共存物质对重金属絮凝齐MCC除镉性能的影响

为进一步拓展天然高分子絮凝剂壳聚糖的应用范围,以壳聚糖、L-半胱氨酸为原料,通过酰胺化反应制备一种具有重金属捕集功能的高分子重金属絮凝剂-2-氨基-3-巯基丙酰壳聚糖（MCC）,研究了水体中常见的阴阳离子、有机配位剂及浊度对MCC除镉性能的影响,探讨了絮体形貌与絮体分形维数及絮凝除镉效果间的关系。结果表明,Na＋、Cl-、N03、F-、SO4 2-的存在对MCC除Cd2＋均有促进作用,Ca2＋表现为明显的抑制作用;低浓度的EDTA对除镉有促进作用,随着EDTA浓度的增大,逐渐转为抑制作用;低浓度的腐殖酸对MCC去除Cd2＋有显著的促进作用;在一定范围内,浊度可促进MCC对Cd2＋的去除;絮体间空隙越多,絮体分形维数越小,除镉效果越好。     

共存物质对重金属絮凝剂 MCC 除镉性能的影响简

为进一步拓展天然高分子絮凝剂壳聚糖的应用范围,以壳聚糖、L-半胱氨酸为原料,通过酰胺化反应制备一种具有重金属捕集功能的高分子重金属絮凝剂-2-氨基-3-巯基丙酰壳聚糖（MCC）,研究了水体中常见的阴阳离子、有机配位剂及浊度对MCC除镉性能的影响,探讨了絮体形貌与絮体分形维数及絮凝除镉效果间的关系。结果表明,Na⁺、Cl^-、NO₃^-、F^-、SO₄^2-的存在对MCC除Cd²⁺均有促进作用,Ca²⁺表现为明显的抑制作用;低浓度的EDTA对除镉有促进作用,随着EDTA浓度的增大,逐渐转为抑制作用;低浓度的腐殖酸对MCC去除Cd²⁺有显著的促进作用;在一定范围内,浊度可促进 MCC对Cd²⁺的去除;絮体间空隙越多,絮体分形维数越小,除镉效果越好。     

西北干旱地区农宅雨水转化为可饮水技术

雨水集流工程对于解决干旱地区人民生活用水问题起着重要作用,甘肃省兰州市榆中县北山地区处于严重缺水的地区,人畜的饮用水为雨水、雪水直接沉淀后的水窖水。经过对北山饮用水进行水质检测,发现水中浊度、锰含量、微生物数量均超过《生活饮用水卫生标准》(GB5749-2006)的规定值。通过对传统滤池进行改造并结合阳光消毒研制出了一种新型水处理器——阳光消毒-生物砂滤池(SBF)家庭水处理设备,通过生物砂滤池中微生物对雨水中污染物的氧化分解及河砂的过滤使水浊度及锰得到有效地去除,日光高温灭活和光氧化降解综合作用杀灭水中致病微生物。用SBF家庭水处理设备对雨水进行处理,水中浊度、锰含量、微生物数量均达到标准的规定值。     

Fe(Ⅱ)EDTA络合吸收-铁粉还原再生脱除NO性能

利用Fe(Ⅱ)EDTA络合吸收-铁粉间歇还原再生脱除NO并回收氨资源的方法,实验研究了铁粉还原再生Fe(Ⅱ)(NO)EDTA的过程及其影响因素。结果表明,以0.015 mol/L的Fe(Ⅱ)EDTA做吸收剂,在起始pH 5.5、温度323K条件下吸收400×10-6~500×10-6的NO,脱除率95%以上;铁粉还原再生Fe(Ⅱ)(NO)EDTA过程可用缩芯模型阐释;铁粉添加量与搅拌强度直接决定了铁粉质点数量,是影响反应的重要因素;实验中Fe(Ⅱ)(NO)EDTA络合液150 mL,氧气含量为5%时,搅拌速度900 r/min、粒径为0.12 mm的铁粉浓度5.3 g/L、温度353 K、pH=6为最适宜再生条件。     

Effects of water-emulsified fuel on a diesel engine generator’s thermal efficiency and exhaust

Water-emulsified diesel has proven itself as a technically sufficient improvement fuel to improve diesel engine fuel combustion emissions and engine performance. However, it has seldom been used in light-duty diesel engines. Therefore, this paper focuses on an investigation into the thermal efficiency and pollution emission analysis of a light-duty diesel engine generator fueled with different water content emulsified diesel fuels (WD, including WD-0, WD-5, WD-10, and WD-15). In this study, nitric oxide, carbon monoxide, hydrocarbons, and carbon dioxide were analyzed by a vehicle emission gas analyzer, and the particle size and number concentration were measured by an electrical low-pressure impactor. In addition, engine loading and fuel consumption were also measured to calculate the thermal efficiency. Measurement results suggested that water-emulsified diesel was useful to improve the thermal efficiency and the exhaust emission of a diesel engine. Obviously, the thermal efficiency was increased about 1.2 to 19.9%. In addition, water-emulsified diesel leads to a significant reduction of nitric oxide emission (less by about 18.3 to 45.4%). However, the particle number concentration emission might be increased if the loading of the generator becomes lower than or equal to 1800 W. In addition, exhaust particle size distributions were shifted toward larger particles at high loading. The consequence of this research proposed that the water-emulsified diesel was useful to improve the engine performance and some of exhaust emissions, especially the NO emission reduction.

Implications:The accumulated test results provide a good basis to resolve the corresponding pollutants emitted from a light-duty diesel engine generator. By measuring and analyzing transforms of exhaust pollutant from this engine generator, the effects of water-emulsified diesel fuel and loading on emission characteristics might be more clear. Understanding reduction of pollutant emissions during the use of water-emulsified diesel helps improve the effectiveness of the testing program. The analyzed consequences provide useful information to the government for setting policies to curb pollutant emissions from a light-duty diesel engine generator more effectively.     

Characterizing wetland change at landscape scale in Jiangsu Province, China

Human activities produced great impacts on wetlands worldwide. Taking Jiangsu Province, China, as a representative wetland region subject to extensive human activities, the aim of this study is to understand the conversion trajectory and spatial differentiation in wetland change from a multi-scale perspective. Based on multi-temporal Landsat images, it was found that the natural wetlands decreased by 11.2% from 1990 to 2006 in Jiangsu Province. Transition matrices showed that the conversion of natural wetlands to human-made wetlands (mostly aquaculture ponds) was the major form of natural wetland reduction, accounting for over 60% of the reduction. Percentage reduction and area reduc tion of natural wetlands were respectively quantified within different wetland cover zones using a moving window analysis. Average percentage reduction showed a decreasing tendency with increasing wetland cover. The high-cover and mid-cover zone presented the largest area reduction at the scales of 1-2 km and 4-8 km, respectively. Local hotspots of natural wetland reduction were mapped using the equal-interval and quantile classification schemes. The hotspots were mostly concentrated in the Lixiahe marshes and the coastal wetland areas. For the area reduction hotspots, the quantile classification presented larger area and more patches than the equal-interval classification; while an opposite result was shown for the percentage reduction hotspots. With respect to the discontinuous distribution of the natural wetlands, area reduction could be more appropriate to represent reduction hotspots than percentage reduction in the study area. These findings could have useful implications to wetland conservation.     

Enantioselective ecotoxicity of the herbicide dichlorprop and complexes formed with chitosan in two fresh water green algae

To reduce the leaching potential, to prevent groundwater contamination and to maintain the efficacy of a pesticide, natural polysaccharides have received increasing attention due to their biocompatibility and useful biological reactivity for controlled release formulations (CRFs) of pesticides. In this paper, the toxicities of the chiral herbicide dichlorprop (DCPP) and its complexes with chitosan molecules (DCPP-CS) and chitosan nanoparticles (DCPP-NP) to two different green algae were determined and compared. The inhibition rates of DCPP, DCPP-CS and DCPP-NP were determined at 24, 48, 72, 96, 120, 144, 168 h, and the results show that (S)-DCPP was more toxic to Chlorella vulgaris than (R)-DCPP, while the (R)-DCPP was more toxic to Scenedesmus obliquus than (S)-DCPP. The study also found that the chiral selectivity of DCPP to Chlorella vulgaris and Scenedesmus obliquus could be changed when DCPP was complexed with chitosan molecules (CS) or chitosan nanoparticles (NP). For Chlorella vulgaris, the order of inhibition was (R)-DCPP-CS > (S)-DCPP-CS and (R)-DCPP-NP > (S)-DCPP-NP; for Scenedesmus obliquus, the order was (S)-DCPP-CS > (R)-DCPP-CS and (S)-DCPP-NP > (R)-DCPP-NP. This phenomenon suggests that the enantioselective behaviors of chiral compounds might shift when interactions with other chiral receptors coexist in different biological environments. Additionally, chitosan molecules and chitosan nanoparticles also showed different toxicities, which could be ascribed to the difference in the physicochemical properties between CS and NP or the differences in the cell walls of the two fresh water green algae.     

大城市污水处理工艺的经济选择因素

城市污水处理设施的建设是今后改善我国城市环境的重要任务之一，其具体工艺和技术的选择除了对污水治理的结果产生影响外，更重要的是直接影响对设施建设的投入强度和运行效果，建议从经济和技术结合的角度研究比较各种技术和工艺，去探讨经济技术最佳结合的方法。     

城市污水脱氮除磷方法探讨

本文综述了城市污水脱氮降磷工艺的几种主要方法，指出生物法因工艺简单、处理能力强、运行方式灵活等优点已成为近年来一种污水处理的重要方法，得到广泛应用。     

Upstream Sediment‐Control Dams: Five Decades of Experience in the Rapidly Eroding Dahan River Basin,Taiwan

Sedimentation is emerging as a key issue in sustainable reservoir management. One approach to controlling reservoir sedimentation is to trap sediment in hydraulic structures upstream of the reservoir. In the 1,163‐km² catchment of the Dahan River (Taiwan) over 120 “sabo” dams were built to reduce sediment yield to Shihmen Reservoir. Built in 1963 for water supply, Shihmen has lost over 40% of its 290‐Mm³ storage capacity to sedimentation. Most of these upstream structures were small, but three had capacities >9 Mm³. Field measurements and historical data from the Water Resources Agency show most smaller dams had filled with sediment by 1976. The three largest were full or nearly so by 2007, when one (Barlin Dam) failed, releasing a pulse of 7.5 Mm³, most of its 10.4 Mm³ stored sediment downstream. The Central Range of Taiwan is rapidly eroding (denudation rates 3‐6 mm/yr), so geologically high loads make sediment problems manifest sooner. Even in other environments, however, eventually small dams built upstream of large reservoirs are likely to fill themselves, creating multiple small sediment‐filled reservoirs, some located in sites inaccessible to mechanical removal. Our analysis suggests sabo dams do not offer a long‐term basis for controlling reservoir sedimentation in such a high‐sediment yield environment. Sustainable solutions must somehow pass sediment downstream, as would be accomplished by a sediment bypass around Shihmen Reservoir, as now being studied.