Treatment The High Salinity Wastewater Generated During Epichlorohydrin Synthesis With Glycerol

With the development of epichlorohydrin (ECH) production technology, the defects of the traditional production technology and the rapid development of biodiesel industry had brought a new opportunity for the epichlorohydrin synthesis with glycerol. But a lot of the high salinity wastewater was produced at the same time. The biological treatment process and reutilization technology of the wastewater from epichlorohydrin synthesis with glycerin were investigated in this paper. Firstly, the microorganism which could live in the high salinity wastewater was accumulated by fed-batch process with the synthetic ECH wastewater containing NaCl and CaCl2, respectively. Effects of salinity and organic loading on the performance of the sequencing batch reactor (SBR) activated sludge process for treating synthetic ECH wastewater was also evaluated. And the accumulated salt-tolerant microorganisms were added to membrane bioreactor (MBR) for treating the synthetic ECH wastewater containing NaCl. Then, the microorganism which could live in the high salinity wastewater was accumulated in the continuous and batch operation processes to treat the actual ECH wastewater, respectively. And the treatment efficiencies of the two biological treatment processes were compared. Finally, a catalytic wet peroxide oxidation (CWPO) process was applied to treat ECH wastewater with high salinity, and the wastewater TOC value was degraded to less than influent limit (200mg/L) of the diaphragm electrolytic cell, so that the treated ECH wastewater could be recycled to a chlor-alkali process for reusing.In order to treat the synthetic ECH wastewater with biological process, the microorganism could live in the high salinity wastewater was accumulated in SBR process. Effluent COD, TOC, SS and turbidity were increased with the influent salinities increasing. As the influent salinity and organic loading were the same, the effluent qualities of the SBR system containing NaCl is better than that of the SBR system containing CaCl2.When the MBR was applied to treat the synthetic ECH wastewater containing NaCl, not only which effluent qualities were better than that of SBR process, but also which effluent qualities were very stable. It was found that the COD removal efficiency was consistently higher than95%when the HRT of MBR system was shortened from3d to Id under the influent salt and COD concentrations remaining unchanged. But the membrane fouling was very serious when the ECH wastewater with high salinity was treated in MBR.As the continuous and batch operation activated sludge processes were applied to treat the actual ECH wastewater, the effluent COD value of the continuous activated sludge process could fit in with the discharge standard for municipal sewerage system (i.e., COD<500mg/L) only when the sanility was less than3%. However, the COD value of ECH wastewater with4%salinity could be degraded to less than500mg/L in SBR process.When catalytic wet peroxide oxidation (CWPO) process was applied to treat the wastewater generated during epichlorohydrin synthesis with glycerol, the optimal temperature, pH, FeSO4-7H2O dosage, H2O2dosage and the reaction time were90℃,2.0-3.0,7.5-8.75g/L,75mL/L and lOOmin, respectively. Multiple additive methods of H2O2and Fe2+significantly enhanced the TOC removal than the one step addition as their total dosages were the same. Under optimal conditions, the TOC value of epichlorohydrin wastewater would be degraded from1790mg/L to lower150mg/L through CWPO process, which was fit in with the influent limit of the diaphragm electrolytic cell, thus the treated epichlorohydrin wastewater could be recycled to a chlor-alkali process for reusing.