Anaerobic Biological Treatment of Alginate Production Wastewaters in a Pilot-Scale Expended Granular Sludge Bed Reactor Under Moderate to Low Temperatures

Psychrophilic anaerobic digestion recently has been demonstrated as a cost-effective option for the treatment of a range of wastewater categories. In this study, the treatment of alginate production wastewaters was carried out in a pilot-scale expended granular sludge bed (EGSB) reactor. After a 40-day startup with two inocula, a 163-day experiment was run, from moderate to low temperatures, to treat seaweedbased-production wastewater. The results showed that inoculating with the active granular sludge instead of flocculent biomass can remarkably speed up the startup, and, at applied organic loading rates of 1.5 to 3.0 kg chemical oxygen demand (COD)/m(3).d, COD removal efficiencies of 55.4 to 72.6% were achieved. The volatile suspended solids ratio decreased slowly with operation time, as a result of the extremely slow growth rates of microorganisms and the accumulation of inorganic substances. Morphological examination and particle-size distribution of the granules revealed their tendency to disintegrate. Inorganic precipitates, microorganism shift, and substrate limitations may have contributed to it. Water Environ. Res., 82, 725 (2010).