Enhanced methylene blue decolourization by Rhodococcus strain UCC 0003 grown in banana peel agricultural waste through response surface methodology

Disposal of agricultural waste which is produced in abundance in Malaysia remains as the primary environmental concern. Interestingly, agricultural waste could be used as source of energy. Therefore, the present study successfully employed banana peel as supporting substrate for the growth of Rhodococcus strain UCC 0003 in the decolourization of methylene blue. Enhanced decolourization of methylene blue was obtained through optimization of interactive effects of three significant factors namely temperature, pH and concentration of banana peel using central composite design of response surface methodology (RSM). The 3.4-fold increase in the decolourization of 2 g/L methylene blue depicts the high significance of the model for the removal of the colourant. Besides, appreciable decolorization activity could be observed at highly alkaline pH (11.2) which is favourable since most textile wastewater is alkaline is nature. The optimized factors for optimum decolourization using polyurethane foam resulted in improved stability and reusability up to 12 cycles without significant loss of activity. Therefore, these findings can assist the designing of an efficient system for the removal of wastewater containing methylene blue through a greener and cost-effective method. •Response surface methodology enhanced decolourization of 2 g/L methylene blue.•The use of banana peel as growth substrate provides smart conversion of waste to wealth.•Decolourization under highly alkaline pH is advantageous since most textile wastewater is alkaline in nature.•Immobilized cells in polyurethane foam could be reused up to 12 cycles without loss in activity.