Abstract:
For intensive food production, a range of chemical compounds are used to increase production, reduce the
amount of weeds, and prevent pest infestation. Therefore, agricultural wastewater discharge to water bodies
creates human health and environmental risks. This highlights the need for technologies to remove organic and
inorganic pollutants, where adsorption using carbon-based materials has emerged as a cost-effective and
promising alternative for agricultural wastewater treatment with high removal efficacy and alignment with the
circular economy concept by generating value-added products, achieving energy conservation and reducing the
environmental footprint. Among the different adsorbent materials, hydrochar (HC) has attracted attention
because, compared to the thermal processes used for synthesizing other carbon-based materials, it requires
relatively milder production conditions and possesses higher adsorption capability for water pollutants. Although
HC holds advantages for the adsorption of water pollutants, HC modification using different methods has been
found to improve the properties, including adsorption capacity. Accordingly, engineered hydrochar (EHC) has
attracted research attention. However, past research publications show that the investigations have focused on
material characterization and removal rates, with little knowledge created of the environmental impacts of HC
production, application, and disposal. This study reviews current knowledge on EHC synthesis, characteristics,
water treatment applications, and life cycle analysis. Initially, production methodologies were investigated to
understand their influence on key surface physical and chemical characteristics. This was followed by assessing
EHC efficacy for water and wastewater treatment. Finally, the environmental footprint of EHC production,
application, and disposal was evaluated to identify critical knowledge gaps and to provide recommendations for
future research.
