Biodegradable local fire suppressant

Biodegradable local fire suppressant

Below is a starting laboratory formula for pilot testing. It is not intended for direct use on a wildfire until toxicity, corrosivity, stability, and effectiveness have been tested and the necessary permits have been obtained.

1. Recommended base formula

Composition of the finished working mixture

Target pH

7,5–9,0

The composition should not be highly alkaline, as this increases the risk of damage to plants, skin, equipment and soil biota.

2. Why potassium bicarbonate was chosen

Potassium bicarbonate is a more suitable candidate than a chemical oxygen scavenger.

When heated it:

absorbs some of the heat;

forms water vapor;

releases carbon dioxide;

creates potassium-containing particles;

interferes with radical flame reactions.

NIST research shows that potassium-containing compounds have a significant flame-inhibiting effect, and potassium bicarbonate has historically proven to be more effective than its sodium counterpart in dry powder extinguishing systems.

Simplified thermal decomposition reaction:

2 KHCO₃ → K₂CO₃ + CO₂ + H₂O

However, the released CO₂ should be considered a supplemental, rather than primary, extinguishing mechanism. On an exposed slope, the gas is quickly dispersed by the wind.

3. Why is the concentration of KHCO₃ limited?

Increasing bicarbonate levels does not always increase effectiveness proportionally.

Excessive concentration may cause:

crystallization;

precipitation;

clogging of injectors;

increasing electrical conductivity;

burns of sensitive vegetation;

soil salinization;

high cost;

corrosion problems.

For initial testing, it is reasonable to start with3%, then compare options4% and 5%.

4. Biodegradable matrix

Main thickener

Hydroxyethylcellulose or carboxymethylcellulose is preferred.

It must ensure:

water retention on vertical vegetation;

slow flow;

stable spraying;

absence of long polymer threads;

the possibility of washing the equipment with water.

Xanthan gum

Used in small doses for:

preventing kaolin precipitation;

stability of the mixture during storage;

maintaining viscosity under mechanical stress.

Too high a concentration will make the mixture unsuitable for drone injectors.

5. Mineral protection block

Kaolin

After some of the water evaporates, it leaves a light mineral layer.

Functions:

reduction of direct heating;

limiting contact of fuel with air;

reducing surface flammability;

visual control of application.

Vermiculite

Vermiculite is able to retain water between layers and form a heat-insulating residue.

Its quantity should be limited because it:

increases viscosity;

has an abrasive effect on the pump;

may settle;

requires nozzles with increased flow area.

6. Wetting agent

Dry needles, leaves and bark are often difficult to wet with ordinary water.

The wetting agent must:

reduce surface tension;

help water penetrate into the litter;

improve the coating of wax leaves;

work at very low concentrations.

Requirements:

PFAS free;

absence of fluoride;

low acute aquatic toxicity;

rapid biodegradation;

absence of persistent metabolites;

absence of strong foaming in the tank.

Important: The designation "fluoro-free" does not necessarily mean environmentally safe. The EPA notes that some fluoro-free foams contain high concentrations of hydrocarbon surfactants, which can also be toxic to aquatic organisms and mammals.

7. Three recommended experimental versions

Formula A — DREVO BioFire Mist

For quick extinguishing of grass and small surface fires.

Features:

low viscosity;

suitability for medium drop;

fast wetting;

minimum mineral residue;

relatively low salt load.

Formula B — DREVO BioFire Gel

The main recommended version.

Purpose:

application to dry grass;

protection of shrubs;

processing of rainwater;

creation of a temporary wet strip;

suppression of re-ignition.

Formula C — DREVO BioFire Eco-Light

For sensitive natural areas where minimal salt load is a priority.

This version will be less chemically effective, but potentially gentler on soil and vegetation.

8. Option without synthetic surfactants

For particularly sensitive areas, you can test a mixture without a surfactant:

water;

potassium bicarbonate;

hydroxyethyl cellulose;

xanthan;

kaolin;

vermiculite.

Flaws:

needles and waxy leaves are less easily wetted;

slower penetration;

possible rolling of drops;

a larger application rate will be required.

This option should definitely be included in comparative tests.

9. What is best not to include in the basic formula?

Ammonium phosphate

It is effective as a long-lasting fire retardant, but in the natural environment it creates a nitrogen and phosphorus load.

Not recommended for basic eco formula near:

streams;

springs;

steel;

drinking water catchments;

rare plant communities.

The US Forest Service separates long-term retardants, foams, and water-based enhancers and evaluates them based on separate performance and environmental risk requirements.

Chlorides

Not recommended due to:

corrosion;

salinization;

impact on vegetation;

high electrical conductivity.

Borax and boric acid

They can suppress combustion, but are phytotoxic when applied in large quantities and can accumulate in the soil.

Sodium silicate

Creates a good mineral layer, but:

highly alkaline;

may damage vegetation;

harden quickly;

block equipment;

add sodium.

PFAS-containing components

Should be completely excluded from the concept due to sustainability and environmental risks.

10. Technology for preparing a pilot batch

Mixing order

Fill the tank with water to approximately 70–75%.

Start stirring moderately.

Slowly disperse the cellulose thickener.

Leave the mixture to fully hydrate.

Add pre-dispersed xanthan gum.

Dissolve potassium bicarbonate in a separate part of water.

Add bicarbonate solution to the main tank.

Gradually add kaolin.

Add vermiculite while stirring continuously.

Enter potassium citrate.

Add the wetting agent last.

Add water to the mixture to achieve the required weight.

Check pH, viscosity, conductivity and sedimentation.

Pass through a filter corresponding to the injectors.

Do not add dry thickener directly to the concentrated salt solution as this may cause lumps and incomplete hydration.

11. Required physical parameters

For drone application, it is necessary to establish not just the composition, but the performance characteristics.

Low viscosity version

freely pumpable;

applied with a medium drop;

does not form threads;

quickly cleans injectors.

Gel version

Must be pseudoplastic:

viscous when at rest;

liquefies in the pump and nozzle;

restores viscosity after contact with the surface.

Key tests:

dynamic viscosity;

yield strength;

restoration of structure;

particle size;

sedimentation rate;

foaming;

freezing and thawing.

12. Nozzles and filtration

For a mixture with kaolin and vermiculite you will need:

diaphragm or chemically resistant pump;

continuous slow stirring;

increased nozzle channel diameter;

a filter that does not remove the useful mineral component;

backwash system;

separate flush water circuit.

Too fine an aerosol is not recommended:

the wind will carry it away;

some of the water will evaporate into the air;

mineral particles can enter the respiratory zone;

the coating will be uneven.

For slopes, a directed medium or large drop is preferable.

13. Possible application rate

The exact standard can only be determined through fire tests.

For initial comparative tests, you can explore:

light coverage;

medium coverage;

complete wetting of the surface;

re-apply after partial drying.

It is important to measure not only liters per hectare, but also:

mass of the product per square meter;

mass of KHCO₃ per square meter;

wet layer thickness;

water retention duration;

percentage of surface covered.

14. Mandatory laboratory series

Series 1. KHCO₃ concentration

0%;

1,5%;

3%;

4%;

5%.

This will show how much the chemical additive improves the result compared to the gel alone.

Series 2. Thickener

0,2%;

0,35%;

0,5%;

0,7%.

Series 3. Mineral residue

without minerals;

kaolin;

kaolin + vermiculite.

Series 4. Wetting agent

without surfactants;

minimum concentration;

double concentration.

15. Fire test indicators

For each composition the following are measured:

open flame cessation time;

maximum temperature;

cooling rate;

mixture consumption;

penetration depth;

water retention duration;

re-ignition after 5, 15, 30 and 60 minutes;

smoke formation;

residual smoldering;

surface condition after drying.

The following are tested separately:

dry grass;

pine;

leaves;

shrub branches;

wood;

forest litter;

smoldering stump.

16. Environmental testing

Before using in nature, it is necessary to check:

acute aquatic toxicity;

impact on algae;

impact on invertebrates;

germination of local seeds;

root growth;

soil respiration;

microbiological activity;

soil electrical conductivity;

pH change;

potassium leaching;

oxygen consumption during thickener decomposition.

Even qualified fire-fighting chemicals can pose a risk to aquatic organisms if concentrate or large volumes of the working mixture are released directly into a small watercourse.

17. Final recommended starting formula

For the first laboratory prototype it is proposed:

WOOD BioFire Gel P1

water —91,5%;

potassium bicarbonate —4,0%;

hydroxyethyl cellulose -0,4%;

xanthan gum -0,1%;

kaolin —2,5%;

micronized vermiculite -0,8%;

potassium citrate —0,65%;

fluorine-free wetting agent -0,05%.

Total amount:100%.

This is not a finished certified product, but a reasonable starting point for research.

The final principle

The most promising composition is not a substance that tries to absorb oxygen from the open atmosphere, but an aqueous biodegradable gel with a limited amount of potassium bicarbonate and mineral filler.

It must act through:

rapid cooling;

deep wetting;

water retention;

localized release of steam and CO₂;

flame chemistry inhibition;

formation of a temporary mineral coating;

preventing re-ignition.

Before field use, the composition must undergo independent fire, toxicological, environmental and technical tests.

WOOD BioFire HydroGel

Biodegradable hydrogel for localized wildfire suppression and vegetation protection.

Basic principles

Unlike ordinary water, hydrogel:

holds 20-100 times more water by its own weight (depending on the polymer system chosen);

evaporates more slowly;

adheres to leaves, needles and wood;

gradually releases moisture;

reduces surface temperature;

reduces the risk of re-ignition;

After decomposition, it should not leave any persistent plastic particles.

Proposed concept of composition

1. Water (90–97%)

The main fire extinguishing component.

Functions:

cooling;

evaporation;

impregnation of vegetation;

hydrogel nutrition.

2. Biodegradable hydrogel (1–3%)

The basis of the system.

Promising materials:

carboxymethylcellulose (CMC);

hydroxyethyl cellulose (HEC);

sodium alginate;

pectin;

xanthan gum;

guar gum;

other natural polysaccharides.

The best option might behybrid systemmade from several biopolymers, providing good water retention at an acceptable viscosity.

3. Mineral thermal insulation component (0.5–2%)

For example:

kaolin;

micronized vermiculite;

bentonite.

Purpose:

reducing heating;

surface protection;

water retention.

4. Potassium block (0.5–2%)

Instead of large amounts of salts, it is better to use moderate amounts of potassium compounds, such as potassium bicarbonate.

It provides additional flame suppression while maintaining the primary role of water and hydrogel.

5. Biological wetting agent (0.02–0.1%)

To improve penetration into dry litter.

Requirements:

PFAS free;

rapid biodegradation;

minimal toxicity to aquatic organisms.

How it works

Stage 1

The gel covers the vegetation.

Stage 2

Water quickly cools the surface.

Stage 3

The hydrogel retains the remaining moisture.

Stage 4

When heated, water gradually evaporates, absorbing a large amount of heat.

Stage 5

Mineral components reduce reheating.

Stage 6

After rain and under the influence of microorganisms, the hydrogel gradually decomposes.

Additional benefits

This composition can be used not only during a fire.

It is suitable for:

protection of young forest crops;

firebreak treatment;

protection of individual trees;

reducing soil drying out;

support of mosses and lichens;

transportation of beneficial microorganisms.

Version for the DREVO project

WOOD BioFire HydroGel Forest

For forests.

thicker;

better adherence to needles and trunks.

WOOD BioFire HydroGel Grass

For grassy slopes.

less viscous;

quickly covers a large area.

WOOD BioFire HydroGel Drone

For spraying by drones.

Peculiarities:

low viscosity for pumps;

no sedimentation;

vibration stability;

adjustable drop size.

WOOD BioFire HydroGel Root

To protect young plantings.

Works simultaneously as:

fire protection;

moisture accumulator;

means of reducing watering.

Prospective development

The most interesting direction may beLiving HydroGel— a biodegradable matrix that, after the fire is extinguished, not only disappears but becomes a carrier for ecosystem restoration. It could potentially include:

spores of mycorrhizal fungi;

nitrogen-fixing and soil-forming bacteria;

seeds of local grasses and mosses;

growth biostimulants of natural origin;

wood biochar (biochar) in finely dispersed form.

In this case, after the fire is extinguished, the hydrogel gradually becomes part of the soil and promotes its restoration, combining fire protection and environmental restoration. This fits well with the project's philosophy.DREVO Living Mountains, where each engineering system must simultaneously reduce risks and accelerate the restoration of the natural environment.

DREVO Cloud & Mist System