Optimization of the humic acid separation and coagulation with natural starch by RSM for the removal of COD and colour from stabilized leachate

Abstract

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.

Humic acid recovery from stabilized leachate: Characterization and interference with chemical oxygen demand–colour removal

“…2019 to December 2020, confirming that there was no rain within 3 days before sampling. PBLS accumulates an average of 2000 tonnes of solid waste per day (Ahmed et al, 2021), while APLS currently receives around 200 metric tonnes of solid waste per day (Zakaria and Aziz, 2018). Air tight polyethene containers (20 L) with higher density and enfolded covers were utilized for collecting and preserving the leachate samples in a cold room (at 4°C) (Reis et al, 2017).…”

Study on the Flocculation Performance of a Cationic Starch‐Based Flocculant on Humic Substances in Textile Dyeing Wastewater

“…The existence of humic substances will bring a series of problems in textile dyeing wastewater treatment. For example, increasing the chroma of water, [ 40 ] causing the blockage and reducing the utilization of membrane, [ 41,42 ] reducing the adsorption capacity of activated carbon, [ 43 ] leading to the breeding and reproduction of microorganisms in the drainage network, [ 44 ] reducing the pipeline life, and generating toxic by‐products by combining with chlorine in the disinfection process. [ 45 ] We chose humic acid (HA) solution to simulate the main dissolved organic matters in textile dyeing wastewater.…”