Removal of high phenol concentrations with adapted activated sludge in suspended form and entrapped in calcium alginate /cross-linked poly(N-vinyl pyrrolidone) hydrogels.

The present work evaluates the aerobic removal of 0.25-2 g/L of phenol by adapted activated sludge in batch and continuous reactors, in suspended form and trapped in polymeric hydrogel beads of calcium alginate(1%) and cross-linked poly(N-vinyl pyrrolidone), x-PVP (4%). The mechanical and chemical resistance of the entrapping hydrogel was also evaluated in three different media: (I) rich in phosphate and ammonium ions; (II) using alternate P and N sources, and (III) without nutrients.

Physical characteristics of poly(vinyl alcohol) and calcium alginate hydrogels for the immobilization of activated sludge.

Hydrogels based on poly(vinyl alcohol), PVA, and calcium alginate were prepared by a freezing and thawing cycle process and characterized, in terms of the role of the polymer mixture percentage and the number of treatment cycles, on their weight swelling ratio, WSR, gel fraction, and activated sludge entrapment and immobilization. The results show that the morphology of these hydrogels is highly dependent on the PVA-Ca alginate ratio of 5 wt % total polymer content in the initial aqueous solution and that the number of entrapped microorganisms which survive the freezing-thawing procedure is independent of this ratio. For 80/20 PVA-Ca alginate hydrogels, results also show that for up to three freezing and thawing cycles, the WSR, which is in average 24, is not severely affected by the number of the cycles.