Affordable AD Systems

The Sasie food waste micro Anaerobic Digester

The Sasie affordable AD system is a micro digester that fits inside one 20′ shipping container. It has a digester volume of 17m³ and is capable of generating over 40m³ of biogas (at 60% methane) per day. This unit can process 530kgs of food waste per day.

The Sasie affordable AD system consists of:-

  • one 20′ shipping container which houses the controller console, feed system, gas clean-up and drying system, and the pumps, valves and meters; and
  • almost any number of 20′ shipping containers that house the 17m³ digester tanks.

Stainless steel AD reactor

The digester tank

The digester tank is the heart (or more accurately, the gut) of the AD system and its design/architecture is fundamental to the performance of the system. The Sasie digester tank consists of two stainless steel tanks, one inside the other with a layer of insulation between. Fresh food waste is fed in at one end and spent digestate is released at the other. Gas recirculation is used to mix the waste/digestate (the most energy efficient method of mixing) but only in the vertical plane. This maintains the correct bacterial ecosystem for the state of decomposition of the waste. Any vertical slice through the digester will contain a different bacterial composition to any other vertical slice, and this is encourage by the design in order to optimise methane production and digester stability. Changes in feedstock composition can stop most AD systems in their tracks, but this architecture maintains the right bacterial ecosystem at the right stage of decomposition. The strategy being to minimise the mixing of the different bacterial colonies performing the four stages of digestion (hydrolysis, acidogenesis, acetogenesis and methanogenesis).  Recirculating biogas (containing CO2) through the hydrolysis phase also increases methane production.

What is included

The Sasie Affordable AD system is a complete food waste processing system sold as a kit due to the fact that the digester container and the ancillary container will need to be piped and wired together on-site. The gas storage bag also needs to be installed and connected.

The complete system consists of:-

  • a 20′ shipping container containing a 17m³ reactor tank
  • a 20′ shipping container containing all ancillary equipment, including:-
  • 1 food shredder (2.2kW)
  • 1 macerator pump
  • 50m³ gas storage bag
  • 1 gas bag pressure release valve
  • 1 control console
  • 1 biogas pump
  • 1 biogas sulphur scrubber
  • 1 dehumidifier
  • 1 digital gas flow & composition meter

All this at a price of £79,000 (plus VAT) delivered.

Even more

Being based within 20′ shipping containers the Sasie Affordable AD system is fundamentally modular. Almost any number of 17m³ reactor units can be coupled together.

The system can also be configured for other feedstock types. Some ancillary equipment changes will be required. Feedstock processing capacity is as follows:-

Raw material Max (Kgs/day)
Food waste 530
Pig manure 945
Cow manure 1275
Chicken manure 567
Human manure 708
Vegetable 1380

If you need a biogas CHP to go with your digester, you’ll find top spec models at affordable prices here.

If you need any other renewable technologies, please have a look at our technologies page.

Any questions? Please email


Need help finding capital for your AD project?

Raw Biomass is a fund dedicated to owning and operating biomass projects operating on the Renewable Heat Incentive. As the fund has grown we now have the opportunity to purchase a larger range of projects representing commercial carbon reduction in some way. These can be either pre-development or already operational. We will pay a premium for operational projects and can also take on a project at any stage in the development through to commission.


The individual project scale we are looking for is from £150,000 to £5million.

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