Open-Pore Sintered Glass as a High-Efficiency Support Medium in Bioreactors: New Results and Long-Term Experiences Achieved in High-Rate Anaerobic Digestion

An open-pore sintered glass material (SIRAN) was developed for the immobilization of slow growing microorganisms. Due to the excellent properties of the inert carrier, e.g. porosity, pore size distribution, surface area, which can be adjusted individually to the applications, good system efficiencies are possible. Thus in the field of anaerobic digestion significant high COD removal rates are achievable. The open-pore structure of the carrier offers surface areas up to 90.000 m 2 /m 3 to be colonized by active biomass. Compared to conventional support media, the use of open-pore carriers results in high start-up and steady-state performance at high process stability. The fixed bed loop reactor guarantees economical process solutions if open-pore sintered glass raschig rings are applied. Granules and beads have been proven in fluidized bed reactor systems, maintaining COD loading rates of 206 kg/m 3 · d by treating evaporator condensates from pulp industry. The paper describes main characteristics of the carrier, treatability studies with pilot plants, scale-up and experiences with full-scale installations at production site using SIRAN carriers.