添加镁渣曝气吹脱预处理对养猪场沼液脱氮效果研究

Study on Nitrogen Removal of Biogas Slurry in Piggery by Aeration Blow-off Pretreatment with Magnesium Slag Addition

为探讨添加镁渣曝气吹脱预处理对猪场沼液脱氮效果的影响,利用猪场沼气发电机余热进行沼液热曝气吹脱,同时添加氧化镁脱硫废渣(镁渣)提高pH,促进形成磷酸铵镁,强化氨氮去除。结果表明,在温度60℃、曝气时间8 h、曝气量2.0 L/min、pH为9.0时,未添加镁渣的曝气吹脱处理NH3-N去除率为61.07%;而镁渣添加量1.0 g/L的曝气吹脱处理NH3-N去除率为69.48%,其中61.07%是以NH3曝气吹脱去除,8.41%是以MAP沉淀去除;经过曝气吹脱预处理,沼液COD/ρ(TN)由0.82提高到2.43,提高了可生化性;沼液沉积物主要成分是磷酸铵镁,可作为高效磷肥利用。添加镁渣曝气吹脱预处理能够降低猪场废水氨氮的同时回收磷肥副产品。

In order to investigate the effect of adding magnesium slag in aeration blow-off pretreatment on the nitrogen removal effect of piggery biogas slurry, this study intends to use the waste heat of the piggery biogas generator to heat the biogas slurry for hot aeration blow-off, and adding magnesium oxide desulfurization waste residue(magnesium slag) to increase the pH, promoted the formation of magnesium ammonium phosphate, and strengthened the removal of ammonia nitrogen. The results showed that when the temperature was 60 ℃, aeration time was 8 h, aeration flow rate was 2.0 L/min,pH was 9.0 and without magnesium slag addition, NH3-N removal rate by aeration blow-off treatment was 61.07%. The removal rate of NH3-N was69.48% by aeration blow-off treatment when the added amount of magnesium slag was 1.0 g/L, of which 61.07% was NH3 aeration blow-off removal and 8.41% was MAP precipitation removal. After aeration blow-off pretreatment, the COD/ρ(TN) of biogas slurry was increased from 0.82 to 2.43,which greatly improved the bioavailability. The main component of the biogas slurry deposits was magnesium ammonium phosphate, which could be used as a high-efficiency phosphate fertilizer. The adding magnesium slag in aeration blow-off pretreatment could reduce ammonia nitrogen in piggery biogas slurry while recovering phosphate fertilizer by-products.