Aerobic treatment of N-nitrosodimethylamine in a propane-fed membrane bioreactor

Ex situ treatment of N-nitrosodimethylamine (NDMA) in groundwater using a fluidized bed reactor

“…The reactor also received a continuous feed of oxygen and propane during this phase. ENV425 was grown in batch culture on propane as a substrate as described previously (Hatzinger et al, 2011). One liter of the culture (OD 550 ¼ 1.0) was added to the FBR, and the unit was placed in complete recycle at 1200 mL/min flow (Day 52).…”

“…One potential advantage of cometabolic degradation is the apparent ability of these organisms to degrade NDMA to ultra low concentrations, as microbial growth depends upon the concentration of the primary substrate (i.e., propane) rather than NDMA. For example, the bacterium Rhodococcus ruber ENV425 has been shown to degrade NDMA from concentrations as high as 80 mg/L to <10 ng/L in batch culture (Fournier et al, 2009) and in a membrane bioreactor (Hatzinger et al, 2011). A mixed culture grown on propane, as well as cultures enriched on other cometabolic substrates such as methane and toluene, also were recently shown to degrade NDMA to <10 ng/L in batch culture (Weidhaas et al, 2012).…”

“…ruber ENV425, the organism used to seed the bioreactor in this study, degrades NDMA though a mixed denitration/ demethylation pathway, producing low levels of innocuous products including, methylamine, nitrite, nitrate, methanol, and carbon dioxide (Fournier et al, 2009). In a laboratory membrane bioreactor (MBR) operated continuously for several months utilizing this bacterium, NDMA was biodegraded from 10 to 80 mg/L to less than 10 ng/L using propane as a primary substrate (Hatzinger et al, 2011). Hence, the ability of a propanotroph to effectively degrade NDMA to below regulatory requirements has been confirmed in a laboratory MBR study.…”

“…The high biomass on the FBR media allows contaminant removal at shorter hydraulic residence times (HRTs) than in other systems (Webster et al, 2009). Results from prior laboratory studies have shown that strain ENV425 develops an extensive biofilm, so the culture may be well suited for growth in an FBR (Hatzinger et al, 2011).…”

Characterization of the microbial community structure and nitrosamine-reducing isolates in drinking water biofilters

“…RR1 (Sharp et al, 2007(Sharp et al, , 2010; and toluene 4-monooxygenases in Ralstonia pickettii PKO129 and Pseudomonas mendocina KR1 (Sharp et al, 2005;Fournier et al, 2006). Different aerobic NDMA biodegradation pathways have been reported in Rhodococcus ruber ENV425 (Fournier et al, 2009;Hatzinger et al, 2011) and KR1 (Fournier et al, 2006(Fournier et al, , 2009. However, these studies only focused on NDMA at high concentrations (μM or mM).…”