Leachate pumps are important to protect the environment from leachate escape into groundwater, from which it could get into water supplies. If a leachate pumping system is inadequate to remove all of the leachate over a period of time, modern landfills which are lined (sanitary landfills) begin to fill-up with liquid, the weight of the liquid puts a positive leakage (outward) pressure on the base lining of the landfill. This both increases the danger of a bottom liner failure, and produces a finite (low) outward liquid flow through the base liner, which although of very low permeability does allow some water to pass through.
Multiply that over the typically huge areas of modern landfills and the amount of flow and the consequential pollution in the water would be likely to be significant amount. That is why any fluid inside a landfill of more than a nominal 1 metre depth is a potential source of pollutant emissions.
It is well known that leachate collection systems and the pumps which drive flow through them and out for disposal can lose their flow capability through a variety of causes. Organic material can silt the pipes up, sand and stones may enter due to landfilling operations, and on occasions they may scale-up up quite rapidly with “calcite" which forms a rock-like deposit, which can be very hard to break-up and jet out of leachate pipes. When pipe flows reduce such that they put a sufficiently large back-pressure, the leachate pumps fail to remove enough of the collected liquid fluid leachate builds up within landfills.
If this is allowed to continue, leachate containment will eventually be lost. When that happens unsustainable leachate leakage will occur. Leachate will escape with potentially toxic effect, and even below the toxic level escape of leachate would have serious consequences on the environment. Leachate is heavily polluted and potentially contains a great many chemicals and micro-organisms (including pathogenic bacteria and billions of minute viruses).
To meet the demanding requirements of modern landfills many leachate pump manufacturers have grown up around the world over recent years to serve the industry with some of the world's most rugged pumps ever known.
In the paragraphs that follow we have listed a number of suppliers with an excerpt from their websites to help explain their leachate pump systems and services offered to the landfill industry:
"A wide variety of electric pump types are used, all must be suitably corrosion protected to a high standard, and non leachate compatible materials avoided. By far the most common are the explosion proof (ATEX zone rated) submersible large solids particle size passing “sewage” type pump types.
The types of electrical pumps used include progressive cavity borehole pumps, multistage submersible pumps, high head dual impeller multistage pumps, explosion proof pumps (inherently safe in explosive landfill gas mixtures).
The web site of specialists Viridian Systems gives a list of the types of electric pumps used in leachate pumping on their web site at:Read more here.
The ATZ Leachate Extraction Pump is a simple, robust solution to landfill leachate problems... The ATZ Leachate Extraction Pump is a positive-displacement piston pump that can be retrofitted into the existing gas well infrastructure. The pump can also be used for condensate knock-out chambers, whether under pressure or vacuum. The pump’s mechanical linkage converts the rotary motion of the DC electric motor to a reciprocating motion of the piston at the foot of the pump. This piston assembly is highly tolerant to particulate matter common in landfill fluids. The pump is also available with a solar-powered drive system which eliminates the need for a source of electrical power at the gas well. Additionally, we also offer a manually operated drive option.Read more here.
Pneumatic positive air displacement leachate pump for harsh liquids in the landfill, brownfield, petrochemical and remediation industries. AP2, AP3 and AP4.Read more here.
The SRX is an air-powered pump used to extract leachate or gas condensate at variable rates equal to the well recharge. Pump flow rates are up to 9.5 gpm at temperatures up to 250°F.Read more here.
It’s pretty common to find buildup inside landfill well casings caused by minerals found in typical landfill leachate. But when industrial sludge or industrial remediation waste is placed in a landfill, the buildup may be accelerated and intensified.Read more here.
So what to do? The short version: If you are getting buildup and the leachate pH is within the range of 4-9, you may be able to get by with silt filters and Teflon®-coated floats, but if you have more drastic changes in pH, or temperatures above 160 °F, you’ll probably have to treat it with acid or bromides. When it’s neutralized, you can revert back to floats and silt filters.
EPG offers a variety of sump drainers, one of which is the SURE PUMP. The sump drainers are stainless steel construction, corrosion resistant, sealed unit with liquid flow drawn past motor for cooling. EPG offers the Sure Pump which offers an innovation that is patented and accurate for level sensing. This leachate pump is used by professionals worldwide. There are horizontal, vertical and TSP Submersible Sump Pump Drainers.Read more here.
The main features of the SPP ACTIVE range are quality and simplicity. SPP leachate pumps are manufactured from 304 Stainless Steel. They work without any bubblers, external controller or bleeders, utilising a simple twin valve control within the pump to regulate air pressure, fluid collection and discharge.Read more here.
For total fluid recovery, bottom and top loading pumps are available. For targeted LNAPL recovery, skimmers can be supplied with SPP2 or SPP3 ACTIVE pump bodies.
An alternative to leachate pumps is a unit known as an eductor, or ejector. This unit is positioned within and close to the base of the borehole. It is connected to a surface mounted pump which in turn controls up to ten individual eductors.
The advantages of units such as these are: firstly, they are lightweight and streamlined for use within relatively narrow boreholes, secondly, there are no moving parts and thirdly they are relatively inexpensive. Eductors operate by circulation of water within a semi-closed system through a venturi located within the body of the eductor. This creates a pressure differential within the bottom of theborehole and causes leachate to be sucked through the eductor to the surface.
Value-giving proven performance ... renowned air-powered, ATEX Zone 0 certified AutoPumps. The improvements extend the service lifetime of the pump and broaden the range of its applications in extreme environmental conditions in landfill and remediation. Bottom or top-fill, the 9.1cm diameter submersible pumps are from 70 cm to 131 cm long and offer a maximum flow of 26.5-69 l/m at depths of 76m with actuation levels from 39-113cm depending on model.Read more here.
Integrated Environmental Technology installs and performs warranty work on a large range of landfill leachate pumps. Our pneumatic landfill leachate pumps are selected from reliable landfill pump suppliers to support our long-term fixed landfill leachate pump maintenance contracts that our clients cherish.Read more here.
We also supply and service methane gas condensate pumps that are cost effective, certified, automatic and reliable. Since our methane gas condensate pumps are self-regulating, they require no external form of actuation.
The Megator self priming positive displacement sliding-shoe pump provides exceptional suction performance, versatility, and the ability to pump at constant capacity against heads to 246 ft (75m). It can run without harm during dry suction, is self compensating for wear, has a simple design with few working parts and single cover access. It might be said to resemble a reciprocating piston pump, and it has indeed all the well known merits of that type - powerful suction and self priming, constant capacity at varying heads, the ability to cope with rough conditions and to handle a great variety of liquids, viscous or free flowing, clean or dirty. Yet in its simplicity, compactness and even flow it more closely resembles the centrifugal pump. It therefore combines the advantageous features of both these two main pump types without their respective limitations.Read more here.