Growth and Foliar Nitrogen Status of Four Plant Species Exposed to Atmospheric Ammonia

A chamber study was conducted to evaluate the growth response and leaf nitrogen (N) status of four plant species exposed to continuous ammonia (NH₃) for 12 weeks (wk). This was intended to evaluate appropriate plant species that could be used to trap discharged NH₃ from the exhaust fans in poultry feeding operations before moving off-site. Two hundred and forty bare-root plants of four species (Juniperus virginiana (red cedar), Gleditsia triacanthos var. inermis (thornless honey locust), Populus sp. (hybrid poplar), and Phalaris arundinacea (reed canary grass) were transplanted into 4- or 8-L polyethylene pots and grown in four environmentally controlled chambers. Plants placed in two of the four chambers received continuous exposure to anhydrous NH₃ at 4 to 5 ppm while plants in another two chambers received no NH₃. In each of the four chambers, 2 to 4 plants per species received no fertilizer while the rest of the plants were fertilized with a 100 ppm solution containing 21% N, 7% phosphorus, and 7% potassium. The results showed that honey locust was the fastest-growing species. The superior growth of honey locust among all species was also supported by its total biomass, root, and root dry matter (DM) weights. For all species there was a trend for plants exposed to NH₃ to have greater leaf DM than their non-exposed counterparts at 6 (43.0 vs. 30.8%; P = 0.09) and 12 wk (47.9 vs. 36.6%; P = 0.07), and significantly greater (P ≤ 0.05) leaf N content at 6 (6.44 vs. 3.67%) and 12 wk (7.05 vs. 3.51%) when exposed to NH₃. Numerically greater leaf DM due to NH₃ exposure was also consistently measured in poplar at both sampling periods. Hybrid poplar, as well as honey locust and reed canary grass, deposited 1.5 to 2-fold greater N in their leaves than red cedar tissues as a result of NH₃ exposure compared to non-exposed plants. Regardless of the effect of NH₃ on foliar color and damage score of the plants, the increase of foliar N content (g 100 g^?1 of fresh foliage weight) after NH₃ exposure at 6 and 12 wk was 0.45 and 0.87 for grass,1.25 and 1.34 for locust, and 2.67 and 6.09 for poplar. However, only honey locust likely benefited from ambient NH₃ as indicated by its consistent leaf color quality and lower damage score, compared with other species that were adversely affected by atmospheric NH₃.     

响应面分析法优化稀土废水MAP沉淀法脱氮

经过预处理后的稀土生产废水，其氨氮浓度大幅降低，但并未达到中华人民共和国《稀土工业污染物排放标准》（GB26451-2011）中氨氮浓度限值。实验通过响应面分析法中的Box-Behnken实验设计（BBD），取pH、n（Mg）：n（N）、n（P）：n（N）3因素，采用Design-Expert 8.0.6，建立合适的剩余氨氮浓度及剩余总磷浓度模型，得到回归方程，并分析模型各项指标，各因素及其相互作用对剩余氨氮浓度及剩余总磷浓度的影响。利用预测模型预测最佳实验条件，在最佳实验条件下验证预测结果，并对沉淀物进行X射线衍射（XRD）分析。结果显示，二次响应模型适用于剩余氨氮浓度及剩余总磷浓度，2个模型均拥有较好的拟合程度、可信度及精密度，最优反应条件为：pH=9.88、n（Mg）：n（N）=1.50：1、n（P）：n（N）=1.38：1时，剩余氨氮浓度为46.58 mg/L，剩余总磷浓度为7.85 mg/L。在最优条件下所得到的沉淀物并非纯净的MgNH₄PO₄·6H₂O，还有Mg₃（PO₄）₂·22H₂O生成。     

Fenton试剂氧化法处理染料结晶废母液

采用Fenton试剂氧化法处理分散橙、分散紫和分散蓝3种染料结晶废母液。研究了H₂O₂加入量、n（H₂O₂）#x02236;n（Fe²⁺）和废母液pH对COD去除率或TOC去除率的影响。对TOC去除反应分段进行了动力学方程拟合，并探讨了反应机理。实验得到的分散橙、分散紫和分散蓝的废母液处理工艺条件：H₂O₂加入量分别为264.4，352.9，441.2mmol/L；n（H₂O₂）#x02236;n（Fe²⁺）分别为20，10，20；废母液pH=3。3种废母液在0~20min和20~120min两个阶段的反应与二级动力学拟合方程的相关性最好。3种废母液经Fenton试剂氧化处理后，部分有机物降解为小分子有机酸，部分有机物完全矿化。     

Ru/γ-Al_2O_3和Ru/AC催化剂的制备及其对氨氧化反应的催化性能

分别以γ-Al_2O_3和活性炭(AC)为载体,采用浸渍法制备了Ru质量分数均为2.0%的Ru/γ-Al_2O_3和Ru/AC催化剂,并用X射线衍射仪和透射电子显微镜等方法对催化剂结构进行了表征.实验结果表明:Ru/AC中Ru沉积在AC表面,分散度较低;而Ru/γ-Al_2O_3中Ru进入到γ-Al_2O_3内部,形成了一种高度分散体系.Ru/γ-Al_2O_3对氨的催化活性高于Ru/AC,氨在Ru/γ-Al_2O_3和Ru/AC上的起活温度分别为200 ℃和266 ℃,T_(90)(氨去除率达90%时的反应温度)分别为267℃和320 ℃.随混合气体空速增大,Ru/γ-Al_2O_3催化剂的T_(90)逐渐升高,气体空速分别为3 600,4 800,5 400 h~(-1)时,T_(90)分别为235,266,303 ℃.随反应前混合气体中氨质量分数增加,氨的去除率降低.     

稻草制浆黑液生物＋混凝处理试验

通过对稻草制浆黑液厌氧、好氧、混凝处理组合工艺的试验研究，探索该工艺的可行性，考察了不同温度、不同有机负荷下，该类废水的生物处理效果以及后续混凝效果。结果表明：中温35℃是厌氧阶段最佳处理温度，好氧阶段不同负荷条件下，CODCr去除率基本相同；经厌氧－好氧处理，黑液CODCr和木质素去除率分别为80％和30％，色度去除不明显；混凝阶段CODCr和木质素去除率分别为70％和90％，色度去除率达90％以上，出水达到国家标准。     

沸石联合微生物固定化去除微污染水体中氨氮的研究

将沸石联合经过驯化的活性污泥微生物固定化,通过静态实验.考察了不同粒径沸石及不同组分固定化方法对沸石联合微生物固定化去除氨氮的影响;通过动态实验,考察了沸石联合微生物固定化去除微污染水体中低浓度氨氮的机制.结果表明,活性污泥经过16 d的驯化,氨氮去除率为90%以上;沸石吸附氨氮为快速吸附,粒径<0.5 mm的沸石的吸附容量明显大于其他粒径的沸石;不同组分固定化小球对氨氮的去除效率不同,各组分均有贡献,吸附容量依次为:沸石固定化小球>沸石联合微生物固定化小球>微生物固定化小球;沸石联合微生物固定化去除微污染水体中低浓度氨氮可分为4个阶段,即沸石吸附阶段、吸附饱和及微生物适应阶段、硝化作用明显加强和沸石部分再生阶段、微生物作用良好和沸石进一步再生阶段,最终沸石吸附与生物再生处于良好的动态平衡中,氨氮去除率达到60%左右.     

氨水土壤混合物脱除CO2温室气体的实验研究

为了脱除CO2温室气体,提出了利用氨水土壤混合物去除CO2的新方法。分别考察了土壤颗粒粒径、CO2初始流量、氨水浓度（质量比）和温度对CO2脱除量和脱除率的影响。实验结果表明,该方法去除CO2的量较土壤物理吸附量和氨水化学吸收量的总和提高了大约15%;随着氨水浓度的增大,CO2的脱除率和脱除量都增大;随着土壤颗粒粒径和CO2初始流量的增大,CO2的脱除率和脱除量都减小;当温度由22℃升高到31℃,CO2的脱除率随着温度的升高而增大,但是继续升高温度到40℃,CO2的脱除率反而下降。     

Ammonia volatilization and availability of Cu, Zn induced by applications of urea with and without coating in soils

Ammonia volatilization and the distribution of Cu and Zn were investigated in two types of soil treated with coated and uncoated urea. The rate of ammonia volatilization in two weeks after fertilizing with coated urea was 8% in soil 1 (soil derived from river alluvial deposits in Dongting Lake Plain) and 5.15% in soil 2 (red soil derived from quaternary red clay), about half the rates observed when fertilizing with common urea, implying that the hydrolysis speed of the coated urea was lower than for common urea, and that the coated urea can increase nitrogen use efficacy. As for the availability of Cu and Zn, their concentrations decreased in the first week after fertilization, and then increased, which was contrary to the effect of treatment on soil pH. For example, when the pH was 7.99, there was 0.79 mg/kg exchangeable Cu and 0.85 mg/kg exchangeable Zn in the soil derived from river alluvial deposits in Dongting Lake Plain. However, the concentrations of exchangeable Cu and Zn were generally lower for the common urea treatments than those with the coated urea because the peak pH for the common urea treatment was greater. The concentrations of these elements correlated well with pH in the range 4-8 in second order polynomial fits.     

粉煤灰基质滤料生物过滤处理生活污水研究

将粉煤灰基质滤料用于曝气生物滤池,该滤料具有较高的比表面积和孔隙率,吸附性能良好,挂膜后生物相丰富。对于中等浓度的生活污水,当水力负荷和COD有机物负荷分别控制在1.53 m3/(m2.h)、3.68 kg/(m3.d)以下时,该曝气生物滤池COD和NH3-N去除率能稳定在85%以上,出水COD和NH3-N达到排放标准要求。该曝气生物滤池对进水水质水量的变动具有较强的抗冲击负荷能力。     

改进测定水中氨氮分子吸收光谱法的试验研究

水中氨氮含量是反应水质状况的重要指标。文章对测定水中氨氮气相分子吸收光谱法(标准号HJ/T195-2005)进行了改进试验研究。第一,对氧化剂的配比进行了改进,使氨氮的测定范围扩展至100μg。第二,对标准HJ/T195-2005中直接使用亚硝酸钠标准溶液做标准曲线的处理方式也做了探讨。通过一系列对比实验认为,应用硫酸铵标准溶液做工作曲线更加准确合理。最后应用改进后的气相分子吸收光谱法和纳氏比色法或滴定法对多种实际废水样品进行同时测定。结果表明,改进后的气相分子吸收光谱法测定氨氮的范围更宽,灵敏度更高和准确度更好。