Phenol removal from four different natural soil types by Bacillus sp PS11

Abstract

Biodegradation of phenol in four natural soils (loamy sand, sandy loam, sandy clay loam and loam) by indigenous microorganisms and in soils augmented by the Bacillus sp. PS11 was studied. During the laboratory soil microcosm experiments, the total removal of 2 g of phenol per kg of soil was achieved in all soil types in between 6 and 21 days. All biodegradation data was found to fit very well to saturation kinetics. The most efficient phenol removal was observed in the loamy woodland soil that contained the least amount of sand (42.5%) and the most silt and clay fraction (57.5%) in comparison to other three soil samples. However, amending sandy loam sample to contain more clay (from 13.5% to 30%) negatively affected the phenol removal rate, while increasing sand content (from 74.4% to 90%) resulted in the two times faster phenol removal in comparison to natural soil type. Bacillus sp. PS11 performed well in both pure culture and in the presence of soil microorganisms. Indigenous bacteria from sandy clay loam soil type possessed the ability of phenol bioremediation and almost whole amount of added phenol (2 g kg soil(-1)) was degraded within 9 days, whereas augmentation by Bacillus sp. PS11 improved the phenol removal by 20%. Carrying out small scale soil model experiments and amending soil granulometric properties by addition of clay or sand minerals is suggested as an effective and economically interesting way of enhancing bacterial soil bioremediation.