New Orleans Bioremediation Basics
March 8, 2006
‘Bioremediation’ means using living things—microbes, plants and fungi– to cleanse and heal soil and water. In practice, ‘bioremediation’ is most often used for techniques involving microbes. ‘Phytoremediation’ means using plants, and ‘mycoremediation’ means using fungi and mushrooms.
Diesel Range Organics
PAHs (polycyclic aromatic hydrocarbons)
Organochlorines (pesticides– Dieldrin, Helptachlor, Heptacholor Epoxide, Notrogenzene)
Heavy metals—anionic and cationic
Diesel range organics, PAHs and Organochlorines are large, chained molecules that can be broken down into simpler, harmless substances. Organichlorines are the most difficult to break down, and unless they are treated, will persist in the soil long term and enter the food chain. Microbes and fungi can be used to break down these substances.
Heavy metals cannot be broken down. They are already elements, made up of atoms of all one kind. They can be taken up in the bodies of plants and mushrooms, which must then be carefully disposed of as toxic waste. Or they can be sequestered, immobilized in the soil so that they do not enter the bodies of plants or animals. Heavy metals may be cationic—tending to give up an electron in chemical bonds, or anionic—tending to take on an electron in chemical bonds. Anionic and cationic metals behave differently in the soil and are taken up and sequestered under different conditions.
Anionic metals (arsenic and chromium) are more soluble under alkaline soil conditions (high pH.) They are more easily bound and sequestered under acidic soil conditions.
Cationic metals (antimony, barium, cadmium, copper, lead, mercury, thallium, zinc,) are less soluble in general than the anionic metals. They are most easily taken up in acidic soil conditions (low pH) and more easily bound and sequestered under more neutral or alkaline soil conditions. Some of the heavy metals, such as lead, are taken up in plants in larger quantities when a chelating agent such as EDTA is added to the soil.
We also have powerful allies from the kingdoms of microbes, plants and fungi:
Anaerobic: (Not needing or wanting oxygen to thrive):
EM, Efficient or Effective Microbes, is a combination of specific, mostly anaerobic micro-organisms that work together symbiotically. It includes lactobacillus (milk-loving microbes), acidophilus, yeasts, and others. Lactobacillus can easily be cultured, and cultures of efficient microbes can be captured from the air and soil, but the preparations we have been using are commercially produced by companies that have the ability to carefully monitor and control exactly which organisms are present. Their EM preparations can be diluted and extended.
Common Ground crews have been using EM sprays against mold with great success. In one trial, using professional spore counting instruments, spore counts dropped by (?)% (can someone find Carolena, or get me her email—I can’t remember her exact figures for this but would like to include them.) The EM preparation eats the mold spores, then colonizes the surfaces upon which they grow and reproduce, preventing their regrowth.
EM is also used to help break down compost and restore life to compacted, poor soils. We don’t know yet how effective it may be in breaking down toxic compounds in the soil, but in Asia it has been extensively used to break down petrochemicals in water.
The company that has donated EM to Common Ground is Sustainable Community Development scdworld.com.
In general, most beneficial bacteria and micro-organisms are aerobic—needing and wanting an oxygen rich environment. Colonies of beneficial micro-organisms can be cultured in Aerated Compost Tea—a preparation of non-chlorinated water inoculated with worm castings or high grade compost and brewed for 36-48 hours with air pumped through it. Molasses, humic acid, fish hydrolase, or other sources of food for the microbes are added, and additional additives can enhance soil fertility or produce a more microbial or more fungal tea for different needs. The micro-organisms in aerated compost tea can break down diesel range organics and PAHs. They are less effective against organochlorines, and cannot break down heavy metals.
Dr. Elaine Ingham of Soilfoodweb Inc. www.soilfoodweb.org is the great authority on aerated compost tea. Scott Kellogg has worked with her and we are drawing heavily on her research.
There are many plants that will uptake heavy metals. Specific plants uptake specific metals. A very short list of plants we are using or considering include:
Indian mustard greens (brassica juncea)—uptake lead, arsenic and other heavy metals.
Brakefern (pteris vitatta)—uptakes arsenic.
Alpine pennycress (thiaspi caerulescens)—uptake lead, cadmium and zinc
Fungi are nature’s recyclers. Fungi excrete enzymes to digest decaying matter and many fungi can break down stable compounds such as lignins and cellulose. Many can also break the chemical bonds of large, organic molecules and are useful in bioremediating diesel range organics, PAHs and organochlorines. Some are also useful in destroying pathogens and fecal coliforms.
Mushrooms are the fruiting bodies of a larger organism. They grow out of a mass of mycelium, a web of threadlike hyphae that grow underground or colonize a substrate, such as dead wood or cardboard. The mycelium excrete enzymes which break down complex substances into simpler molecules.
Mushrooms can also uptake heavy metals into their fruiting bodies. Different mushrooms are effective with different metals. However, it is easier to grow plants than to inoculate substrate and produce mushrooms.
A short list of fungi we are using or hoping to use:
Oyster mushrooms (Pleurotus ostreatus)—effective at breaking down diesel range organics and PAHs.
Turkey tails ( trametes versicolor) –effective at breaking down organochlorines.
Paul Stamets. Mycellium Running. Berkeley, Ten Speed Press, 2005
To learn permaculture, effective activism, and magic with Starhawk and co-conspirators Erik Ohlsen, Penny Livingston-Stark and Charles Williams, see information on Earth Activist Training.
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