Title of Invention

'A PROCESS FOR THE TREATMENT OF TEXTILE INDUSTRIES EFFLUENT'

Abstract

This invention relates to a process for the treatment of textile industries effluent to obtain clear effluent comprising of adjusting the pH of the effluent in the range of 2-10.5, subjecting the said effluent to the step of oxidation by adding oxidizing agents in the range of 50 ppm to 250 ppm, adding 0.5 ppm to 5 ppm strong cationic water soluble commercial polyelectrolytc to said oxidized effluent and removing the residual oxidizing agent therefrom, readjusting the pH in the range of 8-11 by adding required amount of acid/alkali into said effluent and then removing the sludge slurry from the effluent by passing through a specially designed clarifier, adding Fc t + ions to the filtered effluent for removing the residual yellowish colour therefrom, which is subjected to the step of sludge removal by passing through a second clarifier to get the clear effluent being absolutely colourless irrespective of presence of any surfactant in untreated effluent.

Full Text

This invention relates to a process for the treatment of textile industries effluent to obtain clear effluent. The pollution control board has imposed certain restrictions on the fabric dyeing industries to treat the waste water produced by such industries. A conventional process comprises physico-chemical treatment wherein the pH of the effluent is adjusted in the neutral range and then Alum (FeSO4), lime (CaO) and polyelectrolytes (flocculating aid) are added to the waste water/effluent in order to remove the dyestuff alongwith the sludge slurry by passing the treated water through a clarifier. In this process the removal of the colour depends on the dyeing aid and is severely affected by the presence of surfactant. At high concentration of dyestuff specially in the presence of surfactant, the treated effluent/waste water regains colour on air oxidation. Further, the consumption of alum, lime and polyelectrolyte increases with increase in the dye concentration and thus it leads to high recurring cost and excessive sludge generation causing lot of handling problem. Further, in case of composite mills, wherein the organic load is higher, the effluent is also subjected to biological treatment for the reduction in BOD & COD. There are certain disadvantages associated with the conventional process. One of the main disadvantage is high sludge generation. Another disadvantage is excessive chemical dosing. Yet another disadvantage is of re-appearance of colour (reversible behaviour of dye chromophore) and also in complete colour removal. Still another disadvantage is of low treatment efficiency of the effluent. Therefore, the main object of this invention is to propose a novel process for the treatment of effluent of the fabric dyeing industries which obviates the disadvantages associated with the prior art. Another object of this invention is to propose a process wherein the sludge generation is reduced by reducing the use of chemicals. Another object of this invention is to propose a process which is efficient and has high rate of BOD/COD load remova1. Yet another object of this invention is to process a novel process for the treatment of effluent wherein the dyestuff/colouring material is removed permanently and the colour does not re-appear. According to this invention there is provided a process for the treatment of textile industries effluent to obtain clear effluent comprising of: i) adjusting the pH of the effluent in the range of 2-10.5, ii) subjecting the said effluent to the step of oxidation by adding oxidizing agents in the range of 50 ppm to 250 ppm, iii) adding 0.5 ppm to 5 ppm strong cationic water soluble commercial polyelectrolyte to said oxidized effluent and removing the residual oxidizing agent therefrom, iv) readjusting the pH in the range of 8-11 by adding required amount of acid/alkali into said effluent and then removing the sludge slurry from the effluent by passing through a specially designed clarificr, v) adding Fe++ ions to the filtered effluent for removing the residual yellowish colour therefrom, which is subjected to the step of sludge removal by passing through a second clarifier to get the clear effluent being absolutely colourless irrespective of presence of any surfactant in untreated effluent. In accordance with the process of this invention the pH of the effluent/waste water produced by the fabric dyeing industries is adjusted in the range of 2-10.5 by adding acid/alkali in presence of 10 ppm to 50 ppm anions for example sulfate, perchlorate, silicate, borate etc. to said effluent, the effluent/waste water so obtained is then subjected to the step of oxidation fay using 50 ppm to 250 ppm oxidizing agent such as KMnO4, H2O2, NaOCl, NaOCl2, KC1D4, ClO2, K2S2O8. Ca(OCl)Cl etc . To this oxidized effluent a strong cationic water soluble commercial polyelectrolyte is added in the range of 0.5 ppm to 5 ppm for the removal of residual oxidizing agent from the effluent. The pH of the effluent so obtained is readjusted in the range of 8 to H by adding an acid/alkali in the required amount. The effluent so obtained is then passed through a specially designed clarifier at high surface loading T O 30 Thus, it is seen that the BOD and COD loads are satisfactorily removed by treating the effluent/waste water according to the process of this invention and the waste water is prepared to be discharged as per standards of the pollution control board. The process for the treatment of effluent/waste water of the fabric dyeing industries according to a preferred embodiment is herein described with the help of the accompanying drawing wherein:— Fig.l shows the schematic flow diagram of the process. Referring to the drawing the effluent is first collected in a waste water collection container wherein the pH of the effluent is adjusted in the range of 2—18.5 by adding 113 pprn to 50 PPm anions such as sulfate, perchlorate, silicate, borate etc. The effluent is then subjected to the step of oxidization into another container by adding 50 ppm to 250 ppm oxidizing agents such as KMnO4, H2O2, NaOCl, NaOCl2, KC1O4, ClO2, K2S2O8, Ca(OCl)Cl etc. into said container. 0.5 ppm to 5 ppm of a strong cationic water soluble commercial polyelectrolyte is added into said container for the removal of residual oxidizing agent from the effluent and then the pH of the effluent is readjusted between S-11 by adding the required amount of acid/alkali. The effluent 50 obtained is then passed through a specially designed clarifier by the surface loading 30 m3/m2/day for the removal of sludge slurry therefrom. To this effluent Fe++ ions are added for removing the residual yellowish colour. The effluent so obtained is again passed through a second clarifier for removing the residual sludge slurry therefrom so as to obtain the effluent which is absolutely colourless and BOD/COD values within permissible limits. The effluent parameters before and after treatment according to the process of this invention are shown in Table 1 given below from the parameters. It is apparent that the amount of pollutants which were present before the treatment in the effluent has been substantially reduced after the treatment of the effluent. TABLE-1 (Table Removed) * 200 times diluted ** The conventional system totally fails in treating such intensively coloured effluents from cotton processing textile units with reasonably high COD & BOD loads. WE CLAIM; 1. A process for the treatment of textile industries effluent to obtain clear effluent comprising of: i) adjusting the pH of the effluent in the range of 2-10.5, ii) subjecting the said effluent to the step of oxidation by adding oxidizing agents in the range of 50 ppm to 250 ppm, iii) adding 0.5 ppm to 5 ppm strong cationic water soluble commercial polyelectrolyte to said oxidized effluent and removing the residual oxidizing agent therefrom, iv) readjusting the pH in the range of 8-11 by adding required amount of acid/alkali into said effluent and then removing the sludge slurry from the effluent by passing through a specially designed clarifier, v) adding Fe++ ions to the filtered effluent for removing the residual yellowish colour therefrom, which is subjected to the step of sludge removal by passing through a second clarifier to get the clear effluent being absolutely colourless irrespective of presence of any surfactant in untreated effluent. 2. A process as claimed in claim 1 wherein the pH of the effluent is adjusted by adding acid/alkali in presence of anions such as sulfate, borate in the amount of 10 ppm to 50 ppm. 3. A process as claimed in claim 1 wherein said oxidizing agents used are such as KmnO4 , H2 O2, NaOCl, NaOCI2, KCIO4, CIO2 , K2 S2 O8, Ca (OCI) CI. 4. A process for the treatment of textile industries effluent to obtain clear effluent substantially as herein described and illustrated.

Documents:

708-del-2000-abstract.pdf

708-del-2000-claims.pdf

708-del-2000-correspondence-others.pdf

708-del-2000-correspondence-po.pdf

708-del-2000-description (complete).pdf

708-del-2000-drawings.pdf

708-del-2000-form-1.pdf

708-del-2000-form-19.pdf

708-del-2000-form-2.pdf

708-del-2000-form-3.pdf

708-del-2000-gpa.pdf