焦化废水深度回用中粉末活性炭的超声波再生

Regeneration of activated carbon in coking wastewater advanced treatment by ultrasound

在焦化废水深度回用处理中,采用粉末活性炭和浸没式超滤配合工艺对生化出水进行预处理,降低废水中COD,减轻后续处理困难,并在一定程度上缓解膜污染。由于活性炭成本较高,对活性炭进行再生处理。为达到再生过程简单易行、再生能耗低、且再生过程中不产生二次污染等目的,实验中采用超声波技术实现活性炭的重复使用。通过优化实验研究了超声波再生的最优条件,结果表明,焦化废水中吸附饱和的活性炭在超声频率33kHz、功率200W、炭/水质量比1/10~1/20等条件下,再生20min,可以达到50%以上的再生效果。实验室条件下,经过6次循环利用的活性炭经过再生,其吸附容量为1.8mg/gCOD,为新炭的42%。在现场中试条件下,经过20次循环利用的活性炭经过再生,其吸附容量为0.98mg/gCOD,为新炭的23%。此外,以焦化废水生化出水做再生介质,在最佳再生条件下,最大可达到15%的再生效果;而以自来水做再生介质,可以达到至少50%的再生效果。

In advanced treatment of sewage in coking plants,the combination of powdered activated carbon（PAC） and UF membrane process is often adopted as pre-treatment to decrease the COD concentration of the sewage and reduce the difficulty of the subsequent treatment processes.It may also lighten the membrane fouling to some extent.Due to the high cost of using PAC,regeneration of PAC is an effective way to lower the overall cost of the treatment.Ultrasound technology was adopted for PAC regeneration in this research which was a simple and low energy consumptive approach without secondary pollution.Optimization experiment was conducted to determine the optimum conditions for PAC regeneration.The results showed that under the conditions of 33 kHz ultrasound,200 W power,and the mass ratio of carbon to water of 1 /10 ~ 1 /20,the PAC regeneration efficiency could reach to more than 50% after 20 minutes of ultrasound operation.Under laboratory conditions,the re-adsorption capacity of PAC was 1.8 mg/g of COD after six adsorption-regeneration circulations,which was 42% of the new PAC adsorption capacity.Under the pilot test conditions,the re-adsorption capacity of PAC was 0.98 mg /g of COD after 20 adsorption-regeneration circulations,which was 23% of the new PAC adsorption capacity.When using treated wastewater from coking plants as regeneration fluid,the regeneration efficiency of PAC could reach to 15% under the optimum conditions while it was higher than 50% when using tap water as regeneration fluid.