| In this paper, a new kind of composite flocculant, the slag compound flocculant, were prepared by using two kinds of industrial waste slag. According to the different content of iron and aluminum in the blast furnace dust and scrap material of aluminum, the optimum experimental condition that can reach the highest dissolution ratio of iron and aluminum was obtained by a number of experiments. On the basis of those experiments' results and the different hydrolytic features of iron and aluminum, a series of norganic high polymer self-made flocculant with different nAl/nFe and basicity(B) were synthesized by controlling the hydrolytic reaction conditions. The influences of the amount of nAl/nFe and basicity(B) on the characteristics of the slag compound flocculant were investigated. IR^ X-ray and TEM were used to test the structure of self-made flocculant. The Ferron method was used in measuring the species distribution and transformation of slag compound flocculant aggregate. The self-made flocculant can be classified into three kind of major species such as [Al+Fe]a,[Al+Fe]b and [Al+Fe]c. The results of Ferron method denoted that the species distribution depended upon the basicity(B) and nAl/nFe. At last. The flocculating effieieney of slag compound flocculant on treating dyeing wastewater was preliminarily examined by Jar tests. In the process of brewing wastewater treatment by flocculating, the flocculating properties of self-made flocculant under different dosage and the effect of pH value,stirring rate and time were tested by jar tests and the mechanism of the flocculant behavior is analyzed.The experimental results showed that: The dissolution ratio of aluminum can reach 98 percent when the experimental temperature is controlled at 100℃. the reacting time is 1 hours, and the mixing ratio of the scrap material of aluminum and the hydrochloric acid is 1:10. In the process of synthesis of slag compound flocculant, The influence of process parameters such as the polymerization degree, reaction time, temperature, nAl/nFe, basicity(B) and pH value of the effluent on flocculating property was investigated. Among them, the nAl/nFe had the most significant influence.Through infrared spectrum and scanning microscope, it can be found that self-made flocculant contains many nucleuses of polyiron-polyaluminium and chloric, which is a kind of new inorganic polymer flocculant. The results of Ferron method showed that: [Al+Fe]b could trasform [Al+Fe]c with the increase of aging time; the [Al+Fe]a decreased, the [Al+Fe]b and [Al+Fe]c increased with the increase of basicity(B) value, the speed of [Al+Fe]c was more quickly than [Al+Fe]b.The experiments show that slag compound flocculant can effectively remove COD and chromaticity color. The four parameters namely pH of 6-8 , settling of 30 min , agitation of 120 r/min and dosage of 40 mg/L were chosen , the COD and chromaticity color removal rate were recorded as high as 64.7% and 87.5% respectively. The optimum conditions of flocculation experiment were achieved through the static experiment, according to these conditions, the dynamic simulative flocculation test was carried out to investigate the flexibility of removal efficiency on concentration fluctuation in influent wastewater. The results showed that under the optimum dosage 40mg/L and a pH range of 6.0～7.0, the CODCr removal rate and decoloration rate are up to 65% and 90% respectively, and stable removal rate can be assured under normal concentration fluctuation in influent wastewater. As a result, the treatment difficulties in following processes are reduced effectively. Compared with PAC, slag compound flocculant produced bigger and more compact floc, settling time was shorter, the amount of mud and chemical dosage were less , and effluent quality was much better. The results show that PAFC is a high effective and practical compound flocculant agent. The slag compound flocculant polymers coagulate in water by charge neutralization, adsorption bridging and precipitation catching mechanisms, especially by charge neutralization and adsorption bridging mechanisms. It can be concluded from this study that coagulation/flocculation may be a useful pre-treatment process for brewing wastewater before biological treatment.
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