well as efficient use of nutrients found in these waters.  The objectives of the proposed research are:  1) to provide baseline data and scientific knowledge to evaluate the long-term effects of irrigation with treated wastewater; 2) to understand processes that govern the fate and transport of emerging contaminants, pathogens and nutrients found in treated wastewater used for irrigation; and 3) to develop guidelines for the safe reuse of treated wastewater for irrigation of turf and other specialty crops.  These objectives will be achieved through a series of laboratory, greenhouse, and field experiments.  Field data from sites where treated effluent has been used will be gathered and used to determine potential hazards.  Controlled systems including field lysimeters, columns and lab microcosms will be used to elucidate and validate the observed field results.  Results of the research will provide scientifically based decision making tools for the safe reuse of treated effluent for irrigation.

Objectives

Irrigation with degraded water has been a common practice in many places where water resources are scarce.  Typically, treated wastewater was disposed of in natural water bodies and then withdrawn for reuse at some point that was spatially or temporally separated from the wastewater discharge point.  In these cases the wastewater was diluted, transformed, or both by the receiving water before use in irrigation.  The direct reuse of treated municipal wastewater on a large scale is a relatively recent practice.  In the case of direct reuse, the wastewater is transported without dilution directly to irrigation distribution systems.  The objectives of the proposed research will build upon each other to improve understanding of the fate and transport of contaminants found in treated wastewater directly used for irrigation.

Objective 1:           Provide baseline data to evaluate the long term effects of irrigation with treated wastewater.

Very little data exists regarding the presence and persistence of contaminants, such as drugs, hormones and pathogens, found in treated municipal wastewater.  For objective 1 data will be collected from a number of sites with a history of direct wastewater reuse.  In addition, similar sites without reuse will be compared to determine constituents of interest for the remaining objectives.

Objective 2:           Understand processes that govern the fate and transport of emerging contaminants, pathogens and nutrients found in treated wastewater used for irrigation.

Data gathered from objective 1 will be used to identify what contaminants found in treated effluent are of interest.  These constituents of interest will then be investigated under controlled and field conditions to determine specific environmental fate and transport parameters.  These results will be used to test the hypothesis that the constituents found in wastewater behave in a similar manner to analogous constituents previously investigated.  This will provide a basis for scientifically sound strategies to manage the direct reuse of treated municipal effluent for irrigation in objective 3.

Objective 3:           Develop guidelines for the safe reuse of treated wastewater for irrigation.

Objective 3 depends on the outcome of both objectives 1 and 2.  The results of the previous objectives will indicate potential avenues for management of treated municipal wastewater used for irrigation.  The research proposed is expected to result in the outcome that the use of wastewater for irrigation poses definable and manageable risks that can be overcome with proper management.  This will allow for expanded water resources through the multiple uses of limited water supplies.