鸟粪石沉淀法在汽油精炼废水中的应用

Application of Struvite Precipitation in Gasoline Refinery Wastewater Treatment

针对汽油精炼废水中C/N低的特点,研究了鸟粪石沉淀法对后续生化工艺的影响。实验选择硫酸镁和磷酸二氢钾作为沉淀剂,比较了不同pH值和硫化物浓度下氨氮的去除率。实验表明,在pH值为11、Mg2+∶NH4+∶PO43-((摩尔比)为6∶3∶4时,氨氮去除率最高,出水氨氮浓度低于30mg/L。硫离子存在能够形成协同沉淀,有效提高氨氮的去除率。鸟粪石沉淀法能够将C/N比提高到20∶1左右,强化了后续生化处理工艺的出水水质。最终出水氨氮小于10mg/L,CODCr低于50mg/L,达到回用要求。

According to the low C/N in gasoline refinery wastewater （GRW）, precipitation of ammonia-nitrogen as struvite （Magnesium ammonium phosphate,MAP） was investigated to consider the sequent influence of biological treatment. MgSO4 and KH2PO4 were selected and removing efficiency of NH4^＋ was studied in varied pH and the absence and existence of sulfide. The results showed that when the molar ratio of Mg^2＋： NH4^＋： PO4^3- as 6：3：4, pH as 11, existence with sulfide, the NH4^＋ removal efficiency arrived at the highest level and effluent concentration was less than 30 mg/L. The existence of sulfide could function as co-precipitation to improve the removing efficiency. Precipitation of struvite could increase the ratio of C/N to about 20：1, which will enhance the biological process and meliorate the quality of effluent. The concentrations of NH4^＋ and CODcr were less than 15 mg/L and 50 mg/L respectively. The effluent could match the requirements for reclamation, which effectively save the fresh water.