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3.3.2 Skim latex serum

The SLS was collected from Chana Latex Co, Ltd., Songkhla Province; Southern
Thailand. Table 3.1 shows that there are several limitations of using SLS as substrate to generate
biogas such as it still having low C/N ratio about 3 along with it also still having relatively high
sulfate contaminated was 258±0 mg/L which could potentially toxic to methanogens.
Nevertheless, SLS is one of the interest substrate used to generate biogas, thanks to its sufficient
in the macronutrients in nitrogen and phosphorus which is crucial for microbial growing. The
physical and chemical characteristics of SLS are summarized in Table 3.1. The SLS was kept at
2±1°C and was used within a month in order to minimize self-biodegradation and acidification.

3.3.3 Palm oil mill effluent

The POME was collected from the receiving tank of Palm Pattana Southern Border Co,
Ltd., Pattani Province; Southern Thailand. The POME has brown color, pH 4.68±0.00, a
temperature of 70-80°C which could be applied to operate under thermophilic temperature.
POME is deficient in the macronutrients in nitrogen as well as it contains phenolic compounds
which is antibacterial and phytotoxic properties. The physical and chemical characteristics of
POME are summarized in Table 3.1. The POME was kept at 2±1°C and was used within a
month

3.3.4 Empty fruit bunch (EFB) ash

The bottom EFB ash used in this research was collected from a boiler of Palm Pattana
Southern Border Co, Ltd., Pattani Province; Southern Thailand. The EFB ash was then ground in
a blender and passed through a 1.75 mm sieve. In the present study, the EFB as was used as
potassium source since its high potassium content of 175±8 mg/kg which coincided with a study
from Udoetok (2012) found that high potassium content in the EFB ash was 139.35 mg/kg. The
mixtures consisting of SLS and POME at the mixing ratio of 55:45 (%v/v) with initial organic
concentration of 7 g-VS added/L were supplemented with the EFB ash and were then shaken at 130
rpm for 60 min to ensure the potassium contained in the EFB ash was maximal dissolved into the
mixtures. Subsequently, the supernatants were then used as substrate for nutrients optimization to
generate biohydrogen.