Improvement of Nitrification in Rotating Biological Contactors by Means of Alkaline Chemical Addition,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CIVIL ENGINEERING
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This research examined the short and long-term effect of pH upon the nitrification of wastewater within RBC fixed film systems. In the long-term, the rate of nitrification within an RBC fixed film system was dependent upon pH. The rate of nitrification increased with increasing pH up to a maximum at pH 8.5. Approximately five weeks of operation were required to clearly observe these differences. The response of a nitrifying RBC system to short-term changes in pH was relatively constant from pH 7.0 to pH 8.5. Below pH 7.0, the adverse effect of pH becomes more pronounced. However, the absolute level of nitrification was dictated by the biofilms previous history of nitrification performance. There was no significant difference in the performance of the 2-stage nitrifying RBC systems which received calcium hydroxide, solium carbonate and sodium hydroxide. Higher levels of nitrification for the RBC systems were associated with greater disc biofilm uniformity. In all cases, except for the pH 8.8 RBC of the high pH study, the higher pH RBC systems maintained greater concentrations of volatile biofilm per unit of RBC disc area.