Pharmaceutical removal in synthetic human urine using biochar

Abstract

This research addresses the potential for biochar to remove pharmaceuticals from synthetic urine, thereby allowing the treated urine to be used as a contaminant-free nutrient product. Four biochars and one activated carbon from different source materials were tested: activated coconut carbon, coconut shell, bamboo, southern yellow pine, and northern hardwood. Batch tests were conducted for 24 hours using different compositions of synthetic urine and secondary wastewater effluent with biochar doses of 0.8 and 40 g L⁻¹ and an initial pharmaceutical concentration of 0.2 mmol L⁻¹. Seven pharmaceuticals were tested in this study: acetylsalicylic acid, paracetamol, ibuprofen, naproxen, citalopram, carbamazepine, and diclofenac. Activated coconut carbon, bamboo, and southern yellow pine biochars had the highest pharmaceutical removal in urine compositions at 40 g L⁻¹, adsorbing greater than 90% of each pharmaceutical. These biochars also demonstrated the ability to remove pharmaceuticals in the presence of nutrients, where the maximum removal of phosphorus and nitrogen was 36% by activated coconut carbon, 9% by bamboo, and 23% by southern yellow pine in all waste waters. Due to the high concentrations of nutrients naturally present in urine, there remains a high concentration of nitrogen and phosphorus after biochar treatment. The interactions between biochar, nutrients, and pharmaceuticals suggest that biochar has the ability to remove pharmaceuticals while maintaining nutrient concentrations in solution for future use as a nutrient product.