Effects of canopy-deposition interaction on H+ supply to soils in Pinus banksiana and Populus tremuloides ecosystems in the Athabasca oil sands region in Alberta, Canada

Soil acidification has been of concern in the oil sands region in Alberta due to increased acid deposition. Using the canopy budget model, and accounting for H⁺ canopy leaching by organic acids, we determined sources and sinks of H⁺ in throughfall in jack pine (Pinus banksiana) and trembling aspen (Populus tremuloides) stands in two watersheds from 2006 to 2009. In pine stands, H⁺ deposition was greater in throughfall than in bulk precipitation while the opposite was true in aspen stands. The annual H⁺ interception deposition was 148.8-193.8 and 49.7-70.0 mol_c ha⁻¹ in pine and aspen stands, respectively; while the annual H⁺ canopy leaching was 127.1-128.7 and 0.0-6.0 mol_c ha⁻¹, respectively. The greater H⁺ supply in pine stands was caused by greater interception deposition of SO₄²⁻ and organic acids released from the pine canopy. Such findings have significant implications for establishing critical loads for various ecosystems in the oil sands region.     

水解酸化-气浮-厌氧-好氧处理苎麻脱胶废水

江西瑞昌某苎麻公司产生大城污染严重的苎麻废水。废水处理规模300m^3／d。采用水解酸化-气浮-厌氧-好氧为主体的处理工艺,出水达到GB8978—96一级排放标准．该工艺具有耐冲击负荷、运行稳定、易于管理和运行费用低等优点。     

Combustion in porous media and its applications – A comprehensive survey

The rapid advances in technology and improved living standard of the society necessitate abundant use of fossil fuels which poses two major challenges to any nation. One is fast depletion of fossil fuel resources; the other is environmental pollution. The porous medium combustion (PMC) has proved to be one of the technically and economically feasible options to tackle the aforesaid problems to a remarkable extent. PMC has interesting advantages compared with free flame combustion due to the higher burning rates, the increased power dynamic range, the extension of the lean flammability limits, and the low emissions of pollutants. This article provides a comprehensive picture of the global scenario of research and developments in PMC and its applications that enable a researcher to decide the direction of further investigation. The works published so far in this area are reviewed, classified according to their objectives and presented in an organized manner with general conclusions. A separate section is devoted for the numerical modeling of PMC.     

餐饮业烟道油垢燃烧特性及动力学模型

利用热重分析仪研究了餐饮业油烟道油垢在不同升温速率下的燃烧特性.所采用的升温速率分别为5℃/min、15℃/min和25℃/min.吹扫气体为干空气,流量为20 mL/min.结果表明,试样从常温至800℃的升温燃烧经历了第1步水分析出、第2～5步燃烧失重过程.采用Doyle和Coats-Redfern方法建立了"4阶段1级反应动力学模型",计算燃烧反应的动力学参数.并用试验热重曲线验证了模型的可靠性.研究表明,油垢燃烧失重的4个主要过程均可用简单反应动力学模型进行简化,反应级数为1;燃烧总趋势是随升温速率提高,活化能增大.     

Two-stage biodegradation coupled with ultrafiltration for treatment of municipal landfill leachate

The municipal landfill leachate was treated in a hydrolysis–acidification reactor (HAR)/aerobic bio-contact oxidation reactor (ABOR) following a pretreatment with ultrafiltration (UF) membrane. Experiments were conducted continuously for 44 days at a constant flow rate of 20 l d⁻¹ and organic loading rates (OLRs) from 0.75 to 1.5 kgCOD m⁻³ per day. The results showed that COD of the leachate steadily decreased from 20,015 mg l⁻¹ to less than 3000 mg l⁻¹, and NH₄-N decreased from 368.6 mg l⁻¹ to 259.3 mg l⁻¹ in the UF process. The COD and NH₄-N removal efficiency of HAR was 56.7% and 27.7%, and that of ABOR was 94.6% and 86.7%, respectively. The total COD and NH₄-N removal efficiency reached 99.6% and 93.2%, respectively. UF and HAR played a critical role in raising the biodegradability of the landfill leachate, while ABOR had an important function on removing the dissolved NH₄-N in leachate.     

Adsorption and transformation of selected human-used macrolide antibacterial agents with iron(III) and manganese(IV) oxides

The adsorption/transformation of two members (clarithromycin and roxithromycin) of the macrolide (ML) antibacterial agents on the surface of three environmental subsurface sorbents (clay, iron(III) and manganese(IV) oxy-hydroxides) was investigated. The adsorption fitted well to the Freundlich model with a high sorption capacity. Adsorption probably occurred through a surface complexation mechanism and was accompanied by slow degradation of the selected MLs. Transformation proceeded through two parallel pathways: a major pathway was the hydrolysis of the cladinose sugar, and to a lesser extent the hydrolysis of the lactone ring. A minor pathway was the N-dealkylation of the amino sugar. This study indicates that Fe(III) and Mn(IV) oxy-hydroxides in aquatic sediments may play an important role in the natural attenuation of MLs. Such an attenuation route yields a range of intermediates that might retain some of their biological activity.     

光电芬顿氧化法深度处理垃圾渗滤液研究

采用光电芬顿氧化法对北京市某垃圾填埋场已经生化处理后的垃圾渗滤液进行深度处理,分别考察了电流强度和铁的不同价态等因素对渗滤液总有机碳（TOC）、化学需氧量（COD）以及色度去除效果的影响,并对阳极氧化、电芬顿和光电芬顿不同反应过程进行了对比。通过分析渗滤液UV-Vis光谱(200～500 nm)变化和渗滤液中有机污染物的分子量变化,发现光电芬顿反应可以明显改善渗滤液生化性。深入研究了反应过程中铁价态的变化规律。试验结果发现,以高比表面积的活性炭纤维(ACF)为阴极的光电芬顿反应可以有效降解垃圾渗滤液,在pH为3,Fe²⁺ 浓度为1 mmol/L,电流为0.5 A,O₂通入量为250 mL/min条件下降解360 min,垃圾渗滤液TOC和COD去除率分别达到78.9%和62.8%,色度完全去除。     

活性污泥总DNA提取方法的比较

从处理某制药废水的MBR反应器中采集活性污泥,评价不同DNA提取方法对其总DNA提取效率的影响。DNA提取分细胞裂解和DNA纯化2步,对细胞裂解比较了珠磨匀浆法、反复冻融法、十二烷基磺酸钠（sodium dodecyl sulfate,SDS）裂解法等7种方法;对DNA纯化比较了酚/氯仿纯化法和胶回收纯化法。结果表明,SDS裂解法、酚氯仿纯化法最优。通过条件优化实验,确定SDS裂解酚/氯仿纯化法在污泥量1.1 g,10 000 r/min离心5 min的操作条件下,获得的DNA产量（10 774 μg/g泥重）和纯度（OD₂₆₀∶OD₂₈₀=1.84）等综合指标最好。     

微波强化氧化处理垃圾渗滤液工艺研究

考察了最优作用方式下单独微波、单独氧化剂以及两者的结合工艺对垃圾渗滤液的处理效果。单独微波工艺在功率为700 W,辐射10 min,COD、氨氮、磷和色度去除率分别为37.66%、96.14%、40%和80%,BOD5/COD由0.16增加到0.43。渗滤液先微波再氧化,氨氮去除率增加显著,节省了氧化剂用量。微波后渗滤液在pH=5,T=50℃,NaClO=24 mL/L时COD、氨氮、磷和色度去除率分别为98.63%、99.67%、97.25%和98%,BOD5/COD=0.8。总处理效率:微波-NaClO微波-Fenton微波-KMnO4微波-H2O2,微波-Fenton处理效率低于微波-NaClO主要取决微波后滤液中小表观分子质量增加导致氧化剂的混凝作用减弱,其次受反应后pH值变化的影响。     

Fe/C内电解法处理二硝基重氮酚废水实验研究

采用Fe/C内电解法处理DDNP废水,研究了该方法在酸性和碱性条件下对DDNP废水的处理效果,并考察了pH值、反应时间及铁碳比对处理效果的影响。结果表明:Fe/C内电解法可有效去除DDNP废水中由硝基苯类物质引起的COD、S2-、SS和色度,在最佳酸性实验条件下,COD、S2-、SS和色度的去除率分别为85.65%、91.6%、100%和99.63%。在最佳碱性实验条件下,COD、S2-、SS和色度的去除率分别为90.13%、99.73%、100%和99.63%。