固定床厌氧反应器处理高浓度禽畜粪尿

为开展高效厌氧生物技术处理家禽粪便的应用研究,试验依据固定床厌氧反应器(anaerobic pecked bed reac-tor)的特点,设计了一个有效容积为20 L的高效厌氧反应器,以猪粪尿为发酵原料,进水COD浓度范围在4 820~54 000mg/L,实验过程为55 d。按进料的水力停留时间可将实验划分为2个阶段:前期(44 d)和后期(11 d),前期通过提高进料浓度直接提高反应器处理浓度,水力停留时间保持为2 d,每7~8 d为一个周期;后期通过缩短水力停留时间间接提高反应器处理浓度,进料浓度保持不变,每2~3 d为一个周期。通过对厌氧处理系统运行过程中COD、pH、挥发性成分、TN、TP和NH3-N含量的测定,分析了该系统运行特点。结果表明:在发酵的第1~55 d,整个厌氧处理系统能够稳定运行,COD去除率稳定在67%~88%之间;对TN、TP、NH3-N都有很好的去除能力。     

退耕还林:农户、地方政府与中央政府的博弈关系

自退耕还林工程实施以来,该工程进展顺利,并取得了显著的成绩.但随着财政补贴陆续到期,却未能解决退耕还林农户的长远生计问题.从博弈论的视角探讨退耕还林实施中的行为主体关系有利于该工程成果的巩固和工程的持续推进.文章首先评述退耕还林的相关文献,然后,用动态博弈模型分析农户与政府以及中央政府与地方政府的利益互动关系.文章得出的关键结论有:在贴现因子足够大的条件下任何短期的机会主义行为所带来的收益都小于长期合作所带来的长远收益,农户和政府采取长期合作是理性的选择行为;在中央政府先行动的情况下,地方政府实施退耕还林工程所带来的收益要大于中央政府后行动所带来的收益.基于上述结论,文章提出要确保国家政策的稳定性从而提高政府的信誉度、永久性地对退耕还林农户发放财政补贴、提高农户的贴现值从而稳定其预期、确保地方政府执行退耕还林工程的收益等政策建议.     

华山观风电场风能资源评价

利用华山观风电场40 m测风塔2005年4月至2008年3月的测风资料,计算了平均风速、风速频率、风向频率、各方向风能、风功率密度及有效风速时数等各项风能参数,依据国标《风电场风能资源评估方法》（GB/T 18710-2002）中风功率密度等级划分标准对风电场的风能资源进行了评价,并利用距风电场最近的钟祥气象站的累年及同期气象资料,对测风期间的测风背景进行了分析。结果表明：风电场各高度年平均风速在55～57 m/s,年平均风功率密度在190～205 W/m2,年有效风速百分率在808%～823%;华山观主导风向与次多风向完全相反,不同高度两个方向合计频率在449%～505%;各风向风能分布比风向频率更加集中,不同高度主导风向的能量占478%～606%;风功率密度接近3级,具有一定开发利用价值,技术可开发量约3万kW;华山观风电场测风是在年平均风速小于多年平均风速的气候背景下进行的。     

Presence of PAHs in milk of industrial farms from Tizayuca,Hidalgo, Mexico

The objective of this study was to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) in cow's milk from industrial farms that are located near an industrial park in Hidalgo, Mexico. It was found that the concentrations of PAHs in the raw milk of cattle from industrial farms have increased in recent years. Composite samples were collected between 2008 and 2010 and analysis carried out according to 8100 EPA procedures and analyzed by gas chromatography with FID detection. The results show that combustion PAHs were mostly Ace, Acy, and Fla (0.25, 0.32, and 0.22 µg g^?1, respectively). Diagnostic ratios were used to show that the probable sources were grass and fuel combustion. The sum of concentrations of 16 individual PAHs did not breach permissible levels in milk (25 µg g^?1 according to the United States EPA), indicating a limited health risk to animals and humans in the study area. The industrial park has adequate pollutant emission regulations.     

Development of a prefabricated treatment plant for diluted pig wastewater

Abstract

In order to develop a prefabricated treatment and reuse plant for diluted pig wastewater, an entrapped‐mixed‐microbial‐cell (EMMC) process was evaluated for its process performance and economic analysis. At the hydraulic retention time (HRT) of 30 hrs (loading rate of 1.0 g TCOD/L/d) and intermittent aeration of 1 hr of aeration and 1 hr of non‐aeration, it was found that, by using the pretreatment of the ammonium crystallization, both the medium and large carriers were able to reduce TCOD, SCOD, and T‐N by 83.51, 84.11, and 95.10%, respectively. The EMMC unit and lime post‐treatment followed by ammonium crystallization can reduce BOD₅, TCOD, SCOD, TSS, T‐N, and T‐P, respectively by 99.22, 93.85, 92.67, 97.73, 96.43, and 97.27%. The treated wastewater, after disinfection, is able to meet the requirements of the standards issued by the USEPA for reuse of food crops. The economic analysis indicates that based on the process performance of the EMMC unit, a prefabricated wastewater treatment plant for 2000 pigs has comparable net present worth (NPW) comparing intermittent aerated biological systems and less operation and maintenance and land requirement than conventional biological processes for removal carbon and nitrogen. A farm operation of more than 2000 pigs meets the unit cost of US$4.91/pig/yr. This will minimize the problems pertaining to technical factors or considerations that heavily influence planning, construction and operation of a pig wastewater treatment system.     

试论原油罐区环境影响评价中的工程分析 ──以长庆石化分公司原油罐区建设项目为例

原油罐区环境影响评价中的工程分析必须深入、准确。文章总结了该类项目环境影响评价工作中工程分析的要点,并通过长庆石化分公司原油罐区工程实例加以实证说明,对该类项目环境影响评价工作有一定的指导作用。     

Effect of high-voltage direct current link on small signal stability of a power system with different penetration level of doubly fed induction generator and direct drive synchronous generator based wind farms

High penetration level of wind power has significant impact on the dynamic performance of power system. Power system with existing high-voltage direct current (HVDC) link may influence the stability of power system at high penetration level of wind power. This article investigates the stability issues of power system with existing HVDC link for different penetration level of doubly fed induction generator (DFIG) and direct drive synchronous generator (DDSG) based wind farms. The small signal stability analysis shows that power system with HVDC link has improved the stability of the power system for increased penetration of DFIG- and DDSG-based wind farms.     

Contribution of additives Cu to its accumulation in pig feces： study in Beijing and Fuxin of China

Massive amounts of pig manure are produced by intensive pig farm in China, and the composition of pig manure has changed much due to the use of feed additives. However, little is known about the exact Cu （copper） feed as additives or present as contaminants in pig feed and the residues in feces. One hundred and thirty-seven feeds and one hundred and forty-two fecal samples from 48 pig farms were collected in Beijing and Fuxin cities in 1999 and 2005, respectively. The concentrations of Cu were in the range of 6.86-395.19 mg/kg in the feed samples, and the mean values were in the order of weaner〉 grower-finisher〉 sow＇s feeds. The high concentrations over EU recommendations implied that excessive levels of Cu are fed on many pig farms in Beijing and Fuxin. Cu was also present in high concentrations in feces, and concentrations were highly variable. Cu concentrations in the feces from grower-finisher and weaner pigs were significantly greater than feces of sows. The super-intensive and small-scale farms had higher levels of Cu in feces than the middle farms. Cu concentrations in pig feces were approximately 5-times greater than in pig feeds. Feed management in grower-finisher pigs on super-intensive and small-scale pig farms is needed to reduce high Cu concentrations in feces and risks to soil contamination while feces are land-applied.     

Shifting paths to conservation: policy change discourses and the 2008 US farm bill

From 2004 until 2006, reform of US agricultural subsidy programmes seemed a likely result of pressure from the World Trade Organization. Many groups saw this pressure as an opportunity to ‘green’ farm policy by crafting environmental service payments that could replace crop subsidies. Yet the 2008 US farm bill fell short of such drastic changes. This paper uses discourse analysis to trace the decline of prospects for reform of the farm bill, and a shift to incremental policy making between 2006 and 2008. It finds that, in addition to political and situational factors, striking discursive shifts altered policy debates and outcomes to create particular conservation impacts. It thus argues for broader use of rhetoric theory and discourse analysis to assess environmental policy. Implications for land conservation are presented in the context of interest group tactics.     

重金属Zn对猪粪堆肥过程中微生物群落的影响

利用Biolog微平板技术,对不同浓度重金属Zn影响下堆料微生物群落多样性进行了研究.结果表明,较低浓度Zn处理（Zn含量分别为0mg.kg-1,300mg.kg-1,600mg.kg-1,900mg.kg-1）的堆料升温快,在高温期持续时间长,并达到无害化处理,堆料微生物中起分异作用的碳源主要为多聚物类和糖类.重金属...