城市污水处理厂的兴建与运行，是保护水资源和防治水体污染的重要举措。 但是上个世纪九十年代以来，随着我国城市化进程的加快，城市污水处理率逐年 提高，城市污水处理厂的污泥产量也急剧增加。大量的污泥因无稳定合理的处置 出路，侵占人们本来就紧张的生活空间，而未经适当处理处置的污泥进入环境后， 直接给水体和大气带来二次污染，不但降低了污水处理系统的有效处理能力，而 且对生态环境和人类活动构成了严重威胁。按照减量化、无害化和资源化的要求， 污泥应被视为一种资源加以有效利用，在治理污染的同时变废为宝。因此，剩余 污泥的处理处置及其资源化利用等问题日益受到人们的关注。 青岛市现有规模较大的污水处理厂四座（李村河、海泊河、团岛、麦岛）， 其中，除了麦岛污水处理厂采用污水一级处理工艺外（无剩余污泥产生），其余 三座均采用二级生化处理工艺（产生剩余污泥）。这些污水处理厂每天产出大量 剩余污泥堆放在厂区，定期运送到垃圾填埋场填埋或将剩余污泥自然风干脱水 后，焚烧供热。这些处理方式不仅使污泥中的有害成分对环境造成二次污染，而 且污泥中的营养成分得不到有效利用，浪费了资源，因此，需要探讨一种合适的 处理处置方法以实现剩余污泥的减量化、无害化和资源化。 本研究首先对李村河、海泊河、团岛三座污水处理厂剩余污泥的物理、化学 性质和成分进行分析。结果表明，三座污水处理厂的污泥均呈灰黑色，粘着成块 状，不易分散。pH 值呈碱性（pH＝8.68~8.81），含水率（70%~83%）较高。污 泥中有机质、氮、磷、钾含量丰富，重金属和硼的含量较低，符合国家《农用污 泥中污染物控制标准》。依据污泥的上述特征，结合青岛市历史上污泥处理利用 中出现的问题以及经济、安全方面的考虑，提出污泥最为适宜的利用方式是在堆 肥稳定化处理后，作为林地、花卉、苗圃、草地的肥料。同时，根据生态工程中 通过“加环”延长食物链的原理，提出污泥利用的新途径，即首先将污泥中的细 胞蛋白提取后作为饲料蛋白添加剂，剩余部分再用作肥料。2 然后，对污泥中的细胞蛋白提取和沉淀分离技术进行了研究。采用正交试验 优化了酸水解、碱水解、超声波与碱耦合三种方法提取污泥蛋白的工艺条件。其 中，酸水解法的适宜条件为，水解温度 121℃、水解时间 5h、体系 pH 值 1.25、 加水体积为样品质量的 2.5~3 倍；碱水解法的适宜条件为，水解温度 70℃、水解 时间 5h、体系 pH 值 12.5、加水体积为样品质量的 4~4.5 倍；超声波与碱耦合法 的适宜条件为，超声功率 650W、超声时间 35min、体系 pH 值 12.0、加水体积 为样品质量的 6~6.5 倍。在每种提取方法的优化条件下，分别对三座污水处理厂 的脱水污泥进行重复提取，结果表明，李村河污泥适于采用超声波与碱耦合提取 方法；海泊河污泥蛋白提取适于采用酸水解法；而团岛污泥提取适于采用碱水解 法。蛋白质提取效率为 62.71%~69.60%，污泥消减率可达到 29.95%~34.21%，剩 余污泥体积可减少将近 1/3。三座污水处理厂剩余污泥提取液中的蛋白质等电点 均为 5.5。沉淀物中蛋白质纯度（干基）分别为，团岛 83.52%，李村河 81.85%， 海泊河 79.66%。 最后，对蛋白质沉淀物的营养性和安全性进行分析。蛋白质沉淀物中的氨基 酸含量较高，约占粗蛋白质量的 55%~65%。除色氨酸测定时被破坏外，人体和 动物生长所需要的另外七种必需氨基酸均可以检测到，且含量很高，为沉淀物干 重的 21%~24%，约占所有检出氨基酸总量的 50%。另外，在蛋白质沉淀物中还 检测出八种非必需氨基酸，占所有检出氨基酸总量的 50%左右。蛋白质沉淀物中 重金属含量非常少，Pb、Cd 含量符合国家《饲料卫生标准》；Zn 含量符合《饲 料中锌的允许量》（NY929-2005）的规定；Cu 含量也远低于实际生产对饲料中 Cu 含量的要求。 综上所述，从营养性和安全性两方面考虑，将青岛市污水处理厂污泥的蛋白 质提取分离后作为动物饲料添加剂是可行的。 关键词，污泥、蛋白质、提取、营养性、安全性、动物饲料添加剂3 A Study on the Extraction of Protein from Sewage Sludge and the Possibility for Using as Animal Feed Additive Abstract The construction and operation of wastewater treatment plants are important measurements for protecting water resources and preventing water body from pollution. While, since 1990s, the output of the sewage sludge has been increased rapidly, with the acceleration of urbanization and improvement of wastewater disposal efficiency year by year. A great deal of excess sludge occupies limited living space for human because of being short of appropriate treating methods. Water and air will be polluted if the sludge discharged without proper treatement. This will not only reduce treatment abilities of municipal wastewater treatment plants, but also threaten the environment and human activities seriously. According to the request of reduction, harmlessness and recovery, the sludge should be efficiently utilized and become resources. Therefore, more attention has been paid on the disposal and utilization of excess sludge. There are four municipal wastewater treatment plants in Qingdao(Licunhe, Haibohe, Tuandao and Maidao). Maidao wastewater treatment plant adopts primary wastewater treatment(not produce excess sludge) and the others adopt secondary treatment (produce excess sludge). Lots of excess sludge are piled up in the plants everyday and delivered to landfill or incinerated after natural dehydration. In this way, deleterious substances in sludge may cause secondary pollution to environment and nutrients of sludge are losted without being utilized efficiently. So it is necessary to study an appropriate method for the reduction, harmlessness and recovery of excess sludge. Firstly, the physical and chemical characteristic and composition in the excess sludges from Licunhe, Haibohe and Tuandao wastewater treatment plants are4 determinded. The results show that three excess sludge samples are black, lumpish and viscous. They are alkalescent with a pH value ranged from 8.68 to 8.81, and have a moisture content ranged from 70% to 83%. The samples have plenty of organic matter, N, P, K, but less heavy metals and boron (B) in content being up to the Control Standards for Pollutants in Sludges from Agricultural Use (China). According to the above characteristics of sludges and the problems in disposal and utilization of sludge in Qingdao city, it is proposed that the best way for utilizing these sludges be used as a fertilizer in forest, flower and grassland after compost. Furthermore, according to the principle of extending food chains by “added loop” in eco-engineering, a new way by which the single cell protein(SCP) in the sludge should be extrated as a feed additive before application in land is brought forward. Then, the technology about extraction, precipitation and separation of cell protein in sludge are studied. Three methods, acid hydrolyzation, alkali hydrolyzation and ultrasonic-alkali extraction, are selected to extract protein from sludge. Orthogonal tests are introduced into each method to optimize the operation conditions. For acid hydrolyzation, the optimum conditions are listed as follows: temp. 121℃; hydrolyzing time 5h; pH value 1.25 and addition of deionized water is 2.5 ~ 3 times as sample mass. For alkali hydrolyzation, the optimum conditions are listed as follows: temp. 70℃; hydrolyzing time 5h; pH value 12.5 and addition of deionized water is 4 ~ 4.5 times as the sludge sample mass. For ultrasonic-alkali extraction, the optimum conditions are listed as follows: ultrasonic power 650W; ultrasonic time 35min; pH value 12.0 and addtion of deionized water is 6 ~ 6.5 times as the sludge sample mass. Under the optimal conditions, protein extraction experiments with three methods are operated repeatly. It shows that, ultrasonic-alkali extraction is best for Licunhe sludge, acid hydrolyzation for Haibohe sludge, and alkali hydrolyzation for Tuandao sludge. The extraction efficiency of protein changes from 62.71% to 69.60%, the mass of sludge are reduced by from 29.95% to 34.21%, and the volume of excess sludge is cut down by above 1/3. Three sludge extraction liquor have the same protein isoelectric point of pH5.5. Protein purities(dry weight) in the precipitates formed at pH5.5 are 83.52%(Tuandao sludge), 81.85%(Licunhe sludge), 79.66%(Haibohe sludge)5 respectively. At last, the nutrition and security of the precipitates are evaluated. The precipitates contain more amino acids which occupy 55% ~ 65% weight of coarse protein. Besides of tryptophan which is destroyed during the detection, other seven kinds of essential amino acids can be detected, which account for 21%~24% of the precipitates in dry weight 50% of total mass of the amino acids. In addition, eight non-essential amino acids can also be