Utilizing orange peel waste biomass in textile wastewater treatment and its recyclability for dual biogas and biochar production: a techno-economic sustainable approach

Abstract

Abstract Orange peel is a fruit-based biomass produced in huge quantities worldwide, requiring an appropriate management strategy to meet the waste-to-wealth approach. In the current study, this agricultural waste was used (as an adsorbent) to treat dye-laden wastewater, followed by its regeneration and recyclability for dual biogas and biochar production. An adsorbent material was prepared by mixing orange peel powder (OPP) with biochar (1:1, w/w) and used to remove various pollutants from textile wastewater (TWW) within 30 min. This adsorption system achieved chemical oxygen demand (COD), total dissolved solids (TDS), turbidity, and color removal efficiencies of 38.56±1.73%, 29.31±1.25%, 91.92±4.75%, and 74.81±3.96%, respectively. The spent adsorbent was cleaned and mixed with cow dung (as inoculum) to generate biogas via anaerobic co-digestion. This system maintained a bio-CH4 of 411.5±21.7 mL/g volatile solids (VS), equivalent to 14.3±1.1% of CODinitial. Because the digestate of the co-digestion process contained volatile suspended solids (VSS), with a VSS/CODinitial percentage of 45.2±3.2%, it was efficiently pyrolyzed to obtain biochar. The adsorption/co-digestion/pyrolysis combined system revealed a financially feasible scenario, with a payback period of 7.5 years. The study outputs would fulfill various sustainable development goals (SDGs) related to waste minimization, environmental protection, and affordable energy supply. Graphical abstract