Biofilm coupled with UV irradiation for phenol degradation and change of its community structure

Abstract

The extensive use of phenol compounds and the inability to remove these compounds during wastewater treatment have resulted in the widespread occurrence of phenols in the natural environment. Phenols have been linked to serious risks to human and environmental health. Hence, the need to develop technologies that can effectively remove phenols from wastewater and source waters is a pressing challenge. In this study, light ceramic particles were immersed in activated sludge acclimated to degrade phenol, and microorganisms were allowed to attach to the particles surface to form biofilm. Then the ceramic particles with biofilm were moved into the photolytic circulating-bed biofilm reactor made of quartz glass, which was used for the degradation of phenol by three protocols: photolysis with UV light alone (P), biodegradation alone (B), and the two mechanisms operating simultaneously (photobiodegradation, P&B). The experimental results indicated that phenol removal rate was quickest by B experiment. However, P&B experiment gave more complete mineralization of phenol than that by other protocols. During P&B experiment, the microorganisms grown on porous ceramic carrier still kept the bioactivity degrading phenol, even under UV light irradiation. However, the dominant members of the bacterial community changed dramatically after the intimately coupled photobiodegradation, according to molecular biological analysis to the biofilm. Whereas Beijerinckia sp. was the dominant strain in the inoculum, it was replaced by Thauera sp. MZ1T that played a main role on degrading phenol during P&B experiment.

Environmental Behaviors of Procymidone in Different Types of Chinese Soil

“…Three degradation products of procymidone including C 13 According to the analysis of the fragment ions in the tandem mass spectrum, we inferred that M1 was the single dechlorination degradation product of procymidone (Figure 3B1,B2), M2 was the oxidation degradation product of procymidone (Figure 3C1,C2), and M3 was the hydrolysis degradation product of procymidone (Figure 3D1,D2). The degradation pathway of procymidone in the soil is shown in Figure 4.…”

“…The photolysis experiments were performed with an ultraviolet lamp. Four grams of soil were evenly paved in a quartz glass dish with a diameter of 9 cm [13,14]. The n-hexane dissolved procymidone was evenly dripped onto the soil surface, reaching a concentration of 5 mg/kg.…”