Inferred metal toxicity during the biotreatment of high ammonia landfill leachate: Fid-Bau Portal

Inferred metal toxicity during the biotreatment of high ammonia landfill leachate

Manoharan, Ramanathan / Harper, Susan C. / Mavinic, Donald S. / Randall, Clifford W. / Wang, Guoyao / Marickovich, Donald C.

Abstract

ABSTRACT:  Two nitrification‐denitrification systems were used to determine the possible inhibitory and/or toxic effects of supplementa metals addition to the nitrification‐denitrification process in the treatment of a relatively high ammonia, low biodegradable carbon, municipa landfill leachate. The addition of metals likely resulted in the precipitation of phosphorus which caused the nitrification‐denitrification process to be inhibited due to the deficiency of bioavailable phosphorus. Even though the phosphorus concentrations in mixed liquor and system effluent samples filtered through Whatman No. 4 filters or glass‐fiber filters appeared to be adequate, it was discovered that they were considerably lower when filtered through 0.45‐µm membrane filters. This seemed to indicate that although some of the precipitated phosphorus passed through the Whatman No. 4 filter, it was not available as a nutrient for microbial metabolism. Therefore, only the phosphorus that will pass through a 0.45‐µm membrane filter, and is defined as soluble in Standard Methods (1985) is readily available to the microorganisms. This should be monitored ensure sufficient nutrient availability in nitrification‐denitrification treatment systems potentially exposed to metals capable of precipitating phosphorus. It is recommended that a minimum soluble phosphorus concentration of 0.5 mg/L be maintained to ensure adequate phosphorus for nitrification and denitrification; in addition, when conducting activated sludge metal toxicity studies, total or Whatman No. 4‐filtered samples should not be used to determine the presence of adequate phosphorus.