Use of biochar to produce reclaimed water for irrigation use

Emerging contaminants, especially, pharmaceutical and personal care products (PPCPs) are not removed well during conventional wastewater treatment and hence pose water quality risk to the environment and potentially to public health. Long-term use of reclaimed wastewater for irrigation can lead to accumulation of trace contaminants in the soil, ground water and their subsequent uptake by plants and potentially can enter human food chain. This paper uses biochar as an adsorbent to remove emerging contaminants from treated wastewater by performing fixed bed experiments. Ten emerging contaminants namely, carbamazepine (CBZ), caffeine, diethyltoluamide (DEET), diphenhydramine (DPH), meprobamate (MPB), primidone (PMD), sulfamethoxazole (SMX), fluoxetine (FXT), perfluorooctanoic acid (PFOA) and trimethoprim (TMP) were monitored during lab scale experiments. Results from the continuous flow runs showed that the breakthrough curve for compounds caffeine, CBZ, DEET and PFOA follow second order Thomas model with adsorption capacities of 396 μg g^-1, 392 μg g^-1, 1160 μg g^-1 and 32 μg g^-1 biochar, respectively. Whereas compounds such as DPH, TMP and FXT were completely removed throughout the column runs by biochar. Results for rest of the compounds were interfered by leaching of these compounds from biochar. It was observed that commercially available GAC performed much better than biochar for all the compounds considered. Even at 1% of obtained capacity, biochar amendment to soils where reclaimed water is used for irrigation can reduce the uptake of these compounds by plants.