106
4 Nitrogen and Phosphorous Recovery from Municipal Wastewater …
Fig. 4.1 a Activated sludge process, b the original Ludzack–Ettinger system, c the modified
Ludzack–Ettinger system (MLE), d the Bardenpho and Biodenipho processes [20]
tank (anoxic zone) [19]. In this method, the denitrification is limited to the amount of
soluble nitrate in the return sludge. The modified Ludzack–Ettinger process (MLE),
as shown in Fig. 4.1c, is an improvement of the original method in which an internal
recycle transfers the nitrates from the aerobic zone along with the mixed liquor to be
4 Nitrogen and Phosphorous Recovery from Municipal Wastewater …
Fig. 4.1 a Activated sludge process, b the original Ludzack–Ettinger system, c the modified
Ludzack–Ettinger system (MLE), d the Bardenpho and Biodenipho processes [20]
tank (anoxic zone) [19]. In this method, the denitrification is limited to the amount of
soluble nitrate in the return sludge. The modified Ludzack–Ettinger process (MLE),
as shown in Fig. 4.1c, is an improvement of the original method in which an internal
recycle transfers the nitrates from the aerobic zone along with the mixed liquor to be