Greywater treatment using agro-industrial biochar: A novel water reuse approach

The European Union (EU) Blue Deal has dealt with the preservation of vulnerable freshwater supplies and recommended water reclamation and reuse applications. The use of biochar is a promising technique for water treatment and reclamation. From this point of view, malt dust, which is an agro-industrial by-product of the brewery industry, was used as the feedstock of biochar for the treatment of the greywater originating from a kitchen sink and a laundry rinse cycle to obtain the reclaimed water quality. This paper mainly aimed to determine the quality of reclaimed water using biochar application. Turbidity, Biological Oxygen Demand (BOD₅), Total Suspended Solid (TSS), and E. coli analyses were performed to determine the effluent quality. According to the EU Wastewater Reclamation and Reuse Legislation, Class-A-quality reclaimed water can be used for the irrigation of all kinds of agricultural crops. Otherwise, Class-B-quality reclaimed water can be used for the irrigation of above-low-ground and high-ground crops such as tomatoes, peppers, or fruit trees. At the end of treatment, the reclaimed water met the requirement of the Class B quality according to EU legislation, considering all parameters. E. coli values met both Class A and Class B qualities for each season. Only TSS in winter met the Class A quality requirements, while the others met in the range of Class B quality. Turbidity and BOD₅ met the Class B quality criteria. In the results of the overall assessment, the effluent met the Class B reclaimed water quality considering the minimum criterion requirement. This study has verified that malt dust-derived biochar is an efficient and low-cost adsorbent to obtain reclaimed water quality. The reclaimed water was used for the green area irrigation of Osmanbey Campus in Turkey.