Expanded Granular Sludge Bed Treating Cassava Ethanol Wastewater Under Thermophilic Condition

Abstract:

The research focuses on the characteristics of the start up, operation and methane production of the expanded granular sludge bed (EGSB) treating cassava ethanol wastewater. The results show that the start up of the EGSB reactor inoculated with mesophilic granular sludge needs only 20 days. The second start up needs only 10 days after 54 days’ shutdown. The optimal organic load rate range of EGSB is within 10~14 kg·m-3·d-1, and chemical oxygen demand (COD) removal rate maintains 80%~90% during the stable operation. The biogas conversion rate（BCR）of EGSB is 0.315 m3·kg-1 under standard temperature and pressure(STP) condition. It is found that the granulation of sludge in EGSB is good and the large granules with diameter more than 2 mm grow rapidly. The ρVSS/ρTSS ratio of sludge increases from 0.51 to 0.84 after 260 d test. The pH value of the effluent fluctuates with the COD removal rate of the system, and pH can be regarded as a primary indicator of EGSB operation condition.