Integrated applications of water hyacinth biochar: A circular economy case study

Water hyacinth (WH) gasification, which generates syngas and biochar, is a promising thermochemical approach for bioenergy production and greenhouse gas mitigation. In this study, three different WH gasification biochar applications have been demonstrated: agricultural soil amendment, activation for activated carbon, and augmented concrete generation. In the agricultural soil application, the soil characteristics of pH, electrical conductivity and volumetric water content were improved when applying biochar as amendment material. The suggested biochar application ratio was 30–45% for optimal sunflower yield represented by the harvested seed weight. Through the proposed activation approach, the BET surface area of WH biochar was improved from 65.84 to 217.32 m 2 /g. In the augmented concrete application, the ball mill WH biochar resulted in 19.1% and 13.7% enhancements on compressive and flexural strength, respectively. Moreover, all the three proposed applications resulted in negative GHG emissions, showing good potential toward carbon neutrality. • Water hyacinth (WH) biochar improved the harvested sunflower seed weights by 53%. • Activated carbon from WH biochar improved 42% of GHG emission compared to coal. • Water hyacinth biochar improved compressive and flexural strengths of concrete. • Proposed three water hyacinth biochar applications are found to be carbon negative.