Everything is biodegradable, with enough time and in the correct conditions. But is asbestos compost a viable solution?
Asbestos is a big problem in NZ and world-wide. As people renovate their homes, asbestos is being removed because it simply is not safe to remain in homes and businesses. In NZ, this asbestos and all asbestos containing materials have to be wrapped in plastic or secured in metal drums and dumped in special hazardous sections of landfills.
The problem is not sitting there, rotting. It’s getting bigger by the day, taking more and more space, and it’s not going away, simply in storage for our future generations to manage. Today’s asbestos landfill is the problem of the future.
Luckily, researchers in NZ are looking into how asbestos could be composted.
Asbestos’ Kryptonite
Asbestos fibres contain iron. This is what causes much of the harm in humans, causing formation of free radicals that trigger cell mutation. But this iron is also the weakness of asbestos because there are some fungi, bacteria, and lichens that secrete substances which bind to the iron, removing it from the asbestos. By removing the iron from the asbestos, this helps to decontaminate the waste, and make it less hazardous. This is essentially a form of chelation, reducing the toxic effects of metals.
So, by removing the iron, a lot of the potential harm from asbestos is removed. But it’s not as simple as planting a bunch of lichen on asbestos and waving an ecological magic wand.
Bioremediation of asbestos encompasses a range of processes that could look like this:
- Photostabilization: Providing vegetation cover over exposed/buried asbestos that stops air dispersal
- Bioweathering: The biological breakdown of minerals via various methods such as lichens, bacteria, and fungi
- Root processes: Roots can extend long distances beneath the surface (a single wheat plant is estimated to be able to have roots up to 70,000m long) which can host fungi, supplying nutrients from below to the plant host above
Starting with an Easy Task: Soil Remediation
‘Easy’, as opposed to ‘far more difficult’, as the asbestos in soil is more available to microbes and fungi than asbestos embedded in concrete. Asbestos-contaminated soil can be a massive issue, caused by run-off from things like asbestos-containing roofing, or leaching from asbestos dumping. Current soil remediation method could be either:
- Truckloads of toxic soil removed and dumped elsewhere
- Capping of the area in-situ, rendering it unusable and presenting further risk with run-off
Research by Unitec looked at an example, with a school in Rarotonga needing asbestos soil remediation. There were no landfill options on the Island, and disposal at NZ or Australia was infeasible due to quarantine. Besides this, the cost was estimated at US$250,000, completely out of reach for a small island nation. Capping was least preferred due to cost and unavailability of land. In the end, soil was removed and buried on the school site—three metres deep with polythene covering. This is not a permanent solution.
This is just one of thousands of asbestos disposal problems where asbestos composting could be the most feasible, eco positive, and permanent solution.
The Problems with Composting Asbestos
There are a few problems that are hampering the process.
Time
The iron being removed from the asbestos is not an overnight process. It takes time- years. Decades. Maybe even hundreds of years. Also, nature is fickle; the plants may die off, or be inconsistent in their growth.
Asbestos Not in Pure Form
In NZ, there are more than 3000 different asbestos-containing products. This means a whole bunch of items like cladding, linoleum, and stippling from ceilings that the fungus or lichen can’t eat. Asbestos is commonly embedded in some form of concrete; the average concentration of asbestos to other materials is about 5%.
Space
There’s a lot of asbestos being dumped in NZ. Tonnes of it, each year. Lichen and fungi need air and sunshine to grow, so the asbestos can’t just be deposited in a huge pile. It would need to be dispersed in such a way that it encourages the growth of plants. That, combined with the long timeframes for chelation, represents a vast area required.
It’s estimated that worldwide, there’s about four billion tonnes of asbestos-containing waste that requires disposal.
CO2 and Carbon
Asbestos isn’t the only ecological problem that humans have created. Climate change, in part fuelled by CO2 emissions, is a problem now. Lichens absorb large volumes of C02, but weirdly, fungi consume oxygen and respire CO2. This means that fungi may solve one problem, only to add to another.
Does Removing the Iron from Asbestos Actually Make it Safe?
While it appears that removing the ferritin iron from asbestos makes it less harmful, it may not remove all the risk entirely. Research continues to find out more.
Asbestos Motility in Soil
Asbestos in soil does not stay in one place. Erosion means that asbestos is removed via groundwater runoff, and in the air via wind.
Could Asbestos Compost be a Viable Solution?
Absolutely. Research is being untaken now to create the perfect environment that allows growth of the organisms that ‘eat’ the iron in the fastest, safest, and most sustainable way. For NZ’s asbestos landfills, this solution could be on the foreseeable future.
Current ‘solutions’ to asbestos management are insufficient and creating a toxic legacy of asbestos wrapped in plastic. Composting could be a very viable and real solution to save our future generations from a toxic nightmare.
