Column adsorption of chemical oxygen demand (COD) in sugar wastewater using filter cake

Abstract

The objective of this research was to determine the filter cake which is a waste from sugar production use as an adsorbent material via adsorption process to reduce the organic matter in wastewater from the sugar process in the same sugar factory. The adsorption equilibrium of organic matter in form of COD by modified filter cake was studied. Adsorbent from filter cake was prepared by sieving size between 0.5-2 mm and then carbonized at 550°C for 3 hours. Firstly, batch adsorption was conducted under room temperature using 1 g of adsorbent with 50 ml wastewater and shook at mixing speed of 150 rpm. The result found that it can reduce COD for 82.5 mg per 1 g of adsorbent or 25 percent efficiency. Secondly, COD adsorption in 2.54 cm diameter packed bed column with 20 cm high of adsorbent (or 14.75 g weight of adsorbent) at wastewater flow rates of 0.5, 1, and 2 mL/min was tested. The result showed that higher flow rates resulted in lower breakthrough times. According to the principle of Thomas model, it was found that the optimum flow rate is 1 mL/min, which reduced COD in wastewater for 35.2 mg per 1 g of adsorbent. This flow rate presented lowest Thomas’s constant (Kth), highest coefficient of determination (R-square) and bottommost the sum of square error (SSE) which were 1.53 x 10⁻⁶ L/mg.min, 0.9008 and 0.0237, respectively. With respect to Yoon and Nelson model, it was found that the fitted flow rate was 1 mL/min with highest Yoon and Nelson’s constant, maximum R-square and lowest SSE were 0.01 min¹, 0.9268 and 0.0172, respectively. Based on the R-square of both models, Yoon and Nelson model was more appropriate than Thomas model to explain the reduction rate of this adsorption is proportion of the number of adsorbents and breakthrough of the adsorbent.