Experimental Study On Preparation Of Flocculant Based Fly Ash And Its Treatment Of Printing And Dyeing Wastewater

Fly ash is the solid waste generated by the thermal power plant, its emissions islarge, but the rate of use is relatively low. However, the content of aluminum of flyash is relatively high, so it is a cheap raw material of preparing PAC.The paper is based on that fly ash as raw material, and hydrochloric acid assolvent, sodium chloride as a cosolvent, and study the preparation process of the PACprepared by fly ash. This thesis, use the microwave extraction instead of the acidsoluble extraction. And research the impact of the five process parameters such as theratio of microwave power, the rate of fly ash and sodium chloride, heating time withmicrowave, and polymerization time with microwave on properties of polymerizationchloride. According to comparing content of alumina, basicity and the leaching rate ofthe alumina, then determine the optimal process parameters. The research shows thefollowing conclusions: the content of alumina in the liquid flocculant is between3%and10%; basicity is between40%and90%; dissolution rate of alumina is between20%and80%. And the optimum process conditions of preparing flocculant can beshow: concentration of hydrochloric acid is6mol/L, power of microwave is280W,the ratio of fly ash and sodium chloride is100to12, the pyrolysis time withmicrowave is10min, polymerization time with microwave is120min.In this study, the prepared flocculant is yellow liquid, and the pH of it is3.8.Make use of infrared spectroscopy determining the flocculant prepared in theoptimum conditions, and the result showed that according to the characteristic peak ofthe flocculant can draw the conclusion that the flocculant contain Al-OH and H-OH,so the composition can meet the structure of PAC.In this paper, make use of flocculant prepared in experiment to deal with methylorange wastewater. According to comparing the impact of pH, dosage of flocculant,adding amount of coagulant, temperature, time, the mixing time and mixing intensityon the effect of flocculation,then investigate the ability of processing wastewater withprepared flocculant and determine the optimum conditions of flocculation. The bestconditions obtained by experiment: pH is7.0, temperature of flocculation id15°C,dosage of flocculant is50ml/L, time is1h, slow mixing speed is85r/min,stirring timeis4min, and the dosage of coagulant is40g/L. Under these conditions, decolorizationrate of methyl orange is more than95%and removal of CODcr is up to76%. Thus, itdraws the conclusion that the performance of the polyaluminum chloride prepared byfly ash in this experiment is good, and with a wide prospect.