鸟粪石结晶法回收沼液中氨氮

Recovery of Ammonia from Biogas Slurry by the Crystallization of Struvite

为了充分利用沼液,采用向沼液中投加MgCl_2·6H_2O和Na_2HPO_4·12H_2O生成磷酸铵镁(鸟粪石)的方法,以回收其中氨氮的同时获得缓释肥鸟粪石。本研究以生活垃圾厌氧处理后排放的沼液为研究对象,研究了pH值与磷氮物质的量比对鸟粪石结晶法回收氨氮的影响,结果表明pH值对氨氮回收率影响不是很明显,当pH值在7.5~10.0之间变化时,氨氮的回收率均大于78.31%。而磷氮物质的量比对沼液中氨氮回收率影响非常显著,随着磷氮物质的量比从0.8升高到1.3,氨氮的回收率也从64.73%提高到91.05%。利用响应曲面对上述两种因素进行优化,确定了鸟粪石结晶法回收氨氮的最佳工艺条件为:pH值为7.5,磷氮物质的量比为1.183,此时氨氮回收率为88.69%。

A bench scale study was conducted to make full use of biogas slurry with the method of struvite precipitation（MAP）,the process of which is described such as application of Mg Cl2·6H2O and Na2HPO4·12H2O into the biogas slurry to recover the ammonia from biogas slurry.A lab-scale study was performed to investigate the efficiency of MAP precipitation using swamp at different p H and different molar ratios of phosphorus/nitrogen on synthetic struvite in biogas slurry.The results showed that the p H value of ammonia recoveries is not obvious,when the change of p H values between 7.5~10.0,ammonia recoveries were78.31%.The molar ratio of phosphorus and nitrogen effect the recovery of ammonia in the biogas slurry is very significant as phosphorus and nitrogen molar ratio increased from 0.8 to 1.3,the ammonia recovery rate from 64.73%to 91.05%.Use the response surface methodology to optimize of these two factors determine the optimum conditions for recovery ammonia as follows：p H 7.5,molar ratio of phosphorus and nitrogen is 1.183,the ammonia recovery rate of 88.69%.