Biological Denitrification Using a Flocculated Sewage Sludge as a Carbon Source.

概要

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The authors had proposed an anaerobic fluidized pellet bed (AFPB) bioreactor system as upgrading sewage wastewater treatment system. In this system, the denitrification was accomplished in the AFPB bioreactor (1st stage denitrification tank), to which the nitrified liquor was recycled from a biological contact aerator at a rate of 300% of the influent flow. However, the nitrate nitrogen ranging in concentration from 3.5mg⋅l-1 to 8.0mg⋅l-1 was discharged from the contact aerator. In order to remove the remaining nitrate, the 2nd stage denitr-ification tank was added to the system in series. The flocculated sewage sludge produced in the AFPB bioreactor could be effectively used as a carbon source in the 2nd stage denitrification. In this case, the requirement of the hydrolyzed sludge BOD necessary for sufficient denitrification was approximately 3.5mg-BOD⋅mg-NO3--N-1. In addition, it was important to feed a minimum amount of the flocculated sludge required for denitrification, because of the ammonium nitrogen released with hydrolysis of the sludge. With the optimum feeding rate of the flocculated sewage sludge, the concentration of total nitrogen in the final effluent was between 0.5mg⋅l-1 and 1.0mg⋅l-1. Consequently, the efficiency of total nitrogen removal throughout the whole system was over 96%.
日本水処理生物学会の論文