Anaerobic Digestion

Anaerobic digestion is a very effective way to treat high chemical oxygen demand organic streams, such as that generated from MSW during the ISKA® Percolation process.

ISKA Percolation includes an anaerobic, packed bed digester for conversion of the liquefied and soluble volatile solids in the circulating water into biogas.

The hybrid upflow anaerobic digester design has been adopted to provide a high biological conversion capacity under a range of variable feed conditions. Methanogenic bacteria are immobilised on an inert support with granular accretions of bacteria populating above and below the filter bed.

The solution, high in volatile solids, is recirculated through the digester filter bed with fresh liquid feed from the Percolator. The large recirculating load allows the biomass to absorb shock loadings in volatile concentration. The volatile solids are metabolised by the bacteria to produce additional biomass and biogas. The biomass is ultimately recirculated to the Percolator where the acidic environment releases the volatile solids for re-digestion.