The effectiveness of four different electron donors, specifically methanol, ethanol, glycerol, and sulfide (added as Na(2)S), were evaluated in post-denitrifying bench-scale moving bed biofilm reactors (MBBRs). With the requirement for more wastewater treatment plants to reach effluent total nitrogen levels approaching 3 mg/L, alternative electron donors could promote more rapid MBBR startup/ac...

Bedforms are a focal point of carbon and nitrogen cycling in streams and coastal marine ecosystems. In this paper, we develop and test a mechanistic model, the "pumping and streamline segregation" or PASS model, for nitrate removal in bedforms. The PASS model dramatically reduces computational overhead associated with modeling nitrogen transformations in bedforms and reproduces (within a factor...

Tertiary denitrification of the secondary effluent in wastewater treatment plants is necessary to control the eutrophication of receiving water bodies. Two denitrifying biofilters (DNBF), one packed with quart sand with sizes of 2–4 mm (DNBFS) and the other of 4–6 mm (DNBFL), were operated for tertiary denitrification under empty bed retention times (EBRTs) of 30 min, 15 min and 7.5 min, respec...

The coupling between nitrification and denitrification and the regulation of these processes by oxygen were studied in freshwater sediment microcosms with O(2) and NO(3) microsensors. Depth profiles of nitrification (indicated as NO(3) production), denitrification (indicated as NO(3) consumption), and O(2) consumption activities within the sediment were calculated from the measured concentratio...

Denitrifying enzyme activity (DEA) in artificially established denitrification activity zones was, on average, 3.5-fold greater than in bulk soil. Denitrifier biomass was between 1 and 4 orders of magnitude greater in activity zones. Denitrifier specific activity was lower in activity zones and more similar to specific activity values reported for pure cultures of denitrifying bacteria added to...

Formaldehyde and phenol biodegradation during the denitrification process was studied at lab-scale, first in anoxic batch assays and then in a continuous anoxic reactor. The biodegradation of formaldehyde (260 mgl(-1)) as single carbon source and at phenol concentrations ranging from 30 to 580 mgl(-1) was investigated in batch assays, obtaining an initial biodegradation rate around 0.5g CH(2)Og...

This study investigated the effect of external carbon source and bed turnover rate on biological denitrification in the pilot-scale IPNR (Ilshin Phosphorus and Nitrate Removal) process. IPNR process is an up-flow reactor filled with Si-media which removes phosphorus physically and nitrate nitrogen biologically using secondary effluent from sewage treatment plant. Phosphorus (PO4-P) was removed ...

We conducted NO3 – stable isotope tracer releases in nine streams with varied intensities and types of human impacts in the upstream watershed to measure nitrate (NO3 ) cycling dynamics. Mean ambient NO3 – concentrations of the streams ranged from 0.9 to 21,000 lg l NO3 – N. Major N-transforming processes, including uptake, nitrification, and denitrification, all increased approximately two to ...