Main Factors Influencing Anaerobic Digestion of Sludge and Energy Efficiency at Several Large WWTP in Central Europe

摘要

Energy efficiency is one of the most important performance indicators of WWTP operation. It is closely related to all aspects of sustainable development and the level of energy consumption influences directly the environmental impact of a WWTP. It is thus evident that the interest of plant operator is to optimise (decrease) the energy consumption and at the same time increase the energy production. The strategy “consume less & produce more“ has been implemented by the Veolia Water group in Europe at 22 larges WWTPs with anaerobic digestion of sludge and energy recovery from biogas. The energy production is “boosted“ by switching to thermophilic digestion, applying sludge pre-treatment, optimising sludge thickening and implementing biowastes codigestion. These 22 WWTPs consume together 280 Gwhel./y, and produce 160 Gwhel./y, which shows an average electricity self-sufficiency of approx. 60%. Three WWTPs with co-digestion of biowastes are approaching even 100% of energy self-sufficiency.