PILOT-SCALE THERMOPHILIC ANAEROBIC TREATMENT OF WASTEWATERS FROM SEASONAL VEGETABLE PROCESSING-INDUSTRY

Thermophilic anaerobic treatment of food industry wastewaters was stud ied using a 0.65 m(3) upflow anaerobic sludge bed (UASB) reactor. The reactor was operated at 55 degrees C and placed on the premises of a f actory manufacturing deep-frozen goods from vegetables; The hot (>80-9 0 degrees C) and concentrated (GOD 14-79 g/l) wastewater streams, deri ving from steam peeling and blanching of carrot and potato were used. The UASB reactor was inoculated with a small amount of granular sludge from a full-scale mesophilic UASB reactor. Prior to inoculation, the inoculum was acclimated to 55 degrees C for 2 days. The reactor was fe d with a mixture of wastewaters diluted to the desired GOD. The reacto r was started with loading rates of about 1.2 kgCOD/m(3)d. After the i nitial acidification of the process, apparently due to insufficient bu ffer capacity, the COD removal started to improve and reached 60% with in 35 days of inoculation. At the end of the 70 days run, more than 80 % COD removal was achieved with loading rates of about 4 kgCOD/m(3)d. The pilot-study run was limited due to the end of the seasonal product ion in the target factory. The results of the pilot study together wit h the results from the intensive laboratory studies suggest the feasib ility of thermophilic anaerobic treatment for the studied wastewaters. (C) 1997 IAWQ. Published by Elsevier Science Ltd.