Dual Chamber Bio-Digester System

Utilises Biodegradable Organic Products

The system incorporates two chambers; one chamber is allowed to go into the anaerobic state where the bacteria produce gas, while the second chamber is in the loading mode.

The digester chamber in use will be maintained at a minimum of 2.7 to 10 kpa while in the digesting mode, the temperature will be maintained at a constant 35 to 37 degrees caused by the chamber going exothermic (like a hay stack)

The chamber pressure is maintained by the production of CH4, (methane gas) by transferring water to the second digester chamber that is in the loading mode, the first chamber see the excess water as a static head pressure causing the first chamber to hold gas at 1 to 1.5 psi above atmosphere

The ph is maintained at the correct ph for the type of digester feed by means of adding lime, or by dilution (adding more water to the feed).

The equalising chamber maintains the standing level of water, between the bio-digester chambers.

The excess water is transferred to either a Netifim Raam System, or a soakage trench via the stratification filter and the 120micron disc filter through the dosing siphon or dosing pump.

The digester system can be dry fed, with any biodegradable material that is small enough to be fed through the dry feed inlet port.  Care must be observed that the material is biodegradable.

The output CH4 is fed through two scrubber filters, first the iron filter that absorbs the H2 S releasing H2 then the lime filter that absorbs the CO2 if fitted.

The three by-products from the digester plant will be:

• CH4 (methane gas) to be used in heating equipment, cooking equipment and to run your backup generator.
• Recyclable water for general use (is not suitable for drinking) only for irrigation by the above mentioned Netifim system or some thing similar.
• High grade fertiliser that will be free of almost all heavy metals. The fertiliser can be drawn of as either a dry powder or as liquid slurry; the liquid slurry concentration can be adjusted at the time of removal.

If lower concentrations are required than the maximum water ratio to slurry ratio than the volume of the bio-digester volume to slurry ratio, the extra water must be added externally to the slurry.

The output of methane gas will depend on the type of digester feed, the running temperature, and the digestion period.

Please note that for successful biogas generation, the digestion chamber will require between 12% to 40% of solids.

The higher ratio of solids to water the higher the gas yield.

Some biodigester feeds operate better at different temperatures and this will require a certain amount of test trials to achieve the optimum temperature for the digester against the feed.