Green SDG-Based Remediation of Sugarcane Vinasse via HA–nCaO: Integrating Computational Sustainability Evaluation with Innovative COD Removal, Organic Load, and pH Control

The indiscriminate disposal of sugarcane vinasse, a deadly acid-soaked waste, has already begun to poison the planet. This monstrous byproduct is not just contaminating water and soil; it’s pushing ecosystems to the brink of collapse while its treatment remains a significant environmental challenge. In this study for the first time, a novel composite adsorbent was developed by integrating green-synthesized nano-calcium oxide (nCaO) with humic acid (HA), aiming to enhance the physicochemical remediation of vinasse. The HA–nCaO composite was synthesized via a simple aqueous co-precipitation method, followed by ultrasonic-assisted stabilization. Comprehensive characterization by XRD, FTIR, SEM, and BET confirmed the formation of a mesoporous hybrid material with high surface area (112.6 m²/g), strong basicity, and functionalized surface chemistry. Batch experiments were conducted to evaluate the composite’s performance under varying conditions (dosage, contact time, temperature, and initial pH). The results demonstrated that at an optimal dosage of 5 g/L, the HA–nCaO composite achieved a COD removal of 82.4%, total organic carbon (TOC) reduction of 76.1%, and color removal efficiency of 89.5% within 90 minutes of treatment. Additionally, the acidic pH was effectively neutralized to a pH of 7.6 ± 0.2 without the need for external alkali agents. The integration of chalcogel facilitated partial precipitation of suspended solids and volatile fatty acids, reducing the organic load, with kinetic modeling revealing that COD removal followed a pseudo-second-order model (R² = 0.991), indicating a chemisorption-dominant mechanism. Furthermore, reusability tests showed that the composite retained over 68% of its efficiency after four regeneration cycles. Utilizing newly launched sustainability evaluation software metrics using Need Quality Sustainability (NQS) index with Koel’s Pyramid software computational metrics, this study achieves superior results in alignment with the UN Sustainable Development Goals (SDGs).