Enhancement of biofilm formation onto surface-modified hollow-fiber membranes and its application to a membrane-aerated biofilm reactor

Abstract

Surface-modified hollow-fiber membranes were prepared by radiation-induced grafting of an epoxy-group-containing monomer, glycidylmethacrylate (GMA), onto a polyethylene-based fiber (PE-fiber). The epoxy ring of GMA was opened by introduction of diethylamine (DEA). The bacterial adhesivity to this material (DEA-fiber) was tested by immersion into a nitrifying bacterial suspension. The initial adhesion rates and the amount of attached bacteria of the DEA-fiber were 6-10-fold and 3-fold greater than those of the PE fiber, respectively. A membrane-aerated biofilm reactor (MABR) composed of DEA fibers was developed for partial nitrification with nitrite accumulation. Prior to the nitrification test, it was confirmed that the oxygen supply rate (OSR) was proportional to air pressure up to 100 kPa, allowing easy control of oxygen supply. Stable nitrite accumulation was observed in the partial nitrification test at a fixed oxygen supply throughout the operation period, indicating that oxygen was consumed only by ammonia oxidizers. Furthermore, it was demonstrated that oxygen utilization efficiency (OUE) in the ammonia oxidation process was nearly 100% after 300 h incubation.

Redox‐stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: The effect of co‐ versus counter‐diffusion on reactor performance

“…Our simulation results disagree with experimental and theoretical observations on the coexistence of AeAOB and AeNOB in the aerobic region of membrane-aerated biofilms, although in these studies oxygen control was not limited to prevent nitritation (Bell et al, 2005;Schramm et al, 2000). On the contrary, Terada et al (2004) À3 per day) in the outer parts of the biofilm (500-750 mm), which displays a linear ammonium concentration profile (Fig. 2E and F).…”

“…Initial conditions for all simulations assumed a biofilm thickness of 20 mm; fractional composition of the biofilm solid phase of AeAOB (0.72), AeNOB (0.20), and AnAOB (0.08); concentration of all soluble components at zero in the biofilm and bulk liquid. The biofilm was discretized in 20 (Casey et al, 1999b;Terada et al, 2004;Wannner et al, 1994).…”

Bacterial adhesion to and viability on positively charged polymer surfaces

“…Many surface modification techniques, such as surface abrasion (Morgan & Wilson, 2001), chemical coating (Harris & Richards, 2004) and chemical grafting (Gottenbos et al, 1999(Gottenbos et al, , 2000(Gottenbos et al, , 2001Hibiya et al, 2000;Lee et al, 1996Lee et al, , 1997Lee et al, , 1998Park et al, 1998;Pasmore et al, 2001;Roosjen et al, 2003Roosjen et al, , 2004Terada et al, 2004Terada et al, , 2005Wang et al, 2000), have been used to investigate the possibility of inhibiting or promoting bacterial adhesion and biofilm formation. Radiation-induced grafting technology can generate highly reactive radicals and subsequently initiate the polymerization and extension of long graft chains on common polymer materials such as polyethylene (PE).…”

Sequencing batch membrane biofilm reactor for simultaneous nitrogen and phosphorus removal: Novel application of membrane‐aerated biofilm

“…Oxygen, supplied to the inner side of the gas-permeable membrane, penetrates through the membrane and into the biofilm formed on the outer surface without bubble formation. If nitrifying bacteria are immobilized onto the membrane surface, they can be supplied directly with oxygen, facilitating effective nitrification (Brindle et al, 1998;Hibiya et al, 2003;Semmens et al, 2003;Terada et al, 2003Terada et al, , 2004Yamagiwa et al, 2004). In this study, we developed a novel BNR process that uses a sequencing batch membrane biofilm reactor (SBMBfR) capable of simultaneous nitrogen and phosphorus removal in a single reactor creating isolated regions in the reactor conducive to the growth of nitrifying bacteria and DNPAOs (Fig.…”