A FULL LIFECYCLE ANALYSIS OF WASTE-DERIVED BIOCHAR VERSUS ACTIVATED CARBON FOR TEXTILE WASTEWATER TREATMENT AND POST-USE ENERGY VALORIZATION

Abstract

The traditional choice of adsorbents to treat textile wastewater focuses on the adsorption capacity rather than the sustainability in the whole picture. The proposed study fills this gap with data on the first cradle-to-cradle lifecycle assessment, which involves post-use energy valorization to compare waste-derived biochar (BC) and chemically activated carbon (AC). Sugarcane bagasse and corrugated cardboard were used to make biochar and KOH-activated carbon, which were characterized and tested in the removal of methylene blue. The production, use and energy recovery through burning spent adsorbents was modeled by a Net Energy Balance (NEB). Though AC had 2.5-3.5 times greater adsorption capacity (to 386.5mg/g), it had an energy-demanding activation step that dominated the lifecycle. Most importantly, biochar pathways had a near-neutral or positive NEB ( +0.1 to +1.0 MJ /m 3 ), whereas AC routes had a major net energy loss ( -9.0 MJ /m 3 ). It shows that in a circular economy model where one can realize energy recovery, waste biochar is a more sustainable adsorbent compared to high-performance AC, even though the former has lower adsorption efficiency. The results offer paradigm shift in terms of system level sustainability metrics when choosing technology.