Technology Type - Nitrification Denitrification
Technology Strengths,Weaknesses and Critical Indicators
Nitrification/Denitrification Technologies:
- No saleable product produced in most systems
- Vermiculture and some other technologies do produce salable by-products (i.e. worms and worm castings)
- Traditional and modified forms exist with years of experience treating municipal wastewater
- Uses large, multiple reaction chambers seeded with both anaerobic and aerobic bacteria
- Traditional concerns are capital cost, requiring large dedicated tanks and large power consumption for aeration.
- Proven technology for phosphorous recovery, storage reduction, GHG reduction, odor control and pathogen reduction
- This technology loses nitrogen as non-reactive nitrogen gas
Overall Summary
Primary Application
- Dairy farms with surface/groundwater nitrogen-overload concerns as well as those with ammonia particulate matter/odor issues—needing reduction in total nitrogen and ammonia concentrations within their liquid manure.
- Dairy farms that use flush systems resulting in very dilute barn effluent; flush systems are generally employed by large farms.
- All stall bedding materials are acceptable - pre-treatment required to remove sand bedding.
- Open-air nitrification/denitrification systems are limited to dry and temperate climates for suitable operative conditions for microbes to work.
Economic/Return on Investment Considerations
- Capital costs for traditional NDN are high, use of earthworm-catalyzed trickling filter-based and/or modified lagoon systems reduce capital cost.
- Electrical operating costs for traditional NDN systems are higher than for earthworm-catalyzed trickling filter-based systems; the worms reduce the electrical energy demand associated with the aeration.
- Possible returns on investment are in the form of reduced manure application costs and with respect to worm-systems, possible sale of harvested worm casing.
Industry Uptake
- There are very few NDN systems operating on US dairies and a limited number employed world-wide on animal manure, specifically swine.
- Nitrification/Denitrification systems on-farm are located where flush cleaning of barns are employed (dry and tempered climates).
Technology Maturity
- Traditional NDN systems used in wastewater treatment are mature - earthworm-catalyzed trickling filter-based systems developed for treatment of dilute animal wastewaters is in an early adoption stage with the few operating systems reported to be operating successfully.
Primary Benefits
- Strong reduction in inorganic and ammonia nitrogen due to conversion and release of nitrogen gas. Some additional phosphorous reduction in liquid due to assimilation of phosphorous within the bacteria.
- Odors associated with the overall manure management system will be reduced by the system due to removal of ammonia nitrogen.
- Manure organic matter will be reduced to a small extent.
- Pathogen reduction occurs because of the sequencing of anaerobic and aerobic processing.
- GHG emissions can be significant due to some organic solids reduction, aeration of stored liquid to alleviate anaerobic methane emissions, and conversion of ammonia-N to nitrogen (N2) gas, thus potentially avoiding potent downstream emissions of nitrous oxide (N2O) gas.
Secondary Benefits
- Reduced organic matter accumulation in long-term storages, although organic matter accumulation occurs in the NDN vessel and thus will need to be cleaned out periodically.
How it works
- Barn effluent is processed by a sloped screen or other solid-liquid separator.
- In the case of the worm-system, separator liquid effluent is evenly distributed by a manifold pipe system over the worm earthworm-catalyzed trickling filter bed located on top of a porous media. As applied liquid infiltrates into the bed, aeration is used to keep the bed aerobic and is achieved by a blower forcing air through diffusers located at the bottom of the bed. Operative microbes convert ammonia-N to a series of intermediate N compounds and finally to N2 gas. Liquid flows to the bottom of the vessel and is discharged by a point-source effluent pipe.
- In the case of more traditional NDN, solid-liquid separated liquid is pumped between anoxic and aerated zones for conversion of inorganic-N to a final N2 gas. Control of temperature, feed rate, and recycle rates between the different zones, as well as settling/retention of bacterial solids, control the operation and performance.
Pre-treatment and/or Post-treatment Required
- Primary and even fine solid-liquid separation is required.
- For farms using sand bedding, sand-manure separation is required.
- No post-treatment is required of liquid effluent or gaseous emissions.
Limitations
- NDN cannot be used with raw or slightly diluted dairy manure as the solids and nitrogen loading interfere with the process. Solids-separated digested manure can be used however, increased ammonia-N concentrations and reduced availability of carbon complicate the process and its viability.
- Operative microbes only work in areas with dry or temperate climates.
- NDN does not appreciably reduce overall manure storage requirements.
Other Considerations
- Labor is required to manage and operate the system.
- NDN systems are appropriate to consider 1) in the case where a farm has a nutrient imbalance exists, i.e. more N is contained in manure than needed to grow field crops or 2) when farms have large distances between the farmstead and fields resulting in high manure transportation costs.
- Harvesting worm casings and processing for sale is labor intensive and requires specialized equipment.
References
Bèline, F. and Martinez, J. (2002). Nitrogen transformations during biological aerobic treatment of pig slurry: effect of intermittent aeration on nitrous oxide emissions. Bioresource Technology 83: 225-228.
García-González, M. C., Riaño, B., Teresa, M., Herrero, E., Ward, A. J., Provolo, G., ... & Wiśniewska, H. (2016). Treatment of swine manure: case studies in European’s N-surplus areas. Scientia Agricola, 73(5), 444-454.
Lai, E., Zhao, Y., Pan, Y., & Mitloehner, F.M. (2018). Vermifiltration affects gaseous emission profiles from dairy wastewater. Submitted to Journal of Environmental Quality.
Li, C., Salas, W., Zhang, R., Krauter, C., Rotz, A. & Mitloehner, F. (2012). Manure-DNDC: a biogeochemical process model for quantifying greenhouse gas and ammonia emissions from livestock manure systems. Nutr Cycl Agroecosyst 93:163–200.
Obaja, D., Mace, S., Costa, J., Sans, C., & Mata-Alvarez, J. (2003). Nitrification, denitrification and biological phosphorus removal in piggery wastewater using a sequencing batch reactor. Bioresource technology, 87(1), 103-111.
Riaño, B., & García-González, M. C. (2014). On-farm treatment of swine manure based on solid–liquid separation and biological nitrification–denitrification of the liquid fraction. Journal of environmental management, 132, 87-93.
Vanotti, M. B., Szogi, A. A., Millner, P. D., & Loughrin, J. H. (2009). Development of a second-generation environmentally superior technology for treatment of swine manure in the USA. Bioresource technology, 100(22), 5406-5416.
Vanotti, M. B., Millner, P. D., Hunt, P. G., & Ellison, A. Q. (2005). Removal of pathogen and indicator microorganisms from liquid swine manure in multi-step biological and chemical treatment. Bioresource technology, 96(2), 209-214.
Willers, H. C., Derikx, P. J. L., Ten Have, P. J. W., & Vijn, T. K. (1996). Emission of ammonia and nitrous oxide from aerobic treatment of veal calf slurry. Journal of Agricultural Engineering Research, 63(4), 345-352.
Xu, J., Adair, C. W., & Deshusses, M. A. (2016). Performance evaluation of a full-scale innovative swine waste-to-energy system. Bioresource technology, 216, 494-502.
Yang, D., Deng, L., Zheng, D., Wang, L., & Liu, Y. (2016). Separation of swine wastewater into different concentration fractions and its contribution to combined anaerobic–aerobic process. Journal of environmental management, 168, 87-93.
Technology Providers in order of 9 - Point Scoring System