焦化废水生物处理尾水的活性炭吸附及条件优化研究

Research on activated carbon adsorption of biologically treated coking wastewater and its condition optimization

国内焦化企业废水生物处理尾水中COD、色度等指标超标的现象大多是由残留的难降解有机物造成的。针对这种现象,通过采用不同种类和孔结构的活性炭、改变炭表面化学性质、优化吸附环境3种方式对生物处理尾水中的COD成分进行强化吸附,考察炭型、表面化学性质及pH值等因素的影响,以明确焦化废水吸附法深度处理的合理炭型及其优化的条件。把已稳定运行的1 320 m3/d处理规模焦化废水A/O/H/O工艺实际工程生物处理尾水作为研究对象,试验了13种活性炭品种的吸附去除COD及色度的效果,发现甲基蓝值和丹宁酸值大的炭型其吸附容量高;而某一种炭样的吸附特性实验中,不同化学改性时表面酸性官能团含量少的活性炭有利于提高其吸附容量,低pH值条件的吸附能力高于碱性条件,曝气混合方式能够缩短吸附平衡时间。经过优选的活性炭在适宜的反应条件下能够将焦化废水生物处理尾水中的COD值及色度值分别降低至60 mg/L及20倍以下,在较低的运行费用条件下使出水达到工业循环冷却水的水质要求。

The over standard of the COD and the color value mainly resulted from the refractory organics existing in the biologically treated coking wastewater.In this work,the adsorption of these organic compounds on activated carbons（AC） was studied through adopting different kinds of AC,modifying the surface chemical properties of AC,and optimizing the adsorption conditions.Taking the biologically treated coking wastewater from a 1 320 m3/d scaled A/O/H/O process as an object of study,the COD and the color values of the wastewater treated by 13 kinds of AC were analyzed.The results indicated that the AC with higher methylene blue value and tannic acid value had a higher adsorption capability,while after the modification of the AC surface,AC with less acid functional groups were advantageous in enhancing the adsorption capacity.Furthermore,it was found that the AC had higher adsorption capacity under lower pH value conditions,and the aeration could shorten the adsorption equilibrium time.The COD and the color values of the biologically treated coking wastewater could be reduced by the optimal AC under a suitable reaction condition to below 60 mg/L and 20 times,respectively,which could satisfy the industrial circulating cooling water quality under low operating cost conditions.