Exploring alternative water sources is one potential strategy for overcoming agricultural water scarcity issues. When considering new sources, it is important to address the presence of potential contaminants, including pharmaceutical compounds (PCs) and disinfection byproducts (DBPs). Ongoing experiments are investigating these compounds and their uptake in experimental applications of treated wastewater reuse in hydroponic greenhouse grown lettuce, <i>Lactuca sativa</i>. Results of PC uptake show minimal uptake into plant tissues at typical levels in treated wastewater. DBP formation experiments were conducted on wastewater treatment plant effluent. In experiments comparing dosages of 25 mg/L chlorine at reaction times of 30 minutes, 3 hours, and 6 hours, all reactions resulted in similar concentration ranges and DBP compound formation (0.68-24.73 μg/L), with chloroform, bromodichloromethane, and dibromochloromethane as the most abundant DBPs. Additionally, DBP formation potential across pH 5, 6, and 7 only varied slightly, generating total DBPs of 76.02, 85.80, and 89.48 μg/L, respectively. This shows that typical treatment used in greenhouse systems, even with shorter contact times, could result in DBP formation. Work is ongoing regarding the impact of other source water conditions such as DOC and Br<sup>-</sup> concentration. In order to determine if these compounds are taken up and persist in plant tissue, extractions were developed to determine DBP uptake into lettuce roots and shoots. A survey was developed for growers to assess their knowledge and perceptions about alternative water sources and growing food in reuse water. Interviews with growers have examined their management strategies, sources, and disinfection processes for water used in crop production and processing. Understanding growers’ perspectives and water use strategies helps inform water management decisions working towards achieving future food security. Resulting generation, uptake, and translocation of DBPs into plant tissues and grower survey results suggest the potential for reclaimed water to be a viable alternative water source.

Alternative water source contaminant concerns for greenhouse agriculture

2019 Fall National Meeting

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