A treatment plant has an influent flow rate of 16 500 m3/d. The influent BOD7 concentration is 200 mg/l and total nitrogen concentration 60 mg/l. A 55% total nitrogen removal is achieved in the existing activated sludge process based on DN configuration. Dimension a post-denitrification MBBR reactor using a denitrification rate of 2,2 gN/m2d. The carriers have a surface area of 500 m2/m3. Use a filling ratio of 60%. How much methanol should be dosed if we assume that 3 g MeOH is needed per g of nitrogen denitrified?