Anaerobic Digestion

Anaerobic Digester
Anaerobic Digester
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Digester Covers

Fixed – Liquid level is controlled by pipes in drawoff boxes on tanks with steel or concrete covers.

Floating – Hollow steel covers move up and down with the liquid level.

Gas Equipment

Pressure and Vacuum Reliefs – Weights resting on a platten let gas out or air in to prevent excess pressure or vacuum from damaging the cover.

Flame Traps – A stack of metal plates in the gas piping will extinguish fire as it moves toward the tank.

Thermal Valves – Fire in the gas piping will melt a fusible plug, causing the valve plate to drop closed.

Drip Traps – Condensation in the gas piping is collected in drainage pots.

Earthquake Valves – A jiggle will cause the valve plate to drop closed, shutting off gas flow.

Mixing Systems

Steam Injection – Steam is diffused into digester.

Mechanical Mixers – Large propellors provide mixing.

Draft Tubes – Propellers of gas diffusers are surrounded by a large tube to pull sludge from the bottom.

Gas Recirculation – Compressors recirculate gas to shear boxes in the tank bottom or pipes coming down from the cover.

Heating Systems

Steam injection – Steam is diffused into the digester.

Spiral Exchangers – Sludge and hot water flow through several separate spiral passages.

Concentric Pipe – Sludge flows through a pipe within a hot water pipe.

Self – Contained – Digester gas is burned in a unit which also contains sludge piping in a hot water chamber.