Full-scale trials of external nitrification on plastic media nitrifying trickling filter

Abstract

The full-scale single-stage tertiary nitrifying trickling filter (NTF) at the Citrusdal Wastewater Treatment Plant provides for external nitrification of unclarified effluent from the facultative aerobic lagoon in order to meet standard effluent ammonia concentration requirements. The apparent ammonia nitrification rate (ApANR, gN/m 2 media surface•d) of the NTF was sensitive to particulate organic loading rates which were predominantly in the form of algae, and the soluble COD removal rates increased under cold climates. Installation of forced-air ventilation fans improved the nitrification efficiency from 15% to 43%. An increase in hydraulic loading rate (HLR) by effluent recirculation significantly improved the ApANR, eradicated filter flies and decreased the prevalence of worms. Maximum ApANR of ~1.0 gN/m 2 •d was achieved yielding an ammoniaremoval efficiency of approximately 71%. Profile samples collected along the NTF media depth indicated poor media wetting at low HLR resulting in low ApANR (<0.5 gN/m 2 •d). Also during the cold and rainy winter period, poor biofilm activity and prevalence of motile algae were observed, and under low hydraulic loading rates and warmer temperatures, a dominance of filter flies and fly larvae were observed. In contrast, in controlled laboratory studies, ApANRs up to 1.72 gN/m 2 •d (22.1 mgN/ℓ removal) were attained, which, in conformity with full-scale, was also found to be sensitive to hydraulic loading conditions.

Model-based evaluation of a trickling filter facility upgrade to biological nutrient removal

“…The lower nitrification efficiency obtained for higher SB is attributed to the increasing particulate and soluble COD concentration in the nitrifying TF influent (second stage TF). The importance of maintaining low influent suspended solids and biodegradable organic matter to achieve good performance in nitrifying TFs has been previously reported (Parker et al, 1989;Parker et al, 1995;Mofokeng et al, 2009;Dai et al, 2013). In these investigations, it has been suggested that the influence of influent biodegradable organic matter on nitrification is due to the development of a heterotrophic population, which competes with the nitrifiers for oxygen, thereby reducing nitrification rates.…”

Of: Symbolic Regression of Upstream, Stormwater, and Tributary E. Coli Concentrations Using River Flows, Jagupilla, S. C. K.; Vaccari, D. A.; Miskewitz, R.; Su, T.‐L.; Hires, R. I. (2015), 87, 26‐34; correction 87, 576.

“…However, when operated as single units and at half the NH3 loading rate, the performance deteriorated. In a third comparative study, Mofokeng et al (2009) investigated both a full-scale and lab-scale NTF (each a single reactor) treating effluent from a partially aerated lagoon. The NTFs had an area:height ratio of 5.6 and 0.014, respectively.…”

“…While quality empirical data sets from pilot and/or full scale operations are available (e.g. Andersson et al, 1994;Boiler and Gujer, 1986;Goldstein and Smith, 2002;Gullicks and Cleasby, 1986;Mofokeng et al, 2009;Parker et al, 1995;Parker et al, 1989;Parker et al, 1997), of the extensive data sets that were reviewed, only those published by Parker and coworkers include detailed kinetic data within the NTF. The value and importance of such kinetic data within the depths of an NTF relates to the ability to refine and optimize the empirical-based design of full-scale NTFs for site-specific conditions; the NTF design models all integrate and require zero-and first-order NH3 : emoval kinetic parameters.…”

Prologue to the WISA 2008 Conference Special Edition

“…The remaining fractions were not much affected by the polymer treatment. Mofokeng et al (2009) investigated the full-scale singlestage tertiary nitrifying trickling filter at the Citrusdal wastewater treatment plant. The filter provides for external nitrification of unclarified effluent from the facultative aerobic lagoon in order to meet standard effluent ammonia concentration requirements.…”