Fate and Effect of Dissolved Silicon within Wastewater Treatment Effluent

Abstract

In large rivers, the ratios of silicon (Si)/nitrogen (N)/phosphorus (P) have changed dramatically as anthropogenic additions of N or P are not matched by Si. Wastewater effluent is a recognized source of N and P to coastal environments. Few previous studies, however, have examined the Si load of a large wastewater plant's effluent or the molar ratios of Si/N and Si/P in effluent. We examine the annual flux of dissolved silicon (DSi) carried by effluent from the second largest treatment plant by flow in the United States (Deer Island Treatment Plant, DITP, Boston, MA). We compare treatment plant nutrient fluxes to local urban river nutrient fluxes and trace the impact of the DITP DSi loading on receiving waters. Estimates (±95% confidence interval) of treated effluent (67 800 ± 1500 kmol DSi year) compared to untreated (69 500 kmol DSi year) indicate that the process of sewage treatment at DITP likely does not remove DSi. DITP effluent was Si-limited and this Si-limitation is reflected in the receiving waters (Massachusetts Bay). However, Si-limitation appears only in the area immediately surrounding the effluent discharge. We use these results to explain phytoplankton patterns in Massachusetts Bay and to provide the first estimate of DSi loading (3.6 Gmol SiO year) from wastewater effluent across the US.

Atmospheric Inputs of Nitrogen, Carbon, and Phosphorus across an Urban Area: Unaccounted Fluxes and Canopy Influences

“…Using our measured input rates and a land area for the City of Boston of 125 km 2 with 25.5% canopy cover (data from 2006 to 2007, Raciti et al, ), we calculate that the growing season flux of inorganic P from bulk + throughfall inputs to the City of Boston is 10,719 kg P over the 166 days of the study period (9711 kg inorganic P and 1008 kg organic P). This value for inorganic P represents 123% of the inorganic P input to Boston Harbor (7895 kg P) derived from sewage effluent during our study period (http://www.mwra.com/02org/html/whatis.htm; Maguire & Fulweiler, ). Sewage effluent is responsible for the majority of P inputs to surface waters in the continental U.S. (Mainstone & Parr, ; Maupin & Ivahnenko, ), and inorganic P has been shown to compose between 85% and 95% of total P in sewage effluent in nearby Narragansett Bay, Rhode Island (Nixon et al, ; Nixon et al, ).…”

Long‐term variability of nutrient and dissolved organic matter concentrations in Tokyo Bay between 1989 and 2015

“…In contrast, the silicic acid concentrations in the surface waters of both stations did not show inverse correlations with the volume of advanced treatment effluent in the Tokyo Bay watershed (p > 0.001). Maguire and Fulweiler (2017) also reported that the silicic acid concentrations did not decrease during the processes of sewage treatment. Additionally, the increase of silicic acid usage that could have been caused by a shift in phytoplankton composition is small because diatoms were the dominant phytoplankton species in Tokyo Bay throughout the sampling period (Yamaguchi 2011; Yoshida et al 2011).…”

Environmental sustainability of phosphorus recycling from wastewater, manure and solid wastes

“…agricultural fertilizers, feed and food additives, laundry detergents and other industrial applications (Belboom et al, 2015;Mottet et al, 2017;Noya et al, 2017;Van Hoof et al, 2017). The final step corresponds to the dissipation and the recycling of phosphorus (Chen & Graedel, 2016;Fowdar et al, 2017;Harris et al, 2017;Hobbs et al, 2017;Leon & Kohyama, 2017;Maguire & Fulweiler, 2017;Ortiz-Reyes & Anex, 2018). In recycling, other materials such as nitrite associated with phosphorus can be recovered in parallel.…”