Multiple flocculant prepared with dealkalized red mud and fly ash: Properties and characterization

A multiple flocculant for the treatment of diatomite simulated wastewater is prepared with dealkalized red mud and fly ash. During the laboratory experiment, the optimal synthetic conditions of the coagulants and main parameters affecting the flocculation process such as the mass ratio of fly ash to dealkalized red mud, and dosage of polydimethyldiallyl ammonium chloride were investigated. Fourier transform infrared spectrometer and scanning electron microscopy analysis is used to study the molecular structure and morphology of multiple flocculant, respectively. The results show that the optimal mass ratio of sodium carbonate to fly ash is 1:1 to obtain modified fly ash, and that of modification of fly ash to dealkalized red mud is 1:3. The turbidity treatment of diatomite simulated water decreases from 683.6 NTU to 0.67 NTU with the multiple flocculant. The turbidity removal rate is up to 98.76 % when the dosage of the multiple flocculant is 90 μL/L. The multiple flocculant prepared with modified fly ash and dealkalized red mud delivers good performance in turbidity treatment of diatomite simulated wastewater. Through scale-up experiments, the economic cost of multiple flocculant has been analyzed, and this work provides viable methods to utilizing dealkalized red mud and fly ash efficiently.