Treatment of oily bilge waste water using marine fungi

Abstract

Oily bilge waste waters released from ships cause an emerging environmental problem in the seas because they are toxic to many sea organisms. Bilge waters need new treatments that are efficient, economic, and local. The crude oil degradation efficacy of five marine fungal isolates (Acremonium sp., Ceratocystis sp., Cladosporium sp., Emericellopsis sp., Fusarium magnifereae) was studied in controlled conditions. The plate culture technique was used to measure the degradation of crude oil in five concentrations (100, 200, 300, 400, 500 mg/L). In addition, the degradation of oily bilge water (320 mg/L) collected from ships was measured using broth culture technique. The fungi F. magnifereae had the highest crude oil degradation efficacy; the crude oil concentration of bilge water was reduced to one-tenth: from the original 320 mg/L to 32 mg/L. Turbidity (350 NTU) and biological oxygen demand (380 mg/L) were reduced to one-tenth of the original. Acremonium sp. and Ceratocystis sp. degraded crude oil slightly less (to 1/7) and two of the isolates poorly (to 1/5) (Emericellopsis sp. and Cladosporium sp.). The phytotoxicity of bilge water was studied with a seed germination test. The seeds of mung bean did not germinate in bilge water (0% germinated) while 90% of the seeds germinated in F. magnifereae-treated bilge water. The germination in tap water was 81% and in distilled water 74%. Seed germination and crude oil concentration correlated strongly (r = 0.90) giving a significant regression equation. F. magnifereae could degrade crude oil in bilge water and remove phytotoxic compounds. Treated bilge water can be used for irrigation.