A mass transfer model of ammonia volatilization from anaerobic digestate.

Anaerobic digestion (AD) is becoming increasingly popular for treating organic waste. The methane produced can be burned to generate electricity and the digestate, which is high in mineral nitrogen, can be used as a fertiliser. In this paper we evaluate potential losses of ammonia via volatilization from food waste anaerobic digestate using a closed chamber system equipped with a sulphuric acid trap. Ammonia losses represent a pollution source and, over long periods could reduce the agronomic value of the digestate. Observed ammonia losses from the experimental system were linear with time. A simple non-steady-state partitioning model was developed to represent the process. After calibration, the model was able to describe the behaviour of ammonia in the digestate and in the trap very well. The average rate of volatilization was approximately 5.2 g Nm(-2)week(-1). The model was used to extrapolate the findings of the laboratory study to a number of AD storage scenarios. The simulations highlight that open storage of digestate could result in significant losses of ammonia to the atmosphere. Losses are predicted to be relatively minor from covered facilities, particularly if depth to surface area ratio is high.

[1]  J. Meisinger,et al.  Effect of adding alum or zeolite to dairy slurry on ammonia volatilization and chemical composition. , 2001, Journal of dairy science.

[2]  Paul T. Williams.  Waste Treatment and Disposal , 1998 .

[3]  Forbes R McDougall,et al.  Integrated Solid Waste Management: A Lifecycle Inventory , 1995 .

[4]  J. Harwood,et al.  Automated analysis of ammonia in water , 1970 .

[5]  Philip W. Westerman,et al.  MODELING AMMONIA EMISSION FROM SWINE ANAEROBIC LAGOONS , 2002 .

[6]  Measurement and estimation of ammonia emissions from lagoon–atmosphere interface using a coupled mass transfer and chemical reactions model, and an equilibrium model , 2006 .

[7]  E. J. Wilson,et al.  Excess nitrogen deposition: issues for consideration. , 1988, Environmental pollution.

[8]  Viney P. Aneja,et al.  Measurement and analysis of atmospheric ammonia emissions from anaerobic lagoons , 2001 .

[9]  C. Stevens,et al.  Nitrogen deposition and loss of biological diversity : agricultural land retirement as a policy response. , 2008 .

[10]  J. Martínez,et al.  Effect of covering pig slurry stores on the ammonia emission processes. , 2003, Bioresource technology.

[11]  D. Scholefield,et al.  A model of ammonia volatilisation from a dairy farm: an examination of abatement strategies , 2002, Nutrient Cycling in Agroecosystems.

[12]  S. Jarvis.  Nitrogen cycling and losses from dairy farms , 1993 .

[13]  M. Hansen,et al.  Effects of separation and anaerobic digestion of slurry on odour and ammonia Emission during Subsequent Storage and land application , 2005 .

[14]  H. T. Søgaard,et al.  Injection methods to reduce ammonia emission from volatile liquid fertilisers applied to growing crops , 2008 .

[15]  J. Sawyer,et al.  Use of Anaerobically Digested Swine Manure as a Nitrogen Source in Corn Production , 2007 .

[16]  Ji-Qin Ni,et al.  Mechanistic Models of Ammonia Release from Liquid Manure: a Review , 1999 .

[17]  K. S. Creamer,et al.  Inhibition of anaerobic digestion process: a review. , 2008, Bioresource technology.

[18]  K. Ro,et al.  PROCESS MODEL FOR AMMONIA VOLATILIZATION FROM ANAEROBIC SWINE LAGOONS INCORPORATING VARYING WIND SPEEDS AND GAS BUBBLING , 2008 .

[19]  Hal Westberg,et al.  Measurement and modeling of atmospheric flux of ammonia from dairy milking cow housing , 2008 .

[20]  Jørgen E. Olesen,et al.  Modelling effects of wind speed and surface cover on ammonia volatilization from stored pig slurry , 1993 .

[21]  E. Temminghoff,et al.  Volatilization of ammonia from manure as affected by manure additives, temperature and mixing. , 2007, Bioresource technology.

[22]  Helmut Döhler,et al.  Balancing of greenhouse gas emissions and economic efficiency for biogas-production through anaerobic co-fermentation of slurry with organic waste , 2006 .

[23]  D. Broday,et al.  A New Approach for Minimizing Ammonia Emissions from Poultry Houses , 2008 .

[24]  Walter Stinner,et al.  Effects of different manuring systems with and without biogas digestion on soil mineral nitrogen content and on gaseous nitrogen losses (ammonia, nitrous oxides) , 2009 .

[25]  Donald Mackay,et al.  Multimedia Environmental Models: The Fugacity Approach, Second Edition , 2001 .

[26]  P. Liss,et al.  Flux of Gases across the Air-Sea Interface , 1974, Nature.