Denitrification on the top of UASB reactors of rice wastewaters

Parboiled rice industry is one of main food industries in the south of Braz il. The main parts of the processing are the humidification and gelatinizat ion of the grain. This procedure Increases the productivity and nutritive a nd cooking values of the product. Some of these industries in the region ut ilize upflow anaerobic sludge blanket (UASB) reactors as a biological treat ment for carbon removal. For nitrogen removal, the proposed system aims to eliminate an extra denitrification reactor, making this step in the top of the UASB, an anoxic zone of the reactor. Nitrification was performed in aer ated mixed reactor of 3,6 L.A fraction of the NR was recycled in the top of UASB reactor above the sludge blanket. Recycled ratio varied from 0; 1:0.5 ; 1:1.0; to 1:1.5. The maximum removal efficiency of NTK was 80%. The resul ts confirm the viability of the proposed system for denitrification.