Dual Chamber Digester System
The dual digester system has been designed to prevent disrupting the digester plant while in the digesting mode. (Producing Methane Gas) This means it will maintain the optimum digester temperature, while the second chamber is in the loading mode.
The system incorporates two chambers, one chamber is allowed to go into the anaerobic state where the bacteria produces gas.
The digester chamber in use will be maintained at a minimum of 1 to 1.5 psi 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, (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 digester chambers.
The excess water is transferred to either the Netifim Raam system or the soakage trench via the stratification filter and the 120micron disc filter through the dosing Syphon 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). In the event that the material is not biodegradable, the digester displacement will be reduced proportionally. The output CH4 is fed through two scrubber filters, first the fe filter which absorbs the SO4 , then the Lime filter which absorbs the CO2.
Maintenance of the digester system:
Check the fe filter and the lime filter are clear. Remove the top caps, replace if necessary.
The digester chamber will from time to time need to have the scum layer removed. The duration between cleaning times will vary from two to ten years, depending on the feed material.
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 (Not suitable for drinking) only for irrigation by the above mentioned Netifim system or something 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 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 digester 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.
It is recommended that a log be kept to keep track of the performance of the digester when first installed.
While all systems have similar components, there can be differences in the size requirements so please accept the information we send you with this in mind.
If you wish to have more detailed drawings, these need to be approved by an engineer and there is a cost involved.
Installation manual and drawings are supplied when a system is ordered.
NB. Installation and plumbing costs are not quoted for.
Council approval will be necessary before installation, as well as an engineer’s report.
No responsibility is taken for the installation carried out by trades people employed on site during the biogas generator installation.
Pricing and specifications are subject to change without notice.