Page 69 - 048

51

Table 4.1 Physical and chemical characteristics of the skim latex serum and palm oil mill

effluent used.

Parameters Unit SLS POME
pH 5.04±0.01 4.74±0.01
TSC g/L 46.94±0.13 61.44±0.11
VSC g/L 40.61±0.06 50.82±0.13
Alkalinity mg/L-CaCO 3 83±0 42±0
COD mg/L 33600±0 76160±0
TKN mg/L 4975±32 829±6
Protein mg/L 6417±202 5180±35
Carbohydrate mg/L 379±0 10340±0
Oil and grease mg/L 191±5 12083±86
Sulfate mg/L 233±0 -
Soluble phosphorus mg/L 39±0 161±0

4.3.4 Experimental set-up and operation

In this experiment, the sequential productivity of hydrogen and methane was operated in
a continuously stirred tank reactor (CSTR) for the first stage and an up-flow anaerobic sludge
blanket (UASB) reactor for the second stage. The first phase reactor, 1350 mL working volume
was maintained at 55°C with both recirculating hot water inside a water coil and assistance of the
heating plate of the magnetic stirrer which was equipped with a temperature control unit and it
was stirred at 90 rpm by magnetic bar. Meanwhile, the second phase reactor with 2700 mL
working volume was also maintained at 55°C by recirculating hot water through a water jacket
surrounding UASB reactor and control a re-circulating flow rate at 30 mL/h (Kongjan et al.,
2014). Schematic diagram of the two-stage anaerobic process for sequential production of
biohydrogen and biomethane which was operated in the lab-scale CSTR and UASB reactors is
shown in Fig. 4.1.

The enriched hydrogen producing bacteria achieved from batch reactor for 1000 mL was
directly fed into H 2-CSTR reactor. Subsequently, the rest of the reactor active volume was filled
up with a substrate consisting of SLS and POME at the mixing ratio of 50:50 (%v/v)
supplemented with NaHCO 3 2 g/L for acclimation period was applied for three weeks. Then, the
mixing ratio of SLS and POME was changed to the optimal mixing ratio which was achieved