Optimization Modeling and Mechanism Discussion on Specific Industrial Coal-washing Wastewater Treatment
PAN Yitong 1,2, *, WANG Deli 1,2, MEI Kang 1,2, TANG Tian 3
1. College of Ocean and Earth Sciences, Xiamen University, China
2. State Key Laboratory of Marine Environmental Science (Xiamen University)
3. School of Metallurgy and Environment, Central South University, China
Coal-washing wastewater is an important residual produced by coal industries, which can put a high risk to serious environmental problems worldwide. However, prevailing coal-washing processes are hardly ideal for achieving the goal of solid-liquid separation in time due to wastewater's extremely stable physiochemical properties. This research treated the coal-washing wastewater produced by a Northeast China plant by means of coagulation-flocculation processes. The sedimentation ability of different coagulant choices and flocculant dosages were tested and modelled through pseudo-first-order reaction kinetics. Through the employment of Scanning Transmission Electron Microscopy (STEM) and X-ray Energy Dispersive Analysis (EDAX), the sedimentation mechanisms of flocs by means of different coagulation-flocculation combination were analyzed. The three-dimensional response surface method (3D-RSM) shows that the optimized treatment conditions to 100 mL selected wastewater in 60 minutes are: 1.20g m(FeCl3): m(CaO)=1: 3 mixed coagulants+2.00 mL 0.13% Polyacrylamide (PAM) flocculant. Furthermore, some relationships have been shown between the optimal treatment conditions and the properties of wastewater: 1. high-valent metal cations with a lower content in coal-washing wastewater may be a better coagulant choice; 2. a mass ratio of coagulant: flocculant=1000: 2.01~6.56 is likely to speed up the sedimentation.
Keywords：coal-washing wastewater; coagulant; flocculant; sediment optimization
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