A 15-week treatability study was conducted in a greenhouse to evaluate the potential effects of molasses
on the bioremediation and phytoremediation potential of Guinea Grass (Panicum maximum) for treating
energetic contaminated soil from the open burn/open detonation area of the Makua Military Reservation,
Oahu, HI (USA). The energetics in the soil were royal demolition explosive (RDX) and high-melting explosive
(HMX). Among the 6 treatments employed in this study, enhanced removal of RDX was observed
from treatments that received molasses and went to completion. The RDX degradation rates in treatments
with molasses diluted 1:20 and 1:40 were comparable suggesting that the lower dose worked
as well as the higher dose. Treatments without molasses degraded RDX slowly and residuals remained
after 15 weeks. The bacterial densities in molasses-treated units were much greater than those without
molasses. Phytoremediation alone seems to have little effect on RDX disappearance. For HMX, neither
bioremediation nor phytoremediation was found to be useful in reducing the concentration within the
experimental period. The concentrations of nitrogen and phosphorous in the soil did not change significantly
during the experiment, however, a slight increase in soil pH was observed in all treatments. The
study showed that irrigating with diluted molasses is effective at enhancing RDX degradation mainly in
the root zone and just below it. The long term sustainability of active training ranges can be enhanced
by bioremediation using molasses treatments to prevent RDX deposited by on-going operations from
migrating through the soil to groundwater and off-site.