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Surfaces of cationically modified zwitterionic phosphorylcholine (PC) copolymer prepared by spin coating were characterized by spectroscopic ellipsometry (SE), atomic force microscopy, and water contact angle. The obtained PC films bearing cationic charge densities were used to investigate the effect of electrostatic interactions on the adhesion behavior of marine fouling diatom Nitzschia closterium MMDL533. Results show that the settlement of N. closterium MMDL533 cells increases with the positive choline fragment contents in the copolymers. Upon exposure to 8.5-Pa wall shear stress for 2 minutes, the percentage removals of the settled cells on choline containing films were significantly lower than those on the neutral PC1036 films, indicating that the electrostatic attraction between N. closterium MMDL533 cells and the cationic modified PC films could promote the diatom settlement and improve diatom adhesion strength. There were more aggregates adhered on the PC films as compared with the hydroxylated glass slides, which might result from their higher surface hydrophobicity and more heterogeneous surfaces. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Nitrophenols are often found in industrial wastewaters for a wide range of processes; they are highly toxic and potentially carcinogenic. Anaerobic biodegradation of nitrophenols has advantages of relatively low cost, less sludge produced, and high efficiency, when compared with aerobic biodegradation and physical/chemical treatments, although available published results are often contradictory. This paper reports on 2,4-dinitrophenol biodegradation in an anaerobic bioreactor operated in a continuous mode in order to determine optimal operating conditions, and the effects of the main operating parameters such as hydraulic retention time and chemical oxygen demand (COD) loading on the process efficiency. In this study, an 80-day gradual enrichment of an anaerobic culture has been carried out at 25 °C in an anaerobic bioreactor for continuously treating a synthetic wastewater containing 210 mg/l 2,4-dinitrophenol and 100 mg/l nitrate. The results showed that the enriched culture could utilize 2,4-dinitrophenol as a sole electron donor and nitrate as an electron acceptor at the end of the enrichment (on Day 80). Almost all nitrate and 95.5% 2,4-dinitrophenol could be simultaneously removed at a hydraulic retention time of 12 h in the anaerobic bioreactor. The removal of 1 g of the added nitrate required about 4.60 g COD (as provided by the 2,4-dinitrophenol) as the electron donor, and the removal of 2,4-dinitrophenol by this enriched culture was strongly dependent on the presence of nitrate. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

The effect of high-pressure homogenization (HPH) on the primary extraction of intracellular L-asparaginase from Escherichia coli by aqueous two-phase extraction (ATPE) has been investigated. When HPH was operated under a pressure of 120 MPa for four passages, 17.8% of L-asparaginase activity was lost. The addition of EOPO (a triblock copolymer of a central hydrophobic poly(propylene oxide) (PPO) block with hydrophilic poly(ethylene oxide) (PEO) blocks on each side) could improve the endurance of L-asparaginase to high pressure; while the existence of KHP (a mixture of KH2PO4 and K2HPO4) could strongly facilitate such deactivation. When HPH was operated in the ATPE system formed from EOPO and KHP, the recovery of L-asparaginase was greatly enhanced, as compared to the conventional HPH process. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.