Effect of process conditions on the aerobic biodegradation of phenol and paracetamol by open mixed microbial cultures

Abstract

In the context of xenobiotics' removal in biological wastewater treatment processes, this study investigated the biodegradation of phenol and paracetamol as sole carbon sources by open mixed cultures. Biodegradation of these chemicals was investigated in batch and SBR (Sequencing Batch Reactor) lab-scale experiments. In batch experiments, phenol was biodegraded by unacclimated microorganisms at concentrations 0.2-0.5 g/l. The acclimation time increased with increasing phenol concentration and no biodegradation was observed with an initial concentration of 1 g/l. However, 1 g/l of phenol was biodegraded after previous exposure of the microorganisms to lower concentrations of phenol or to yeast extract and peptone. Batch degradation of paracetamol (0.5 g/l) only occurred after previous exposure of the microorganisms to yeast extract and peptone. SBR experiments were run with 1.0 g/L feed concentration of phenol or paracetamol in a range of SRT (solids residence time, 1-45 d for phenol and 1-145 d for paracetamol). Both substrates were removed as sole carbon sources and COD removal generally increased as the SRT increased, and was higher than 90 % for phenol and 80 % for paracetamol. A higher fraction of the removed substrate was assimilated into microorganisms for paracetamol than for phenol with growth yields 0.51 and 0.20 g/g COD, respectively. This study shows how process conditions (acclimation, substrate concentration, medium composition, SRT) affect the removal of phenol and paracetamol and gives guidance on their selection for the optimum biodegradation performance.

Phenol Degradation Kinetics by Free and Immobilized Pseudomonas putida BCRC 14365 in Batch and Continuous-Flow Bioreactors

“…The theoretical concentration profile of phenol in bulk liquid phase, liquid film phase and gel bead phase was assumed ( Figure 1). In order to model phenol biodegradation kinetics by immobilized cells, the following assumptions are made: (1) all beads are spherical in shape; (2) the mass transfer phenomenon of phenol from liquid film phase to gel bead phase is dominated by Fick's law; (3) phenol is migrated from bulk liquid phase to the gel bead phase through the liquid film by molecular diffusion; (4) the cells are distributed uniformly in the gel bead; (5) all phenol concentrations in the bulk liquid are the same; and (6) the effects of suspended cells in the bulk liquid phase are insignificant.…”

“…Since phenol can be degraded by P. putida cells as a sole carbon source, and presents cell growth inhibition, the phenol utilization rate (r s ) in the spherical granule [Equation (1)] was expressed by the Haldane equation as follows [25]:…”

“…Phenols, such as xenobiotic contaminants, emerge from various anthropogenic activities due to industrialization, and are often found in different environmental conditions [1,2], such as surface waters, wastewater, groundwater and sludge products [3][4][5]. Phenol, as a major component present in the effluents from several industries (oil refineries, coking plants, steel industries, etc.…”

In silico environmental risk assessment of fate and effects of pharmaceuticals and their TPs generated and treated by coupling tertiary processes in hospital wastewater

“…As a consequence, it is commonly found in surface waters and wastewaters. 38,39 PCT is easily degraded under aerobic conditions 40 and readily eliminated in WWTPs, with high removal percentages. [41][42][43][44] The in silico biodegradability predictions showed that PCT and its TPs were biodegradable compounds.…”

Experimental investigation and mathematical modelling of batch and semi-continuous anaerobic digestion of cellulose at high concentrations and long residence times

“…The inoculum was stored in fridge (2 °C) in order to minimise its degradation and was maintained at room temperature for 24 h before use. In Runs B and C soil from Craibstone Farm (Aberdeen, Scotland), characterised in other studies [25,26] and used in previous studies in our group [27,28], was used as inoculum. The VS and VSS content of the Craibstone soil was 0.13 gVS g −1 and 0.12 gVSS g −1 .…”