Green flocculation for sustainable remediation of municipal landfill leachate using Parkia biglobosa extract: optimization, mechanistic insights and implication for design

The escalating challenges posed by municipal landfill leachate (MUNL) necessitate the quest for green and sustainable solutions. This study aims to introduce Parkia biglobosa seed extract (PKSE) as a potential novel eco-friendly flocculant for efficacious removal of total suspended solids (TSS) from MUNL. Real MUNL samples were obtained from an active landfill managed by Anambra State Waste Management Authority (ASWAMA) Nigeria, enabling the optimization of operational parameters. The objectives encompass assessing PKSE applicability in MUNL treatment, extending beyond removal efficiency; optimizing the MUNL remediation process using response surface methodology (RSM); conducting a comprehensive cost–benefit analysis; exploring the coagulation–flocculation kinetics governing the treatment process; and utilizing optimized parameters for designing a type II settling tank. Physiochemical characteristics of PKSE were determined via Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methodologies, which revealed its suitability for this purpose. Optimal conditions unveil a remarkable TSS: 95.84% with a 29-min settling time, employing 50 mg/L PKSE dosage at pH 12. Stochastic appraisal endorses cost–benefit viability and sedimentation models, ensuring residuals ≤ 30 mg/L. The proposed tank geometry (aspect ratio of 2/1) aligns with MUNL concentration, offering a pragmatic design implication. This study pioneers green flocculation, harmonizing environmental remediation.