Quantification of denitrification potential in carbonaceous trickling filters.

Biofilm samples from a carbonaceous trickling filter (TF) were evaluated in bench scale reactors to determine their maximum potential denitrification rates. Intact, undisturbed biofilms were placed into 0.6 L bench-scale reactors filled with sterilized, primary clarifier effluent spiked with nitrate to a final concentration of 16-18 mg/L as N.

Linking nitrifying biofilm structure and function through fluorescent in situ hybridization and evaluation of nitrification capacity.

Fluorescent in situ hybridization (FISH) was used to quantify the ammonia-oxidizing populations within intact biofilm samples collected from a full-scale nitrifying trickling filter (NTF). Ammonia, nitrite, and nitrate concentrations were measured for aqueous samples taken in conjunction with biofilm samples at multiple filter depths. The ammonia removal capability of collected biofilms was evaluated by transferring the biofilms to laboratory batch reactors.

Effect of alkalinity type and concentration on nitrifying biofilm activity.

The effect of alkalinity on nitrifying biofilm activity was determined by collecting 21-day-old biofilm samples from the top of a full-scale nitrifying trickling filter and evaluating bench-scale nitrate plus nitrite generation rates at (1) various initial carbonate alkalinity concentrations and (2) with four types of available alkalinity: carbonate only, phosphate only, phosphate plus hydroxide, and phosphate plus carbonate. Initial carbonate alkalinity concentrations were varied between 308 and 20 mg/L as calcium carbonate (CaCO3). Ammonia, nitrite, and nitrate concentrations were measured at time zero, 90 minutes, 180 minutes, and 270 minutes.

Nitrifying biofilm development with time: activity versus phylogenetic composition.

The development of nitrifying biofilms collected from a full-scale nitrifying trickling filter was evaluated through the application of fluorescent in situ hybridization (FISH) and by quantification of nitrification rates in bench-scale reactors. Two sampling campaigns were conducted to evaluate the structure and function of biofilms between 14 and 70 days old. The structure, or number of ammonia-oxidizing bacteria, was quantified with Nso190.