Overhaul of digester mixing system delivers better biogas yields

Following an extensive upgrade of its reception tank and digester mixing system, Eco Verde Energy (EVE) has put a once troublesome Anaerobic Digestion (AD)+ plant firmly back on track with encouraging new biogas yields. At Holton in Suffolk, England, which receives around 65% of its feedstock from the adjacent Bernard Matthews poultry facility, the AD plant, under a series of different operators, had seen biogas production drop significantly, and eventually to a complete halt for a much-needed overhaul. Initially, the primary digester (2,700m3) was drained down, discovering, as expected, faults with the mixers, but also a broken stanchion. Later, further inspections revealed that there was damage to the roof of the digester, so the decision was taken to postpone operations for a complete maintenance revamp. “The mixers that were sold in as part of the biogas package were never going to last in the long-term,” said Eco Verde’s site manager at Holton, Kris Martin. “It is hard to understand a...