This blog is part 2 of a two part blog. To find part one,
click here.

While the food waste problem in America is a rather complex and difficult one to solve, perhaps it is a small mercy that there are only a few basic categories of food waste disposal systems on the market today. Three, in fact: non-biological (mechanical) systems, in-vessel dry composters, and biological (wet) systems.

This blog post will attempt to briefly outline each of the three categories and provide popular examples of each. For a more in-depth exploration of the topic, check out

this 54-page document commissioned by the government of Massachusetts
which delves much deeper into the details.

As you embark on your journey into the world of on-site food processing systems, it’s advisable to examine each of the systems while actively assessing the following variables:

• Calculate return on investment based on current waste hauling costs and the electricity, water and sewer use of the particular system.
• Calculate physical space and utility requirements of the system.
• Conduct a waste audit to help your business understand your waste profile and develop systems to ensure that pure food waste is available for the on-site system.
• Consider likely points of failure of an on-site system and develop contingency plans.
• Decide how the end product of on-site systems will be managed with an eye to prepare it for beneficial reuse.

Non-Biological or Mechanical Systems

The first category of system is the non-biological (or mechanical) system. This type of system uses mechanical processes and heat to reduce the weight of food waste by removing the water content. This category can be broken down into two basic types: pulpers/shredders and dehydrators.

A pulper or shredder system starts by pulverizing food waste, after which it will remove the water content and therefore most of the weight. A pulper will reduce the waste to a slurry before removing the water, whereas a shredder simply grinds the waste and then presses it. Each type of system generally reduces the weight by around 80-90%, and is typically found in or near either the food processing or dishwashing area.

One major benefit of having a pulper or shredder system is that generally they can accept non-organic products in addition to the organic materials, thereby eliminating the need for food workers to painstakingly sort the two away from each other.

A downside of this type of system is that the resulting reduction has to either be refrigerated or picked up frequently due to unpleasant odor that tends to attract pests.

Dehydration systems use heat to render organic material into a sterile, odorless material. Often this system will be used in conjunction with a pulper or shredder in order to maximize the space available within the dehydrator and reduce the resultant waste even more efficiently.

The resulting product from a mechanical process is not suitable for compost and requires further treatment before it can be used as fertilizer.

In-Vessel Dry Composting

The second category of on-site food processing systems is in-vessel dry composting. This uses a biological process to heat and break down organic material into a nutrient-rich product that can be used as fertilizer.

At their most basic, composters are simply enclosed containers that allow natural processes to take place in a limited area. As the size increases, different levels of technology are necessary to control them with a regulated consistency.

To begin the process, clean and separated organic materials are loaded into the enclosed container, after which controlled air is moved through the chamber to increase oxygenation. If the material is too wet, brown material such as wood chips, paper or sawdust must be added. Heat and microorganisms are then introduced, with automated rotation and aeration, to speed up the process compared to natural decomposition.

The material is then cooled and cured, yielding a product that is usable as fertilizer once properly tested and treated.

The major benefit of composting is that it produces a “zero waste” or full circle product that can recycle waste back into the food production system.

Some downsides include the additional effort of sorting food waste, proprietary microorganism formulas, and the relatively larger container size. Additionally, if a business cannot use the resulting compost, disposal may still incur fees.

Wet Systems

The third and final category is a wet system, or anaerobic biodigester, which maintains internal temperatures and oxygen levels while integrating fresh water to break down food waste into filtered effluent or gray water that is deposited into the municipal sewer system.

By introducing proprietary blends of enzymes, microorganisms or nutrient mixes, a biodigester functions like a metal stomach, breaking food waste down within a water mixture until it fully dissolves.

Along with composters, biodigesters produce a “zero waste” outcome and are considered biogenic, meaning they are part of the natural carbon cycle.

Primary advantages include fewer plastic disposal bags, reduced pest-control chemicals, improved measurement of waste processing efficiency, and elimination of odors.

However, wet systems often require significant upfront investment and customized integration. Some models have also been criticized for inconsistencies in effluent contaminants exceeding municipal limits.

Although the categories of on-site food processing systems are relatively limited, there are many considerations when making a final decision about which system will be most effective for your specific situation.