Design and Performance of Pulsed Anaerobic Digesters

The development of a Pulse-Driven Loop Reactor (PDLR), a Pulsed Anaerobic Filter (PAF) and a Pulsed Anaerobic Baffled Reactor (PABR) is described. In a PDLR internal circulation is achieved by a specially designed pulse-nozzle together with a concentric draft tube. In a PAF and PABR an oscillation is superimposed onto the biosuspension by means of a pulsator unit. Pulsed digesters enhance mass transfer processes. Consequently they facilitate degassing and prevent a build-up of acid spots in sludge beds. Laboratory- and pilot-scale evaluation using highly polluted distillery slops (pear, cherry, raspberry) as industrial wastewater show a COD removal efficiency of 70 -80 % at loading rates of 10 - 5 kg/m3*d. Contamination, both by sulfate (2 g/L) and copper (0.2 g/L), has a most adverse effect on anaerobic treatment of cherry-mashes, giving rise to a build-up of volatile fatty acids. Consequences for distillery plant operation are discussed.