VSEP Case Study – Virginia, USA

Written on February 3, 2015

A landfill in Virginia has implemented VSEP systems to prevent high surcharge costs for discharging leachate water in sewer systems.  The leachate water contained higher levels of Biological Oxygen Demand (BOD) than acceptable and so incurred the surcharges.  Before installing the VSEP system the landfill tried unsuccessfully to use a dissolved air filtration (DAF) unit to pre-treat the leachate and was unsuccessful.

The treated water was only to be discharged into the sewer, so a nano-filtration (NF) system was tested and proved capable at producing permeate with less BOD, arsenic and ammonia to meet the standards.

One 84″ VSEP module was installed and able to extract 80% of the leachate as filtrate and the remaining 20% returned to the landfill as concentrate.

The location of the site experiences large amounts of rainfall and during these times the leachate is more dilute and meets the discharge requirements without treatment. Therefore the VSEP system does not need to be operated all year. The VSEP system is able to process 190 cubic metres of leachate, which is higher than other VSEP systems, but due to the more permeable NF membrane opposed to the tighter RO membrane, it produces less clean permeate.

Limitations with the NF membrane are that it doesn’t process salts and ammonia well, but is still capable of cleaning solids, biological material, hardness, bacteria and other large species. The convenience is that if necessary, the NF system can be swapped with the RO system at any time.

Many landfills in America discharge wastewater to sewer systems, but as sewage treatment facilities reach maximum capacity this will become an issue and alternatives will be needed.  VSEP systems are one solution to reduce wastewater or at least minimise the amount of contaminants in wastewater.

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