Aerobic treatment of swine manure to enhance anaerobic digestion and microalgal cultivation

ABSTRACT

Aerobic treatment of swine manure was coupled with anaerobic digestion and microalgal cultivation. A 14-day aerobic treatment reduced the total solid content of swine manure by >15%. Ammonia and carbon dioxide were stripped by the air supplied, and this off-gas was further used to aerate the culture of Chlorella vulgaris. The microalgal growth rates in Bristol medium and the wastewater with the off-gas increased from 0.08 to 0.22 g/L/d and from 0.15 to 0.24 g/L/d, respectively. Meanwhile, the aerobically treated swine manure showed a higher methane yield during anaerobic digestion. The experimental results were used to establish a demonstration unit consisting of a 100 L composter, a 200 L anaerobic digester, a 60 L tubular photobioreactor, and a 300 L micro-open raceway pond.

KEYWORDS:

• Aerobic treatment
• swine manure
• microalgae
• off-gas
• anaerobic digestion

Acknowledgments

This publication was made possible by Grant Nos. NC.X2013-38821-21141 and NC.X-294-5-15-130-1 from the U.S. Department of Agriculture—the National Institute of Food and Agriculture (USDA-NIFA). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIFA.