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Smith D.P.,Applied Environmental Technology Tampa Inc. | Smith N.T.,University of California at Davis
Water Science and Technology | Year: 2016

An anaerobic/ion exchange (AN-IX) system was developed for recovery and reuse of wastewater nitrogen at point-of-origin. AN-IX combines upflow solids blanket anaerobic treatment with ammonium ion adsorption onto granular natural zeolite. AN-IX operates passively and without energy input. A 57 L empty-bed prototype was operated for 355 days on wastewater primary effluent. Total nitrogen removal exceeded 95% over the first 214 days of operation and ammonia reduction exceeded 99%; accumulation of oxidized nitrogen species (NO3-+ NO2-) was not observed. The wastewater flowrate was increased during the last 35 days of operation to deliberately exhaust the ion exchange media. Spent granular media was removed from the AN-IX prototype and deployed in plant chamber experiments for cultivation of Solanum lycopersicum (cherry tomato). Wastewater nitrogen captured on zeolite was capable of supplying the total growth requirement for nitrogen. Canopy volume and plant flowering and fruiting were higher for wastewater nitrogen than for artificial fertilizer. The AN-IX process is a passive, mechanically simple and reliable system for local-scale nitrogen recovery. AN-IX is modular, scalable, adaptable and can be applied in diverse treatment contexts and recycling scenarios. AN-IX benefits include appropriate technology for localscale nitrogen recovery, low capital and energy costs, and protection of health and the environment. © IWA Publishing 2016.


Smith D.P.,Applied Environmental Technology Tampa Inc. | Smith N.T.,University of Maryland University College
Bioresource Technology | Year: 2015

An anaerobic-ion exchange (AN-IX) process was developed for point-of-origin recovery of nitrogen from household wastewater. The process features upflow solids-blanket anaerobic treatment (ammonification) followed by ammonium ion exchange onto natural zeolite. The AN-IX system is configured as a series of linked upflow chambers that operate passively without energy input, and is amenable to intermittent and seasonal operation. A 57L prototype was operated for over 1.8years treating actual wastewater under field conditions. Total nitrogen removal exceeded 96% through the first 160days of operation and effluent ammonium nitrogen remained below detection for 300days. Ion exchange chambers exhibited sequential NH4+-N breakthrough over extended operation and complete media exhaustion was approached at Day 355. The ammonium capacity of zeolite was estimated as 13.5mg NH4+-N per gram dry weight. AN-IX is a resilient and cost effective process for local-scale nitrogen recovery and reuse, suitable for small scale and larger systems. © 2015 Elsevier Ltd.


Smith D.P.,Applied Environmental Technology Tampa Inc.
Water Science and Technology | Year: 2012

A passive biofiltration process has been developed to enhance nitrogen removal from onsite sanitation water. The system employs an initial unsaturated vertical flow biofilter with expanded clay media (nitrification), followed in series by a horizontal saturated biofilter for denitrification containing elemental sulfur media as electron donor. A small-scale prototype was operated continuously over eight months on primary wastewater effluent with total nitrogen (TN) of 72.2 mg/L. The average hydraulic loading to the unsaturated biofilter surface was 11.9 cm/day, applied at a 30 min dosing cycle. Average effluent TN was 2.6 mg/L and average TN reduction efficiency was 96.2%. Effluent nitrogen was 1.7 mg/L as organic N, 0.93 mg/L as ammonium (NH 4-N), and 0.03 as oxidized (NO 3 +NO 2) N. There was no surface clogging of unsaturated media, nitrate breakthrough, or replenishment of sulfur media over eight months. Visual and microscopic examinations revealed substantially open pores with limited material accumulation on the upper surface of the unsaturated media. Material accumulation was observed at the inlet zone of the denitrification biofilter, and sulfur media exhibited surface cavities consistent with oxidative dissolution. Two-stage biofiltration is a simple and resilient system for achieving high nitrogen reductions in onsite wastewater.


Smith D.P.,Applied Environmental Technology Tampa Inc.
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

Biofiltration shows promise as an appropriate technology to increase nitrogen removal in onsite wastewater treatment systems. This presentation will summarize ongoing studies of passive, two-stage biofiltration systems for onsite nitrogen removal that have been funded by the Florida Department of Health. Passive systems utilize a single pump, no aerators, and reactive media for denitrification. Biofilter media include expanded clay, natural zeolite, silica sand, elemental sulfur, lignocellulosics, limestone and oyster shell. Over twenty biofilters have been operated in upflow, downflow, horizontal flow, and in saturated and unsaturated configurations, all fed by primary effluent. Total nitrogen reductions of 95% have been achieved. Oxygen transfer analysis suggests that the unsaturated biofilter designs provide high oxygen ingress rates that support efficient nitrification. Simulation modeling shows high denitrification rates at the entrance region of sulfur biofilters and agrees qualitatively with field observations. The goal of the pilot study and process modeling is to produce functional designs for nitrogen reducing systems at single family residence and larger scale. © ASCE 2012.


Smith D.P.,Applied Environmental Technology Tampa Inc.
Journal of Environmental Engineering (United States) | Year: 2015

The plenum-aerated biofilter (PA biofilter) is an unsaturated, single pass vertical flow biofilter with horizontal air plena within the media to enhance passive aeration. Plena enlarge the surface area of the air/media interface, increase oxygen ingress, and permit a reduction in the footprint of ammonium oxidizing biofilters. An experimental PA biofilter was operated on household wastewater pretreated in a primary settling tank. The prototype was a 7.3 cm (3 in.) inner diameter circular column, containing 61 cm (24 in.) of granular clinoptilolite media. Three 5.1 cm (2 in.) aeration plena were placed at successive 7.6 cm (3 in.) media thicknesses below the upper filter surface. The biofilter was operated for 28 weeks at hydraulic loading of 69.8∈∈cm/day (17∈∈gal./ft2-day) and a 60-min dosing cycle. Performance was characterized by monitoring from days 180 to 196. Influent NH4+-N was reduced by 99% (mean 51.6∈∈mg/L to 0.61∈∈mg/L, n=3), with substantial conversion to NO3 - N (mean 38.4∈∈mg/L, n=3). Solute profiling showed ammonia reduction was substantially complete after passage through 45 cm (18 in.) of porous media and nitrite accumulated between 15 and 30 cm (5.9 and 11.8 in.). This short-term study suggests that the PA biofilter can provide a compact and passive ammonium oxidation system that is suitable for on-site wastewater treatment. Further studies are needed to verify that effective nitrogen transformations can be sustained over longer periods of operation. © 2015 American Society of Civil Engineers.


Smith D.P.,Applied Environmental Technology Tampa Inc.
Journal of Environmental Engineering | Year: 2010

A methodology was developed to monitor and evaluate the removal of solids and associated constituents by a nutrient separating baffle box (NSBB) storm-water treatment device treating runoff from a 4.3 ha (10.6 acre) residential watershed discharging into the Indian River Lagoon, Florida. The NSBB was monitored over a 359-day time period using autosamplers to quantify water column removal during runoff events, and by quantifying and analyzing solids that accumulated within the NSBB. Flow composited influent and effluent samples were collected to represent water column performance. Event mean concentration (EMC) reduction was moderate (mean: 17%) and variable (range: -39 to 68%) for suspended solids, and negative for nitrogen, phosphorus, fecal coliforms chromium, and copper. The mass of solids that accumulated in bottom chambers and in a strainer screen was quantified and analyzed for nitrogen, phosphorus, heavy metals, and polycyclic aromatic hydrocarbons. A quantitative evaluative framework was devised to estimate the total pollutant mass removal by NSBB, which consisted of the summation of the separately calculated mass removals for water column, bottom chamber material, and strainer screen material. The water column accounted for only 4% of total solids that accumulated in the NSBB, which was equally divided between bottom chamber and strainer screen. Removal of nitrogen, phosphorus, and metals could be accounted for only by considering mass accumulations. Results suggest that overall assessment of pollutant removal by NSBB must be cognizant of the materials not captured by typical autosamplers: larger size sediment particles, large floating and suspended matter, and the pollutants associated with these materials. Using water column EMCs as the sole measure of performance significantly underestimated loading reduction of storm-water constituents by the NSBB. The monitoring and evaluative methodology applied to the NSBB may be applicable to load reduction evaluations for other storm-water treatment devices with a similar function. © 2010 ASCE.


Smith D.P.,Applied Environmental Technology Tampa Inc.
Water Environment Research | Year: 2011

Enhanced nitrogen removal from stormwater using chabazite, a natural cation exchanger, was evaluated in a pilot-plant biofilter operated for 216 days. A parallel sand filter served as the control. The biofilters were subject to various operating modes including baseline periods of steady flowrate and loading, simulated high flowrate (storm) events following steady flowrates, high flowrates following extended no-flow periods, and with limited influent dissolved oxygen. Under steady-flow operation, chabazite removed 93% of ammonium and sand removed 87%; total inorganic nitrogen was reduced 35% by chabazite versus 15% by sand. In a simulated storm event following steady-flow operation, 97% of cumulative ammonia mass was retained by the chabazite biofilter versus 70% for sand. Following a 40 day no-flow period, the chabazite biofilter retained 98% of influent ammonium in a storm event while sand exhibited high effluent ammonium. Chabazite ammonium retention was high under limited influent dissolved oxygen, verses significant breakthrough by the sand biofilter. Chabazite media provided superior performance resiliency under dynamic conditions that typify stormwater treatment. © 2010 Publishing Technology.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: SMALL BUSINESS PHASE I | Award Amount: 225.00K | Year: 2016

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is to address the grand challenge of human-induced nitrogen loading to the environment. An easy-to-use and affordable system will target a major source of nitrogen releases to watersheds: the on-site systems that treat wastewater from millions of households and commercial facilities across the U.S. The need to mitigate harmful algal blooms and prevent other damaging cumulative effects to aquatic ecosystems have created an urgent demand for onsite technologies that remove nitrogen at its source. The proposed nitrogen removal technology is modular and adaptable for use in small-scale systems that treat wastewater from individual homes, community systems and commercial establishments. The project employs an innovative biological nitrogen removal process that that will be verified and optimized for high priority applications in rural, peri-urban, and urban settings. The system is mechanically simple, generates no waste products, and operates passively with minimal maintenance, energy or consumables. The results from this project will help to solve the critical challenge of nitrogen control by providing a highly efficient, low-cost, commercializable system that is practicable for on-site wastewater treatment in new and retrofit systems.

The technical objectives of this Phase I research project are to design, construct, field-test, and critically evaluate variant prototypes of an innovative bioreactor system to remove nitrogen from onsite wastewater. Prototype bioreactors will be operated and monitored over multiple months to investigate their salient operational characteristics and define effective design and treatment regimes. The bioreactors will be installed to treat real household wastewater under field conditions. Nitrogen analytes will be monitored across the bioreactor systems to delineate the effects of biotreatment on four nitrogen species: organic nitrogen, ammonium, nitrate and nitrite. The effects of the biotreatment system on chemical and biochemical oxygen demand, inorganic chemical parameters, and other wastewater constituents of interest will also be elucidated. The project will critically evaluate the effectiveness of total nitrogen removal and the stability and resiliency of individual nitrogen removal transformations. The work will confirm the longevity and robustness of the nitrogen removal process and identify design and operating parameters that optimize an innovative approach to remove total nitrogen from on-site wastewater while mitigating nitrogen releases to the environment. Prototype design and monitoring will facilitate scale-up of results to full-scale biotreatment systems.


Grant
Agency: Environmental Protection Agency | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 79.94K | Year: 2013

Onsite wastewater systems are a significant source of nutrient loading to the environment and there is a demand for technologies that remove nutrients at the source. Most desired are passive, low cost systems that can consistently remove ninety percent or greater nitrogen while having low energy input and easy operation. While numerous proprietary devices have been developed that typically employ multiple mechanical apparatus, they require active attention and provide only partial nitrogen removal. AET is developing a unique multi-chamber treatment process that provides high percent nitrogen removals, passive operation, low life cycle cost, and resilient performance. The AET process applies anaerobic biological treatment in a multi-chamber upflow solids blanket bioreactor to remove organics and recover energy, followed by selectively configured ion adsorption, aerobic and anaerobic biofilter that employ judiciously specified designer media. No operation energy is required. Nitrogen and phosphorus reductions exceeding ninety-five percent have been achieved with initially configured components, suggesting that a viable commercial system can be developed. The objective of SBIR Phase 1 is to experimentally validate two prototype designs and provide scale-up basis for Phase 2 evaluation of full scale systems. Two seventy liter multi-chamber systems will be fabricated and field tested on house sanitation water, one using whole house wastewater and the second using primary tank effluent. Monitoring will be conducted to delineate critical performance metrics, including organic conversion, suspended solids reduction and biological stability prior ion capture filtration process, speciation and retention of nitrogen and phosphorus, and the crucial role of media and water chemistry. The SBIR Phase 1 project will provide critical evaluation of system design, and identify key factor pertinent to process efficacy, long term operation, life cycle cost and commercial viability. Phase 1 results will lead directly to design of full scale Phase 2 systems. There is a high market potential for commercial application of the AET technology. Single family homes and community systems comprise greater than 25% of total U.S. wastewater flow. The AET system is projected to be life cycle cost competitive with currently available nutrient removal technologies in the single home arena. It is eminently modular and adaptable to a wide variety of recycling and reuse schemes, including blackwater treatment. The modular design is also appropriate at larger community scale and for resource recovery within centralized treatment areas. Low cost systems that recover energy and nutrients at local scale are absent in current U.S. practice.


Grant
Agency: National Science Foundation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 225.00K | Year: 2016

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is to address the grand challenge of human-induced nitrogen loading to the environment. An easy-to-use and affordable system will target a major source of nitrogen releases to watersheds: the on-site systems that treat wastewater from millions of households and commercial facilities across the U.S. The need to mitigate harmful algal blooms and prevent other damaging cumulative effects to aquatic ecosystems have created an urgent demand for onsite technologies that remove nitrogen at its source. The proposed nitrogen removal technology is modular and adaptable for use in small-scale systems that treat wastewater from individual homes, community systems and commercial establishments. The project employs an innovative biological nitrogen removal process that that will be verified and optimized for high priority applications in rural, peri-urban, and urban settings. The system is mechanically simple, generates no waste products, and operates passively with minimal maintenance, energy or consumables. The results from this project will help to solve the critical challenge of nitrogen control by providing a highly efficient, low-cost, commercializable system that is practicable for on-site wastewater treatment in new and retrofit systems. The technical objectives of this Phase I research project are to design, construct, field-test, and critically evaluate variant prototypes of an innovative bioreactor system to remove nitrogen from onsite wastewater. Prototype bioreactors will be operated and monitored over multiple months to investigate their salient operational characteristics and define effective design and treatment regimes. The bioreactors will be installed to treat real household wastewater under field conditions. Nitrogen analytes will be monitored across the bioreactor systems to delineate the effects of biotreatment on four nitrogen species: organic nitrogen, ammonium, nitrate and nitrite. The effects of the biotreatment system on chemical and biochemical oxygen demand, inorganic chemical parameters, and other wastewater constituents of interest will also be elucidated. The project will critically evaluate the effectiveness of total nitrogen removal and the stability and resiliency of individual nitrogen removal transformations. The work will confirm the longevity and robustness of the nitrogen removal process and identify design and operating parameters that optimize an innovative approach to remove total nitrogen from on-site wastewater while mitigating nitrogen releases to the environment. Prototype design and monitoring will facilitate scale-up of results to full-scale biotreatment systems.

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