Rescue Earth System
Bioremediation LID Systems
We need to collaborate globally, regionally, and locally at an unprecedented scale to create “elegant solutions carefully adapted the the uniqueness of place” (John Todd). To do so, we need to do more than just learn from nature, we need to design as nature, and that means changing the human impact on Earth from being predominantly degenerative to being regenerative.
Biostimulation, Bioaugmentation & Adsorption
To be most effective, it is sometimes necessary to help the Bioremediation process get going. Local soils may lack microbial diversity and compost is often not a good enough inoculant for certain pollutants. Biostimulation and Bioaugmentation are used in areas that require additional measures to degrade pollutants.
Biostimulation involves the modification of the environment to stimulate existing bacteria capable of bioremediation. This can be done by addition of various forms of rate limiting nutrients and electron acceptors, such as phosphorus, nitrogen, oxygen, or carbon (e.g. in the form of molasses).
Biological augmentation is the addition of archaea or bacterial cultures required to speed up the rate of degradation of a contaminant. Organisms that originate from contaminated areas may already be able to break down waste, but perhaps inefficiently and slowly.
Adsorption is the attachment or adhesion of atoms, ions and molecules (adsorbates) from a gaseous, liquid or solution medium onto the surface of an adsorbent — like activated carbon. The porosity of activated carbons offers a vast surface on which this adsorption can take place.
Bioremediation LID Systems
We envision implementing two key types of Bioremediation LID Systems. While both treat contaminated water — stormwater and seepage streams — one is more Urban and the other more Industrial / Agricultural in nature.
Bioremediation Systems for the removal of Urban Toxic Contaminants from Stormwater primarily as small filter addons to Rain Garden LID Systems.
Urban stormwater contains a variety of contaminants that can adversely impact receiving waters. Contaminants of greatest concern include compounds derived from road materials and car tyres, biocides, and pathogens. Low-impact development systems built to manage urban stormwater often utilize some form of engineered infiltration or subsurface filtration to reduce the volume of runoff leaving a developed site.
With improved designs based on known mechanisms of contaminant removal, engineered infiltration has the potential to provide reliable treatment of urban stormwater, resulting in a water resource that is safe for aquifer recharge or urban stream restoration.
The chemical and biological contaminants of concern in urban stormwater and the mechanisms by which they are removed during infiltration through porous media systems, including filtration, adsorption, and chemical and biological transformation.
Three Stage Filtration System
A three stage filtration system to more effectively optimise the treatment of stormwater:
Stage 1: Caged Biochar Geofabric-lined Filter Bed
Purpose: Stage 1 is primarily used to filter out and adsorb nano-particles (nano-plastics, etc.) small enough to pass through the geofabric screen and to adsorb toxic contaminants from the first flush of water. The first flush of water is often very contaminated and concentrated.
- Activated Carbon (Biochar) is effective at adsorbing chemical contaminants for several reasons. Its high surface area means it can adsorb a higher quantity of adsorbates at higher rates. Furthermore, activated carbon has a chemical affinity for many organic molecules. Activated carbon can also remove residual disinfectants such as chlorine through chemical adsorption, or “chemisorption.” This makes the product uniquely qualified for bioremediation projects.
- The Biochar we use is made from pure wood derived from sustainable forestry management practice / invader eradication projects and is produced in cogeneration or combined cooling heat and power (CCHP) systems.
- The geofabric screen allows nano-particles and toxins to pass through to the Biochar layers and filters out the larger contaminants which are washed off the geofabric cover screen by water flow so that they can be filtered by the Sand Biochar Filter Bed.
- Three sizes of Biochar are used: Powder at the bottom, small in the middle (+/- 1 mm) and medium (+/- 3 mm) on top.
- Biochar is replaced on a regular basis and the cage is refilled with fresh Biochar. Contaminated Biochar and filtrates are dumped in a landfill essentially locking away toxic compounds for hundreds of years where they can slowly degrade.
- The base of the Caged Biochar Geofabric-lined Filter Bed is lined with heavy duty plastic.
Stage 2: Sand Biochar Filter Bed
Purpose: Stage 2 is primarily used as a plant free substrate to filter out micro, small and large-particle contaminants from the first flush of water and adsorb pollutants.
- The use of sand filtration to improve water quality is not a new concept. Slow sand filtration has been used for decades to treat wastewater and purify drinking water in many parts of the globe. In this respect, sand filtration has been demonstrated to be both an economical and effective option for removing pollutants.
- Sand combined with activated carbon (Biochar) facilitates water flow and adds an additional substrate to adsorb pollutants.
- Most of the litter and leaves are washed up to and filtered by a crushed stone barrier which divides the Sand Biochar Filter Bed from the Rain Garden LID System. This makes it easy to collect and dispose of litter and leaves.
- The crushed stone barrier slows the water flow, enabling the Sand Biochar Filter Bed to also double up as a silt trap. The small-particle contaminants, clay, silt, sand and macerated litter, etc. deposited on the surface of the Sand Biochar Filter Bed, can be scraped off using a spade and dumped in a landfill.
- The base of the Sand Biochar Filter Bed is lined with heavy duty plastic.
Stage 3: Rain Garden Low Impact Development (LID) System
Purpose: Stage 3 is primarily used to biodegrade remaining organic pollutants and to use up plant nutrients from stormwater before the water infiltrates into the groundwater (aquifer recharge) or flows into urban streams.
A strong motivation to implement the rapid deployment of Rain Garden LID Systems is to mitigate the increased water flows in the local watersheds caused by impervious surfaces and reduced natural vegetation. Rain Garden LID System features are purposely designed using a combination of natural and constructed materials to facilitate bioremediation and other functions provided by natural systems.
- A rock lined water channel that feeds water to zone 1 is lined with plastic and geofabric so that the second flush of water which overflows from the Stage 2 Sand Biochar Filter Bed reaches Zone 1 Basin, the primary biological remediation area of the Rain Garden LID System
- Zone 1 the Basin
- The soil base is lined with Bentonite Clay so that water remains in Zone 1 for longer to facilitate bioremediation.
- A Clay Soil / Powdered Biochar / Peat planting medium
- Zone 1 is planted with water loving yet drought tolerant plants
- Zone 2 the Slope
- A Sandy Soil / Powdered Biochar / Compost planting medium
- Zone 2 is planted with water tolerant grasses and forbs
- Heavily mulched with Ramial Chipped Wood
- Zone 3 the Berm / Ridge
- A Sandy Soil / Compost planting medium
- Zone 3 is planted with shrubs and forbs
- Heavily mulched with Ramial Chipped Wood
Bioremediation Systems for the removal of Toxic Contaminants from Agriculture and Wastewater (sewage and industrial) using multistage bioremediation processes.
More information coming soon …
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