高铝粉煤灰提取氧化铝后硅钙渣用作水泥混合材

为了使高铝粉煤灰提取氧化铝后所产生的硅钙渣被大量的用作水泥混合材,通过水泥强度、水化放热和干缩性实验研究了原状硅钙渣和脱碱硅钙渣对水泥强度和稳定性的影响。结果表明,当硅钙渣掺量达30%时,硅钙渣水泥强度仍可满足P·C 32.5水泥要求。且随硅钙渣掺入量的增加,水泥早期水化放热速率增加的同时水泥累计水化放热量和干缩率还会显著降低。与原状硅钙渣相比,在同等掺量的情况下,脱碱硅钙渣更有利于保持水泥强度,降低其水化热和改善干缩性。     

US-UV-Fenton降解硝基苯

采用超声波(US)、紫外光(UV)和Fenton联合降解硝基苯,初步探讨了其作用规律。研究结果表明,UV可以促进双氧水转化自由基的效率,而US同时具有强化传质作用和超声氧化作用,两者均能够强化Fenton氧化硝基苯的降解过程。正交实验结果表明,H2O2初始浓度是硝基苯降解和矿化的最显著影响因素,反应时间和超声功率是矿化的显著影响因素。最佳反应条件为:H2O2500 mg/L、Fe2+10 mg/L、反应时间60 min、超声波功率100 W,此时,硝基苯完全降解,TOC去除率达到73.0%。Fenton、UV/Fenton和US/UV/Fenton降解硝基苯过程均符合伪一级反应动力学模式,反应速率常数分别为3.37×10-2、3.81×10-2和5.10×10-2min-1。     

柴油低温临界吸收法回收装车挥发油气

研究了采用柴油低温临界吸收法回收装车挥发油气的效果。实验结果表明：按装车挥发油气中的总烃体积分数为20.88%、装车挥发油气流量为280 m³/h、年运行时间为2 668 h计,装置年回收油气量为291 t,装置年最大运行功率为206.770 MW,装置投资回收期为3 a;处理后净化气中的总烃体积分数为1.24%,排放质量浓度低于25 g/m³,油气回收率达95%。处理后净化气满足GB 20950—2007《储油库大气污染物排放标准》,取得了较好的环保效益和经济效益。     

改性活性炭对水中铬离子(Ⅵ)的吸附性能

为了研究改性前后活性炭对水中铬离子(Ⅵ)的吸附效果,以磷酸活性炭(PAC)为原料,用10%硝酸改性得到硝酸改性活性炭(N-PAC)及直接蒸发法载铁改性得到载铁活性炭(Fe-PAC)。通过静态吸附研究表明,改性后活性炭对Cr(Ⅵ)的吸附率有较大提高。在常温、自然pH条件下,0.2 g活性炭处理50 mL浓度为100 mg/L的含Cr(Ⅵ)溶液,N-PAC和Fe-PAC对Cr(Ⅵ)的吸附率分别为79.21%和90.59%,都高于原PAC对Cr(Ⅵ)的吸附率49.58%。pH从2.2升高到11.92,Fe-PAC对Cr(Ⅵ)的吸附率从99.86%降低到14.77%,N-PAC则从99.86%降低到3.23%,PAC从97.05%降低到2.53%。温度从25℃升高到70℃,3种活性炭对Cr(Ⅵ)吸附率都有较大提高,都增加到98%以上。且吸附过程较符合Langmuir等温吸附模型。     

膜吸收法净化低浓度甲醛和氨气简

基于膜吸收技术自制双层平板式膜吸收器,搭建净化低浓度甲醛和氨气污染模拟系统,考察不同膜结构参数、进气流量、吸收剂流量等因素对其净化效果的影响。结果表明,聚偏氟乙烯PVDF对低浓度甲醛和氨气的净化效率高于聚四氟乙烯PTFE。对同一材质膜,随着膜孔隙率的增大,甲醛和氨气的净化率呈上升趋势。随着进气流量的增加,甲醛和氨气的净化效率降低;而吸收剂流量对其净化效率影响不大。对于所有实验条件,平均膜孔径为0.22 μm的PVDF 4^#在进气流量u_g=120 L/h时,甲醛和氨气的净化效率最高,分别达94.7%和96.3%。     

人工湿地基质对NH4＋-N吸附性能

为研究建筑废物红砖和工业废物煤渣用作人工湿地脱氮基质的可行性,分别通过静态吸附实验和动态NHf—N去除效果实验进行考察。结果表明,红砖和煤渣对NH4＋-N最大静态吸附量分别为0．2533mg／g和0．0533mg／g,其吸附等温曲线均符合Freundlich型吸附方程,吸附常数分别为0．0419和0．0091;红砖煤渣组合对污水中NH4＋-N平均动态脱除率达到41．18％,高于红砖的37．63％和煤渣的30．92％。     

干式厌氧消化过程挥发酸对硫酸盐还原菌的影响

在牛粪干式厌氧消化过程中,通过添加不同挥发酸(乙酸、丙酸、丁酸),考察消化稳定阶段,挥发性脂肪酸的分布特征,挥发性脂肪酸酸组成变化对硫酸盐还原菌(SRB)的影响,微生物种群组成和种群间关系。实验结果表明,挥发性脂肪酸对SRB还原速率的贡献依次为:丙酸丁酸乙酸。相比乙酸和丁酸,添加一定量的丙酸,更有利于激活SRB的活性,从而加强SRB与产甲烷菌(MB)的种间协同,保证厌氧系统的稳定运行。     

Expansion of cropland area and formation of the eastern farming-pastoral ecotone in northern China during the twentieth century

Land cover changes induced by historical cultivation in ecologically fragile areas involving important issues such as environmental change, ecology, and human sustainability are particularly worthy of attention. This paper reconstructs the spatial distribution of cultivated areas at the county level in the eastern farming-pastoral ecotone of northern China for four time periods during the twentieth century. The paper also analyzes how the location of cultivation ratio contours of 15 and 30 %, representing the boundaries of agricultural areas, have moved and the formation process of farming-pastoral ecotone patterns during this period. The study concludes that the area and ratio of cultivated land fluctuations increased during the twentieth century. The boundaries of the cultivation ratio contours of 15 and 30 % continually moved west and north. Moving north took priority over the other directions during the period of 1916–1940, when its center moved the farthest during the twentieth century, and the boundaries primarily moved westward during 1940–1980 and northwestward during 1980–2000. The distance, direction, and extent of the movement of the cultivation boundaries are all related to agricultural area expansion processes during this period, finally resulting in the creation of the modern farming-pastoral ecotone pattern.     

The living environment and children's fears following the Indonesian tsunami

The tsunami that struck South-east Asia on 26 December 2004 left more than 500,000 people in Aceh, Indonesia, homeless and displaced to temporary barracks and other communities. This study examines the associations between prolonged habitation in barracks and the nature of fears reported by school-age children and adolescents. In mid-2007, 30 months after the tsunami, the authors interviewed 155 child and parent dyads. Logistic regression analysis was used to compare the fears reported by children and adolescents living in barracks with those reported by their peers who were living in villages. After adjusting for demographic factors and tsunami exposure, the data reveals that children and adolescents living in barracks were three times more likely than those living in villages to report tsunami-related fears. The study demonstrates that continued residence in barracks 30 months after the tsunami is associated with higher rates of reporting tsunami-related fears, suggesting that barracks habitation has had a significant impact on the psychological experience of children and adolescents since the tsunami.