Title of Invention

A METHOD OF TREATING WASTE WATER CONTAMINATED WITH HIGH SULPHUR AND IRON FINES

Abstract

A method of treating waste water contaminated with high sulfur and iron fines, comprising the steps of : -introducing organic waste after pretreatment into an aeration tank of a waste water treatment plant; -maintaining an aerobic bacterial culture in suspension in said aeration tank; and -introducing air into said aeration tank for providing oxygen required for the biological treatment; characterized in that said organic waste comprises along with other reagents, ordinary soil containing thiobacillus ferroxidan bacteria strain.

Full Text

FIELD OF APPLICATION The present invention generally relates to a method of treating waste water contaminated with high sulfur and iron fines. In particular, the invention relates to treating the water contaminated with iron fines and sulfur, from the effluents of a running mill like a cold rolling mill complex, BACKGROUND OF THE INVENTION In a cold rolling mill, various kinds of solid and liquid wastes are generated from the roiling and galvanizing process. The liquid effluents are treated in a waste water treatment plant (WWTP), producing acceptable discharge quality. According to existing practice, organic waste after pretreatment is introduced into the aeration tank where an aerobic bacterial culture is maintained in suspension. Organic matter is brought into intimate contact with the sludge from the secondary clarifier in the aeration tank. The concentration of microorganism in the sludge is very high and is in active state of growth. Micro- organisms utilize the oxygen of the air and convert the organic matter according to the following equations. In an oily waste treatment section of a waste water treatment plant a typical problem faced with the liquor may be due to increasing content of iron varying between 20 ppm to 720 ppm or more and sulphite, The aeration tank liquor may then become black. If SO4-- is present in waste water, it is biologically reduced under an aerobic condition to sulfide, which in turn combines with hydrogen to form H2S. The evolving H2S from the process may poison the surroundings. In such a situation the normal bacteria culture described above does not help. If waste water contains iron (Fe), H2S combines with the same to form FeS that in turn might cause black colour of the airation tank liquor. Though an aeration tank is an aerobic reactor, the type of surface aerator provided is perhaps unable to maintain the required dissolved oxygen level up to a certain depth of the aeration tank. Consequently, an aerobic condition exists at and near the bottom of the tank. Thus, the smell of H2S emanating from the aeration tank will confirm the presence of SO4--, while black colour of airation tank liquor will confirm the presence of iron in sufficient quantity. The Fe that is formed not only blackens the airation tank liquor but increases the F/M ratio as well. As a result, aerobic bio-degradation is drastically reduced. SUMMARY OF THE INVENTION The main object of the present invention is to treat waste water contaminated with high sulfur and iron. This is achieved by applying soil along with other reagents [di-ammonium phosphate, urea, cow dung]. For using the right reactant, several samples of soil were collected and one sample from near a pond was found to contain thiobaciiius ferroxidan, a special bacterium, known to be particularly effective in situations with high iron and sulfate. This special property is due to its nature to derive energy by oxidation of sulfide to sulfate and ferrous to ferric. Thus the present invention provides a method of treating waste water contaminated with high sulfur and iron fines, comprising the steps of: introducing organic waste after pre-treatment into an aeration tank of a waste water treatment plant; maintaining an aerobic bacterial culture in suspension in said aeration tank; and introducing air into said aeration tank for providing oxygen required for the biological treatment; wherein said organic waste comprises, along with other reagents, soil containing thiobacillus ferroxidan bacteria strain. DETAILED DESCRIPTION Waste water contaminated with iron fines and sulfur from the effluent of a running mill can be treated in a waste treatment plant for producing acceptable discharge quality. Organic wastes after pre-treatment with soil and other reagents like diammonium phosphate, urea and cow dung are introduced into an aeration tank of a waste water treatment plant and an aerobic bacterial culture is maintained in suspension. Air is introduced into the aeration tank to provide the required dissolved oxygen in the water. Air is introduced into the tank either in the form of bubbles through nozzles or by surface aerators. Several samples of soil were tried and ultimately a sample was collected from near a pond which was containing the special bacterium thiobacillus ferroxidan which derives energy by oxidation of compounds from sulfides to sulfates and ferrous to ferric, Thus the present invention provides an eco-friendly approach for solving the problem of deteriorating water quality in a treatment plant due to the high presence of sulfur and iron fines. Ordinary soil containing a special bacteria strain-thiobacillus ferroxidan can be directly used for bio- augmentation in waste water contaminated with high iron and sulfate. Ordinary soil has been directly used for the first time in running any biological treatment process creating a medium required for micro- organism growth. Normally in activate sludge process, bacteria culture is made by addition of cow-dung of sludge, brought from other BOD removal plant. This invention shows that soil micro-organisms could have a vital role in biological treatment process, because they serve as biochemical agents for the conversion of complex organic compounds into simple inorganic compounds or into their constituent elements. The analytical parameters (Table 1) show the efficiency of the process. Excellent BOD removal in the aeration tank, indicating presence and appreciable growth rate of carbonaceous BOD removal bacteria e.g. Nocordia, Micromonospora species. Maintenance of orange yellow color; this is an indication of the presence and growth of Thiobacillus ferroxidan. It was established for an efficient operation of biological treatment process, SVI should be maintained between 40 to 100. It is evident from the test results relating to MLSS and SVI that the aeration tank is workings satisfactorily (Table -2). Consequently, one could use this soil directly, as an inexpensive source of desirable micro-organism for biological treatment process. WE CLAIM: 1. A method of treating waste water contaminated with high sulfur and iron fines, comprising the steps of : -introducing organic waste after pretreatment into an aeration tank of a waste water treatment plant; -maintaining an aerobic bacterial culture in suspension in said aeration tank; and -introducing air into said aeration tank for providing oxygen required for the biological treatment; characterized in that said organic waste comprises along with other reagents, ordinary soil containing thiobacillus ferroxidan bacteria strain. 2. The method as claimed in claim 1, wherein air is introduced into said aeration tank in the form of bubbles through nozzles. 3. The method as claimed in claim 1, wherein air is introduced into said aeration tank by surface aeration. 4. A method of treating waste water contaminated with high sulfur and iron fines, substantially as herein described. A method of treating waste water contaminated with high sulfur and iron fines, comprising the steps of : -introducing organic waste after pretreatment into an aeration tank of a waste water treatment plant; -maintaining an aerobic bacterial culture in suspension in said aeration tank; and -introducing air into said aeration tank for providing oxygen required for the biological treatment; characterized in that said organic waste comprises along with other reagents, ordinary soil containing thiobacillus ferroxidan bacteria strain.

Documents:

99-kol-2005-granted-abstract.pdf

99-kol-2005-granted-claims.pdf

99-kol-2005-granted-correspondence.pdf

99-kol-2005-granted-description (complete).pdf

99-kol-2005-granted-examination report.pdf

99-kol-2005-granted-form 1.pdf

99-kol-2005-granted-form 13.pdf

99-kol-2005-granted-form 18.pdf

99-kol-2005-granted-form 2.pdf

99-kol-2005-granted-form 3.pdf

99-kol-2005-granted-form 5.pdf

99-kol-2005-granted-gpa.pdf

99-kol-2005-granted-reply to examination report.pdf

99-kol-2005-granted-specification.pdf