Perfluoroalkyl Acids and other Trace Organics in Wastederived Organic Products: Occurrence, Leachability, and Plant

Rooney Kim Lazcano, Purdue University

Abstract

Waste-derived organic products are nutrient-rich materials often applied to agricultural land as a fertilizer to enhance agricultural production and soil quality. Commercially available biosolid-based products, which are sold and distributed in bags or bulk, are rapidly gaining popularity for urban and suburban use. Although biosolid-derived products have many benefits, they may contain trace organic contaminants such as per- and polyfluoroalkyl acids (PFAAs) and pharmaceutical and personal care products (PPCPs), in varying levels, depending on waste source composition. These organic compounds have been used in a variety of consumer and industrial products and are known to accumulate in biosolids due to their recalcitrance in conventional wastewater treatment processes. Thus, the application of commercially available biosolids-based products on urban and suburban gardens may lead to transfer and accumulation of organic contaminants into food crops, raising food safety concerns. Most studies to date have focused on municipal biosolids application on agricultural lands with very few studies focused on commercial products available for home and urban gardens. For the latter, the evaluations of bioavailability and subsequent plant uptake of organic contaminants from biosolids have also often been conducted by adding organic contaminants to the growing media (e.g., soil or hydroponic) at a concentration that greatly exceed environmentally relevant concentrations. Moreover, there are currently no studies evaluating leaching and plant uptake potential of contaminants from commercially available (e.g., local stores) biosolids. The research described in this dissertation 1) assessed the occurrence of PFAAs and representative PPCPs in commercially available biosolidbased products and their porewater concentrations in saturated media as a measure of bioavailability and leachability; 2) investigated how heat-treatment, composting, blending and thermal hydrolysis processes on biosolids to convert them to commercial biosolid-based products affect PFAA concentrations in the production of commercial biosolid-based product; and 3) assessed the bioavailability and plant uptake of PFAAs and targeted PPCPs by kale and turnips grown in soil-less potting media amended with Milorganite (a commercially available biosolidsbased fertilizer product) at the recommended rate and four times the recommended rate.The biosolid-based products displayed varying levels of organic contaminants. Higher PFAA concentrations were detected in biosolid-based products compared to nonbiosolid-based products. The common treatment processes used in taking biosolids to commercially available products were ineffective in reducing PFAA levels in the products except for blending with other essentially PFAA-free materials, thus served as a simple dilution. Porewater concentrations of PFAAs and PPCPs as an indicator of leachability and bioavailability were higher for the less hydrophobic compounds (e.g., short-chain PFAAs and diphenhydramine and carbamazepine with lower octanol-water partition coefficient). Leachability alone did not explain the observed plant uptake potential of PFAAs and PPCPs. With similar leachability and molecular weight/size between diphenhydramine and carbamazepine, higher uptake was observed with a positively charged compound (diphenhydramine compared to a neutral compound (carbamazepine). However, not all positively charged compounds were taken up by the plant. Azithromycin, a positively charged compound, had lower uptake than other contaminants which may be due to its large molecular size compared to diphenhydramine. Higher concentrations of miconazole, triclosan, and triclocarban were found in the biosolids-fertilizer; however, these compounds had low leachabilities and limited uptake by plants. Also, for PPCPs, the application rates of biosolidbased products did not necessarily correlate with the higher uptake and translocation of contaminants to the above-ground portion of plants.

Degree

Ph.D.

Advisors

Mashtare, Purdue University.

Subject Area

Agriculture|Agronomy|Urban planning

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