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Abstract:
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Vegetable oil and grease polluted wastewater caused many problems in wastewater plan
such as physical blockages in sewer, pump, screens and filter distributor arms. Its occurrence in
effluent increase COD significantly even its amount is not high. In this paper, bioremediation was
investigated to remove vegetable oil and grease. Four strains were positive with lipid degrading
test. Cell morphology and optimal conditions such as pH, temperature anf lipid concentration was
found. The lipid-degrading activity of A12, B13 and D15 was highest at 30oC and pH 7 while that
of D14 is at 34oC and pH 7.5 . The result also showed that the highest lipase production of strains
A12, B13 and D14 were observed at 0.1 %w/v of lipid, but for strain E15 concentration of lipid
was 0.15 %w/v. Addition of antifoam and surfactant was studied. The optimal concentration of
antifoam (CF-18) and surfactant (PVA) was found as 0.4%w/v and 0.2 %w/v respectively. 10%
w/v of straw in the best ration of support particle, at which the cell density of bioremediatior was
2x108 cfu/g. The best temperature for storage was 5-7oC, even so at the conditioned temperature
(20-25oC) the bioremediation was good until 20 weeks. At optimal moisture 10% and under low
temperature (5-6oC) the bioremediator was still as good as its initial after 20 weeks. Application of
bioremediator in 25 m3/day wastewater treatment plan indicated that COD removal yield increased
s6-7% compared with normal case (no bioremediation). |