The agricultural use of reclaimed wastewater for irrigation is constrained by the persistence of pharmaceutical residues which can enter the food chain and pollute natural water bodies. Biochar derived from agricultural wastes was demonstrated by researchers from Pennsylvania State University and the U.S. Department of Agriculture Agricultural Research Service to efficiently remove these emerging contaminants of concern from wastewater, enabling its safe reuse for irrigation.

The utility of biochars produced from cotton gin waste and guayule bagasse in adsorbing three common pharmaceutical compounds from an aqueous solution was evaluated. Emphasis was placed on the effect of Biochars based on agricultural wastes can act as effective adsorbents to remove pharmaceuticals from reclaimed water prior to irrigation. Source: Marlene C. Ndoun et alBiochars based on agricultural wastes can act as effective adsorbents to remove pharmaceuticals from reclaimed water prior to irrigation. Source: Marlene C. Ndoun et albiochar pyrolysis temperature on adsorption affinity for sulfapyridine, docusate and erythromycin.

The biochar derived from cotton gin waste proved the most efficient, as it adsorbed 98% of the docusate, 74% of the erythromycin and 70% of the sulfapyridine in aqueous solution. The material derived from guayule, a desert shrub, adsorbed 50% of the docusate, 50% of the erythromycin and just 5% of the sulfapyridine. A temperature increase from about 650° F to about 1,300° F in an oxygen-free pyrolysis process used to convert the agricultural waste materials enhanced biochar capacity to adsorb the pharmaceutical compounds.

The results published in Biochar confirm the potential for this material to serve as a low-cost additional treatment for reducing pharmaceuticals in treated wastewater prior to beneficial reuse in a wastewater irrigation system.

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