Co-hydrothermal carbonization of digested sewage sludge and sugarcane bagasse: Integrated approach for waste management, optimized production, characterization and Pb(II) adsorption

Abstract

Integrated biomass waste management and fresh water supply are crucial environmental problems that researchers are laboring to clarify today. The co-hydrothermal carbonization (co-HTC) of sugarcane bagasse (SB) and digested sewage sludge (DSS), with KOH activation, for SB and DSS waste management, was accomplished. In this research, the effect of process parameters and biomass ratio during co-HTC on modified hydrochar adsorption capacities was critically evaluated. To optimize operating parameters (temperature, time, catalyst/precursor ratio, water/precursor ratio, and SB/DSS ratio, response surface methodology was used. The optimum condition was 180 °C, 9.6 h, 3/1 DSS/SB ratio (ww), 5.00 water/precursor ratio (ww), and 3.50 ZnCl2/precursor ratio (ww). The optimum hydochar was featured using BET, SEM, FTIR, TGA, and elemental analysis and used to study the adsorptive ability of lead. The adsorption isotherm and kinetic model matched reasonably with the Langmuir (127.61mgg) and pseudo-second-order models (130.68mgg). Moreover, the kinetic adsorption studies showed that 85 percent of adsorption capacity was achieved in the first 15 min. Our study strongly confirmed that co-HTC of DSS and SB, can be used as a green and environmental safety approach for sludge management and clean water supplement followed by lead removal with acceptable reusability of adsorbent.

Keywords

• Sludge handling
• Co-hydrothermal carbonization
• Waste management
• Pb adsorption
• Hydrochar