【作者】 蔡建波；

【导师】 黄巧云； 朱端卫；

【作者基本信息】 华中农业大学 ， 土壤学， 2015， 博士

【摘要】 随着我国生猪养殖业的规模化和集约化,铜、锌等元素作为高效、廉价、操作方便的生长促进剂被广泛应用于生猪饲料添加剂中,导致猪场粪污中存在着大量未被吸收转化的铜、锌等重金属。在上流式厌氧污泥床反应器(UASB)处理养猪废水的过程中,为了探索铜对厌氧污泥中微生物群落多样性的影响及其与反应器处理效果的关系,本研究综合利用PCR-DGGE技术和Real-time PCR技术,以两台UASB反应器运行过程中厌氧污泥的相关特性为对比,考察了反应器在活性污泥驯化期和加铜胁迫期的微生物群落变化规律,明确了适应高浓度铜养猪废水的微生物菌群,为提高UASB处理养猪废水的效率提供理论依据。同时,鉴于养猪废水沼液的处理现状,本研究进一步利用人工湿地的围隔试验,模拟达标排放后的微污染养猪废水,探索了在生态处理微污染水时其中重金属铜和锌在芦苇、不同粒径沉积物、水体之间的迁移转化规律,以揭示水体-植物-沉积物体系中重金属的归趋,并从芦苇种植对不同粒径表层沉积物中重金属分布的影响出发,探究芦苇种植抑制沉积物中重金属向上覆水迁移的机制。主要结果如下:1.以水泡粪废水为对象,当工艺条件控制在水力停留时间(HRT)为48 h,有机负荷在3.00~5.00 kg COD/(m3·d),运行温度为35℃~37℃时,UASB反应器内厌氧接种污泥在经历了适应期、负荷提高期和稳定期共计86 d的驯化过程后,对养猪废水COD有80%以上的去除率,说明UASB反应器对水泡粪养殖方式所产生的养猪废水具有良好的处理效果,是值得推广的一种养猪废水处理工艺;由于氨化细菌的作用将水中有机态氮转化为氨态氮,使反应器运行过程中出水NH3-N值比进水有最高为84.16%的提高,说明仅用厌氧方法无法去除养猪废水中氨氮,必须结合其他工艺对其进行联合处理;在驯化过程中,进水铜在0.1~4.2 mg/L的情况下,污泥中铜累积最高为0.42 mg/g;外加铜含量在1.0 mg/L以下,铜对提高UASB的COD去除率有一定促进作用,但是作用不显著。随着外加铜含量超过1.0 mg/L,与对照相比,反应器对COD的去除率有20%的下降,说明外加铜源在1.0 mg/L以上时,铜对UASB工艺去除养猪废水中的COD有抑制作用。2.基于产甲烷菌16S r RNA的PCR-DGGE分析表明,外源铜的添加对UASB中产甲烷菌群的影响主要在于各菌群的数量方面,而对于菌群种类多样性的影响基本可以忽略不计;外源铜的添加打乱了产甲烷菌菌群结构的稳定性。投加外源铜小于1 mg/L时,对三种产甲烷菌都有促进作用,其中对甲烷杆菌目(MBT)的促进作用最为显著。当外源铜达到1.5 mg/L时,甲烷微菌目(MMB)和甲烷八叠球菌目(MSL)已经出现抑制趋势,甲烷杆菌目(MBT)处于促进状态。当外源铜达到4 mg/L时,甲烷微菌目(MMB)和甲烷八叠球菌目(MSL)都会发生明显的抑制情况,而甲烷杆菌目(MBT)仍有一定的促进作用;甲烷球菌目(MCC)在处理养猪废水的UASB反应器内难以生存。甲烷杆菌目(MBT)和甲烷八叠球菌目(MSL)含量较多,甲烷微菌目(MMB)含量较低。在不添加外源铜的情况下,甲烷八叠球菌目(MSL)在三种产甲烷菌群中数量最多,其16S r RNA基因的平均浓度占到产甲烷菌16S r RNA基因浓度总量的49.6%;甲烷杆菌目(MBT)其次,为42.5%;甲烷微菌目(MMB)最少,为7.9%。在添加外源铜的情况下,甲烷杆菌目(MBT)在三种产甲烷菌群中数量最多,其16S r RNA基因的平均浓度占到产甲烷菌16S r RNA基因浓度总量的58.3%;甲烷八叠球菌目(MSL)其次,为36.7%;甲烷微菌目(MMB)仍最少,为5.0%。3.人工湿地生态处理模拟的微污染养猪废水的研究表明,种植芦苇能在短时间内降低水体中Cu和Zn的浓度。5 d后对照水体上下层水样Cu浓度分别为1.20 mg/L和0.40 mg/L,而种植芦苇上下层水样Cu浓度分别为0.52 mg/L和0.37 mg/L;同样条件下,5 d后对照水体上下层水样Zn浓度分别为1.55 mg/L和0.69 mg/L,而种植芦苇上下层水样Zn浓度分别为0.68 mg/L和0.52 mg/L。芦苇不同部位Cu和Zn含量基本呈现根>茎>叶,且随芦苇生长,其根、茎和叶Cu和Zn的累积量逐渐增加;芦苇不同部位Zn含量均高于Cu。芦苇能显著降低沉积物中Cu和Zn含量,且对沉积物中不同粒径中重金属含量具有显著影响。相同粒径条件下,种植芦苇可以显著降低沉积物中重金属含量。因此,可利用人工湿地处理微污染养猪废水的生态措施使废水中重金属有效地沉降到沉积物中;当湿地在外力扰动条件下,种植芦苇可抑制沉积物再悬浮,同时可显著降低小粒径沉积物中重金属的含量,从而有效减少因沉积物的重新悬浮而再次迁移到水体中的重金属。更多还原

【Abstract】 With the rapid development in scale and intensification of pig farming industry in China, copper, zinc and other elements are widely used in pig feed’s additives as efficient,inexpensive and operational convenient growth promoter, which leads to a large number of unabsorbed and untransformed copper, zinc and other heavy metals existing in pig manure and swine wastewater. In order to explore the effect of copper on microbial community diversity in anaerobic sludge and its relationship with the treatment efficiency of the reactor, PCR-DGGE and Real-time PCR technology were employed to investigate the changes of microbial community during acclimation period of activated sludge and copper stress period in swine wastewater treatment by the upflow anaerobic sludge blanket reactor(UASB) basing on the comparison of the related properties of the anaerobic sludge in the running process of two UASB reactors.These results could identify the microbial flora survived under the high concentration of copper, in the swine wastewater, further provide the theoretical basis for improving the efficiency in swine wastewater treatment by UASB. Meanwhile, in view of the treatment status of biogas slurry from swine wastewater, the simulated slightly polluted swine wastewater was treated by the artificial wetlands barricading and the migration and transformation of copper and zinc among reed, sediment and water was explored to reveal the fate of heavy metals in the water- plant- sediment system. Then the mechanism that reed planting inhibited heavy metals moving from the sediments to the overlying water was probed basing on the effect of reed planting on heavy metals distribution in surface sediments with different particle sizes.The main results are as follows:1. Taking vesicular feces wastewater as the object, the COD removal rate of swine wastewater by UASB was more than 80 % after a total of 86 days treatment including the adaptation period, the loading increase period and stable period, when the process conditions was controlled in the hydraulic retention time(HRT) of 48 h, organic loading of 3.00~5.00 kg COD/(m3·d), the operating temperature of 35°C~37°C., This indicated that UASB reactor had good effect on swine wastewater treatment and was worthy of popularization as a swine wastewater treatment process. Due to transformation of organicnitrogen into ammonium nitrogen by ammonifiers, the concentration of NH3-N in the effluent was up to 84.16% higher than that of the influent during the reactor running. It indicated that the ammonium nitrogen could not be removed by anaerobic process alone in swine wastewater. Thus other processes needed to be combined in ammonium nitrogen treatment. During acclimation process, the copper content of sludge was up to 0.42 mg/g due to accumulation in the case of influent copper concentration of 0.1~4.2 mg/L and the removal of COD in UASB could be accelerated by exogenous copper under 1.0 mg/L.However when the copper addition was higher than 1.0 mg/L, the COD removal by reactors decreased by 20%, indicating that influent copper with concentration higher than1.0 mg/L would restrain the COD removal in the process of UASB treatment on swine wastewater.2. The analysis of PCR-DGGE based the methanogen 16 S r RNA indicated that the addition of exogenous copper to the UASB mainly affected the number of the group of methanogens, not the diversity of the fiora species and the addition of exogenous copper disrupted the structural stability of the methane producing bacteria. When the concentration of exogenous copper was less than 1 mg/L, the promoting effect on MBT was the greatest among the three kinds of methanogen. When the concentration of exogenous copper reached 1.5 mg/L, only MBT was promoted When the exogenous copper reached 4 mg/L, both MMB and MCC were inhibited obviously, but MBT was still in the process of improvement and MCC could not survive in the UASB reactor. The quantity of MBT and MSL were both higher than that of MMB. Among the three kinds of methanogenic bacteria, MSL’s quantity was maximum without exogenous copper addition.Beside, the average concentration of the 16 S r RNA gene in MSL accounted for 49.6% of the total concentration of 16 S r RNA gene in methanogenic bacteria, MBT and MMB were42.5%,and 7.9%, respectively, In addition, the quantity and the average concentration of the 16 S r RNA gene of MBT were highest with the exogenous copper exist.The average concentration of the 16 S r RNA gene of MSL and MMB were 36.7%and 5.0%,respectively.3. Studies on the treatment of simulated slightly polluted swine wastewater by artificial wetland ecological process implied that the concentration of Zn and Cu could bereduced via reed planting in short time. After 5 days, the Cu concentrations of the upper and lower water samples were 1.20 mg/L and 0.40 mg/L, respectively. While the Cu concentrations of the upper and lower water samples with reed planting were 0.52 mg/L and 0.37 mg/L, respectively. under the same condition, the Zn concentrations of the upper and lower water samples without reed planting were 1.55mg/L and 0.69mg/L,respectively. And those with reed planting were 0.68mg/L and 0.52mg/L, respectively.The contents of Zn and Cu in different parts of the reed followed the order of roots >stem>leaves, which increased gradually with the growth of the reed The content of Zn was higher than that of Cu in different parts of the reed. Reed could significantly reduce the contents of Zn and Cu in sediments and had great effect on the contents of heavy metals in different particle sizes of sediments. In the case of the same sizes, reed planting could largely cut down the content of heavy metals of sediment. Accordingly, the artificial wetland treatment could be effectively applied as an ecological measurement in slightly polluted swine wastewater treatment through sedimentation of heavy metals from wastewater. Reed planting could inhibit sediment resuspension when the wetland disturbance by the external force and reduce the content of heavy metals in the sediments of small particle size significantly, thus reduced the content of heavy metals in water effectively due to the movement of heavy metal by resuspension of sediment into the water.更多还原