In this case the US experts have re-discovered something known to the rest of the world for years! Columns packed with high surface area media of all sorts have been found to be effective for ammonia reduction from leachate, but building plants to do that at full-scale doesn't work. Recently, for example about 10 such plants were built for Powys Council in the UK, the designs were all based upon this principle and combined with reed beds, and they are failing their discharge consent requirements, which means by definition that they are causing pollution.
None of the South Wales leachate plants built in this way has proved satisfactory and all need to be re-built based upon more reliable treatment methods. I expect that many of our readers know why this type of plant does not work reliably for sustained periods of years through all seasons and weather conditions. If you do, please give us your thoughts in the comments box below. Otherwise, your blogger feels he may be blogging to no purpose. Show me you are alive! By commenting - even if only to say; "Hi! - Why has this method of leachate treatment been found unworkable?"
Leachate, the wastewater from the Oswego County Landfill, contains too much ammonia to be sent directly to the county's wastewater treatment plant so the landfill operators were looking at a $500,000 solution."We were looking at all various systems from mechanical, electrical, removal of ammonia, all which are very expensive. And we were ready to proceed with a constructive wetland which would probably be in a half million dollar range," said Frank Visser, Oswego County Director of Solid Waste.
The constructed wetland would use bacteria to reduce the ammonia level, but instead of a wetland they are trying something different.
"The challenge is to reduce the concentration of ammonia in the leachate. We built a column, like a home for the bacteria, high surface area with a reservoir at the bottom. We use this to culture the bacteria from the natural wetland and circulate the water through it," said Dr. David Johnson, of SUNY-ESF. "What happens in this case, is the ammonia is in its reduced form, just the way carbon is in its reduced form in methane. When it gets oxidized you get energy from it, and this is what the actual bacteria is living off of. The energy comes from that oxidation."
The ammonia gets oxidized to nitrates, so the concentration of ammonia decreases and the effluent is now ready for the wastewater treatment plant. According to Dr. Johnson, people from New York and from other states are very interested because the results have been very good.
"If this system works, we hope to build a reactor to take care of the ammonia, probably in the range of $150,000 to $200,000, which would be a lot less that what a constructed wetland would cost," said Visser.
IF Dr. Johnson would like to come to Wales and meet me, I will show him why this leachate treatment process design doesn't work.
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