常温还原铁氧体法处理含铬废水

Treatment of chromium-containing wastewater by room-temperature reduction ferrite process

实验探究了常温还原铁氧体法处理含铬废水的最优工艺条件,研究了不同亚铁盐及氨氮和COD对处理效果的影响,对沉淀进行了化学分析与材料表征。实验表明,在n(Fe2+)∶n(Cr6+)=6,共沉淀pH=10.0,还原时间为2 min,共沉淀时间为15 min条件下,处理含铬废水可达最好效果,总铬浓度从1 600 mg/L降至1.5 mg/L以下,符合国家《污水综合排放标准》(GB 8978-1996)的要求,实现了常温条件下铁氧体法对含铬废水的处理。对于不同亚铁盐,氯化亚铁处理废水的性能要强于硫酸亚铁,沉降速率快且沉淀致密。一般浓度的氨氮(50 mg/L)与COD(500 mg/L)对处理效果没有明显影响。对沉淀进行酸稳定性分析和XRD表征,确定生成了稳定的含铬复合铁氧体。

Chromium-containing wastewater was treated at normal temperatures with ferrite process in this study. The influences of ferrous salts, ammonia nitrogen and COD on the treatment efficiency were explored. Furthermore, the precipitate was analyzed with the chemical method and XRD. The experiments indicated that the best treatment effectiveness was achieved under the following conditions： n（ Fe^2＋ ） ：n（ Cr^6＋ ） = 6, co-precip- itation pH = 10.0, reduction time = 2 min, and co-precipitation time = 15 min. The concentration of chromium i- ons in the effluent reduced from 1 600 mg/L to less than 1.5 mg/L, reaching the discharge standard stipulated in Integrated Wastewater Discharge Standard （GB 8978-1996）. Ferrous chloride performed better than ferrous sul- fate, with fast sedimentation rate and dense precipitation. Normal concentrations of ammonia nitrogen （50 rag/ L） and COD （500 mg/L） had no obvious influence on the treatment efficiency and acid stability and XRD ana- lyses indicated that stable chromium ferrite could be generated under the optimum process conditions.