Career summary

Researcher and educator working in environmental engineering. Present focus on ammonia and greenhouse gas emission from agriculture, as well as biogas production from wastes. Skills in data analysis and mathematical modeling.

Research summary

Primary focus is mathematical modeling of physical, chemical, and biological processes related to pollution prevention and resource recovery from wastes. Also development of simple, accurate laboratory methods for research and industry. Applications include biogas production, biological treatment of wastewater sludge, and emission of air pollutants from agricultural systems. Selected research achievements are listed below (numbers refer to publications and software given below).

• Standardized algorithms and software for measurement and prediction of methane potential. Applied work on flexible and powerful software for biogas research and the biogas industry. High level of usage suggests software is useful. (38, 50, S2, S3)
• New methods for measurement of biogas production in laboratory trials. Focus on gravimetric measurement has resulted in three new methods that contribute to better accuracy or greatly reduce labor and equipment needs. Implications for research and practice include improved accuracy and better plant management. Also, these tools empower groups without resources for expensive equipment, e.g., in developing countries (26, 36, 40, 42, 43)
• Aerobic inter-stage treatment: new approach to biological treatment of organic wastes. Work with wastewater sludge shows potential for improving organic matter conversion with energy recovery through biogas production. (33 & 35)
• New approach and new model for predicting emission from field-applied manure. Ammonia emission from agriculture contributes to many thousands of deaths annually. Better management requires better emission predictions. I developed a new model for predicting emission based on a new semi-empirical approach and a large dataset. (34, 39, S4, alfam.dk)
• Quantitative understanding of ammonia emission. I explored ammonia speciation and developed mechanistic reaction-transport models for understanding the processes controlling emission from manure. This work contributed to a new understanding of simultaneous ammonia and carbon dioxide emission, and has applications in ammonia emission but also areas as diverse as carbon dioxide scrubbing and functioning of fish gills. Major predictions from first-principles models (steep pH gradient formation) have been verified by recent measurement. (8, 11, 17, 24, & 30)
• New understanding of emission of volatile organic compounds from fermented animal feed. Research clarified VOC sources and transport mechanisms, and highlighted the importance of this problem for secondary air pollution (still underappreciated in Europe and the US). Later efforts presented practical approaches for reducing VOC emission. (13, 15, 19, 20, 23, & 25)
• Practical algorithms and software for detection and identification of animal vocalizations. Unrelated to engineering, but included here to demonstrate the wide range of application of my skills. New software has become a popular tool for research. (28 & 29, S1)