More Like this

1. Hybrid Ion Exchange and Algae for High Strength Sidestream Wastewater Treatment

   Wang, M.; Payne, K.; Tong, S.; Ergas, S.J. (June 2017, WEF 2017 Nutrient Symposium)

   A hybrid ion-exchange and algae photosynthesis (HAPIX) process was used for treatment of side stream centrate from an anaerobic digester treating waste activated sludge. Although the high NH4+ -N concentration of the centrate (~1180 mg/L) inhibited the algae growth in unamended controls, addition of 150 g/L of zeolite reduced the ammonia toxicity due to its ion exchange capacity. NH4+-N was reduced from 1,180 mg/L to 107 mg/L within 24 hours by ion exchange. Na+ was the major cation exchanged with NH4+. The addition of algae further reduced the NH4+-N concentration to 10.5 mg/L after 8 days of operation. Zeolite that was saturated with NH4+ can be bioregenerated by the algae growth so that the zeolite can adsorb more NH4+ in the wastewater. The mathematical model that combined ion-exchange and algal photosynthesis processes predicted the aqueous NH4 + -N concentration well. The HAPIX process is feasible to treat high NH4+-N side stream wastewater. 

   more » « less
2. Resource recovery from anaerobic digestion effluent by a hybrid algal photosynthesis and ion-exchange process

   Wang, M.; Payne, K.; Tong, S.; Ergas, S. (May 2018, IWA Leading Edge Technology Conference on Water and Wastewater Treatment)

   A hybrid algal photosynthesis and ion exchange (HAPIX) process was developed that uses natural zeolite (chabazite) and wild type algae to treat high ammonium strength wastewater. In the HAPIX process, ammonium ions are temporarily adsorbed from the liquid, which reduces the free ammonia concentration below the inhibitory level for algal growth. The slow release of adsorbed NH4+ subsequently supports the continuous growth of algae. In this study, a HAPIX reactor reduced NH4+-N concentrations in centrate from an anaerobic digester from 1,180 mg/L to below 10 mg/L without dilution. Chabazite doses of 60 g/L produced more biomass, with higher protein and starch contents, than doses of 150 g/L and 250 g/L. Approximately 67-70% of fatty acids in the biomass harvested from HAPIX reactors were unsaturated. A mathematical framework that couples a homogeneous surface diffusion model with a co-limitation algal kinetic growth model reasonably predicted the biomass production and NH4+-N concentrations in the HAPIX reactors. The HAPIX process has the potential to serve a two-fold purpose of high NH4+-N strength wastewater treatment and agricultural or commercial biopolymer production. 

   more » « less
3. Goose Feces Effects on Subarctic Soil Nitrogen Availability and Greenhouse Gas Fluxes

   https://doi.org/10.1007/s10021-022-00752-x  

   Beard, Karen H.; Kelsey, Katharine C.; Choi, Ryan T.; Welker, Jeffrey M.; Leffler, A. Joshua (March 2022, Ecosystems)

   Vertebrate herbivore excrement is thought to influence nutrient cycling, plant nutrition, and growth; however, its importance is rarely isolated from other aspects of herbivory, such as trampling and leaf removal, leaving questions about the extent to which herbivore effects are due to feces. We hypothesized that as a source of additional nutrients, feces would directly increase soil N concentrations and N2O emission, alleviate plant, and microbial nutrient limitations, resulting in increased plant growth and foliar quality, and increase CH4 emissions. We tested these hypotheses using a field experiment in coastal western Alaska,USA, where we manipulated goose feces such that naturally grazed areas received three treatments:feces removal, ambient amounts of feces, or double ambient amounts of feces. Doubling feces marginally increased NH4 +-N in soil water, whereas both doubled feces and feces removal significantly increased NO3--N; N2O flux was also higher in removal plots. Feces removal marginally reduced root biomass and significantly reduced productivity (that is, GPP) in the second year, measured as greater CO2 emissions. Doubling feces marginally increased foliar chemical quality by increasing %N and decreasing C:N. Treatments did not influence CH4 flux. In short, feces removal created sites poorer in nutrients, with reduced root growth, graminoid nutrient uptake, and productivity. While goose feces alone did not create dramatic changes in nutrient cycling in western Alaska, they do appear to be an important source of nutrients for grazed areas and to contribute to greenhouse gas exchange as their removal increased emissions of CO2 and N2O to the atmosphere. 

   more » « less
4. NanoSIMS single cell analyses reveal the contrasting nitrogen sources for small phytoplankton

   https://doi.org/10.1038/s41396-018-0285-8  

   Berthelot, Hugo; Duhamel, Solange; L’Helguen, Stéphane; Maguer, Jean-Francois; Wang, Seaver; Cetinić, Ivona; Cassar, Nicolas (October 2018, The ISME Journal)

   Abstract Nitrogen (N) is a limiting nutrient in vast regions of the world’s oceans, yet the sources of N available to various phytoplankton groups remain poorly understood. In this study, we investigated inorganic carbon (C) fixation rates and nitrate (NO3−), ammonium (NH4+) and urea uptake rates at the single cell level in photosynthetic pico-eukaryotes (PPE) and the cyanobacteria Prochlorococcus and Synechococcus. To that end, we used dual 15N and 13C-labeled incubation assays coupled to flow cytometry cell sorting and nanoSIMS analysis on samples collected in the North Pacific Subtropical Gyre (NPSG) and in the California Current System (CCS). Based on these analyses, we found that photosynthetic growth rates (based on C fixation) of PPE were higher in the CCS than in the NSPG, while the opposite was observed for Prochlorococcus. Reduced forms of N (NH4+ and urea) accounted for the majority of N acquisition for all the groups studied. NO3− represented a reduced fraction of total N uptake in all groups but was higher in PPE (17.4 ± 11.2% on average) than in Prochlorococcus and Synechococcus (4.5 ± 6.5 and 2.9 ± 2.1% on average, respectively). This may in part explain the contrasting biogeography of these picoplankton groups. Moreover, single cell analyses reveal that cell-to-cell heterogeneity within picoplankton groups was significantly greater for NO3− uptake than for C fixation and NH4+ uptake. We hypothesize that cellular heterogeneity in NO3− uptake within groups facilitates adaptation to the fluctuating availability of NO3− in the environment. 

   more » « less
5. A hybrid algal photosynthesis and ion-exchange (HAPIX) process for side stream wastewater treatment: Experimental and modeling studies

   Wang, M.; Payne, K.; Tong, S.; Ergas, S.J. (September 2017, Water Environment Federation Technical Exhibition and Conference (WEFTEC 2017))

   A hybrid ion-exchange and algal photosynthesis (HAPIX) process was used for treatment of side stream centrate from an anaerobic digester treating waste activated sludge. Although the high NH4+-N concentration of the centrate (~1180 mg/L) inhibited algal growth in unamended controls, addition of zeolite reduced the ammonia toxicity due to its ion exchange capacity. Na+ was the major cation exchanged with NH4+. Growth of algae further reduced the NH4+-N concentrations. Different zeolite dosages (60, 150, and 250 g/L) resulted in different concentrations of NH4+-N in solution. Algae grown in lower zeolite dosage (60 g/L) had high protein contents. A mathematical model that combined ion-exchange and algal photosynthesis processes predicted the aqueous NH4+-N concentration well. The HAPIX process is feasible for treatment of high NH4+-N strength side stream wastewaters while regulating intracellular algal biomass contents by adjusting zeolite dosages. 

   more » « less