Abstract:
The purpose of this research is to start-up UASB reactor treating wastewater from dehydrated fruit factory by using sludge with 44.5 percent of 0.06-0.42 mm in size distribution and specific methanogenic activity (SMA) of 0.263 gCOD/gVSS-d from existinganaerobic pond of the factory as seeding microorganisms. The characteristics of the wastewater are as followed: pH of 4.09 - 4.54, COD of 30,300-57,800 mg/l and BOD of 26,700 - 51,200 mg/l. The experiment was conducted at the Department of Environmental Engineering, King Mongkut's University of Technology Thonburi with the 4.825 litres bench-scale UASE reactor. It was founded that when the UASB reactors were fed with the mentioned wastewater without any alkalinity addition, whether to strip CO2 from recycledeffluent with aeration or to dilute wastewater, the system could not keep its stabilitythough its volumetric loading rate (VLR) was lower than 1.0 gCOD/l-d. The decreasingeffluent pH was the first parameter indicating its unstability prior to no biogas production observed. With sufficient alkalinity, the system could achieve COD removal over90 percent under VLR of 7 gCOD/l-d and fluffy sludge washout of more than 5,800 mg SS/lwas observed. The seed sludge was developed to better characteristics with 54.3 percentof 0.60-1.18 mm in size distribution and SMA of 0.75 gCOD/g VSS-d at the end of experiment.