Bio-remediation of palm oil mill effluent (POME) using Aspergillus niger immobilized on coconut husk and free cell fermentation

Abstract

Aspergillus niger which is ubiquitous and acts as good biological agent has been chosen to treat POME in this study. Use of, free cell fermentation limits the uptake of substrate as compared to immobilization method which provides larger surface area for cell growth. Therefore, the idea of using coconut husk as immobilization medium has been proposed. Coconut is widely available in Malaysia almost at no cost. Hence, the purpose of this study is to evaluate the bio-degradation of palm oil mill effluent by Aspergillus niger through immobilization on coconut husk and free cell fermentation. Substrates from different types of POME such as. raw, sterile, treated using Aspergillus niger through free cell fermentation and treated with Aspergillus niger cells which are immobilized on coconut husk were prepared at different concentration range from 0 to 100%. Aspergillus niger cells (1 X 105 cells per ml were inoculated into Erlenmeyer flasks and incubated at 30 ± 2 °C and 150 rpm for seven days. Fermentation slurry were used to analyse for turbidity, COD and pH. The results were compared with free cell fermentation method. Raw POME has significantly low turbidity as compared to sterile and treated POME. Autoclaving POME increases the turbidity. 100% sterile POME shows the highest turbidity which is 979.5 FAU and 100% POME which was treated by immobilization on coconut husk shows a reduction in turbidity which gives 900.5 FAU. The presence of coconut husk has significantly increased the COD value as 0% POME (distilled water) with coconut husk shows 3320 mg/l of COD. However, at the end of seven days of treatment, 100% POME which was treated through immobilization shows lower COD as compared to free cell fermentation. pH reading is a concern as treatment method might influence the pH of POME. Range of pH for POME throughout the experiment was between 7.1 and 9.6. Degradation of POME using Aspergillus niger immobilized on coconut husk provides additional incentive that is cheap and sustainable.