No abstract

A 6.5 L Upflow Anaerobic Sludge Bed (UASB) reactor was operated with an industrial fruit canning wastewater of fluctuating strength and characteristics (pH = 4-10, COD total = 940-5080 mg/L, COD soluble = 890-3900 mg/L) at 25-36 o C. The UASB reactor operated successfully at Hydraulic Residence Times (HRT) of 6-12 h and Organic Loading Rates (L RS ) between 4-16 kg/(m 3 d). Reactor start-up was performed within 2-3 d after seeding with granular sludge from an Expanded Granular Sludge Bed (EGSB) reactor. Effluent COD was constantly below 800 mg/L and correspondingly COD removal efficiency higher than 75 %. An increase in effluent COD was observed when the reactor was re-started after short term starvation (1-3 d) at high Organic Loading Rate [10-12 kg/(m 3 d)]. Biogas and methane selectivity were 0.37 L/g CODr and 0.24 L CH4 /g CODr respectively. The UASB reactor proved to be an interesting option for the pre-treatment of wastewater from the fruit canning industry.