为降低沼液氮磷脱除的操作费用,提出向沼液中添加生物质灰来辅助氮磷脱除。试验研究了水稻秸秆、花生壳、棉花秸秆和玉米秸秆4种生物质在600℃下燃烧后的生物质灰对沼液pH值、氨氮浓度和总磷的影响。同时考察了生物质灰添加对沼液化学需氧量、悬浮物质量浓度、浊度及植物生理毒性的影响。结果表明,棉花秸秆灰在沼液中的溶解度最大,为12.97%,而花生壳灰溶解度最低,仅为10.67%。通过Ca~(2+)、Mg~(2+)和OH~-等离子的引入,生物质灰添加可部分沉淀沼液中的CO_2,提升沼液p H值至9.5~11.0,满足“热-吹脱”氨氮脱除工艺对p H值的要求。同时,随着生物质灰添加量的增加,沼液中总磷含量基本呈现先降低后略微升高的趋势,当添加100 g/L棉花秸秆灰时,沼液总磷最高脱除率可达78.74%,其质量浓度可由初始值19.66 mg/L降低至4.18 mg/L。这表明生物质灰添加有利于氮磷脱除,理论上可降低氮磷脱除的操作费用。另外,添加生物质灰可在一定程度上降低沼液化学需氧量、悬浮物质量浓度和浊度,其中棉花秸秆灰的综合表现最优,对三者的降低幅度分别达56.71%、57.24%和77.37%。最后,用添加生物质灰后的沼液富CO_2溶液培养大白菜种子,其发芽指数整体大于0.8,表现出较低的植物生理毒性。因此,生物质灰可用于辅助沼液氮磷脱除,有利于沼液后期施用,其中,棉花秸秆灰的效果最优。 In order to reduce the operating costs of nitrogen and phosphorus removal from biogas slurry, it is proposed to add biomass ash to the biogas slurry to assist the removal of nitrogen and phosphorus. The effects of biomass ash, which was burned at 600 ℃ on the pH value, ammonia nitrogen concentration and total phosphorus of biogas slurry, were studied experimentally with four kinds of biomass of rice straw, peanut shell, cotton stalk and corn stalk. At the same time, the effects of adding biomass ash on chemical oxygen demand, suspended matter mass concentration, turbidity and plant physiological toxicity were investigated. The results showed that cotton straw ash had the highest solubility in biogas slurry of 12.97%, while peanut shell ash had the lowest ash solubility of only 10.67%. Through the introduction of Ca ~ (2 +), Mg ~ (2+) and OH ~ - ions, the addition of biomass ash can partially precipitate the CO_2 in the biogas slurry and increase the pH of the biogas slurry to 9.5 ~ 11.0, which satisfies the requirement of “ - Stripping ”ammonia nitrogen removal process on pH value requirements. At the same time, with the increase of biomass ash, the total phosphorus content in biogas slurry showed a slight decrease at first and then increased slightly. When adding 100 g / L cotton straw ash, the maximum removal rate of total phosphorus in biogas slurry reached 78.74%, the mass concentration can be reduced from the initial value of 19.66 mg / L to 4.18 mg / L. This shows that the addition of biomass ash is conducive to the removal of nitrogen and phosphorus, in theory, can reduce the operating costs of nitrogen and phosphorus removal. In addition, the addition of biomass ash can reduce the chemical oxygen demand, suspended solids concentration and turbidity of the biogas slurry to some extent, of which the comprehensive performance of cotton straw ash is the best, the reduction rate of the three reached 56.71%, 57.24% And 77.37%. Finally, the germination index of Chinese cabbage was increased by more than 0.8 with CO2-enriched solution of biogas slurry added with biomass ash, showing lower plant physiological toxicity. Therefore, the biomass ash can be used to aid the removal of nitrogen and phosphorus in biogas slurry, which is favorable for the later application of biogas slurry. Among them, cotton straw ash has the best effect.