Anaerobic compost. Minus the putrid smell and slimy mess.

 

DESIRED Outcomes

The development of low-cost and open-sourced infrastructure, tools and manuals on community-scale beneficial anaerobic composting

 

Background

In April 2019, our team was introduced to a leading-edge method of composting using Beneficial Anaerobic Microbes (BAM), thanks to Daniel Schuurman at Biologix. For most of our composting journey, we have been firm users of purely aerobic methods (using oxygen-dependent organisms) and done everything possible to stay away from anaerobic conditions, which are usually pretty nasty.

As we began reading about the benefits and potential of anaerobic composting, and learning how this anaerobic process is vastly different to the smelly and polluting process that happens in a landfill, we got very excited and have begun experimenting with it to iron out the bugs and determine best practice for our system.

Some of the benefits are:

  • Faster composting process

  • Fewer turns required

  • Reduced odours

  • Higher compost returns — most aerobic systems reduce to 20-30% of the input volume

  • Higher carbon sequestration due to very low CO2 and CH4 generation

 

Where we are at

BAM inoculations have been part of our standard compost recipe for a couple of years now, and we have been able to reduce our compost turning frequency to once a month. This is a great labour saving, as well as reducing the loss of moisture and carbon as CO2 from turning. Despite turning far less frequently than we used to, we’ve found a reduction in bad odours.

We use a backpack sprayer to apply the diluted (1:10) BAM in a fine mist to thoroughly cover each layer of food scraps being added to our compost batches. Then we add arborist mulch and coffee chaff/silverskin to balance the moisture and carbon:nitrogen levels, and mix it altogether using a drag fork.

We are happy to share our learning to date with other interested composters; feel welcome to get in touch with us at compost@kaicycle.org.nz.

 
 

This project was made possible by & in collaboration with

  • For the Love of Bees

  • Biologix

  • Wellington City Council (Waste Minimisation Fund)