The removal of concentrated colour (around 5039 Pt–Co) and chemical oxygen demand (COD; around 4142 mg L⁻¹) from matured landfill leachate through a novel combination of humic acid extraction and coagulation with natural oil palm trunk starch (OPTS) was investigated in this study. Central composite design from response surface methodology of Design Expert-10 software executed the experimental design to correlate experimental factors with desired responses. Analysis of variance developed the quadratic model for four factors (e.g. coagulant dosage, slow mixing speed and time and centrifugation duration) and two responses (% removal of colour, COD). The model confirmed the highest colour (84.96%) and COD (48.84%) removal with a desirability function of 0.836 at the optimum condition of 1.68 g L⁻¹ coagulant dose, 19.11 rpm slow mixing speed, 16.43 minutes for mixing time and 35.75 minutes for centrifugation duration. Better results of correlation coefficient (R² = 0.98 and 0.96) and predicted R² (0.94 and 0.84) indicates the model significance. Electron microscopic images display the amalgamation of flocs through bridging. Fourier transforms infrared spectra confirmed the existence of selected organic groups in OPTS, which eventually signifies the applied method.

通过腐植酸提取和凝结与天然油棕树干淀粉 (OPTS) 的新组合，从成熟的垃圾渗滤液中去除浓缩色素（约 5039 Pt-Co）和化学需氧量（COD；约 4142 mg L ^-1）是在这项研究中进行了调查。来自 Design Expert-10 软件响应面方法的中心复合设计执行实验设计以将实验因素与所需响应相关联。方差分析为四个因素（例如凝结剂剂量、缓慢的混合速度和时间以及离心持续时间）和两个响应（颜色去除百分比，COD）开发了二次模型。该模型证实，在 1.68 g L ^-1的最佳条件下，颜色 (84.96%) 和 COD (48.84%) 去除率最高，合意性函数为 0.836混凝剂剂量，19.11 rpm 慢速混合，混合时间为 16.43 分钟，离心时间为 35.75 分钟。相关系数( R ²  = 0.98 和0.96) 和预测R ² (0.94 和0.84) 的较好结果表明模型显着性。电子显微图像显示絮凝物通过桥联融合。傅里叶变换红外光谱证实了 OPTS 中选定的有机基团的存在，这最终表明了所应用的方法。