- Tank based Leachate Treatment system with
- AFM® filtration
applications home | technical reports | client list | Landfill leachate is one of the most difficult types of effluent to treat to a high standard. At Dryden Aqua we have been working on these systems for 20 years. We have developed SBR ( Sequencing Batch Reactors) using extended fine bubble diffused aeration and stabilised aerobic activated sludge. When the system is combined with AFM® filtration we can achieve an extremely high level of effluent treatment. Typically ammonium levels and BOD reduction will be 99%, COD reduction 90% to 95%. The AFM® system allows us to recycle the bacterial cell biomass back into the aeration tanks. The AFM® system also prevents the release of prescribed substances. The system provide by Dryden Aqua are manufactured by Dryden Aqua and are covered by International patent. Dryden Aqua are marine biologists, as part of our on-going research we are now developing wetlands at the back end of our leachate and effluent treatment systems. The wetlands are not specifically required to treat the effluent, however they offer a area of potential amenity value and serve to illustrate the green image and high performance of the leachate treatment systems. The application of a wetland can also prove to the regional Environment Agency the high level of environmental protection offered by Dryden Aqua treatment systems |  | | The system comprise of 4 x tanks. Three of the tanks are 20m in diameter by 6 m in depth. The raw leachate water enters tank 1 via an automatic valve which is controlled by both the oxygen level in the first tank and by water volume. The volume of leachate is approx. 200 cubic metres per day, at 1000mg/l ammonium and approx., 4000mg/l COD. Ammonium levels are consistently reduced to less than 10mg/l, and better than 95% COD reduction is achieved. air diffusers |  | | Dryden Aqua fine bubble diffused aeration is used to mix the water, and to provide oxygen. Fine bubble diffusers are inherently much more efficient than any form of mechanical aeration. It is essential to maintain bacterial floc stability in biological systems. Our fine bubble systems promote a stable floc as opposed to venturi systems and many mechanical system that simply shatter the bacterial colonies. The diffusers maintain a minimum dissolved oxygen level of 2mg/l in tank 1, 4mg/l in tank 2, 6mg/l in tank 3 and 95% + saturation in the discharge tank. oxygen probes |  | | Air blowers The process technology employed is sequential batch fine bubble diffused aeration incorporated stabilised nitrification. Our fine bubble air diffusers are central in achieving this task. The air is supplied to our diffusers using roots type blowers. The first part of the pipe is in steel to help reduce the air temperature. The steel pipe then connects onto MDPE pipe. The system in this report, uses 2 x 22kw blowers, each absorbing approx. 15kw of energy and delivering 1000 cubm/hr of air, with a transfer efficiency of approx. 20% which equates with approx. 1400 Kg of oxygen per day. |  | | AFM® filtration The aeration system is helping to provide the right conditions for the bacteria to treat the effluent. It is therefore very important to keep the bacteria in the system and to provide a very highly clarified effluent. To achieve this task, all of the water after stage 3 aeration tank is pumped through our AFM® filter. The AFM® filer removes all particles down to approx. 5 microns. The filter is back-flushed back into the system in order to recycle the bacteria. The AFM® filtered product water is sent to tank 4 for continual discharge. The water is normally sent directly for irrigation, river discharge, or sewer discharge. The photograph opposite shows the front end of our AFM® filter and automatic valves. The complete process is automatic from start to finish. The water is treated to a very high standard, and there is no concentrated effluent discharge as you have with Reverse Osmosis. However if you are required to achieve almost potable water standard, Ozonation, UVc ad sub micron filtration can be added onto the end of the process. This is relatively easy to accomplish, because the water has already been treated to a high standard. some early results from the system, are presented below |  |  |
The graph below presents the effluent water quality from our landfill leachate treatment system. The average influent water quality is approx 400-mg/l as COD and 1000 mg/l of ammonium. The graph below shows that the ammonium levels have dropped below 1mg/l and they have stayed below 1 mg/l. The COD has averaged out at approx 250mg/l, however it is now slowly dropping and as diversity of bacteria is developing in the system. 
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