Experimental Study On The Treatment Of Printing And Dyeing Wastewater With Compound Flocculant

China is currently the world's largest coal producer and consumer.The disposal of waste fly ash resulting from coal combustion has gradually become a hot research point.In this paper,fly ash preparation of high-efficiency composite flocculant for dyeing wastewater treatment research,on the one hand make fly ash can reuse waste and reduce the problem of environmental pollution caused by stacking,on the other hand also reduces the flocculant The cost of production is widely sourced.The authors used powdered waste fly ash from combustion in Shijiazhuang Thermal Power Plant as the main experimental material,used Na2CO3 as an activator,and was roasted in a muffle furnace at 850? for 2 hours for activation.The acid pyrolysis was followed by microwave pyrolysis to extract fly ash.Al2O3,in order to increase the leaching rate of aluminum.Single-factor experiments and L9(34)orthogonal experiments were used to study the amount of sodium carbonate,concentration of hydrochloric acid,microwave power and pyrolysis time.The optimum conditions for the extraction of Al2O3 from fly ash were obtained.After comparison of the leaching rate of Al2O3 and the content of the solution alkalinity after acid dissolution,the optimum extraction process conditions for Al2O3 were as follows:Na2CO3 and fly ash were prepared at a ratio of 0.8:1;hydrochloric acid concentration was 24%;microwave power 300 W;microwave pyrolysis time is 10 min.The important order of factors affecting the leaching rate of Al2O3 is as follows:hydrochloric acid concentration>sodium carbonate dosage>microwave power>microwave pyrolysis time.Under this condition,the extraction rate of Al2O3 in fly ash is the highest.Then,the hydrochloric acid leached solution was reacted with FeCl3 under microwave irradiation to produce a composite flocculant,polyaluminum ferric chloride(PAFC).The decolorization rate and CODcr removal rate were used as evaluation indicators,and the single factor experiment and L9(33)orthogonality were used.Experiments on the aluminum-iron ratio,alkalinity,microwave polymerization time and other studies conducted to obtain the optimal polymerization of flocculants to produce the process conditions.The results showed that the ratio of aluminum to iron was 9:1,the degree of alkalization was 1.5,and the microwave polymerization time was 120 minutes.At this time,the decolorization rate and CODcr removal rate were the highest.In this paper,the simulated dyeing wastewater of methyl orange was treated with the prepared flocculant(PAFC),and the six main process conditions of pH,flocculant dosage,flocculation time,flocculation temperature,stirring time and stirring strength were studied through single factor experiments.To check its effect on the treatment of printing and dyeing wastewater,and to obtain the best processing conditions for printing and dyeing wastewater treatment.The optimum treatment conditions were as follows:flocculant dosage was 100 mg/L,flocculation temperature was 25?,stirring speed was 85 r/min,stirring time was 4 min,pH was 7.0,flocculation time was 4 h.In this environment,the decolorization rate of simulated dyeing wastewater of methyl orange was as high as 98%,and the CODcr removal rate was 93%.