In the photograph below, you can see some of the organic waste, with some of the completed compost in the lower right. The target for the compost is to improve agricultural production around Mexico City.

Symphony of the Soil is a fascinating web based documentary on the importance of our soil. I recommend it.

A debate unfolded during the plenary sessions – should biosolids be recycled into the soil? One viewpoint is that biosolids (solid residual from wastewater treatment) may contain unknown and untested chemicals that may negatively impact our health, and should be kept out of our soil ecosystems. The main reason for this is that we do not regulate what we through in our toilet, nor do we know the contents of some of our industrial wastewater. The other viewpoint is that biosolids compost contains carbon and plant nutrients, increases water holding capacity and productivity of soil, and has produced incredible ecosystem improvements in mine sites. The net benefit outweighs any risk.

We need to keep this dialogue going – we need to understand and be comfortable with risks, and keep them in perspective. In 2009, the Canadian Council of Ministers of the Environment published a report called “Emerging Substances of Concern in Biosolids” outlining substances that are not currently tested for, and the potential implications of some of these compounds. This report concluded that there may be substances of concern in biosolids, and that the general public needs to understand this. It also cites reports showing that a composting process reduces the concentration of some of these substances.

My own community produces a soil produced from raw biosolids. The website promoting this soil suggests that it has been tested and has been is completely safe for vegetable production. It meets the guidelines for the products that are required to be tested, but we know that there are many other compounds that we deposit into our toilets that are not tested for. I have some unease about recommending this product for vegetable production, although some communities have done this successfully for years. I do not have the same unease with using biosolids compost for landscaping, turf or other non-food growing applications. Biosolids reuse has had incredible benefits in soil and ecosystem restoration and should be promoted for that use.

We all have to be comfortable with the risks that we take with all of our activities, food we eat, and places we go. …

Most of the world does not have the luxury of dictating that plastics be removed from organic waste before composting. This means that as composters, and compost technology suppliers, we are left with the challenge of removing plastics from compost. The technology already exists whereby plastic present in organic waste during the composting process poses minimal process concern. It is also well understood that removing plastic after the composting process is simpler and more effective than trying to separate film plastic from wet sticky organic waste. There are many who are working on the challenge of effectively separating plastic from compost.

This week I had the privilege of seeing creative thought and ingenuity come together in a new plastics removal system for compost. The Plastovac 6000 system is a second generation plastics removal system developed by Garret Gillespie, an agricultural engineer who was faced with removing plastic from the compost in Whitehorse. I watched this unit at a food scrap composting facility and I was very impressed with the design, the components, and the performance.

Of particular interest was the panel of leading composters and anaerobic digestion developers who spoke at the plenary session. We heard that anaerobic digestion and biogas production is the way of the future – its the right thing to do. We heard that it is currently not economically viable, but the time will come when the costs will decrease. We heard that relying on grants for capital construction of anaerobic digesters is a good thing. This is of particular interest to me because as a microbiologist, I was trained in the last era of anaerobic digestion, and have actually built a small scale unit. They work, but the real question is the economics of the process!

Last October at the Biocycle conference on anaerobic digestion, some of the European speakers addressed their concern of what would happen if their countries withdrew their subsidies for anaerobic digestion. What this means is that even with higher landfill tipping fees and higher energy costs, anaerobic digestion still had to be subsidized by the taxpayers. So, the costs haven’t come down yet…

I’d like to see some more real data on the economics of this process. We know that after anaerobic digestion, the material still needs to be composted. There will also be nutrient rich liquids to manage. This will also cost money. Simply saying that this is the right thing to do is not a logical rationale for using tax payers dollars to fund these processes.

Globally, we need to recycle organic matter to produce valuable organic matter for our soils in order to sustain a healthy food system and healthy communities. There are many studies available on the worldwide loss of organic matter from our soils, and its impact on the loss of food production.

To include organics recycling as part of a healthy community, we need to do this in an economically, environmentally and socially acceptable manner. We cannot pollute our air or water, or produce unacceptable odor in our communities. The end goal is not only to reduce our waste to landfill, but produce valuable organic matter for our soils.

The importance of our industry is illustrated by my experience with the US border official this week, who shared his experience with some dwarf apple and cherry trees that he planted last year. The plants that had compost added grew to 8 ft and produced fruit in the first year. The trees that didn’t receive compost grew only 3 ft. Compost works, it gives us wonderful results for efforts at producing sustainable food locally!