Removal of Reactive Orange 16 Dye using Casuarina equisetifolia seeds as Packing Media for Microbial Biofilm Formation

Abstract

Dyes effluent mostly is toxic and mutagenic to living organism. Casuarina equisetifolia seeds are usually found in coastal and have potential as a packing media for microbial biofilm formation. The present study was designed to evaluated the performance of three laboratory scale reactors namely, sequencing batch biofilm reactor (CES-SBBR), a combination of adsorption and biological process, sequencing batch biofilm reactor (FC-SBR), and packed bed reactor (CES-PBR) on the removal of RO16 dye. The CES-SBBR and CES- PBR were packed with Casuarina equisetifolia seeds. The microorganism was collected from textile industry and undergo the preadaptation period with the 2 mg/L of RO16 solutions in CES- SBBR and FC-SBR. The biomass concentration initially reduced from 0.12 to 0.03 mg/L. Upon the addition of nutrients, the biomass concentration was increased to 0.22 mg/L. The performance study of three reactors was performed with the initial concentration of RO16 solution and hydraulic retention time (HRT) of 2 mg/L and 24 hr, respectively. The RO16 dye removal efficiencies were in range of 80.00-82.26%. The removal efficiencies were reduced to 70.00-71.28% when the initial concentration of RO16 dye increased to 4 mg/L. The removal efficiencies were continued to reduce with only 48.06-50.00% as the initial concentration of RO16 dye increased to 6 mg/L. The removal efficiencies were improved when the HRT was extended to 48 hr. The biomass concentration of CES-SBBR and FC-SBR increased up to 0.50 and 0.33 mg/L, respectively. The RO16 removal percentage for FC-SBR and CES-PBR were found to be lower compared to as for CES-SBBR. This study shows that the combination of adsorption and biological process enhanced the removal efficiency of RO16 dye.