AQUAFIN (ANTWERP, BE)
N-RECOVERY FROM ACTIVATED SLUDGE DIGESTATE
Aquafin wants to investigate stripping/scrubbing as a promising technique for sludge water treatment.
The sludge comes from the post-sedimentation tanks of the sewage treatment plant, digested to produce biogas and then flows on to the thickening tables when later the sludge centrifuges for separation of the solid fraction.
The dewatered sludge is removed, while the ammonium-rich sludge water (the centrate) is passed through a drum screen (100 μm), which filters the coarse sludge particles from the centrate. This centrate normally flows back to the water treatment plant, but due to its high ammonium concentration (1550 mg NH4-N), it can interfere with the operation of the water treatment plant. Moreover, the nitrification-denitrification of ammonium is a source of emissions of nitrous oxide, a strong greenhouse gas.
Finally, cost savings on aeration energy in wastewater treatment and revenue from the sale of the recovered nitrogen product are also important factors. To investigate this, Aquafin installed a pilot plant at the Antwerp-South sewage treatment plant.
Dijkstraat 8, B-2630 Aartselaar