Decolorization and COD reduction of dyeing wastewater from a cotton textile mill using thermolysis and coagulation.
The decolorization and reduction of COD of dyeing wastewater from a cotton textile mill was conducted using catalytic thermal treatment (thermolysis) accompanied with/without coagulation. Thermolysis in presence of a homogeneous copper sulphate catalyst was found to be the most effective in comparison to other catalysts (FeCl(3), FeSO(4), CuO, ZnO and PAC) used. A maximum reduction of chemical oxygen demand (COD) and color of dyeing wastewater of 66.85% and 71.4%, respectively, was observed with a catalyst concentration of 5 kg/m(3) at pH 8. Commercial alum was found most effective coagulant among various coagulants (aluminum potassium sulphate, PAC, FeCl(3) and FeSO(4)) tested during coagulation operations, resulting in 58.57% COD and 74% color reduction at pH 4 and coagulant dose of 5 kg/m(3). Coagulation of the clear fluid (supernatant) obtained after treatment by thermolysis at the conditions previously used resulted in an overall reduction of 89.91% COD and 94.4% color at pH 4 and a coagulant dose of 2 kg/m(3). The application of thermolysis followed by coagulation, thus, is the most effective treatment method in removing nearly 90% COD and 95% color at a lower dose of coagulant (2 kg/m(3)). The sludge thus produced would contain lower inorganic mass coagulant and, therefore, less amount of inorganic sludge.
Kumar
Pradeep
P
Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, India.
Prasad
B
B
Mishra
I M
IM
Chand
Shri
S
D000534:Alum Compounds / Q000737:chemistry*; D002712:Chlorides; D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D019327:Copper Sulfate / Q000737:chemistry*; D032561:Cotton Fiber; D005290:Ferric Compounds / Q000737:chemistry; D005427:Flocculation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D015034:Zinc Oxide / Q000737:chemistry
D000534:Alum Compounds; D002712:Chlorides; D004396:Coloring Agents; D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C041524:aluminum sulfate; C024823:ferric sulfate; D003300:Copper; D019327:Copper Sulfate; D010100:Oxygen; D015034:Zinc Oxide; C024555:ferric chloride; C030973:cupric oxide