An anaerobic hybrid digester is an anaerobic digester that combines a free moving zone with a fixed media zone. This combination is an advanced form enabling improved solid retention time in the treatment of waste water. Anaerobic digestion is an established bioconversion technology for high strength wastewater treatment.
Hybrid reactor configurations combine the positive features of both suspended and attached growth systems and provide effective treatment in anaerobic treatment of different wastes. At the lower portion of hybrid anaerobic digester, anaerobic sludge is present, agitated with submersible mixers. The upper portion of the hybrid anaerobic digester is filled with fixed media (open design plastic media) so that the effluent, after passing through the lower portion, passes through this media where the removal of largely soluble organics as well as gas / solid separation takes place.
Advantages of hybrid anaerobic digester:
We have installed more than 20 Hybrid Anaerobic Digesters for various industries such as petrochemicals, breweries, paper, soaps & cosmetics, food, etc.
The Anaerobic hybrid digester is a combination of an Up-flow Anaerobic Sludge Blanket (UASB) digester and an Upflow Filter (UFF) digester – the open design plastic media offers a high specific surface area and maximum void space. The bottom portion (~40%) of the anaerobic hybrid digester is maintained with an acclimatized sludge bed. The effluent is first passed through this sludge bed and is intimately mixed with highly active microorganisms in the sludge bed. As a result, the effluent receives a significant portion of its treatment in the sludge bed zone itself. The other portion of the anaerobic hybrid digester is filled with fixed media (open design plastic media) so that the effluent, after passing through the sludge blanket, passes through this media where the removal of largely soluble organics takes place. It also provides critical retention of the biological solids in the reactor. Effluent recycle pumps are provided to return a portion of the anaerobic hybrid digester effluent back to the anaerobic hybrid digester. Excess sludge is wasted from the bottom of the anaerobic hybrid digester via dedicated sludge wasting pumps. The biogas generated in the anaerobic hybrid digester will be removed by use of biogas blowers. The Anaerobic hybrid digester provides consistent performance due to a high biomass inventory in the USB zone as well as biomass growth on the surface of the fill media.
An advantage that the Anaerobic hybrid digester technology has over other high rate anaerobic reactors is that, due to the presence of a fixed film of biomass that grows on the plastic fill media, there is no need to develop and maintain a granular sludge. Thus, the time required to start-up and stabilize the Anaerobic hybrid digester is significantly lower than other high rate anaerobic reactor technologies.
Anaerobic hybrid digesters have been designed to achieve BOD and COD (organic pollutants) reductions of up to 90% and 70% respectively and have the advantage of requiring less volume. Additionally, the biogas generated has been used to replace fuel in boilers, reducing operating costs and adding value for our clients.