Degradation of 2-naphthol orange in anaerobic treatment and its degradation mechanism

Abstract

The discharge of Palm Oil Mill Effluent (POME) has increased drastically due to the increasing demand. The wastewater treatment can no longer be handled properly. Hence, the ability to reuse solid biomass will greatly help to reduce pollutants being discharged to the watercourse. In this study, bacteria culture isolated from Palm Oil Mill Effluent (POME) was used as anaerobic degradation to biodegrade coloured wastewater. The isolated bacteria identified were Bacillus subtilis, Enterobacter cloacae, and Paenibacillus pabuli using 16S rDNA sequencing. The synthetic dye wastewater used in this research study was 2-Naphthol Orange. Under optimized culture condition, Chemical Oxygen Demand (COD) and colour of the synthetic 2-Naphthol Orange wastewater removed were 50.58 and 97.00 %, respectively, with the initial 2-Naphthol Orange concentration of 200 mg/L. This was because the bacteria degraded 2-Naphthol Orange into two intermediate products which are naphthalene and benzene at the absorbance peaks of 290 and 237 nm, respectively, in UV- Visible spectra. The decline of absorbance peaks for naphthalene and benzene showed that the intermediate products were further degraded to simple hydrocarbon chains which were used by bacteria as their additional substances. In conclusion, the isolated bacteria from Palm Oil Mill Effluent was able to perform colour biodegradation to simple hydrocarbon chains as their nutrients sources. This research has potential to help reduce the pollutants of Palm Oil and dye being discharged to the watercourse without proper treatment.