【作者】 寿宗奇；

【导师】 朱南文；

【作者基本信息】 上海交通大学 ， 环境科学与工程， 2020， 博士

【摘要】 堆肥是常用的污泥稳定化处理技术之一,具有投资少,堆肥产品可用于土地利用等优点。然而,传统污泥堆肥普遍存在有机物降解速度慢,氮素大量损失等问题,影响了污泥堆肥技术的推广。本论文以“促进污泥腐熟”和“减少氮素损失”为主要目标,考察了磷酸盐缓冲溶液（K₂HPO₄-KH₂PO₄）对污泥堆肥腐熟及氮素损失的影响;进一步考察了在投加磷酸化缓冲溶液的基础上额外投加Mg²⁺对污泥堆肥腐熟及氮素损失的影响;研究了堆肥过程中各种形态的氮素、碳源、微生物种群结构以及氨同化酶活性的变化,明确了磷酸盐缓冲溶液-Mg²⁺促进污泥腐熟和减少氮素损失的相关机理;设计了日处理量为1吨（以含水率80%计）的污泥堆肥中试工程,验证了磷酸盐缓冲溶液-Mg²⁺在污泥堆肥中试规模上的有效性。主要结论如下:（1）磷酸盐缓冲溶液对污泥腐熟及氮素损失的影响磷酸盐缓冲溶液的投加可以加速污泥堆肥腐熟进程和减少堆肥过程中氮素的损失。在磷酸盐缓冲溶液投加量为0.6 mmol·g^-1DS（以P元素计）时,与对照组相比,堆肥34 d后,有机物去除率提高了25.7%,NH₃-N逸出量减少了45.4%,总氮损失率降低了41.5%。在磷酸盐缓冲溶液投加量为0.6 mmol·g^-1DS时,不同的投加时间对污泥堆肥腐熟促进效果不显著,但对氮素损失的影响显著。堆肥34 d后,与对照组相比,在堆肥第4 d投加磷酸盐缓冲溶液的实验组NH₃-N逸出量减少了51.9%,总氮损失率降低了48.3%。（2）磷酸盐缓冲溶液-Mg²⁺对污泥腐熟及氮素损失的影响不同类型的镁化合物对污泥堆肥腐熟进程和总氮损失的影响各不相同。投加硫酸镁的实验组每降解1%的有机物造成的氮素损失(N_loss/OML)最低,比对照组降低了68.9%。MgSO₄的投加量对污泥堆肥腐熟促进作用不明显,但可以进一步降低堆肥过程中NH₃-N的逸出。与对照组相比,当磷酸盐缓冲溶液和MgSO₄投加量分别为0.6和0.4 mmol·g^-1DS时,堆肥34 d后,有机物去除率提高了26.1%,NH₃-N逸出量减少了73.1%,总氮损失率降低了73.4%。（3）磷酸盐缓冲溶液-硫酸镁投加工艺参数的优化采用响应曲面法进一步优化了磷酸盐缓冲溶液投加量、磷酸盐缓冲溶液投加时间及MgSO₄投加量等工艺参数。根据构建的响应曲面模型确定最佳磷酸盐缓冲溶液投加量为0.582 mmol·g^-1DS、最佳磷酸盐缓冲溶液投加时间为2.85 d,最佳MgSO₄投加量为0.428 mmol·g^-1DS。在该工艺参数下,污泥堆肥34 d后,有机物去除率为31.6%,总氮损失率为11.7%。（4）磷酸盐缓冲溶液-硫酸镁促进污泥腐熟和减少氮素损失的机理研究基于污泥堆肥过程中胞外聚合物（EPS）和可溶性有机物（DOM）含量变化探讨了磷酸盐缓冲溶液-硫酸镁提高堆体中DOM含量的作用机制。结果表明,磷酸盐缓冲溶液促进了EPS的分泌,而松散型胞外聚合物（LB-EPS）中的多糖类可与K⁺结合转移至可溶性有机物中,与对照组相比,在整个堆肥过程中,投加磷酸盐缓冲溶液的堆体中可溶性多糖的平均含量提高了68%以上,而MgSO₄对促进EPS分泌的作用不明显。从氮素平衡、氨同化酶活性及堆肥微生物种群变化探讨了投加磷酸盐缓冲溶液-硫酸镁减少污泥堆肥过程中氮素损失的机理。结果表明,磷酸盐缓冲溶液的投加明显提高了堆体中α-酮戊二酸的含量,增强了氨同化酶活性,促进具有氨同化功能的放线菌、芽孢杆菌、假单胞菌等菌属的增长。额外投加MgSO₄使堆体中发生了鸟粪石结晶反应,降低了堆体中可溶性NH₄⁺-N的含量,进一步减少由NH₃-N的逸出造成的氮素损失。（5）污泥堆肥中试运行效果分析在上海国际旅游度假区内设计了日处理量为1吨（以含水率80%计）的污泥堆肥中试工程,验证了磷酸盐缓冲溶液-硫酸镁在污泥堆肥中试规模上的有效性。在磷酸盐缓冲溶液投加量为0.582 mmol·g^-1DS、磷酸盐缓冲溶液投加时间为2.85 d,MgSO₄投加量0.428 mmol·g^-1DS的工艺参数下进行中试堆肥试验,与对照组相比,堆肥34 d后,有机物去除率提高了28.6%,堆肥产品中的有机氮的含量提高了55.5%,NH₃-N逸出量减少了76.8%,总氮损失率减少了68.4%。投加磷酸盐缓冲溶-硫酸镁后,堆肥产品总养分（N+P₂O₅+K₂O）的质量分数为8.95%,高于有机肥标准中的限值（≥5%）,而对照组中总养分质量为3.82%,未达到有机肥的标准。更多还原

【Abstract】 Composting is a low-cost technology for waste active sludge（WAS）treatment,in which organic matters are biologically converted into nutrient-rich,humus-like material for cropland application to improve soil fertility.However,massive nitrogen is lost via ammonia emission during the sludge composting process due to the low C/N ratio of WAS,which influenced sludge composting popularization.The main objective of this paper was to promote sludge maturation and reduce nitrogen loss.The effects of phosphate buffer solution（PBS）on sludge compost maturation and nitrogen loss were investigated.Then,Mg²⁺was added to further investigate the influence of sludge compost maturation and nitrogen loss.The changes of nitrogen,carbon source,microbial population structure and ammonia assimilation enzyme in various forms during compost were studied,and the related mechanism of PBS-Mg²⁺promoting sludge maturation and reducing nitrogen loss were clarified.Finally,a pilot project of sludge compost with a daily treatment capacity of 1 ton（moisture content:80%）was designed to verify the effectiveness of PBS-Mg²⁺on the pilot scale of sludge compost.（1）Effects of PBS on maturation and nitrogen loss in sludge compostingPBS addition was proved as an effective strategy to promote sludge maturation and reduce nitrogen loss.When the dosage of PBS was 0.6mmol·g^-1DS,compared with the Control,the organic matter loss（OML）increased by 25.7%,the cumulative NH₃-N emission decreased by 45.4%,and the total nitrogen loss decreased by 41.5%.When the dosage of PBS was 0.6mmol·g^-1DS,the effect of different adding time on sludge maturation is not significant,but the effect on nitrogen loss is significant.After 34 days of composting,compared with Control,the cumulative NH₃-N emission and total nitrogen loss of the experiment group treated with PBS on 4^th day decreased by 51.9%and 48.3%,respectively.（2）Effects of PBS-Mg²⁺on maturation and nitrogen loss in sludge compostingThe results showed that different types of magnesium compounds have different effects on sludge maturation and nitrogen loss(N_loss).The experiment group with MgSO₄ had the lowest nitrogen loss(N_loss/OML)for every 1%of organic matter degraded,which was 68.9%lower than that of Control.The addition of MgSO₄ has no obvious promoting effect on OML,but it can further reduce NH₃-N emission during composting.Compared with Control,after 34 days of composting with 0.4 mmol·g^-1DS MgSO₄addition,OML increased by 26.1%,cumulative NH₃-N emission decreased by 73.1%,and N_loss decreased by 73.4%.（3）The optimization of process parameter for PBS and MgSO₄The response surface method（RSM）is used for optimization of technological parameter,which were the PBS dosage,PBS dosage time and MgSO₄ dosage.According to RSM model,it’s determined that the optimal dosage of PBS was 0.582 mmol·g^-1DS,optimal addition time of PBS was2.85 d,and the optimal dosage of MgSO₄ was 0.428 mmol·g^-1DS.Under this process parameter,after 34 days of composting,OML and N_loss were31.6%,and 11.7%,respectively.（4）The mechanism of PBS-MgSO₄ to promote sludge maturation and reduce nitrogen lossThe addition of PBS facilitated extracellular polymeric substances（EPS）solubilization in sludge,releasing carbon resources internally for microbial utilization.The results showed that K⁺in PBS could promote the transfer of polysaccharide in loosely bound EPS（LB-EPS）to dissolved organic matters（DOM）.Compared with the Control group,during the entire composting process,the average content of polysaccharide in the compost with PBS increased by more than 68%.The effect of MgSO₄ on EPS secretion was not obvious.Moreover,the addition of PBS significantly increased the content ofα-ketoglutaric acid during sludge composting,which enhanced the activity of assimilation enzyme and promoted the growth of Actinobacteria,Bacillus and Pseudomonas with ammonia assimilation function.The additional MgSO₄ caused struvite crystallization in the compost,which made part of the water soluble NH₄⁺-N in the compost convert to acid soluble NH₄⁺-N,reduced the content of water soluble NH₄⁺-N,thus further reduced the emission of NH₃-N and the nitrogen loss.（5）Evaluation of sludge composting in pilot-scale bioreactorsA pilot project of sludge composting with a daily treatment capacity of1 ton was carried out under the optimal technological parameters.After 34days of composting,the OML increased by 28.6%.The content of Org-N in composting products increased by 55.5%,the emission of NH₃-N decreased by 76.8%,and nitrogen loss decreased by 68.4%.Due to the addition of PBS-MgSO₄,the content of total nutrients（N+P₂O₅+K₂O）of composting products was higher（8.95%）than the limit value of organic fertilizer standard（≥5%）,while the total nutrient mass of control group was 3.82%,which did not meet the standard of organic fertilizer.更多还原