Cell immobilization of Trichosporon cutaneum strain with phenol degradation ability on new modified polymer carriers

Removal of phenol in phenolic resin wastewater by a novel biomaterial: the Phanerochaete chrysosporium pellet containing chlamydospore-like cells

A novel biomaterial, the Phanerochaete chrysosporium pellet (CP) composed of chlamydospore-like cells (CLCs), was prepared and its potential in treating phenolic resin wastewater was evaluated. CP possesses higher phenol removal ability in contrast with mycelial pellets of P. chrysosporium, and CLC can be seen as the naturally immobilized enzymes. At shake-flask level, the ideal pH value, temperature, and inoculation quantity of CP for treatment of 1430 mg/l phenol wastewater were pH 4-6, 30 °C, and 5.0 g/l, respectively, and the maximum specific removal rate, 41.1 mg phenol/g CP/h, was obtained in fixed bed reactor (FBR) when the flow rate of wastewater was 3.4 l/h. During the treatment, FBR harbored amounts of bacteria (135 genera) and eukaryotes, as analyzed by metagenomic sequencing. Bacterial pollution not only decreased reactor performance but also had a negative impact on reusability of CP. Hot water treatment (80-85 °C) is effective to inhibit bacterial pollution, and heat resistance of CLC makes the repeated regrowing of CP be feasible. This work presents an innovative and low-cost biomaterial for phenol removal and will be helpful for the practical application of P. chrysosporium in wastewater treatment.

Biodegradation of phenol by immobilized Aspergillus awamori NRRL 3112 on modified polyacrylonitrile membrane

Covalent immobilization of Aspergillus awamori NRRL 3112 was conducted onto modified polyacrylonitrile membrane with glutaraldehyde as a coupling agent. The polymer carrier was preliminarily modified in an aqueous solution of NaOH and 1,2-diaminoethane. The content of amino groups was determined to be 0.58 mgeq g(-1). Two ways of immobilization were used-in the presence of 0.2 g l(-1) phenol and without phenol. The capability of two immobilized system to degrade phenol (concentration-0.5 g l(-1)) as a sole carbon and energy source was investigated in batch experiments. Seven cycles of phenol biodegradation were conducted. Better results were obtained with the immobilized system prepared in the presence of phenol, regarding degradation time and phenol biodegradation rate. Scanning electron micrographs of the polyacrylonitrile membrane/immobilized Aspergillus awamori NRRL at the beginning of repeated batch cultivation and after the 7th cycle were compared. After the 7th cycle of cultivation the observations showed large groups of cells. The results from the batch experiments with immobilized system were compared to the results produced by the free strain. Phenol biodegradation experiments were carried out also in a bioreactor with spirally wound membrane with bound Aspergillus awamori NRRL 3112 in a regime of recirculation. 10 cycles of 0.5 g l(-1) phenol biodegradation were run consecutively to determine the degradation time and rate for each cycle. The design of the bioreactor appeared to be quite effective, providing large membrane surface to bind the strain.

Isolation and selection of phenol-degrading microorganisms from industrial wastewaters and kinetics of the biodegradation

Among 22 species of microorganisms isolated from phenol-containing wastewaters, Candida parapsilopsis was found to be capable of growth on a medium with 1 g/L phenol. Kinetic parameters of phenol biodegradation in a batch reactor were determined by measuring biomass growth rates and phenol concentration as a function of fermentation time. The Haldane equation described cell growth adequately, with kinetic constants mumax = 0.174/h, KS = 11.2 mg/L and Ki = 298 mg/L.