猪场废水处理中的沼气热电联产工程案例分析

中高浓度畜禽废水处理中的沼气热电联产是保障沼气工程常年稳定运行的有效手段.以典型猪场废水处理沼气热电联产工程为案例,在工程介绍的前提下,引入相关数学模型,对沼气热电联产相关工艺参数进行了计算分析,结果表明,该工程沼气产量最高为1 678 m3/d,沼气发电机组发电效率为31.3％,发热效率为38.8％,总发电效率为70.1％,该沼气工程投资回报期为3.6年;CSTR厌氧罐秋季可达温度为24.3℃,冬季为15.9℃,CSTR厌氧罐内温度分布为秋季罐内平均温度(T)5.4(换热器顶部温度)=25.4℃,平均温度梯度grad1=1.83℃/m,grad2=0.80℃/m;冬季(T)5.4=19.6℃,(grad)1=1.44℃/m,(grad)2=1.06℃/m;通过参数分析,搅拌器宜尽可能置于换热器所在区域,并控制进水量稳定以保证CSTR厌氧罐的消化效果.     

蓝藻与污泥混合厌氧发酵产沼气的初步研究

为了实现太湖蓝藻打捞后的快速处置,对厌氧颗粒污泥、消化污泥、剩余污泥与蓝藻混合厌氧发酵产沼气进行了研究。结果表明,蓝藻与污泥混合可以有效促进沼气发酵。在蓝藻与厌氧颗粒污泥物料比为6∶1时,产气效果最佳,沼气产率为73 mL/g VS,平均甲烷含量为69%,最大产气速率为138 mL/d,累计产甲烷量为50 mL CH₄/g干物质,分别是蓝藻与消化污泥、剩余污泥混合发酵时的1.5倍和2.3倍。厌氧颗粒污泥、消化污泥、剩余污泥与蓝藻混合,其VS降解率为11.40%～13.73 %,COD减少了27.97%～46.38%。厌氧发酵对蓝藻藻毒素的含量有较大影响,分别从356、366和244 μg/L降低到检测限5 μg/L 以下。     

以沼气为纽带的生物循环生态模式研究

介绍了仪征市久闻农业科技示范园以沼气为纽带,通过沼气、沼液、沼渣的综合利用,形成了以“鸭粪喂猪、猪粪产沼、沼气育雏、沼液养鱼、沼渣肥林（菜）”为主的“鸭-猪-沼-鱼（林、菜）”循环生态模式,并完善了相应的配套技术。该模式的应用,使得畜禽生产的粪便污水等污染物得到了有效处理和利用,改变了园区的卫生状况,改善了生态环境;实现了资源的高效合理循环,减少了企业生产生活过程中燃料、肥料、饲料等投入,降低了生产成本,取得了较好的经济效益。     

Effect of two biogas residues’ application on copper and zinc fractionation and release in different soils

Biogas residue (BR) is widely used as a new green fertilizer in agriculture in China. However, it often contains a high concentration of heavy metals so its application should cause our concern. An incubation experiment was conducted to study the risk of pig biogas residue (PBR) and chicken biogas residue (CBR) application on Liuminying soil (LS) and Yixing soil (YS). The soils were incubated for one, three and six months with 0, 2%, 4% and 6% addition of BRs. According to BCR extraction results, the PBR and CBR applications induced an increase in the concentration of exchangeable fraction of Zn. As for the concentration of exchangeable fraction of Cu, an increase was only observed in the treatments with PBR application. The heavy metal binding intensity also showed a similar trend. With the PBR application, for the LS and YS, the highest concentrations of exchangeable Zn increased 3.6 and 9.5 times, respectively, while the exchangeable Cu was increased by 52.6% and 187.1%. Dissolved organic carbon was the limiting factor for the exchangeable Cu while the exchangeable Zn was controlled by soil pH. PBR presented more agricultural risk than CBR when used as fertilizer. Meanwhile, BRs were more adaptable to LS than YS according to the heavy metal release results.     

HN-AD菌生物强化接触氧化工艺处理猪场沼液

针对养猪废水采用传统工艺经厌氧发酵处理后,形成高氨氮低碳氮比沼液,导致脱氮效果差、工艺流程复杂、启动周期较长等问题.本研究以异养硝化-好氧反硝化(HN-AD)菌为生物强化剂,以PAN活性炭纤维作为填料的生物接触氧化池(BCO)为生物膜反应器,形成生物强化BCO工艺处理猪场沼液.前期污泥驯化阶段发现,NH_4~+-N浓度高于500 mg·L~(-1)时,污染物去除率明显降低,经HN-AD菌剂生物强化后,耐受NH_4~+-N浓度可高于600 mg·L~(-1)且能保持污染物的高效去除.采用HN-AD生物强化的BCO工艺处理真实猪场沼液,对NH4+-N、TN和COD的平均去除率分别为86. 9%、70. 5%和74. 4%,分别高于传统处理工艺的57. 6%、50. 3%和50. 0%,出水浓度均低于相关污染物排放标准.采用高通量测序技术研究了功能菌富集过程中微生物群落结构的变化规律,结果表明,生物膜内属于HN-AD菌的优势菌由Alcaligenes这一种菌属增加为生物强化后的Diaphorobacter、Acinetobacter和Thauera等多种菌属,且Acinetobacter菌属的相对丰度明显高于接种菌剂.扫描电子显微镜结果也进一步证实了生物强化的存在,紧密附着在填料上的生物膜层表面富集了以杆状和球状为主的HN-AD功能菌.     

生物沥浸对牛粪沼液脱水性能的影响研究

采用嗜酸性硫杆菌,通过摇瓶试验研究了不同硫杆菌及其复合生物沥浸对含固率为3.4%的沼液脱水性能的影响.设置了如下5个处理：①原始沼液（作对照）;②4 g.L-1 Fe2＋（不接菌）;③2 g.L-1S0＋25 mL A.t;④4 g.L-1Fe2＋＋25 mL A.f;⑤2g.L-1 S0＋4 g.L-1 Fe2＋＋12.5 mL A.t＋12.5 mL A.f.考察了不同的处理生物沥浸过程中的pH、Fe2＋、Fe3＋、总Fe、比阻、毛细吸水时间（CST）、沉降性能及沉降12 h后上清的浊度等的变化.结果表明,原始沼液＋Fe2＋、原始沼液＋Fe2＋＋A.f和原始沼液＋Fe2＋＋S0＋A.f＋A.t这3个处理沼液的比阻和CST都得到了不同程度的降低,综合沼液的脱水性能、沉降性能以及沉降12 h后的上清液浊度,结合经济成本分析,建议选择原始沼液＋Fe2＋＋A.f作为沼液生物沥浸处理比较合理.生物沥浸后沼饼中的有机质、N、P、K的含量分别降低了1.14%、0.09%、0.05%、0.1%,不影响肥效,对沼饼中的重金属Cu、Zn的去除率分别为63.2%和91.3%,同时对沼液中的总大肠杆菌的杀灭率超过了99%.可见,生物沥浸技术为沼液的资源化利用提供了一个全新的途径.     

Characteristics of volatile compounds removal in biogas slurry of pig manure by ozone oxidation and organic solvents extraction

Biogas slurry is not suitable for liquid fertilizer due to its high amounts of volatile materials being of complicated composition and peculiar smell. In order to remove volatiles from biogas slurry efficiently, the dynamic headspace and gas chromatography-mass spectrometry were used to clear the composition of volatiles. Nitrogen stripping and superfluous ozone were also used to remove volatiles from biogas slurry. The results showed that there were 21 kinds of volatile compounds in the biogas slurry, including sulfur compounds, organic amines, benzene, halogen generation of hydrocarbons and alkanes, some of which had strong peculiar smell. The volatile compounds in biogas slurry can be removed with the rate of 53.0% by nitrogen stripping and with rate of 81.7% by the oxidization and stripping of the superfluous ozone. On this basis, the removal rate of the volatile compounds reached 99.2% by chloroform and n-hexane extraction, and almost all of odor was eliminated. The contents of some dissolved organic compounds decreased obviously and however main plant nutrients had no significant change in the biogas slurry after being treated.