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  • Rob Furness

The Environmental Hazards of Landfill Leachate, and How it Can be Remedied.

Updated: Apr 3

Whilst modern landfills are designed with robust containment systems, the reality is that landfill sites inevitably produce leachate - the liquid that drains or 'leaches' from a landfill. This leachate can contaminate groundwater and surface waters if not properly collected and treated.

Let’s briefly overview the hazardous substances commonly found in landfill leachate and the consequences of their uncontrolled release into the environment.


The biological degradation of nitrogenous substances such as proteins and amino acids present in municipal solid waste forms ammonia. High ammonia levels make leachate extremely toxic to aquatic life if discharged untreated into water courses. Excessive ammonia can also lead to eutrophication, depleting oxygen levels and creating 'dead zones' uninhabitable for aquatic flora and fauna.

Volatile Organic Compounds (VOCs)

These carbon-based chemicals like benzene, toluene and chlorinated solvents evaporate easily at room temperature. They are toxic, carcinogenic, and hazardous even at minute concentrations in leachate or emissions. VOCs directly poison aquatic organisms and disrupt their metabolic, reproductive, and immune systems.

Heavy Metals

Heavy metals such as mercury, cadmium, chromium, and lead are significant pollutants in leachate. These metals are highly toxic, non-biodegradable, and persist in the environment, bioaccumulating through the food chain. Exposure can cause genetic mutations, birth defects and metabolic dysfunctions in aquatic life.

Persistent Organic Pollutants (POPs)

POPs like dioxins, PCBs, certain pesticides, and plastics degrade extremely slowly. They bioaccumulate and bio-magnify through the food chain, with top predators facing the greatest exposure risks. POPs are linked to cancers, reproductive deficits and endocrine disruption in fish, birds, and mammals.

Hydrogen Sulphide

Landfill leachate and gases also have hydrogen sulphide (H2S), formed from anaerobic bacterial breakdown of sulphur-containing organic matter. This flammable, corrosive gas has a characteristic rotten egg odour. Even low-level H2S exposure causes respiratory issues, while higher concentrations rapidly become toxic and potentially fatal to humans and wildlife.


Anaerobic decomposition produces significant quantities of methane, a potent greenhouse gas. Uncontrolled venting poses explosion risks on site but also contributes to climate change and atmospheric warming.

Ecological Impacts of Untreated Runoff

If allowed to seep untreated into streams, rivers, marshes or coastal waters, the hazardous substances in landfill leachate can devastate aquatic ecosystems. Heavy metals and POPs accumulate in sediments, biomagnifying through the food web to affect top predators. Ammonia, nutrients and organic matter trigger eutrophication and excessive algal blooms that deplete oxygen, creating dead zones.

Of particular concern are blooms of cyanobacteria - the blue-green algae that can produce toxins like microcystins, cylindrospermopsins and anatoxins. When cyanobacteria flourish in nutrient-rich, warm waters, these toxins accumulate in the algal mats. Consuming water contaminated with toxic cyanobacteria can cause liver damage, neurotoxicity, gastrointestinal illness, and even acute fatal poisoning in humans.

Dogs are especially vulnerable due to their tendency to drink from stagnant ponds or lakes with algal blooms. Exposure to cyanobacterial toxins can rapidly cause severe neurological and liver dysfunction in canines. Dogs have died within hours from liver failure after ingesting toxic cyanobacterial blooms proliferating in eutrophic waters contaminated by landfill leachate.

Livestock like cattle, sheep and horses can also be affected by drinking from or grazing near waters contaminated by cyanobacterial blooms. Ingestion of the toxins leads to illness with symptoms like excessive salivation, diarrhoea, weakness, and photosensitization. Severe cases result in liver failure, respiratory paralysis, and death of the animals.

Cyanobacterial toxins not only present ingestion risks but also pose hazards from inhalation exposure. If toxic cyanobacteria become aerosolized and airborne, inhaling them can cause asthma-like symptoms including chest tightness, coughing, and wheezing in humans. More serious inhalation exposure to elevated levels of cyanotoxins may potentially lead to pneumonia, and liver, or neurological damage. Protective equipment like respirators may be needed for workers in affected areas with airborne cyanobacteria.

Directly toxic components like VOCs, phenols and cyanides are acutely poisonous to fish, plants, microorganisms, and bottom-dwelling species - disrupting fragile freshwater and marine habitats. Their presence in water bodies leads to genetic mutations, birth defects, immune dysfunction, and mass die-offs of aquatic life.

The Necessity of Containment and Treatment

To safeguard environmental and public health, responsible management of landfill leachate via robust containment, collection and treatment is of paramount importance. Effective maintenance of impermeable liners, leak detection systems and leachate collection infrastructure is essential to prevent uncontrolled discharges.

Leachate must undergo proper treatment using chemical-based and physical separation techniques like air stripping, chemical oxidation, activated carbon and membrane filtration to remove VOCs, heavy metals, and recalcitrant organics. Biological treatments like aerobic digestion may also be useful in breaking down ammonia and organic compounds before safe discharge within strict regulatory limits.

For landfill gases, rigorous capture and flaring or energy recovery systems are crucial to destroy or use methane, VOCs, and other harmful air pollutants rather than venting them. Oxidation processes may also be needed to scrub hydrogen sulphide and convert it to safer sulphur compounds. Enzymatic processes can break down the bacteria before methane can be produced if the waste is treated as soon as it enters the landfill.

Robust environmental regulation, enforcement and investment in proper collection, containment and treatment infrastructure is essential. This is the only way to effectively prevent contamination from the hazardous substances in landfill leachate and protect vulnerable watersheds, wetlands, and coastal habitats from permanent harm.

Mitigating Risks with Enzyme Disinfectants


Whilst robust containment and treatment of leachate is essential, accidental leaks or runoff incidents can still occur at landfill sites. Enzyme-based disinfectants provide an effective remediation approach to mitigate the hazardous impacts of such events.

Enzyme disinfectant products have specialised blends of microbial enzymes and cultures that rapidly degrade a wide range of organic pollutants in leachate - including toxic VOCs, phenols, ammonia, and nitrogen-based compounds. Their microbial formulations are particularly adept at digesting recalcitrant compounds like PCBs, dioxins and other persistent organic pollutants that resist conventional treatments.

The enzymes essentially 'unlock' these stable molecules, allowing the microbial cultures to metabolise them through biodegradation processes. Application is simple - the disinfectant solutions are sprayed or misted over affected land areas and waterways contaminated by leachate runoff. As the microbes and enzymes proliferate, they detoxify sites through rapid biodegradation of pollutants.

This bioremediation approach uses natural processes to neutralise a diverse array of hazardous leachate components simultaneously, without harsh chemicals. Enzyme treatments target the full spectrum of organic contaminants that conventional methods cannot remediate effectively.

Crucially, enzyme disinfectants can also remediate toxic cyanobacterial blooms caused by nutrient overloading from leachate runoff. The microbes and enzymes break down and digest the cyanobacteria, removing the toxins while converting the biomass into a nutrient-rich food source that helps the aquatic ecosystem. Rather than causing dead zones, the remediated algae support fish populations, and other aquatic life.

Implementing enzyme disinfectant programs provides landfill operators with a comprehensive solution to mitigate odour issues, safeguard surrounding environments from harmful runoff events, and revitalise impacted waterways. These microbial products rapidly remediate accidental releases through environmentally friendly biodegradation technology.

Starting to use enzyme disinfectants, means the waste management industry can ensure compliance, protect environmental and public health, and prove their commitment to sustainable, effective remediation of landfill leachate incidents. This proven solution cuts hazardous leachate pollutants while avoiding legacy contamination issues - a win-win for communities, aquatic ecosystems, and the environment.

Further reading can be found here in the follow-up article about methane

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