Biology+ozonation Biology+ozonation +
Raw water flow rate (m3/hour) Influent COD (mg/L)
2.9 1800 800 150
2.9 1800 800 300 150 1650
Effluent biology I COD (mg/L) Effluent ozonation COD (mg/L) Effluent biology II COD (mg/L) Total COD removal (mg/L)
1650 1000 650
COD removal biology I+II (mg/L) COD removal ozonation (mg/L)
1150 (1000+150) 500
Ozone mass requirement (COD removal with ozonationx2.5) (g/hour) Factor (ozone mass/COD removed within ozonation+biology) (kg O3/kg CODrem0ved)
The ozone dosage required for COD removal according to the limits was set in the range 0.9-1.2 kg O3/kg CODremoved. This allowed for reduction of the COD, on average, by 7182%, whereas the biological stage assures COD removal of 40%. At the same time, total nitrogen removal reached 98%.
The improved version of the BIOQUINT® system was applied at the landfill leachate treatment plant in Friedrichshafen, Germany, where the biological stage consists of nitrification and denitrification activated sludge reactors having volumes 100 and 25 m3, respectively, followed by an ozonation/biological recycle step. The ozone step (1.5 kg O3/hour) merged with a fixed-bed bioreactor (10 m3) allowed for elimination of nonbiodegradable COD that had not been removed in the first biological stage. The achieved average COD reduction of 82% was
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