Simultaneous organic matter removal and nitrification of an inert self-supporting immersed media to upgrade aerated lagoons

Abstract

A pilot study was performed to evaluate the potential of an inert self-supported immersed fixed film media to upgrade aerated lagoons. Simultaneous organic matter removal and nitrification was assessed under different loading rates and temperatures (near 0 °C) using 12 laboratory-scale reactors operated in parallel. Test results showed that both the temperature and the load have an influence on organic matter effluent concentrations. Effluent quality seemed related to the observed biofilm thickness. Thicker biofilm is believed to have contributed to biomass detachment and increased particulate organic matter concentrations in the effluent. Simultaneous organic removal and nitrification was obtained at loads above 5 g CBOD/m·d. The highest nitrification rate at 0.4 °C was obtained for the smallest load, which showed a nitrification limitation close to freezing point.

Nitrification in a biofilm‐enhanced highly loaded aerated lagoon

“…During the maximum nitrification period, the organic loading rate was on average 6.2 g total CBOD 5 /m 2 day. This result is in accordance with the conclusions of Boutet et al (2018) who observed important nitrification at high organic loading rate with the same biofilm support media. An average ammonia concentration of 2.9 g N/m 3 was measured at the effluent of the system during the maximum nitrification period despite a nitrification loss episode (Figure 2b) observed from the end of July to the end of August (discussed below).…”

“…Such results were expected since the average observed surface loading rate is lower than the reported critical rate of 10 g total CBOD 5 /m 2 day that would typically result in low CBOD 5 removal efficiencies in biofilm reactors (MBBRs and rotating biological contactors; Morgenroth, 2008). It is also below the average loading rate of 7.6 g total CBOD 5 /m 2 day for which Boutet et al (2018) observed, using the same media as in the KAMAK™ system, a significant increase in effluent CBOD 5 concentrations at very low temperatures (<1°C). The relatively high SD of the total CBOD 5 data is mainly caused by the temporary episode of solids resuspension during the warmer months which is explored below.…”

“…Biodegradable organic matter loading rates over 5 g total CBOD 5 /m 2 day were reported in literatures as preventing nitrification in MBBR systems (Hem, Rusten, & Ødegaard, 1994; Rusten, Hem, & Ødegaard, 1995). However, the pilot study used as a basis for the design of this study's KAMAK™ system (Boutet et al, 2018) showed that important nitrification was possible at even higher loading rates (>7 g total CBOD 5 /m 2 day).…”

“…The KAMAK™ technology, developed by Bionest (Shawinigan, QC, Canada), is an example of upgrade technology using an inert, self-supported, submerged media which is inserted directly in the aerated lagoon. Its design is based on the results of a pilot-scale study (Boutet et al, 2018) that showed potential for simultaneous removal of ammonia and organic matter under high organic loading rates (>5 g total CBOD 5 / m 2 day) and cold temperatures (<1°C). It includes two aerated biofilm reactor zones (RX1 and RX2) as well as three minimally aerated (CL1) or unaerated zones (CL2 and CL3) for sedimentation and accumulation of solids ( Figure 1).…”

“…The use of a support material inserted directly inside the lagoon to host biofilm growth has also been identified as a promising solution (Boutet, Baillargeon, Patry, & Lessard, 2018; Choi, Johnson, Hayes, & Xu, 2008; McCall et al, 2013; Wang, Jin, Bishop, & Li, 2012). Its interest resides in the simplicity of its implementation, which uses no additional operation nor reactive volume.…”