Aims: To immobilize Methylobacterium sp. NP3 and Acinetobacter sp. PK1 to silica and determine the ability of the immobilized bacteria to degrade high concentrations of phenol.
Methods and Results: The phenol degradation activity of suspended and immobilized Methylobacterium sp. NP3 and Acinetobacter sp. PK1 bacteria was investigated in batch experiments with various concentrations of phenol. The bacterial cells were immobilized by attachment to or encapsulation in silica. The encapsulated bacteria had the highest phenol degradation rate, especially at initial phenol concentrations between 7500 and 10 000 mg l−1. Additionally, the immobilized cells could continuously degrade phenol for up to 55 days.
Conclusions: The encapsulation of a mixed culture of Methylobacterium sp. NP3 and Acinetobacter sp. PK1 is an effective and easy technique that can be used to improve bacterial stability and phenol degradation.
Significance and Impact of the Study: Wastewater from various industries contains high concentrations of phenol, which can cause wastewater treatment failure. Silica‐immobilized bacteria could be applied in bioreactors to initially remove the phenol, thereby preventing phenol shock loads to the wastewater treatment system.
Palm oil mill effluent (POME) is usually treated using biological systems. However, phenolic compounds remain in the treated POME. This study aimed to remove phenolic compounds from POME using silica‐immobilized Methylobacterium sp. NP3 and Acinetobacter sp. PK1. Treated POME samples were collected from the final stabilization ponds of two palm oil mills in Thailand. In batch experiments, the silica‐immobilized bacteria effectively degraded 100–500 mg/L phenolic compounds (e.g., caffeic acid, ferulic acid, 4‐hydroxybenzoic acid, catechol, and 3‐methylcatechol) in synthetic wastewater and completely removed up to 1000 mg/L amended phenol from both treated POME samples. When 25 g/L silica‐immobilized bacteria were used in an internal loop airlift bioreactor with a hydraulic retention time of 5 h, 83 and 60% of the initial 26.7 and 112 mg/L phenolic compounds in the treated POME samples were removed. The bioreactor was operated continuously for 1200 h, and scanning electron microscopy revealed that the bacteria remained trapped inside the silica matrix. This bioreactor could be used for post‐treatment of POME.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.