The Research And Application Of Ozonation For The Advanced Treatment Of Coal Chemical Wastewater

As organic wastewater with high concentration pollutants and low biodegradability,currently coal chemical wastewater is widely treated by A2/O which could effectivelyremove COD_crand NH₃-N, but the effluent with high color, nitrogen, COD_cris difficultto meet the discharge standards, and still contains many harmful and persistent organic.Therefore, the technologies of advanced treatment in the field become hot spot, bydepth treatment the effluent could meet standards, hazardous materials are effectivelyremoved, and the rate of reuse is increased, which has a great ecological and economicsignificance. Ozone is widely used in the advanced treatment of industrial wastewater,which could effectively remove the water color, converted stable organics tobiodegradable substances resulting in the improvement of biodegradability. Threeaspects including utilization of ozone, catalyst and reactor are the emphases of the paperwhich studied and designed the advanced treatment of coal chemical ozone advancedwastewater treatment process.The inner loop reactor is applied in the catalytic ozonation. The reactor wasdivided into up flow and down flow zone. The liquid could be driven by the mixed gascontaining ozone to circulate in two zones, and the gas could mix and dissolve in theliquid by microbubbles produced by the diffuser of the bottom. The light and solidcatalyst pushed by the mixed fluid could circulate in the reactor. The design haseffectively promoted heterogeneous ozonation. In continuous experiment, utilizationrate of ozone has effectively improved by adding pre-reactor. The exposure andoxidation time of organics in the reactor has been increased effectively, which lead to agood processing performance.The results of studying the factors affecting ozonation indicated that pH and ozonedosage are two main aspects. Ozonation could effectively decrease COD_cr, TOC, UV254,increase B/C and decompose organics significantly. By comparing the threeheterogeneous catalysts including MnO_X/γ-Al₂O₃, MnO_X/pumice, MnO_X/AC, thepaper chose MnO_X/AC as the final catalyst and study its stability and effect onutilization of ozone.A set of advanced treatment technology included catalytic ozonation as thecore, pre-control of pH and coagulation unit for coal chemical wastewater was designedin the paper, and determined the main parameters of each unit. The study focused on themultiple effects of pH on coagulation, oxidation and the utilization rate of ozone. Theresult of continuous experiment of the technology has indicated that it runs well and theoperation is stable. The effluent can meet level one-B of emission standards （GB18918-2002） and the standards of recycled water （GB50050-2007）, the technologyin the advanced treatment of coal chemical wastewater showed a strong practicalsignificance.