Research on Advanced Treatment Technology of Fluorine Containing Wastewater from Graphite Production

Abstract

With the gradual improvement of environmental emission requirements in China, the graphite industry is facing environmental pressure from advanced treatment. This article first conducted a study on the current status of advanced treatment technology for fluorinated wastewater. Subsequently, a single defluorination agent experiment was conducted, and it was found that compared to several agents used in the experiment, such as PAC, PAFS, and CaCl2, PAC had the best defluorination effect. The optimization of PAC conditions showed that its optimal reaction pH was 7, and equilibrium could be achieved after 3 minutes of reaction. The study also conducted orthogonal experiments with mixed salts, and the best conditions for the combination of fluoride removal agents were found to be PAC adding 400 mg/L, CaCl2 adding 400 mg/L, PAFS adding 200 mg/L, which can remove fluoride to 0.92 mg/L, below 1 mg/L, meeting the Class III water standard in the " Environmental quality standards for surface water ".The SEM image of the sludge generated by the reaction between the composite fluoride removal agent and fluoride containing wastewater shows a larger particle size of up to 50 μm which is beneficial for the separation and removal of sludge. The generated sediment sludge is mainly composed of Al, Fe, Ca, O, and Si according to EDS results, and belongs to general industrial solid waste.