Optimising the bioremediation of free cyanide containing wastewater by Fusarium oxysporum grown on beetroot waste using response surface methodology

Abstract

This work reports the use of a cyanide resistant fungus Fusarium oxysporum for the bioremediation of wastewater containing free cyanide, its preference for beetroot agro-waste as the primary carbon source, and the optimization of the free cyanide (CN-) bioremediation conditions using statistical modelling of response surface methodology (RSM). Higher growth rate of F. oxysporum was observed on beetroot waste (OD = 3.430) compared to glucose (OD = 1.953). The cultures highest free cyanide biodegraded was 180.9 mg CN-/L from an initial 300 mg CN-/L after 72 h at 25°C, pH of 12.70, and substrate concentration of 300 mg/L. The ANOVA of the quadratic model indicated the model obtained is highly significant (R2 = 0.9240). The response from the central composite design (CCD) indicated that temperature and substrate concentration are significant factors affecting the CN- biodegradation. The fungus growth on cheap agro-waste would ensure economic sustainability of free cyanide biodegradation system in environmental engineering applications. This study provides a platform for further research on the thermodynamics of CN- biodegradation.