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Bacteria are flocculated with high molecular weight cationic synthetic flocculants and chitosan. High charge density polymers are the most effective of the synthetic flocculants. Only chitosan is effective in flocculating the E. coliand B. subtilis cultures in complex broth. The difference in effectiveness between the synthetic flocculants and chitosan for flocculating E. coli, B. subtifisand Z. mobilismay be attributed to hydrogen bonding between the polysaccharide flocculant and cell surface polymers in addition to electrostatic interactions, and, in complex media, complexation of synthetic polymers with anionic polyelectrolytes.

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ABSTRACT:We report, for the first time, our experimental investigation of inverse phase suspension polymerization of acrylamide in a batch oscillatory baffled reactor. In such a reactor, the oscillatory motion is achieved by moving a set of orifice baffles up and down the column at the top of the reactor. The effects of both operational and design parameters on the mean particle size and size distribution of polymer beads were investigated, including oscillation amplitude, oscillation frequency, baffle spacing, baffle free area, and monomer addition time. The experimental results indicated that the mean particle size and size distribution of the polymer beads depended predominantly on the product of oscillation frequency and amplitude, i.e., the oscillation velocity. The size distributions are narrow and of essentially a Gaussian distribution. The level of fines produced is consistently less than 1% for all 100 experiments performed. We demonstrated that the mean particle size and size distribution in an oscillatory baffled reactor can be controlled precisely by simply selecting the appropriate oscillation velocity. The effect of the baffle spacing on the mean particle size is much less compared with that of the baffle free area. The monomer injection time has a noticeable influence on the mean particle size, but the rate of change is relatively small.