Landfill Leachate Treatment
The treatment for landfill leachate can vary depending on the different discharge requirements and contaminant components.
Leachate is characterized by a series of contaminants including dissolved solids (TDS), high biological oxygen demand (BOD) and/or chemical oxygen demand (COD), high ammonia, color and heavy metals. These all factor into possible discharge options.
Discharge options for leachate include discharge to groundwater or surface water when there is no access to a sewer available, or discharge to publicly owned treatment works (POTWs). Treatment requirements are much greater when leachate is discharged to ground water or surface water opposed to discharging to POTW.
When discharging leachate to ground water or surface water the removal of BOD/COD, ammonia, color, heavy metals and quite possibly TDS will all be required.
However, when you discharge leachate to a POTW, the removal of these components may not all be necessary. The removal of ammonia and heavy metals may be required along with the removal of some BOD or COD. Some permits may also include color and TDS removal though it’s not typical.
Leachate Treatment Options
There are different leachate treatment options that we can provide to you, one being the Membrane Bioreactor (MBR). This is a process where an aerated biological mixed liquor process operates at in very high solid concentrations.
Advantages to the Membrane Bioreactor (MBR)
- Older sludge produces a well acclimate biomass and provides a high reaction rate due to high concentration (approx. 12,000 to 20,000 mg/l)
- Exceptional nitrification and de-nitrification
- Smaller footprint than traditional aerated systems
- Use of membranes for final clarification leads to high quality effluent (runoff)
- Less sludge production than traditional systems
The leachate effluent from this process is distinguished by low contaminates including BOD, heavy metals, ammonia, little remaining color and high dissolved solids. The Membrane Bioreactor system also produces bio-sludge which can be, depending on requirements, disposed of as liquid sludge or further dewatered for disposal.
Other Leachate Treatment Methods
Reverse osmosis (RO) is an alternative method to treat leachate. This generally applies to smaller flows. Reverse Osmosis removes both inorganic and organic contaminates and color. There are several different configurations for this kind of membrane available to accommodate for different levels of suspended solids. When high solids are present, the use of tubular reverse osmosis membranes is ideal. When lower solids are present, a narrow channel configuration can be taken into account.
The two effluent streams for a RO system are RO permeate and a concentrate stream that represents approximates between 10% – 30% of the feed flow. Normally, this can be reintroduced into the landfill.
A final treatment system configuration available when high levels of treatment are desired is the Membrane Bioreactor followed by Reverse Osmosis. The Membrane Bioreactor ensures the highest possible levels of organic removal, with virtually zero suspended solids in the effluent. This is the ideal feed system for the Reverse Osmosis leachate treatment. The RO permeate can continue on to be used for other non-potable purposes including irrigation, truck washing and dust control.
Leachate Treatment Summary
- The Membrane treatments offer reliable and consistent control of landfill leachate
- Membrane Treatment has been applied in both nationally and internationally and is well proven
- The systems are both cost effective and require low operator interface
- System configurations for each method are individually assessed