Salinity Effects from Treated Effluent as Irrigation

Author(s): Brock, M.; Tagert, M.

Around the world, increasing and sometimes competing demands on water for irrigation, industrial processes, aquifer recharge, drinking and other systems require investigation into additional viable water sources. Effluent from industrial and municipal wastewater treatment systems is gaining more attention as a potential source to meet these demands. By receiving further treatment beyond these systems, reclaimed or recycled water has been developed as a means to use this effluent as a viable source. Southwest Florida has proven its successful use on a large scale for more than 40 years with 62 treatment facilities and widespread applications without harmful impacts on local water and soil quality (Reclaimed Water, 2014). Risk factors that must be addressed include pathogens, nutrients, and salinity. While standard treatment facilities meet established limits for these components, reclaimed water requires extra treatment in potential applications that have more direct contact with humans. Salinity is considered one of the greatest risk factors associated with irrigation applications as it affects hydraulic conductivity of soils and water uptake of plants. This study assesses salinity in wastewater effluent and examines its potential for irrigation. A potential solution combines effluent with other water sources to reduce salinity risks to soil. Using samples from Starkville Wastewater Plant, electrical conductivity and total dissolved solids of the effluent are tested and compared to values established by the Food and Agriculture Organization as water quality restrictions to irrigation (US EPA, 2012). Using these restrictions, effluent is diluted using a predetermined ratio with controls set as undiluted effluent and freshwater. Results will provide a basis for potential application of treated water for irrigation in Mississippi or demonstrate a need for additional treatment of wastewater to meet standards adopted by current reclaimed water facilities.

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