总磷总氮在线水质分析仪实际水样测量影响因素分析

总磷总氮在线水质分析仪实际水样测量结果与实验室国标方法测量结果存在着差异,本文分析了影响总磷总氮在线水质分析仪测量结果的因素。     

流化床Fenton在废水处理中的研究进展

流化床Fenton将异相结晶技术引入到Fenton反应中,将反应产生的Fe 3+以结晶的形式披覆在填料表面,在削减铁泥产量的同时强化催化氧化。阐述了流化床Fenton的结晶机理;流化床Fenton的影响因素,包括p H、Fenton反应加药量、填料种类、无机盐与有机物等;并介绍了流化床Fenton在氧化和结晶两方面的应用现状;最后对流化床Fenton技术研究的部分提出了建议和展望。     

有效微生物技术在城市环境治理领域中的应用

随着经济的快速发展,人口数量急剧增长,我国城市水污染及生活垃圾的安全处置问题日益严重,因此找到一种简单、经济的处理方法是目前迫切需要解决的问题。介绍了有效微生物的种群特点以及处理污水的机理,阐述了有效微生物对污水处理效果的影响因素,综述了有效微生物技术在污水处理、河湖富营养化治理、生活垃圾处置等方面的研究现状,并指出了该技术在城市环境治理领域的发展趋势和研究方向。     

Effects of protein properties on ultrafiltration membrane fouling performance in water treatment

Protein-like substances always induce severe ultrafiltration (UF) membrane fouling. To systematically understand the effect of proteins, regenerated cellulose UF membrane (commonly used for protein separation) performance was investigated in the presence of bovine serum albumin (BSA) under various water conditions. Results showed that although trypsin enhanced the membrane flux via proteolysis, catalysis took a long time. Membrane fouling was alleviated at high solution pH and low water temperature owing to the strong electrostatic repulsion force among BSA molecules. Both Na⁺ and Ca²⁺ could increase membrane flux. However, Ca²⁺ played a bridging role between adjacent BSA molecules, whereas membrane fouling was alleviated via a hydration repulsion force with Na⁺. The order of influence on membrane fouling was as follows: Ca²⁺ concentration > Na⁺ concentration > pH > temperature > trypsin concentration. Furthermore, a polyvinylidene fluoride UF membrane experiment showed that Ca²⁺ could reduce the fouling induced by BSA. Thus, the differences in UF membrane performance will have application potential for alleviating UF membrane fouling induced by proteins during water treatment.     

Microbial aerosol particles in four seasons of sanitary landfill site: Molecular approaches, traceability and risk assessment

Landfill sites are regarded as prominent sources of bioaerosols for the surrounding atmosphere. The present study focused on the emission of airborne bacteria and fungi in four seasons of a sanitary landfill site. The main species found in bioaerosols were assayed using high-throughput sequencing. The SourceTracker method was utilized to identify the sources of the bioaerosols present at the boundary of the landfill site. Furthermore, the health consequences of the exposure to bioaerosols were evaluated based on the average daily dose rates. Results showed that the concentrations of airborne bacteria in the operation area (OPA) and the leakage treatment area (LTA) were in the range of (4684 ± 477)–(10883 ± 1395) CFU/m³ and (3179 ± 453)–(9051 ± 738) CFU/m³, respectively. The average emission levels of fungal aerosols were 4026 CFU/m³ for OPA and 1295 CFU/m³ for LTA. The landfill site received the maximum bioaerosol load during summer and the minimum during winter. Approximately 41.39%– 86.24% of the airborne bacteria had a particle size of 1.1 to 4.7 µm, whereas 48.27%– 66.45% of the airborne fungi had a particle size of more than 4.7 µm. Bacillus sp., Brevibacillus sp., and Paenibacillus sp. were abundant in the bacterial population, whereas Penicillium sp. and Aspergillus sp. dominated the fungal population. Bioaerosols released from the working area and treatment of leachate were the two main sources that emerged in the surrounding air of the landfill site boundary. The exposure risks during summer and autumn were higher than those in spring and winter.     

Technological disaster factors

Major Hazard Installations (MHIs) deal with the hazardous substances which exceed the threshold quantity. Although MHIs are safe organizations, they cannot fail due to a single error. However, due to their high complexity, the designer and the operator make errors during the design, and operation of the plants. Consequently, the technical, operational and organizational errors may lead to a major accident. The world has seen many incidents due to the operation of the MHIs. Malaysia has experienced several technological disasters. Four investigation reports have been reviewed in detail. This paper reviews the causes of the technological disasters in general. This paper also summarizes the causes of the technological disasters in Malaysia. Finally the paper rearranges the technological disaster causes and errors.     

Experimental investigation of gas explosion in single vessel and connected vessels

Gas explosion in connected vessels usually leads to high pressure and high rate of pressure increase which the vessels and pipes can not tolerate. Severe human casualties and property losses may occur due to the variation characteristics of gas explosion pressure in connected vessels. To determine gas explosion strength, an experimental testing system for methane and air mixture explosion in a single vessel, in a single vessel connected a pipe and in connected vessels has been set up. The experiment apparatus consisted of two spherical vessels of 350 mm and 600 mm in diameter, three connecting pipes of 89 mm in diameter and 6 m in length. First, the results of gas explosion pressure in a single vessel and connected vessels were compared and analyzed. And then the development of gas explosion, its changing characteristics and relevant influencing factors were analyzed. When gas explosion occurs in a single vessel, the maximum explosion pressure and pressure growth rate with ignition at the center of a spherical vessel are higher than those with ignition on the inner-wall of the vessel. In conclusion, besides ignition source on the inner wall, the ignition source at the center of the vessels must be avoided to reduce the damage level. When the gas mixture is ignited in the large vessel, the maximum explosion pressure and explosion pressure rising rate in the small vessel raise. And the maximum explosion pressure and pressure rising rate in connected vessels are higher than those in the single containment vessel. So whenever possible, some isolation techniques, such as fast-acting valves, rotary valves, etc., might be applied to reduce explosion strength in the integrated system. However, when the gas mixture is ignited in the small vessel, the maximum explosion pressures in the large vessel and in the small vessel both decrease. Moreover, the explosion pressure is lower than that in the single vessel. When gas explosion happens in a single vessel connected to a pipe, the maximum explosion pressure occurs at the end of the pipe if the gas mixture is ignited in the spherical vessel. Therefore, installing a pipe into the system can reduce the maximum explosion pressure, but it also causes the explosion pressure growth rate to increase.     

无公害蔬菜基地规划建设中的几个环境问题探讨

无公害蔬菜生产是农业产业结构调整的重要内容,也是农民增收的重要途径。在无公害蔬菜基地的规划建设中要充分考虑土壤、大气、水源等方面的环境因素,以确保产品的安全性。基地的规划建设要尽可能远离城市和污染较重的工厂区域,要与公路保持一定的距离,基地附近要有清洁的水源,不得使用城市污水直接灌溉,城市污泥作为有机肥施用要首先进行无害化处理。     

薄壁管螺旋槽的旋压工艺研究

介绍了薄壁管螺旋槽旋压时的测力装置和各工艺参数对旋压力的影响,可为设计旋压机床、编制旋压工艺,设计工夹具提供理论依据。     

酸沉降区作物对汞的积累及其影响因素的研究

介绍了重庆市近郊的蔬菜含汞量随时距发电厂越近而浓度越高的趋势，蔬菜所生长的土壤及其附近的地下水含汞量，亦与蔬菜有类似的情况，但不同作物吸收汞的能力各异，不同来源的汞在作物在内的分布也不相同，来在大气的汞，大都集中地上部，来自土壤则大都聚积于根，土壤粘粒类型的差异，也对作物吸汞能力及汞在材料体内的分布有明显的影响，土壤肥力不单影响植物吸收土壤汞，而且制约作物吸收大气汞。