This process is built around a rotating drum, similar to a ball mill or hay dryer. Everything else in this picture is for sorting, screening and reloading. What is not composted is loaded into trucks to take to the garbage dump. Ten tons of MSW loaded into the system produces only about 2 to 3 tons of compost, the balance is taken to the landfill. It would be much more effective to presort the waste before loading it into the drum. The contamination from broken glass, plastic and other contaminants makes the compost produced virtually worthless.

Each digester drum has very limited input capacity. The compost mix only stays in the drum for a few hours to a few days, which isn't sufficient time to stabilize any compost mixture and it is questionable if it remains in the drum long enough to meet the EPA 3 days at 55 degrees specification. The finished compost produced from this facility is only a small fraction of what is delivered after all the sorting and removal of the non-compostable elements is completed. Rating the facility based on what is brought to it by truck is misleading. The majority of the waste is reloaded on trucks and brought to the landfill.

The composting system is nothing more than another static pile composting inside a building. The "Magic Drum" on the front end has little effect on the composting process, other than being a very crude mixer. In order to process at designed rates, 3 days total plant capacity has to fit into each of the three drums shown.

The light blue cylinders are the drums, the balance of the building is for so called compost "curing".

The number of amount of biosolids (sewage sludge) that can be added to the process is minimal. The biosolids cannot be added as dewatered cake because the heavy mud cake forms balls up as the drum rotates. The Washington DC Blue Plains plant piloted the drum for dewatered sludge composting years ago and they decided against it for numerous reasons, one was the forming large "anaerobic mud snow balls" from the sludge as it rotated. Sludge has to be added into the drum at only 4 % or 5% solids, which isn't much more than dirty water, to moisten the MSW organic waste.

The obvious question that anyone looking at this system or any system should ask is what is actual plant compost production. You shouldn't get caught up with big inflated numbers that are not measuring production rates. Rating the system by the amount of waste unloaded at the door, and not taking into account what is removed before composting process, is a very deceptive way of rating a facilities composting capacity.

Finally, let's visit the Tunnel Composting concept.