2.1. Experimental set up
The whole experiment was conducted at a commercial plant
owned by Enviro-Green Biotech Sdn Bhd which is located at Johor,
Malaysia. The materials used for the experiment were not exposed
to direct rainfall because the buildings of the commercial plant
were properly roofed. The adopted composting technique at the
plant is the turning furrow type where it involves placing the mixture
of compost raw materials in long narrow rectangular furrows
with regular transferring and turning of the materials by mechanical
means in batches. There are altogether 24 furrows in the compost
plant, namely 1A–8A, 1B–8B and 1C–8C. Each furrow
contains nine equally sized compartments and each compartment
is 5 m long, 2 m wide and 2.5 m deep. Different compartments represent
the composting stages of the EFB. Compartment 1 contains
the fresh materials while compartment 9 contains the composting
materials that are nearly matured. The composting materials are
transferred from compartment to compartment by turning machine
during its operation. The composting materials that move
from compartment 1 to compartment 9 are considered to have gone
through one operational cycle and required two operational cycles
to reach maturity. All precautions were taken to make sure that the
materials were not mixed up or contaminated in the whole process.
The maturity state is attained when the C/N ratio of the composting
materials is less than 20 and temperature and moisture content
were less than 40 C and 40%, respectively. (Heerden et al., 2002).
This state could be achieved after 3 months of composting. The final
product needs to be at low temperature and moisture content to
make sure that the decomposition process has been slowed down.
The raw materials used were EFB, POME and decanter cake slurry.
Table 1 summarizes the treatments used in the whole experimental
study. The first treatment was prepared by adding POME and decanter
cake slurry to the EFB and mixed at the pre-mix building before
it was assigned to furrow 1C, 2C and 3C in the production line.
The compost in these furrows represents the replicates for the
treatment. For the second treatment, only POME was added to
EFB and mixed at the pre-mix building before it was assigned to furrow
6B, 7B and 8B in the production line. The third treatment which
is a mixture of EFB and POME was left at the pre-mix building of the
compost plant where it was treated as control in the experiment.
The turning operation was done using a tiller machine at an interval
of three days. While turning, POME was sprayed into the
composting material to maintain the moisture content of the composting
material in the compartment. The turning operation
enhances the passive aeration of the compost materials by increasing
its porosity. Hence, the availability of more air within the composting
materials favours the microbial activities which indirectly
increase the decomposition process of the composting materials.