SREL Reprint #1888

Batch anaerobic digestion of water hyacinth: effects of particle size, plant nitrogen content, and inoculum volume

K. K. Moorhead1 and R. A. Nordstedt2

1Department of Soil Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
2Department of Agricultural Engineering, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA

Abstract: Batch anaerobic digestion (at 35ºC) of water hyacinth plant material was evaluated for differences in particle size and nitrogen content of plants, and for differences in inoculum volume. Particle sizes of 1·6, 6·4 and 12·7 mm and a nitrogen content of 10 and 34 mg N kg-1 dry plant material were evaluated as well as inoculum Volumes of 2·5, 5 and 10 liters. Differences in cumulative biogas production were maximum at 15 days. Cumulative biogas production was highest for a plant particle size of 6·4 mm. Cumulative biogas production at 15 days increased with increasing inoculum volume for plants with a high N content but not for plants with a low N content. Total biogas and methane yields at 60 days were similar for plant material regardless of particle size, N content, or inoculum volume. Total biogas yields ranged from 0·20 to 0·28 liters g-1 volatile solids. Mineralization of organic 15N to 15NH4-N accounted for 72% of added 15N for plant material with high N content and 35% of added 15N for plant material with low N content.

Keywords: anaerobic digestion, water hyacinth, inoculum volume, particle size

SREL Reprint #1888

Moorhead, K.K. and R.A. Nordstedt. 1993. Batch anaerobic digestion of water hyacinth: effects of particle size, plant nitrogen content, and inoculum volume. Bioresource Technology 44:71-76. 

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).