Main Article Content
This research aims to determine the biogas production from thinner wastewater, containing the chemical oxygen demand (COD) 48,000 mg/L and total volatile solids (TVS) of 27,160 mg/L, by using high rate anaerobic digestion. Completely Stirred Tank Reactor (CSTR) with size 6 L was used to run the experiment for the organic loading rate (OLR) at 2.4, 4.0 and 5.6 kgCOD/m3.day, which were controlled by the hydraulic retention times (HRT) at 20, 12 and 8.6 days, respectively. Under the experimental conditions operated at room temperature, pH balance of wastewater was adjusted before pushing to the system which the numbers of sludge in the system were 18,000 mg/L at the initial state.
According to the research results, the system could produce the maximum methane yield (88 L at STP/kg of COD degraded that is 162 L at STP/kg of TVS degraded) with the organic loading rate (OLR) at 2.4 kgCOD/m3.day (at flow rate 0.3 L/day and hydraulic retention time 20 days). The efficiency of COD removal was 54.12% and 51.29% respectively. In this case, the average pH in the reactor was 6.88. The pH of system must be controlled to be for the proper state of biogas production during the experiment. However, it was found that the organic loading rate 2.4 kgCOD/m3.day was for biogas production made by thinner wastewater.
 Department of Industrial Work. 2545. Ministry of Industry and Thailand Environmental Engineering Association. Wastewater System Control Book. Thailand Environmental Engineering Association. (in Thai)
 Punika Kummarel. 2553. The Biogas Production from Sa Paper Wastewater by the Codigestion with Cow Dung and Food Waste Using Sequencing Batch Reactor. Environmental Engineering Master Thesis, Chiengmai University.
 Piyanee Sangsee. 2557. The Biogas Production from Napier Grass Using Co-digestion with Cow Dung. The 13th Thai National Environmental Conference.
 APHA, AWWA, and WEF. Standard Methods for the Examination of Water and Wastewater, 20 ed. Washington, D.C., 2005.
 Suthep Vittayapakorn. 2552. Wastewater Technology, 2nd printed. Environmental Engineering Department, Faculty of Engineering, Kasetsart University, Bangkok.