复合填料土壤渗滤系统处理农村生活污水的效果

为了加强农村生活污水综合治理,本研究以农村生活污水为研究对象,选择了以粉煤灰和腐熟牛粪作为填料配合土壤的2套不同装填方式的土壤渗滤系统,分别用于去除污水中的COD、总磷、总氮和氨氮。系统1对COD、总磷、总氮和氨氮的平均去除率分别为85.8%、98.1%、78.4%和93.7%,系统2的去除率分别为87.1%、96.0%、73.4%和95.5%。结果表明,两系统对污水中的污染物均有较好的去除效果。通过方差分析比较两系统的去除效果发现,装填方式对COD去除效果影响不大,而对总磷、总氮和氨氮的去除效果差异显著。但从污水处理效果综合比较,以分层装填方式的系统1对污染物的去除效果优于全混合装填方式的系统2。     

气田高浓度含硫废水的化学氧化处理

采用亚硫酸钠(Na2SO3)氧化法对气田高含硫废水进行了实验研究。考察了硫化物初始浓度、Na2SO3/Na2S(摩尔比)、初始pH值和反应时间对Na2SO3氧化去除硫化物效果的影响,进行了对氧化产物的元素分析。结果表明,在Na2SO3/Na2S(摩尔比)为0.7、初始pH值为5和反应时间为5 min时,硫化物从1 100 mg/L降至1.80 mg/L,去除率高达99.84%,达到了气田回注水水质标准。元素分析发现,氧化产物中C、N、S、H和O元素的含量分别为0.11%、0.06%、98.73%、0.90%和1.10%,且其产率达到90.59%。     

Greenhouse gas emissions from dairy open lot and manure stockpile in northern China: A case study

The open lots and manure stockpiles of dairy farm are major sources of greenhouse gas (GHG) emissions in typical dairy cow housing and manure management system in China. GHG (CO₂, CH₄ and N₂O) emissions from the ground level of brick-paved open lots and uncovered manure stockpiles were estimated according to the field measurements of a typical dairy farm in Beijing by closed chambers in four consecutive seasons. Location variation and manure removal strategy impacts were assessed on GHG emissions from the open lots. Estimated CO₂, CH₄ and N₂O emissions from the ground level of the open lots were 137.5±64.7 kg hd^-1 yr^-1, 0.45±0.21 kg hd^-1 yr^-1 and 0.13±0.08 kg hd^-1 yr^-1, respectively. There were remarkable location variations of GHG emissions from different zones (cubicle zone vs. aisle zone) of the open lot. However, the emissions from the whole open lot were less affected by the locations. After manure removal, lower CH₄ but higher N₂O emitted from the open lot. Estimated CO₂, CH₄ and N₂O emissions from stockpile with a stacking height of 55±12 cm were 858.9±375.8 kg hd^-1 yr^-1, 8.5±5.4 kg hd^-1 yr^-1 and 2.3±1.1 kg hd^-1 yr^-1, respectively. In situ storage duration, which estimated by manure volatile solid contents (VS), would affect GHG emissions from stockpiles. Much higher N₂O was emitted from stockpiles in summer due to longer manure storage.

Implications: This study deals with greenhouse gas (GHG) emissions from open lots and stockpiles. It’s an increasing area of concern in some livestock producing countries. The Intergovernmental Panel on Climate Change (IPCC) methodology is commonly used for estimation of national GHG emission inventories. There is a shortage of on-farm information to evaluate the accuracy of these equations and default emission factors. This work provides valuable information for improving accounting practices within China or for similar manure management practice in other countries.     

Source,distribution, and health risk assessment of polycyclic aromatic hydrocarbons in urban street dust from Tianjin,China

To better assess and understand potential health risk of urban residents exposed to urban street dust, the total concentration, sources, and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in 87 urban street dust samples from Tianjin as a Chinese megacity that has undergone rapid urbanization were investigated. In the meantime, potential sources of PAHs were identified using the principal component analysis (PCA), and the risk of residents’ exposure to PAHs via urban street dust was calculated using the Incremental Lifetime Cancer Risk (ILCR) model. The results showed that the total PAHs (∑PAHs) in urban street dust from Tianjin ranged from 538 μg kg^?1 to 34.3 mg kg^?1, averaging 7.99 mg kg^?1. According to PCA, the two to three- and four to six-ring PAHs contributed 10.3 and 89.7 % of ∑PAHs, respectively. The ratio of the sum of major combustion specific compounds (ΣCOMB)?/?∑PAHs varied from 0.57 to 0.79, averaging 0.64. The ratio of Ant/(Ant?+?Phe) varied from 0.05 to 0.41, averaging 0.10; Fla/(Fla?+?Pyr) from 0.40 to 0.68, averaging 0.60; BaA/(BaA?+?Chry) from 0.29 to 0.51, averaging 0.38; and IcdP/(IcdP?+?BghiP) from 0.07 to 0.37, averaging 0.22. The biomass combustion, coal combustion, and traffic emission were the main sources of PAHs in urban street dust with the similar proportion. According to the ILCR model, the total cancer risk for children and adults was up to 2.55?×?10^?5 and 9.33?×?10^?5, respectively.     

类氧化硅气凝胶吸附材料的制备及其吸附性能

以有机硅高沸物和Na₂SiO₃·9H₂O为原料,采用溶胶-凝胶法制备出疏水性的类氧化硅气凝胶吸附材料。采用透射电子显微镜、傅里叶变换红外分析仪和比表面与空隙度分析仪对该吸附材料的结构进行表征。表征结果显示,该吸附材料呈海绵状多孔结构,比表面积为294.48 m²/g,孔径分布较宽（为2 ~140 nm）,平均孔径为8.95 nm。实验结果表明：采用该吸附材料常温下静态吸附处理质量浓度为10 mg/L的罗丹明B（RhB）溶液,在类氧化硅气凝胶吸附材料加入量50 g/L、静态吸附时间5 h的最佳静态吸附工艺条件下,RhB去除率为98.8%,吸附后RhB质量浓度为0.124 mg/L;采用该吸附材料常温下动态吸附处理质量浓度为15 mg/L的RhB溶液,吸附4 h后开始穿透,吸附7 h后完全穿透。穿透时间较长,表明该吸附材料具有较大的吸附容量。     

磺胺和四环素类抗生素对活性污泥性能的影响

废水处理工艺中抗生素类污染物的存在可能会对生物处理过程产生长期而深远的影响,为探明此类污染物对废水生物处理主体活性污泥性能等方面的影响,采用间歇培养法研究了活性污泥法处理污水时,抗生素类污染物的存在对活性污泥性能如胞外聚合物（EPS）、污染物处理能力、脱氢酶活性和群落结构的影响。结果表明,抗生素的存在会导致活性污泥的胞外聚合物总量及其主要组分蛋白质和多糖增加,以产生保护屏障;且由于污泥絮体解体,细胞破裂导致EPS中DNA和色氨酸含量增加。同时,由于蛋白质大量增加引起的表面负电荷的增加,使污泥疏水性增强,絮凝性能恶化;污泥絮体解体导致污泥颗粒变小,SVI也随之下降;在活性污泥脱氢酶活性急剧下降的同时,出水TOC迅速升高。此外,抗生素类污染物在抑制活性污泥中大部分细菌的同时,对部分菌群也有刺激生长作用,最终导致活性污泥生物群落结构的改变。四环素类抗生素对活性污泥的EPS和絮凝沉降性能的影响大于磺胺类,而对污水处理能力和群落结构的影响则不如磺胺类。抗生素类污染物的长期存在会对活性污泥沉降性能、絮凝性能、脱氢酶活性以及活性污泥群落结构等产生一系列负面影响,进而影响污染物去除效果,导致出水水质恶化。     

不同挂膜方式生物滴滤塔处理含H2S恶臭气体

采用菌剂挂膜,活性污泥挂膜和自然挂膜3种不同方式形成生物滴滤塔,考察挂膜方式对生物滴滤塔去除H2s恶臭气体的影响。结果表明,当进气H2S浓度为5mg／m3时,菌剂挂膜、活性污泥挂膜、自然挂膜形成的生物滴滤塔出气H2s浓度分别为15．7～17．4、11．6～14．8和15．0～15．9μg／m3;塔内压降分别为3—4mm水柱、6mm水柱和4—5mm水柱;喷淋后滤出液中硫酸根的浓度分别为14、22和17mg／L,硫的转化率分别为45％、60％和50％。当进气H2S浓度增大至7mg／m3时,3个塔经过7d的调整后,均能达到稳定状态,稳定后3个塔中出气H2s浓度和压降基本没变,喷淋后滤出液中硫酸根浓度依次增大至25、31和30mg／L左右。采用活性污泥挂膜形成的生物滴滤塔处理H2s的能力比菌剂挂膜和自然挂膜的高。     

亚硝态氮对同时产甲烷反硝化工艺处理畜禽粪水的影响

为进一步提高同时产甲烷反硝化反应对畜禽粪水化学需氧量(COD)和氮的去除效率,应用畜禽粪水于接种颗粒污泥的厌氧混合式反应器,进行不同COD与亚硝态氮浓度比值(COD/NO-2-N)对同时产甲烷反硝化反应的影响研究。通过实时监测反应器内COD、凯氏氮(TKN)、辅酶F420、β-葡萄糖苷酶、产气率、pH和氧化还原电位(ORP)等指标得出,COD/NO-2-N为30/1、40/1时,COD去除率、辅酶F420和β-葡萄糖苷酶含量与空白无亚硝态氮的变化规律一致,亚硝态氮几乎未对糖类水解菌及产甲烷菌活性产生抑制作用;而COD/NO-2-N为10/1、20/1时,COD去除率、辅酶F420和β-葡萄糖苷酶含量较低,糖类水解菌及产甲烷菌活性受到抑制。     

稻壳生物质炭对水中氨氮的吸附

以稻壳生物质为原材料,在350℃和500℃2种温度条件下制备生物质炭(BC350和BC500),采用扫面电镜(SEM)和红外光谱(FTIR)对稻壳生物质炭进行了表征。通过实验考查了稻壳生物质炭对氨氮的吸附等温线、影响因素和动态吸附。结果表明,稻壳生物质炭的平衡吸附量随着平衡浓度的增大而增大后趋缓,Langmuir方程比Freundlich方程更好地描述稻壳生物质炭吸附氨氮的行为,BC500比BC350具有更大的吸附氨氮的能力,其最大吸附量分别为5.82 mg/g和6.51 mg/g。p H和离子强度影响BC500对氨氮的吸附效果。动态吸附实验表明,BC500对氨氮的平均吸附量为1.78 mg/g。可见,稻壳生物质炭可以用作高效吸附剂去除废水中的氨氮。     

改进碳纳米管/聚氨酯复合材料吸附硝基苯

以酸化碳纳米管(CNTs)强化聚氨酯泡沫(PUF),通过原位聚合法制备碳纳米管/聚氨酯复合材料(CPUF)。借助红外光谱(FT-IR)、扫描电镜(SEM)、热失重分析(TGA)和力学性能测试等方法研究和表征了CPUF复合材料的性能和结构。研究了用CPUF复合材料对人工模拟废水中硝基苯(NB)的吸附性能、影响因素及其再生后吸附效果。结果表明,CPUF复合材料对硝基苯具有较强的吸附能力,在p H=5.4、投加量为2 g/L、接触时间24 h的条件下,升高温度会降低CPUF复合材料的饱和吸附量,但会提高初始吸附速率,等温吸附过程符合Langmuir方程,属于单分子吸附。饱和后的复合材料可采用简单热再生,再生后对NB的吸附能力没有明显下降。