Heterotrophic denitrification kinetics in a pressurized sewer biofilm reactor

Nitrogen transformation of reclaimed wastewater in a pipeline by oxygen injection

“…An apparent half-order kinetics, in relation to NO X -N is obtained, when plotting (g NO X -N m −2 ) 0.5 versus retention time (surface rates), for the three oxygen doses utilized ( Figure 5), at the same temperature (23.2 ºC), which leads to three parallel straight lines, providing a half-order rate constant k 1/2 = 0.066 (g NO X -N) 0.5 m -1 h -1 . This is in agreement with other studies where it has been stated that at over 1 mg l -1 the denitrification order is 0.5, and for NO X -N concentrations below 1 mg l -1 it is first order [24] Also, a recent study [35] indicated that an apparent half-order kinetics for denitrification in sewers can be a result of biofilm biomass concentration decrease along the pipe. This half-order denitrification kinetics obtained in this study contrasts with a first order found in a nitrate dosage study carried out in the same pipeline [13].…”

“…Regarding that NO X -N reduction occurred in the biofilm, the rate should be first, half or zero order depending on the combination of mass transfer, transport and reaction in the biofilm [22,33,34]. In addition to this, other research has indicated that denitrification rate can also depend on the availability of soluble organic matter [35]. An apparent half-order kinetics, in relation to NO X -N is obtained, when plotting (g NO X -N m −2 ) 0.5 versus retention time (surface rates), for the three oxygen doses utilized ( Figure 5), at the same temperature (23.2 ºC), which leads to three parallel straight lines, providing a half-order rate constant k 1/2 = 0.066 (g NO X -N) 0.5 m -1 h -1 .…”

Nitrate attenuation potential of hypersaline lake sediments in central Spain: Flow-through and batch experiments

“…Majority of the kinetic studies of NO 3 − attenuation processes have focused on attenuation induced by adding an external organic or inorganic substrate (Dinçer and Kargi, 2000;Koenig and Liu, 2001;Nielsen et al, 1996) or a specific bacteria strain (Joshi et al, 2007). Kinetic studies can be based on batch experiments (Joshi et al, 2007;Rodríguez-Escales et al, 2014;Vasiliadou et al, 2008) and/or flow-through systems (Andre et al, 2011;Fu et al, 2009;Mathioudakis and Aivasidis, 2009;Roychoudhury and Viollier, 1998). In lakes contaminated by NO 3 − , denitrification can occur in the benthic environment (Nizzoli et al, 2010), when water flows through lake bottom sediments, or by NO 3 − diffusion into the lake sediment (Lehmann et al, 2003).…”

Investigating nitrogen removal using simultaneous nitrification-denitrification in transferring wastewater through collection networks with small-diameter pipes

“…Microorganisms play a major role in the nitrogen cycle. Among others, Ganesh et al (2014), and Mathioudakis & Aivasidis (2009) studied how nitrogen sources were removed from wastewater, and investigated nitrifying and denitrifying conditions. Simultaneous nitrification and denitrification (SND) is a newly identified biological removal method for nitrogen compounds, and a number of researchers have shown that some processes are capable of SND in reactors (Ding et al 2011;Vijayalayan et al 2014).…”