2.4 Analytical methods
The liquids samples from sampling port were withdrawn every 5 days to analyze COD, TS and VS
followed standard methods [5]. The total amount of biogas was measured everyday regarding to the amount of water volume displaced by the existing gases. Gas
composition was analyzed off line by gas chromatography
(Shimadzu GC-14B) equipped with a thermal conductivity
detector (TCD) and 1 M Porapak Q (80-100 mesh) GC column. Helium was used as carrier gas with a flow rate of 25 ml/min. The column, injector and detector temperature were at 60, 120 and 120 O C, respectively.
3. Results and Discussion
3.1 Biogas production in batch process
In this study, the chemical properties of pineapple
peel were analyzed in order to investigate the biogas generation potential of raw material (Table 1).
The accumulative gas recorded for 30 days with original pH (4.6) by using microorganism from sewage sludge was shown in Fig. 1. (Other seed microorganism was not made the system to generate gas, so the result was not shown). At present system, the acidogenesis process was occurred within 8 days of the experiment which appeared pH was lowest. After that the pH was gradually higher while the gas formation was noticeably accumulated for 20 days. However, less efficiency resulting from fewer amounts of total gas and methane were detected at this initial pH because of high content in both acid value and carbon to nitrogen ratio. This condition was not suitable for methane formation bacteria to grow up [4].