Aran H-Kittikun, Sopha Chantaphaso, and Poonsuk Prasertsan

pp. 797 - 806

Abstract

Powdered enzyme was produced by freeze-drying the enzyme solution extracted from 3 days culture
of Aspergillus niger ATCC 6275 on palm cake with the addition of 0.2% glucose and 2% urea. The product
yield was 38% by weight. The half-life of the enzyme was 9 months keeping at 4ºC. The enzyme was tested
with decanter effluent with different characteristics from two palm oil mills. The decanter effluent possessing high suspended solid (SS) and low oil (9.5 g/l) content was selected for studying the factors affecting the
separation of SS and oil as bulking solid. Results indicated that the effluent must contain oil not less than
15 g/l so that the bulking solid would occur from the reaction of the enzyme (with xylanase activity of 200 U/
ml) after incubation at 40ºC for 6 h. Minimum concentrations of the enzyme from A. niger ATCC 6275 and commercial xylanase (Meicellase) were 200 and 600 U/ml, respectively. The optimum pH was 4.5. Treatment
of palm oil mill effluent by the enzyme from A. niger ATCC 6275 for 3 h under the optimum conditions
resulted in 78% separation of suspended solids with oil & grease removal of 95% and COD reduction of
35%.