The Effect of Avocado Seed Charcoal and Bamboo Charcoal Filtration Model on Chromium Reduction in Tannery Wastewater [Accepted]

Abstract

Background: Industrial tanning wastewater contains high concentrations of total chromium (Cr) due to the use of chromium sulphate in the tanning process. This study aims to evaluate the effect of filtration using avocado seed charcoal, bamboo charcoal, and a combination of both in a multi-stage filtration device model on the reduction of total chromium in leather tanning wastewater. Methods: The study used a quasi-experimental method with a pretest–posttest group design, involving 60 samples (30 pretest, 30 posttest). The wastewater flowed through three filtration units (Tank I = avocado seed charcoal; Tank II = bamboo charcoal; Tank III = combination of avocado seed charcoal + bamboo) with a flow rate of 800 ml/minute, a media height of 9 cm, and a contact time of 1 hour. Data analysis included Kolmogorov–Smirnov normality test and One-Way ANOVA test (α=0.05) followed by LSD test. Results: The results showed that the highest Cr reduction occurred in Tank III with an average reduction of 22.72 ppm, compared to Tank I (19.14 ppm) and Tank II (14.46 ppm). The ANOVA test showed a significant difference between treatments (p = 0.034). The LSD test confirmed a significant difference between Tank II and Tank III (p = 0.010), with the best effectiveness in combination filtration (Tank III). The filtration model combining avocado seed charcoal and bamboo charcoal has the potential to be an efficient and environmentally friendly adsorption technology for reducing chromium in leather tanning wastewater.