Fruit and vegetable wastes were prepared
to the same composition as the representative waste
from the Si-Mum Muang Market, Thailand,(11) and is
shown in Table 1. The fruit and vegetable wastes
were shredded by hand into 1 - 2 cm pieces (strips or
squares) and mixed together to enhance the
homogeneity of waste. The shredded waste was
mixed with 1 L of anaerobic digested sludge, obtained
from wastewater treatment plant of the Utility
Business Alliance Co., Ltd. The reactors were
operated for 519 days with the addition of alkali
(NaOH 5 M) after day 200 in order to increase the
alkalinity and pH for methanogenesis bacteria. The
pH of the recycled leachate was adjusted to neutral
pH (7.0) with NaOH (5 M) three times per week
before introduction back into the reactors. Simulated
leachate samples were collected from both reactors
regularly and were used as test extracting agents.
Leachate samples collected at the same times were
used as representatives of the same landfill phase but
note that they exhibited different properties and