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Influence of dose volume on nitrogen removal in a two stage vertical flow treatment wetland: Bridger Bowl ski area case study
(Montana State University - Bozeman, College of Engineering, 2023) Brush, Kristen Onofria; Chairperson, Graduate Committee: Otto Stein
Treating wastewater in remote locations does not require compromising the effluent quality discharged to the environment. A two-stage vertical flow treatment wetland (VF TW) with recycle meets this objective by removing high inputs of chemical oxygen demand (COD) and nitrogen (N) while requiring minimal maintenance and operator oversight. A 95.2 m 2 pilot scale VF TW at Bridger Bowl Ski Area, near Bozeman, MT, effectively treats the high strength domestic wastewater produced onsite. The partially saturated first stage of the VF TW removes influent COD and an unsaturated second stage nitrifies influent ammonium. Recycling second stage effluent to the first stage allows for nitrate removal by denitrification in the saturated zone of the first stage. Previous research indicated the system experiences near complete nitrification in the second stage and that total nitrogen removal is limited by denitrification in the first stage, potentially due to low organic carbon (COD) availability in the saturated zone. Therefore, the goal of the current study was to increase the COD:N ratio of the water entering the first-stage saturated zone by increasing the dose depth of influent (septic) water, high in COD, thereby reducing COD removal in the unsaturated layer. To evaluate denitrification performance a simplified stoichiometric process model accounted for both nitrate created and COD removed in the first stage unsaturated zone. During the 21-22 season, approximately 7 cm/day of septic water was applied to the first stage in either 1.2 or 2.5 cm doses. The larger doses showed enhanced nitrate removal efficiency in the saturated zone; however, a changing influent water quality may have supplemented efficiency improvement. During the 22-23 season, 12 cm/day of septic water was applied to the first stage in either 1 or 4 cm doses. During this experiment, influent water quality was the same, and the larger dose depths did not show enhanced nitrate removal. However, decreasing the septic dose depth increased first stage nitrification from 20 to 48% and COD removal from 77 to 82%. Throughout both experiments, system COD removal was > 95% (influent COD > 750 mg/L) and system ammonia removal was > 98% (influent NH 4 >160 mg/L).
Effects of hydraulic loading on nitrification and denitrification processes in a two-stage, vertical flow treatment wetland at Bridger Bowl Ski Area
(Montana State University - Bozeman, College of Engineering, 2020) Panighetti, Robert Arthur; Chairperson, Graduate Committee: Otto Stein
A pilot-scale two-stage vertical flow treatment wetland (VFTW) at the Bridger Bowl Ski Area was used to evaluate the influence of hydraulic loading rate on COD removal, nitrification, and denitrification in the system. Hydraulic loading rates ranged between 36 cm/d to 60 cm/d over system years 2018 and 2019. Total nitrogen loading (sum of NH 4+ and NO 3-) ranged from 12 g/m 2d to 65 g/m 2d, and COD loading ranged from 58 g/m 2d to 172 g/m 2d. The system effectively removed COD in both years, with removals of 95% and 96% for influent COD concentrations of 555 mg/L and 607 mg/L, respectively. Influent total nitrogen was 141 mg/L in 2018 and 105 mg/L in 2019, and removals were 67% and 54%, respectively. At a hydraulic loading rate of 60 cm/d, COD removal declined in the first stage and ammonium removal declined in the second stage. At lower hydraulic loading rates (up to 48 cm/d), removal of COD, ammonium and nitrate increased in a consistent pattern with increased mass loading of the respective contaminant, suggesting a maximum hydraulic loading rate limit between 48 and 60 cm/d. The effect of hydraulic loading cannot be completely separated from mass loading of a contaminant, likely influenced by the level of partial saturation within the first stage and the recycle ratio; neither were varied in this study. A key limiting factor is hydraulic overload to the first stage, limiting removal of COD which interfered with nitrification in the second stage. A multivariate model for ammonium removal in the second stage predicts increased ammonium removal with increasing ammonium load but decreasing COD load. Despite operational performance variation the system met applicable discharge requirements, reinforcing the ability of a VFTW system to perform secondary wastewater treatment, even for high-strength wastewater and in cold climates.
Influence of saturation on denitrification in a two-stage, vertical flow treatment wetland at Bridger Bowl ski area
(Montana State University - Bozeman, College of Engineering, 2018) Woodhouse, Shayla Lee; Chairperson, Graduate Committee: Otto Stein
A full-scale two-stage vertical flow treatment wetland (VF TW) pilot system was installed at the Bridger Bowl Ski Area in 2013 to test its capability as a secondary wastewater treatment system. Water quality was monitored throughout the 2015-2016 and 2016-2017 ski seasons with the primary objective to optimize the system for total nitrogen removal. Eight different combinations (schemes) of daily hydraulic and nutrient loading, dose frequency, effluent recycle, and depth of saturation of the first stage were tested. Average system removal was 93% and 95% for chemical oxygen demand (COD) and 70% and 75% for total nitrogen (TN) in 2016 and 2017, respectively, despite elevated influent concentrations of 930 mg x L -1 COD and 195 mg x L -1 TN. In addition, the system converted virtually all influent TN to nitrate. Both 1:1 and 2:1 (recycle to influent) ratios were effective as were saturation depths of 53 and 71 cm. At the 2:1 recycle ratio, the higher saturation level was superior at light hydraulic and constituent mass loadings while the lower saturation level was superior at higher loadings, but the differences were small. Overall, TN removal and nitrogen species transformations were linearly related to the mass load applied (surface area basis) over the range evaluated. In addition, the maximum removal capacity of the system was not exceeded during any scheme, thus the inherent removal capacity of the system is greater than evaluated. Nevertheless, the removal efficiencies of the VF TW from the past two seasons has shown that this technology can successfully perform secondary wastewater treatment in cold climates with efficient nitrogen removal and can exceed the regulatory requirements under which Bridger Bowl operates.
Selecting filter media for phosphorus removal at the Ennis National Fish Hatchery three-stage subsurface flow treatment wetland
(Montana State University - Bozeman, College of Engineering, 2017) Wallis, Jack Enoch; Chairperson, Graduate Committee: Otto Stein; Otto R. Stein, Christopher R. Allen and Ellen G. Lauchnor were co-authors of the article, 'Selecting wetland media for phosphorus removal' submitted to the journal 'Water science and technology' which is contained within this thesis.
In western Montana, phosphorus is one of the most common contaminants found in rivers and streams, threatening the health of aquatic ecosystems. In response to growing water quality concerns and new regulatory requirements, a three-stage treatment wetland was recently constructed at the Ennis National Fish Hatchery to treat wastewater generated by raceway cleaning operations. Currently only the first two stages of this system are complete and over the first two months of operation have removed over 98% of influent chemical oxygen demand, 99% of total suspended solids, 59% of total nitrogen, and 95% of total phosphorus. However, the effluent phosphorus concentration is expected to increase as organic matter accumulating in the wetland mineralizes and the phosphorus adsorption capacity of the wetland media is saturated. To maintain long-term phosphorus removal, the treatment wetland was designed with a filter unit to be filled with media capable of adsorbing large quantities of phosphorus. The purpose of this research is to choose the optimal media for this filter unit, comparing three manufactured materials (lightweight aggregate, juniper biochar, and lodgepole biochar) and four natural materials (limestone, dolomite, shale, and gravel). Batch adsorption experiments were conducted with coarse media in deionized water, coarse media in Blaine Spring Creek water, and fine media in deionized water. The difference between these batch experiments showed that water chemistry and particle size significantly affect phosphorus adsorption for a given material. Based on their high performance in batch experiments, lightweight aggregate and lodgepole biochar were tested in continuous flow columns, along with gravel to provide a baseline performance comparison. Gravel and lightweight aggregate removed more phosphorus in continuous flow columns than in batch experiments, likely due to ongoing precipitation with calcium ions in the influent. Lightweight aggregate was the top performing media in all experiments, and is recommended for use in the filter units at the Ennis National Fish Hatchery treatment wetland. Based on its phosphorus removal capacity in column experiments (1200 mg P kg -1 lightweight aggregate), the filter beds will be saturated in 14 months if the current effluent phosphorus concentration of 2.3 mg L -1 is maintained.
Operation and optimization of a two-stage, vertical flow constructed wetland system at Bridger Bowl Ski Area
(Montana State University - Bozeman, College of Engineering, 2016) Moss, Jefferson Jack, IV; Chairperson, Graduate Committee: Otto Stein
Treatment wetlands are an internationally accepted technology for treatment of domestic wastewater and modern designs have become the preferred option for small communities in several European countries for their ability to produce a high quality effluent. To evaluate performance of modern treatment wetland designs with respect to carbon and nitrogen removal in Montana and other challenging contexts, a two-stage, vertical flow system with recycle capabilities has been constructed and tested at a ski area near Bozeman, Montana. Site climatic and operational conditions provide a 'worst-case' scenario to test the efficacy of treatment wetlands in Montana. Intensive sampling of influent and effluent concentrations of chemical oxygen demand (COD) and nitrogen containing compounds after the second season of plant growth is used to optimize and correlate performance as influenced by loading rate, dose volume, and recycle ratio. COD removal was greater than 90% and increased linearly with loading rate even when loading rate exceeded European design guidelines by nearly a factor of 10, with effluent concentrations approximately 100 mg·L -1. The system was also able to nitrify and denitrify. With the use of water recycling, effluent could be optimized for complete removal of ammonium and total nitrogen removal around 50%, even though influent concentrations were approximately 4 times greater than typical domestic wastewater. Mass removal rates were as high as 20 g-N·m-2·day -1, higher than expected based on European guidelines. These results indicate that treatment wetlands are capable of high nitrogen and organic carbon removal, even when applied at a high concentrations, low temperatures, and variable flow situations.
Denitrification at the microscale in treatment wetlands
(Montana State University - Bozeman, College of Engineering, 2015) Spengler, Justin Warren; Chairperson, Graduate Committee: Robin Gerlach; Anne Camper (co-chair)
Treatment wetlands (TWs) have been in use for over three decades for wastewater treatment, agricultural water treatment, and some industrial wastes. Thousands of TWs exist for treating wastewater globally, but the microbial processes and controls in situ primarily responsible for water treatment are poorly understood. In this study, 16 separate model TW columns consisting of three plant groups and one non-planted group were fed synthetic post-secondary wastewater with half receiving no added carbon and half receiving 0.391 g L -1 as sucrose. Core samples were taken from each of the TW columns and separated into three distinct habitats (roots, gravel, particulates). Each habitat was assayed for its ability to produce N 2O, consume N 2O, and emit N 2O, as well as for denitrification gene abundances (nirS, nirK, and nosZ) and bacterial gene abundance (16S rDNA). The addition of organic carbon to the wetland was found to increase denitrification activity and gene copy abundance in non-root fractions, but organic carbon addition did not affect the root fraction. Plant presence within the TW was found to increase gas assay and gene abundance values in non-root habitats. Differences between three plant species were minor compared to differences attributed to carbon addition and plant presence. Of all habitats, gravel was found to have the highest denitrification activity and denitrification gene copy abundance relative to the number of 16S rDNA copies, as well as the highest ratio of N 2O produced to N 2O emitted. Implications for this study suggest the gravel and root fractions should be studied in further detail for their ability to accommodate denitrifying microbes.
Nitrogen removal and associated greenhouse gas production in laboratory-scale treatment wetlands
(Montana State University - Bozeman, College of Engineering, 2016) Allen, Christopher Robert; Chairperson, Graduate Committee: Otto Stein; Mark D. Burr, Anne K. Camper, Jefferson J. Moss and Otto R. Stein were co-authors of the article, 'Plant influence on denitrification in treatment wetlands' submitted to the journal 'Water research' which is contained within this thesis.; Mark D. Burr, Anne K. Camper, Jefferson J. Moss and Otto R. Stein were co-authors of the article, 'Influence of plants and organic carbon addition on greenhouse gas emissions from model treatment wetlands' submitted to the journal 'Environmental science and technology' which is contained within this thesis.; Otto R. Stein was a co-author of the article, 'Empirical modeling of plant influence and organic carbon addition on nitrogen removal in treatment wetlands' submitted to the journal 'Ecological engineering' which is contained within this thesis.
Treatment wetlands (TWs) are designed to treat domestic wastewater and water polluted from non-point sources such as agricultural runoff. Because many recent design improvements have increased aerobic removal pathways, nearly complete removal of biological oxygen demand (BOD) and oxidation of ammonium to nitrate in domestic wastewater is possible. These improvements have come at the expense of reducing the TW capacity to remove nitrate. Nitrate is also a main pollutant of concern in many non-point pollution sources. Organic carbon (OC) is a limiting factor for microbial nitrate removal and in wetlands can be supplied externally or provided by plants. Nitrate removal has the potential to release greenhouse gases (GHG) resulting in TWs being capable of acting as a net source or sink for GHG. Increasing our understanding of nitrogen removal and GHG production in TWs is the overarching goal of this project. A multi-year controlled environment greenhouse study measured water quality within 15-day incubations over annual cycles of temperature as well as greenhouse gas production at the seasonal extremes of the annual cycle. The experiment consisted of microcosms planted with either Carex utriculata, Deschampsia cespitosa, Phragmites australis, Schoenoplectus acutus, Typha latifolia or left unplanted. The fully factorial experiment also included three levels of OC addition, ranging from zero to two times the stoichiometric equivalent required for complete nitrogen removal. Nitrogen removal was affected by all experimental factors; plant species, OC addition, and temperature, with plant species mediating the effects of carbon and temperature in some treatments. The three highest performing species, C. utriculata, P. australis and S. acutus, removed nitrogen at an annual rate exceeding 166 g m -2 yr -1, without OC; only C. utriculata showed less N removal in winter. Incubation time series analysis indicated greater total and seasonal removal capacity for these plant treatments. Total GHG emission was dominated by summer CO 2 emission and varied by plant treatment and carbon load. CO 2 emission correlated negatively with OC addition in the high performing species attributable to plant biomass that decreased with OC addition. N 2O production significantly increased with the addition of organic carbon and did not vary significantly by season.
Processes of alkalinity addition to passive wetland systems near Great Falls, MT
(Montana State University - Bozeman, 1998) Allen, Diana L.
A review of substrates and vegetation in wetlands constructed to treat acid mine drainage
(Montana State University - Bozeman, 1995) Tickner, Darcy Nina; Chairperson, Graduate Committee: Douglas J. Dollhopf
Understanding Escherichia coli O157:H7 presence, pervasiveness, and persistence in constructed treatment wetland systems
(Montana State University - Bozeman, College of Letters & Science, 2015) VanKempen-Fryling, Rachel Joy; Chairperson, Graduate Committee: Anne Camper; Otto R. Stein and Anne K. Camper were co-authors of the article, 'Presence and persistence of wastewater pathogen Escherichia coli O157:H7 in hydroponic reactors of treatment wetland species' in the journal 'Water science and technology' which is contained within this thesis.; Anne K. Camper was a co-author of the article, 'Escherichia coli O157:H7 attachment and persistence within root biofilm of common treatment wetlands plants' submitted to the journal 'Water research ' which is contained within this thesis.; Anne K. Camper was a co-author of the article, 'Using molecular and microscopic techniques to track the wastewater pathogen Escherichia coli O157:H7 within model treatment wetlands' submitted to the journal 'Applied and environmental microbiology' which is contained within this thesis.
Treatment wetlands (TW) are a wastewater remediation technology that relies on the natural ability of wetland plant species and the associated microbial consortia to remove pollutants and improve water quality. Although there is substantial research on chemical pollutant remediation by TW, the removal of bacterial pathogens is much more varied and limited in scope. Escherichia coli O157:H7 is a bacterial pathogen that has caused numerous outbreaks and infections in the United States alone and is closely associated with improper water treatment. Understanding how E. coli O157:H7 could potentially persist and survive through a TW process is important in order to appropriately determine the efficacy of TW for treating water and protecting human health. This work used epifluorescent microscopy and qPCR relative DNA abundance to track E. coli O157:H7 tagged with a fluorescent DsRed protein in various environments pertaining to a TW. Two high performing wetland plant species, Carex utriculata and Schoenoplectus acutus, were used in hydroponic and simulated TW columns to better understand how the bacteria localize and persist. Teflon nylon strings (diameter 0.71-1.02 mm), cleaned and with established biofilm, were run hydroponically as control inert surfaces. Unplanted gravel columns were used as a nonplanted control for column experiments. E. coli O157:H7-DsRed were observed by microscopy on root surfaces both in hydroponic reactors and lab scale TW columns. The organisms persisted, forming microcolonies shortly after initial inoculation on both root and nylon surfaces. In the lab scale columns, cells persisted for three weeks, although strong biofilm formation was not observed. qPCR also provided evidence that E. coli O157:H7 was able to persist on the tested surfaces of plant roots, nylon inert surfaces, and gravel, showing higher abundance S. acutus roots than on the inert surface and gravel, however higher in unplanted gravel overall. For the plant types, C. utriculata was statistically lower for E. coli O157:H7 abundance than S. acutus over time. This work provides evidence that E. coli O157:H7 is able to colonize and persist in a TW environment, and plant surfaces may offer a higher inactivation than an inert matrix.

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