Treatment of composite wastewater of a cotton textile mill by thermolysis and coagulation.
Catalytic thermal treatment (thermolysis) accompanied with coagulation was used for the removal of COD and color of composite wastewater from a cotton textile mill. CuSO4, FeSO4, FeCl3, CuO, ZnO and PAC were used as catalytic agents during thermolysis. Homogeneous copper sulphate at a mass loading of 6 kg/m3 was found to be the most active. Similarly during coagulation aluminum potassium sulphate [KAl(SO4)(2).16H2O] at a coagulant concentration of 5 kg/m3 was found to be the best among the other coagulants tested, namely, commercial alum, FeSO4, FeCl3 and PAC. During thermolysis, a reduction in COD and color of composite wastewater of about 77.9 and 92.85%, respectively, was observed at pH 12. Coagulation of fresh composite waste using aluminum potassium sulphate resulted in 88.62% COD reduction and 95.4% color reduction at pH 8. Coagulation of the supernatant obtained after treatment by catalytic thermolysis resulted in overall reduction of 97.3% COD and close to 100% color reductions at pH 8 at a lesser coagulant concentration of 3 kg/m3. The results reveal that the application of coagulation after thermolysis is most effective in removing nearly 100% of COD and color at a lower dose of coagulant. The sludge thus produced would contain lower inorganic mass coagulant and can be used as a solid fuel with high calorific value of about 16 MJ/kg, close to that of Indian coal.
Kumar
Pradeep
P
Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India.
Prasad
B
B
Mishra
I M
IM
Chand
Shri
S
D000534:Alum Compounds / Q000737:chemistry; D002384:Catalysis; D019327:Copper Sulfate / Q000737:chemistry; D005374:Filtration; D003368:Gossypium; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D013696:Temperature; D013784:Textiles; D013816:Thermodynamics; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D000534:Alum Compounds; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; C041524:aluminum sulfate; D019327:Copper Sulfate