Treatment of Low Strength Wastewater by Rubber Granules Media AFB Reactors without Internal Recirculation

Thipaporn Sirinukulwattana, Wiboonluk Pungrasmi, Chaiyaporn Puprasert



In this research, the efficiency of wastewater treatment and biogas production by the Anaerobic Fluidized Bed (AFB) reactors using rubber granule as a media were performed under condition of no internal recirculation. A low density rubber granule is easy to form a fluidization state which beneficial conserves more energy for the process. The experiment was divide into two parts, first is a system startup, which the synthetic wastewater with a COD of 1,045 mg/L (equivalent to OLR of 30 kg COD/m3-d) was continuously feed into two AFB reactors at a constant rate of 46.8 L/day and hydraulic retention time as low as 0.84 hrs. After those two reactors reached steady state, the step up OLR variation was performed. The OLR loading for the 1st reactor was changed to 15 and 2 kg COD/m3-d (equivalent to COD of 522 and 70 mg/L), whereas the OLR loading for the 2nd reactor was changed to 5 and 2 kg COD/m3-d (equivalent to COD of 174 and 70 mg/L), respectively. The result showed that COD removal efficiency of the 1st reactor was achieved to 81.45%, 88.44% and 81.18%, while the amount of biogas was 0.17, 0.28 and 0.18 L/g COD removed. Besides for the 2nd reactor, the efficiency for COD removal was 96.49%, 91.40% and 91.02%, together with 0.08, 0.18 and 0.05 L/g COD removed for biogas production. This research could be concluded that the rubber granule media AFB without internal recirculation in this research has the comparable efficiency to other general AFB reactors with internal recirculation. Moreover, this knowledge reveals an advantage of this AFB reactor in terms of a shorter retention time, which can save more energy and simultaneously performed a larger amount of wastewater treatment.

Keywords: Anaerobic Fluidized Bed (AFB); Rubber granule; Organic Loading Rate (OLR); low strength wastewater; without internal recirculation