Letting tiny critters do the job


Composting is currently the most common system for processing and repurposing pet waste.

The word “composting’” is often used in a very generic sense to describe processes that break down organic matter. Products and systems designed specifically for managing pet waste are often called pet composters when, in fact, they rely on biodigestion.

True composting is an open air above ground managed system. It uses oxygen to biologically decompose organic material – including pet waste – to produce a soil conditioner. Composting works through the use of microorganisms, primarily a wide range of  bacteria and fungi, that break down the organic matter.

Bulking material, typically, shredded bark mulch, straw, leaves or sawdust, is added to energize the process, and help maintain a porous texture that circulates air and moisture. Pathogens are killed by the high heat naturally generated by heat-loving microbes during the initial process. During the cool-down, other organisms kick in to complete the process.

The compost material needs to be left alone (also termed “seasoned” or “cured”) for a period of time. This ensures that the finished compost is mild enough to nurture plants when added to the soil.

Some private composting facilities are unwilling to accept pet waste for a variety of reasons including permit limitations, concerns about odor and potential pathogens, and an assumption that there is no market for compost made from pet waste. In addition, composters might be unsure of regulations and whether special processes are needed. Research in recent years has proven that all these concerns can be addressed, with pet waste successfully composted in many locations around the world.

Smaller on- or off-site composting systems usually involve bins that are periodically turned or that include tumblers. These methods can be labor-intensive or inefficient when attempted without good information or guidance. But some communities have set up successful working systems that can be easily duplicated.

Additional information

A study by Jason Hofman, Ph.D commissioned by the Nova Scotia Resource Recovery Fund Board confirmed the viability and safety of composted pet waste.

“There are no compelling reasons to not compost CLDF based on the chemical and biological aspects of the material.”  J.H., Halifax NS 2010

Vermicomposting is a method of using earthworms to transform organic waste into a nutrient-rich soil amendment. Since worms have no teeth or stomachs, they simply ingest nearby microorganisms that predigest available food inside their guts. Worms will scarf down dog or cat waste and leave behind castings that gardening professionals call “black gold” because of its amazing ability to stimulate healthy plant growth.

The process can be done indoors in plastic bins, outdoors in managed piles. Professionals often produce vermicompost for the commercial market on raised beds in hoop houses. Using worms for large community-scale pet waste transforming might prove impractical due to the need for observation and labor-intensive harvesting.

Bokashi is sometimes called “bokashi composting” but it’s really an anaerobic fermentation system that can be used to decompose all organics, including pet waste, into liquid or solid soil enhancers. You will eventually need to work a good bit of the residue into workable soil or use it as a compost accelerator.

Instead of worms, bokashi uses super-hungry effective microorganisms (EM microbes) mixed with grains in a sugary solution to slowly “pickle” the poo to make it palatable for plants. Look online for lots of bokashi mix recipes and instructions on how to work the transformation magic. Like vermicompost, bokashi is best done in smaller batches.

Composting, vermicomposting and bokashi systems slow down as temperatures drop.

Commercial composting

Commercial compost facilities optimise the process to ensure rapid biodegradation of organic material.

Each step of the decomposition process is optimised by shredding material to the same size or controlling the temperature and oxygen levels. These measures ensure rapid biodegradation of the organic material to high quality, toxic-free compost.

There are different types of commercial composts:

  • Aerated static pile (outdoors)
  • Turned windrow (outdoors)
  • In-vessel