ENVIRONMENTAL AWARENESS The rules on pumping contaminated water
The control of leachate is a vital component in preventing contaminated water from entering groundwater and the water supply. Mike White, an expert in groundwater extraction at QED Environmental, looks at the issues involved in pumping contaminated water and offers a number of potential solutions
extreme temperatures with frequent start-stops and can cope with high pH levels along with suspended or dissolved solids and with corrosive and aggressive chemicals. Being ATEX certified, there is no explosion hazard and can cope with varying liquid levels and flow rates while in operation, ultimately being capable of pumping up to 45 litres per minute.
Poor leachate handling can lead to breaches of environmental regulations, have a negative impact on operational effectiveness and potentially damage expensive equipment. The worst cases can lead to very significant fines.
When calculating the flow rates with AutoPumps various factors need to be taken into account, including flow rate, static/TDH head, inside diameter of the discharge hose, air inlet pressure and the level of submergence of the pump fluid inlet.
All in all, AutoPumps can provide a very T
he national and international standards now in place to control the leakage of toxic and dangerous substances into groundwater have created an extraordinarily strict environment
for businesses to work in.
Poor leachate handling can lead to breaches of environmental regulations, have a negative impact on operational effectiveness and potentially damage expensive equipment. The worst cases can lead to very significant fines. Leachate has a number of characteristics. Firstly, different sites will create different amounts of leachate depending upon the type of operation. Traditionally, leachate is associated with landfill sites, where leachate results from atmospheric precipitation, waste breakdown, and discarded fluids as part of methane gas production.
The type and volume of liquids that need to be pumped can be highly variable and can contain a wide mix of contaminants. What’s more, leachate often has elevated temperatures, as a result of the landfill or silage process for example, and high levels of suspended and dissolved solids that can give rise to foaming, high viscosities and extreme pH values. In short, it can be a corrosive and aggressive substance that can endanger people and equipment. There are a number of reasons why it is important to pump leachate safely as part of a water treatment process. Strict rules govern the monitoring, pumping, collection and treatment of leachate, in order that contaminants are removed from the fluid, which can then be returned to the watercourse. Critical in this process is pumping and there
are three common types of pumps used, namely electric submersible, automatic pneumatic and piston.
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Electric pumps have some advantages, namely widespread familiarity and availability. Their main advantage is that they are low cost and develop a high flow, but there are also disadvantages associated with this type of pump. Specifically, they are mostly designed and are warranted for clear, cool water pumping. Most are non-ATEX certified but are classed as safe as long as the pump motor is totally saturated in the borehole. From an operational standpoint, a power supply has to be installed, but that does mean there is a heightened electrocution risk with the power cables.
Maintenance can also be an issue. The close tolerance impellers can be prone to clogging, and other failures, to the motor for example, can be expensive to repair and get back up and running. The alternative is an air-powered automatic pump, a simple high clearance design for solids handling that has to be highly effective in extreme pumping conditions. The air-powered automatic pump is an explosion-proof solution for a safer mode of operation and the pumps are often equipped with a soft failure mode to simply flush solids out. However, again there are disadvantages. Air- powered automatic pumps have limited flow rates, circa 15 gallons per minute and the air to liquid contact can aid precipitation in pipework. A better alternative is AutoPumps, which are specifically designed for the most challenging and difficult conditions combining both reliability and safety.
AutoPumps are suitable for extreme pumping conditions, specifically those which are dealing with corrosive fluids, land remediation, solvents, clean-ups and with fluids containing suspended solids, silts and high viscosities. They also have the advantage of being able to operate at
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reliable solution for total fluids handling applications. My advice would be to seek expert guidance on the type of pump best suited to your application and that should include whether ATEX certification is required along with flow rates and other variables.
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