ENV · Landfill leachate
Landfill leachate treatment
High COD, persistent nitrogen, colour and a load that changes with the weather. Leachate needs a train designed for variability, not a standard effluent plant.
Overview
Overview
Landfill leachate is one of the most difficult effluents an operator can be handed. It is high in COD and ammoniacal nitrogen, carries heavy metals and colour, varies enormously with rainfall and with the age of the cell, and has to be treated to a consent standard that was usually written without much regard for how variable it is.
Conventional biological treatment alone rarely holds. The load swings, the nitrogen is persistent, and the recalcitrant organic fraction simply passes through. What works is a train built for variability: buffering and pre-treatment, biological removal of what is biodegradable, membrane separation to concentrate what is not, and a polishing stage that deals with the residual COD, colour and trace contaminants.
Where discharge is not available at all — a common situation on remote or closed sites — concentration and evaporation take the volume down to a manageable residue, and the recovered water becomes a resource rather than a liability.
Detail
A treatment train built for variability
Buffering and pre-treatment
Equalisation to absorb rainfall-driven swings, followed by physical and chemical pre-treatment to remove suspended solids and the fraction that would otherwise foul everything downstream.
Biological treatment
Removal of the biodegradable COD and nitrogen load. Membrane bioreactor configurations are frequently the right answer here because they hold biomass independently of settling, which is what fails first when the load swings.
Membrane separation
Ultrafiltration, nanofiltration and reverse osmosis to separate the treated water from the concentrate. Recovery is set by what the consent allows you to do with the reject.
Polishing
Adsorption for residual COD, colour, heavy metals and ammoniacal nitrogen, and advanced oxidation for trace organics that survive everything upstream.
Concentrate management
Where no discharge route exists for the reject, evaporation and crystallisation reduce it to a solid. Where a limited discharge is permitted, minimum liquid discharge is usually the better commercial answer.
Detail
Capabilities that matter on leachate
Adsorbent systems
Up to 90% COD removal without electricity, taking COD to 50–70 ppm; heavy metals including up to 99.5% of lead; cyanide, pesticides, ammoniacal nitrogen and colour. Regenerable on site for hundreds of cycles.
Read moreAnaeroMBR
Where the organic load is high enough to be worth capturing, anaerobic membrane treatment converts it to biogas rather than spending electricity to destroy it.
Read moreAdvanced oxidation
On-site hydrogen peroxide with UV activation for trace organic contaminants, with no bulk chemical deliveries to a remote site.
Read moreZero liquid discharge
Where the site has no discharge route at all, evaporation and crystallisation close the balance and produce a handleable solid.
Read moreApplications
Applications and challenges
Where it applies
- Active landfill cells with rainfall-driven flow variation
- Closed and capped sites with long-term aftercare obligations
- Municipal landfills discharging to a sewer under trade effluent consent
- Remote sites with no discharge route and no chemical delivery access
- Hazardous waste landfills with metals and recalcitrant organics
- Leachate lagoons requiring drawdown before a site can be closed
Common challenges we are asked to solve
- COD that biological treatment cannot reduce far enough
- Ammoniacal nitrogen above consent after full biological treatment
- Flow that trebles after heavy rain and collapses in summer
- Colour that fails a visual consent condition on its own
- Membrane concentrate with nowhere to go
- Chemical deliveries that are impractical at the site location
FAQ
Frequently asked questions
Can leachate be treated to discharge standard reliably?
Yes, provided the train is designed for the variability rather than the average. The failures we are asked to fix almost always come from a plant sized on a mean analysis that never occurs in practice.
What do you do with the membrane concentrate?
It depends on what the site is permitted to do. Where a limited discharge is available, minimum liquid discharge keeps the concentrate volume small and is the cheaper answer. Where there is no discharge route, evaporation and crystallisation reduce it to a solid residue.
Is on-site oxidant generation practical at a landfill?
It is often the strongest argument for it. On-site hydrogen peroxide generation needs only water, air and electricity, which removes chemical deliveries, bulk storage and handling exposure from a site where all three are awkward.
How long does it take to design a leachate plant properly?
The design is quick; the data is not. We want at least a full seasonal cycle of flow and quality data, or a sampling campaign that credibly stands in for one. Anyone quoting firm without it is transferring risk to you.
Evidence
Projects
Sample layout. Reference projects are being cleared for publication with the clients concerned. The structure below is final; the content is placeholder.
SampleWater reuse retrofit — sample card
Card layout for a completed water reuse project: stream data before and after, recovery achieved, scope Glorinda held, and the client's own words.
SampleZLD package — sample card
Card layout for a zero liquid discharge package: feed characterisation, evaporator type selected, solid output route, and commissioning duration.
SampleOwner's engineer mandate — sample card
Card layout for an advisory mandate: the client's decision, the options assessed, and what changed in the tender as a result.
Conversion
Take this further
Send us the stream data, the discharge limit or the equipment list you are working from. An engineer reads every enquiry and replies with the questions that actually decide the solution — not a brochure.
Contact
Talk it through with an engineer
Send the constraint you are designing around and we will tell you what is realistic before anyone writes a specification.