This Paper presents the method and results of the commissioning study carried out at the two Full scale downflow fixed-film reactor (SMAG) supplied by Reva Enviro Systems Pvt. Ltd., Nagpur To Dhampur Sugar Mills Ltd., Bijnor Distt., U.P. as a primary treatment system for treatment of Distillery wastewater. The capacity of each reactor is 400 m3/day (i.e. Diameter: 23.5 m, Height : 9.0). The total project cost was around 6.0 crores. This study was carried out by the Author under his project work of M. Tech. (Sponsored by M/s Reva Enviro. Systems P. Ltd.) done from V.N.I.T. (V.R.C.E.) Nagpur.