The response of river nitrification to changes in wastewater treatment (The case of the lower Seine River downstream from Paris)

Abstract

-In the early 2000s, most of the effluents from the Paris agglomeration (12 million inhabitants) were still discharged after only a standard activated sludge treatment of carbon, thus releasing a high ammonium load. This triggered the growth of nitrifying bacteria in the river and caused a deficit of dissolved oxygen concentration 200 km downstream, at the entrance of the estuarine area. From 2007 on, improvements of the wastewater treatment plant (WWTP) helped to nitrify most of the ammonium, and to denitrify 70% of the nitrate produced since 2012. This paper documents the effect of these recent changes in the treatment of Paris effluents, based on measurements of nitrogen species concentrations and nitrifying activities along longitudinal profiles of the lower Seine River. These observations are put into perspective with respect to previous observations, and a modeling approach is developed to evidence the role of ammonium and nitrifying organisms released with the WWTP effluents into the receiving water body. Today, a larger biomass of ammoniumoxidizing microbes is being discharged by the WWTP, but the microorganisms released do not grow, possibly because of the low substrate in the river. The same is true for nitrite-oxidizing microbes, which explains the persistence of nitrite often discharged with the effluents because of incomplete nitrification and/or denitrification in the treatment line. Taking into account the development of microbial populations of nitrifying organisms is essential to explain the observed spatial and temporal pattern of the nitrogen species.

Landward Perspective of Coastal Eutrophication Potential Under Future Climate Change: The Seine River Case (France)

“…As an example, the low oxygen concentrations observed in July 2001 must be related to wastewater treatment plant failure and associated releases of high ammonium and/or organic matter concentrations from the 6.5 million equivalent inhabitants wastewater treatment plant. This type of event has already been highlighted by Aissa-Grouz et al (2015). As a consequence, low oxygen concentrations has been observed in the data in July 2001.…”

“…Simultaneously, nitrate and phosphate concentrations increases during low flow, particularly in the 7th stream order, are most likely related to the lower dilution of point sources in the urbanized river basin, as commonly observed downstream of large sewage treatment plant effluents. In addition, the increase in nitrate is also related to higher nitrification rates resulting from higher ammonium concentrations and higher water residence time, as already observed in the Seine River Aissa-Grouz et al, 2015;Raimonet et al, 2017a). The biogeochemical impacts of river flow decrease are thus expected to be greater downstream of conurbations with major sewage treatment plant effluents.…”

Season‐specific trends and linkages of nitrogen and oxygen cycles in Chesapeake Bay

“…Many previous studies have identified high‐nitrification rates near low‐salinity estuarine turbidity maxima (Iriarte et al 1996; Brion et al ; Damashek et al ) and have associted these high rates with particle‐dominated microbial communities, and with NH 4 + sorption and desorption, as well as elevated heterotrophic activity. Low‐salinity regions of estuaries have also been locations where extremely high‐wastewater discharges of NH 4 + have supported high‐nitrification rates (Lipschultz et al ; Gazeau ; Soetaert et al ; Aissa‐Grouz et al ) and contributed to oxygen depletion. While the nitrification bursts that occur during vertical mixing in seasonally stratified and hypoxic systems may be short lived (Horrigan et al ), they potentially contribute substantially to annual cycles of inorganic nitriogen species and can support denitrification in underlying sediments during this period (Kemp et al ).…”

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO2 and N2

“…NI was included with a maximum specific growth rate coefficient of 1E−4 . Ranges of NI rate coefficients can be found in the literature (Admiraal & Botermans, ; Aissa‐Grouz et al, ; Raimonet et al, ; Sheibley et al, ; Strauss et al, ). Half‐saturation constants for O 2 were (3.125E−6 M), CH 2 O (1.0E−4 M), and NO 3 − (8.064E−6 M).…”