Microbiological treatment of oil mill waste waters

Abstract

Experiments of the biological treatment of the oil mill waste waters, deriving from continuous system, have been carried out with selected mutant ferments, adapted to rather forced toxic conditions. The commercial microbic formulations SNKD, LLMO and PSBIO have been utilized; the last two are liquid suspensions, constituted by living micro-organisms that, in contrast to those frozen or lyophilized, do not need be revitalized before their use and became completely active in short time. The experiments with the SNKD biological preparation were carried out both on filtered oil mill outflows (type A) with an initial COD of approximately 43 g/l and on waste water dephenolized by Caro-acid (type B) with a COD equal to 30 g/l. The experiments with LLMO and PSBIO complexes were conduced both on oil mill outflows filtered and diluted (ratio 1:0.5) with an initial COD equal to 44 g/l (type C), and on waste water that were filtered and preventatively subjected to a cryogenic treatment (type D), with an initial COD of approximately 22 g/l. The residual COD with the microbic formulation SNKD, was about 15 g/l (type A) and 5 g/l (type B); with the PSBIO it was about 7 g/l (type C) and 1.5 g/l (type D); with the microbic formulation LLMO it resulted in 6 g/l (type C) and 1.3 g/l (type D).