Page 49 - 048

31

the mixtures was increased. The biohydrogen production yield obtained from the optimum
mixing ratio of SLS and POME was 4 times greater than that of individual fermentation of SLS.
Subsequently, it was further transferred into the BMP test in the second stage.

In the Fig. 3.1 shows that cumulative hydrogen production achieved from sole
st
nd
fermentation of POME is dramatically increase from the 1 to the 2 days of fermentation. The
possible reasons is that the microorganisms can be easily broken down the complex organic
contained in the POME such as carbohydrates to generate biohydrogen. Subsequently,
th
nd
cumulative hydrogen production is gradually increased during the 2 to the 4 days of
fermentation. The possible cause for gradually increased of biohydrogen was generated due to
the microorganisms are broken down lipid contained in POME was slow, this is due to lipid is a
large molecules which makes it difficult to degrade. At the end of fermentation, cumulative
hydrogen production is dramatically increased possibly correlates to reduced products which
expected mostly achieved from lipid hydrolysis was utilized to generate biohydrogen. Similarly
to co-digestion of SLS and POME with a relatively high proportion of POME in the mixture
such as SLS: POME mixing ratio of 50:50 %v/v as shown in Fig. 3.1.

On the other hand, the lowest cumulative hydrogen production achieved from individual
fermentation of POME with initial organic concentration of 21 g-VS added/L due to it is a
concentrated substrate with high lipid content which could potentially inhibit or overload the
process and lead to decrease in biodegradability. At the same time, cumulative hydrogen
production achieved from sole fermentation of SLS around 17 times greater than that achieved
from sole fermentation of POME. The possible reason is that the complex organics contained in
SLS would be easily broken down as compared with POME. In the Fig. 3.2 shows that when the
proportion of POME was increased in the mixture, resulting in increase in cumulative hydrogen
production was obtained. Nevertheless, when the proportion of POME in the mixture was higher
than 40%, cumulative hydrogen production is gradually decreased as previously mentioned.