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1. Introduction and shell (5%) for every ton of fresh fruit bunches (FFBs)

processed in the mills. Thus, the utilized of POME has
Research in dark co-fermentation for hydrogen gained interest from many researchers due to the abun-
production from various organic substrates has much dant amount generated in the mills.
received attention in recent years, however many Currently, most of latex concentrates plants and
researchers utilize typical simple sugars or starch (1-5) palm oil mill plants use SLS and POME as feedstock to
which is not economically feasible due to their high cost. produce biogas in Malaysia and Thailand (8). Hydrogen
The new strategy of market-driven research is to focus on is one of the prototype alternatives renewable energy to
using cheap, organic waste-based feedstock, employing fossil fuels. Hydrogen can be produced by many methods
indigenous mixed cultures and improving the hydrogen among that biological method by dark fermentation. This
production yield (6). Natural rubber (NR) latex is milky method is environmentally friendly and capable to utilize
white or slightly yellowish opaque fluid of the rubber tree the organic waste to eliminate the pollution (9). Dark
(Hevea brasiliensis). NR latex harvested from plantations fermentation has various advantages, for example, high

needs to be processed soon after harvesting to maintain its rate of bacterial growth, requires low energy input, no
quality. One of the major types of processed rubber is the oxygen limitation problems and low costs (10, 11).
preserved latex concentrate. Ammoniated field latex con- Various types of waste materials can be used as
taining 30–33% rubber is concentrated by centrifuging to substrate for biohydrogen production such as palm oil mill
60% rubber and skim latex (containing 4–6% rubber) effluent (POME) (8), starch-based materials (12), ligno-
using high speed centrifuges. The skim latex (contains cellulosic materials (13), food wastes (14), dairy wastes
about 0.8% ammonia) is coagulated with 98% sulfuric (15), glycerol waste (16) and skim latex serum (17).
acid to recover rubber. The skim serum produced after Co-digestion of various organic wastes for energy

coagulation of rubber is stored in a separate trap. It contains production has several advantages compared to single
significant amount of non-rubber matters, including substrate digestion such as improved biogas yield,
proteins, carbohydrates, sugars, carotenoids, organic and economic advantages derived from the sharing of equip-
inorganic salts which are originated from the latex and ment, easier handling of mixed wastes, and synergistic
very little amount of un-coagulated latex. These constituents effect (18, 19). Mixed culture is more appropriate for
are excellent substrates for the proliferation of microor- hydrogen production from non-sterilized organic wastes
ganisms generating high biochemical oxygen demand under mesophilic temperatures at 20 to 40 C (14, 15, 20)
o
o
(BOD) (7). or thermophilic conditions at 50 to 60 C (21-23). Thermo-
The production of palm oil as one of the major philic operation may be suitable to meet legislation for
edible oils consumed in the world has increased tremen- treatment of feedstock containing pathogens. Additionally,
dously in the last decade and is led by Malaysia, Indonesia thermophilic hydrogen production process was more
and Thailand. However, the milling process produces a efficient than the mesophilic one in both hydrogen production

huge volume of palm oil mill effluent (POME). One ton of rate and yield (8, 24).
oil palm fruit approximately 0.87 m POME is generated The current study aimed to determine the potential
3
or 3.7 ton of effluent per ton of oil produced. Oil palm mill of using POME, wastewater from palm oil mill plant for
plant also generates large amount of solids wastes such as co-digestion with SLS to produce hydrogen via mixed
empty fruit bunch (EFB) (23%), mesocarp fiber (12%) cultures fermentation.