Conversion of biomass residues into (activated) biochar for the removal of metals from industrial wastewater

Abstract

The removal of 99% of metals is possible with standard physicochemical wastewater treatment systems. As a consequence of stricter legislation with regard to metal concentrations in industrial waste water, companies use ion exchangers to remove the residual metals. These ion exchangers are expensive and sometimes do not meet targeted metal concentrations in case of complex wastewater streams, e.g. wastewater containing both a high concentration in metals and organic matter. In this case, the best practice is to use an activated carbon filter to avoid fouling of the resin used in the ion exchanger. Companies are, therefore, on the lookout for alternative, cheaper, and more efficient technologies.

At the same time pyrolysis allows transforming organic residue streams into valuable products. In this study this innovative research path will be further explored. Activated biochar will be produced by pyrolysis of biomass residue streams. In the next step, this activated biochar will be used to test its use in the removal of the remaining metals in real wastewater samples of different companies. A techno-economic analysis (TEA) will be performed which consists of four different steps (1) market analysis, (2) mass and energy balance, (3) economic analysis, and (4) sensitivity analysis. It allows verifying whether the process is economically feasible from an early phase. Moreover, a TEA assists in identifying the parameters that should be focused on to increase the chances of market success. This implies that the technical and economic calculations are directly linked. Using the technical analysis and the TEA, we will identify which biomass residue sources are most interesting to produce an activated carbon with a high quality that can be used for wastewater treatment. We closely collaborate with the industrial stakeholders (i.e. waste processing companies, manure processing companies, water treatment companies and technology suppliers) and Flemish government to identify the main problems and find solutions to overcome the remaining barriers.