Anaerobic digestion of high-strength cheese whey utilizing semicontinuous digesters and chemical flocculant addition

Semicontinuous digesters were used to anaerobically treat high-strength whey (70 kg/m(3).COD). A maximum loading of 16.1 kg COD/m(3).day was obtained with soluble COD removal efficiencies greater than 99%. The use of a chemical flocculant resulted in an increased biomass concentration in the digester compared to a control, thus enabling correspondingly higher space loadings to be applied. With the onset of substantial levels of granulation of the biomass, flocculant dosage was able to be discontinued. This article discusses the performance of the digesters in detail and, briefly, the long-term operational difficulties experienced and the control strategies employed on such systems.