Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Process involving micro-organisms of different genera in the...
Reexamination Certificate
2000-03-27
2002-06-18
Lilling, Herbert J. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Process involving micro-organisms of different genera in the...
C435S178000, C435S179000, C435S281000
Reexamination Certificate
active
06406882
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an immobilized microbial consortium and a process for the preparation of the said microbial consortium useful for the treatment of phenolic waste-water.
DESCRIPTION OF THE PRIOR ART
Phenols are hydroxy derivatives of benzene which originate both from anthropogenic sources such as forest fire, decay of lignocellulosic materials as well as from various human activities which originate from pharmaceutical industries, pesticide industries, petroleum refineries and wood processing industries.
In petroleum refineries, crude petroleum passes through various stages of refining before it is finally used as a fuel. The effluent of petroleum refineries contains a large number of compounds, most of which are hydrocarbons. In addition to the hydrocarbons, the effluent also contains grease (0.01 to 2%), sulphur (0-6%), cyanide (0.1 to 0.2%), suspended solids etc. (Khan 1995, Abdulbasher, 1985).
Phenols are by-products obtained during the refining process. The concentration of phenols in the waste-waters depends largely on the nature of the crude oil processed. Phenol when present in waste-waters not only leads to odour and taste problems but also poses a serious threat to fish and other aquatic organisms due to its highly toxic nature. Apart from this, some phenolic compounds also accelerate tumour formation leading to carcinogenicity. For these reasons, refinery waste-waters exceeding the limit of 0.05 mg/l of phenols are not permitted to be discharged into the main streams. In order to bring the concentrations of phenol within the permissible limit of the set standards, it becomes necessary to treat the refinery waste-water before it is discharged into the main stream.
For the removal of phenolic compounds from the industrial effluents, biological methods using single micro-organisms or a group of micro-organisms present in activated sludge have been used which utilize the organic compounds through a process called biodegradation (Rajakumar et al. 1991, Subhani et al. 1991). During biodegradation, the micro-organisms convert organic compounds into their inorganic forms which in turn serve as energy source or substrate for micro-organisms. The drawback of single bacteria is that it may not be able to fully biodegrade phenol and phenolic compounds due to non-availability of an array of enzymes responsible for complete biodegradation, wherein a microbial consortium proves to be better than a single bacterium for biodegradation because a number of enzymes present in different bacteria undergo co-metabolism. The micro-organisms present in the activated sludge have low efficiency because of suppression of specific bacteria present therein, thereby resulting in the inadequate and variable micro-flora and are not able to degrade the compounds of interest present in specific waste-waters. Another drawback of the conventional biological treatment method is that free microbial cells are unable to tolerate high concentrations of phenol present in petroleum refinery because of high toxicity of phenol on micro-organisms containing phenol degrading enzymes. Whereas, the advantages of the present invention over the above conventional methods envisage an effective and efficient removal of phenolic compounds from the waste-waters of petroleum refinery by selecting a blend of specialized micro-organisms from the source habitat which are capable of degrading them.
Though few micro-organisms have been immobilized on various supports to biodegrade phenol present in waste-waters, there are many drawbacks of the used supports as disclosed in the prior art. The supports are biodegradable, toxic, expensive, have low mechanical strength and have less surface area. Therefore, it is essential to develop microbial consortium, immobilized on a non-biodegradable, non-toxic, mechanically strong, having more surface area and economically cheaper support to enhance the biodegradability of phenol.
To overcome this problem, in the present invention, a defined microbial consortium is formulated as well as immobilized on non-biodegradable and economically cheaper support to achieve an effective as well as efficient biological treatment of phenolic waste-water of petroleum refinery. Immobilization of micro-organisms leads to a reduction in cell growth and protection of the microbial cells from the toxicant. Due to these reasons, immobilized cells offer a promising potential for an effective and efficient biological treatment of waste-waters. Immobilized bio-catalysts have also been used on an industrial scale for treating effluents containing phenolic compounds (Anselmo and Novail, 1992) as well as other toxicants (Wong et al, 1993 and Cijzen et al, 1988).
For solving the aforementioned problem, the applicants have realized that there exists a need to provide a process for an effective and efficient treatment of phenolic compounds present in petroleum refinery using microbial consortium immobilized on a non-biodegradable and economically cheaper support.
In the present invention, coconut fibre is used as a support for immobilization of microbial consortium having wider surface area of coconut fibres which enables adsorption of higher number of cells on the surface of the support which results in faster biodegradation of phenol. Coconut fibre as such is not easily biodegradable. Therefore, it has longer shelf life. This support is non-toxic to micro-organisms as well as is mechanically strong.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide an immobilized microbial consortium and a process for the preparation of the said immobilized microbial consortium on a non-biodegradable and economically cheaper support for the treatment of phenolic waste-waters, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide a process for the preparation of immobilized microbial consortium on non-toxic and mechanically strong support for the treatment of phenolic waste-waters.
Still another object of the present invention is to provide a process for the preparation of immobilized consortium on a support having wider surface area which enables the easy diffusion of oxygen as well as the nutrients which help in biodegradation of phenolic compounds.
SUMMARY OF THE INVENTION
The present invention relates to a process for the preparation of immobilized microbial consortium on coconut fibre for treatment of phenol present in petroleum refinery. Wider surface area of coconut fibres used for immobilization enables adsorption of higher number of cells on the surface of the support which results in faster biodegradation of phenol. Coconut fibre as such is not easily biodegradable. Therefore, it has a longer shelf life. The support is non toxic to micro-organisms as well as is mechanically strong.
DETAILED DESCRIPTION OF THE INVENTION
The composition provided according to the present invention contains bacteria consisting of:
Prior art
strains having
characteristics
similar to that of
S.No.
Cultures
Accession No.
CBTCC No.
(a)
Aeromonas hydrophila
CBTCC/MICRO/10
ATCC 7966
(b)
Pseudomonas fluorescens
CBTCC/MICRO/11
ATCC 13525
(c)
Pseudomonas aeruginosa
CBTCC/MICRO/3
ATCC 49622
(d)
Bacillus circulans
CBTCC/MICRO/12
ATCC 4513
(e)
Yersinia enterocolitica
CBTCC/MICRO/4
ATCC 27739
(f)
Enterobacter cloaca
CBTCC/MICRO/1
ATCC 29813
(g)
Bacillus brevis
CBTCC/MICRO/13
ATCC 8246
which facilitate effective and efficient treatment of phenol present in effluent of petroleum refinery. Above micro-organisms are deposited at Centre for Biochemical Technology Culture Collection (CBTCC) designated as stated above and will be made available to public on request as per normal official procedures.
The main characteristic features of all the bacterial cultures used for the invention which are similar to ATCC cultures are given below:
Characteristic Features of
Aeromonas hydrophila
(CBTCC/Micro/10)
Gram-negative
Motile by a single polar flagellum
Metabolism of glucose is both respiratory and fermentative
Oxidase
Kumar Archana
Kumar Rita
Sharma Alka
Council for Scientific and Industrial Research
Ladas & Parry
Lilling Herbert J.
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