SREL Reprint #1888
BATCH ANAEROBIC DIGESTION OF WATER HYACINTH:
EFFECTS OF PARTICLE SIZE, PLANT NITROGEN CONTENT,
AND INOCULUM VOLUME
K. K. Moorheada & R. A. Nordstedtb
aDepartment of Soil Science, bDepartment 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.
Key words: 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.
