SO2在碳钢初期大气腐蚀中的作用

通过自建的模拟大气腐蚀系统,借助金相显微镜、扫描电镜(SEM/EDX)、X-射线衍射(XRD)和x-射线光电子能谱(XPS),研究了SO2对碳钢初期大气腐蚀行为的影响,并进一步用原子力显微镜从更微观的角度观察了在SO2环境中初期阶段腐蚀形貌变化.研究结果表明:在SO2污染大气环境中,随SO2浓度的升高碳钢腐蚀加快.在体积分数为5×10(-6)SO2的大气环境中,碳钢和耐候钢表面腐蚀主要以条状物生长,随着SO2浓度的升高,腐蚀产物的形貌发生改变,在体积分数为5×10(-5)SO2的大气环境中,条状锈和胞状锈同时生长.在锈层中S元素以FeSO4·4H2O的形式存在,腐蚀产物中还有γ-FeOOH.SO2在初期阶段加速了碳钢的腐蚀,降低了碳钢的耐蚀性.     

Multi-response optimization of Fenton process for applicability assessment in landfill leachate treatment

Fenton process, as a pretreatment method, was found to be effective in the primary treatment of mature/medium landfill leachate. However, the main problem of the process is the large amount of produced sludge that requires an accurate feasibility evaluation for operational applications. In this study, the response surface methodology was applied for the modeling and optimization of Fenton process in three target responses, (1) overall COD removal, (2) sludge to iron ratio (SIR) and (3) organics removal to sludge ratio (ORSR), where the latter two were new self-defined responses for prediction of sludge generation and applicability assessment of the process, respectively. The effective variables included the initial pH, [H₂O₂]/[Fe²⁺] ratio and Fe²⁺ dosage. According to the statistical analysis, all the proposed models were adequate (with adjusted R² of 0.9116–0.9512) and had considerable predictive capability (with prediction R² up to 0.9092 and appropriate adequate precision). It was found that all the variables had significant effects on the responses, specifically by their observed role in dominant oxidation mechanism. The optimum operational conditions obtained by overlay plot, were found to be initial pH of 5.7, [H₂O₂]/[Fe²⁺] ratio of 17.72 and [Fe²⁺] of 195 mM, which led to 69% COD removal, 2.4 (l sludge/consumed mole Fe²⁺) of SIR and 16.5 (gCOD removed/l produced sludge) for ORSR in verification test, in accordance with models-predicted values. Finally, it was observed that [H₂O₂]/[Fe²⁺] ratio and Fe²⁺ dosage had significant influence on COD removal, while Fe²⁺ dosage and [H₂O₂]/[Fe²⁺] ratio had remarkable effects on SIR and ORSR responses, respectively.     

EFFECTS OF COAL PILE RUNOFF ON STREAM QUALITY AND MACROINVERTEBRATE COMMUNITIES1

Samples of coal pile runoff, Georges Creek water, and macrobenthos above and below two coal storage areas along Georges Creek, Allegany County, Maryland, were collected in July, August, and September 1982, and February and July 1983. Coal pile runoff was collected under high- and low-flow conditions. Water samples were analyzed for Hg, Zn, As, Fe, Mn, Al, SO₄^?2, pH, filterable and non-filterable residue, conductivity and acidity. Leachate from coal piles along Georges Creek contained high concentrations of heavy metals, particularly manganese, aluminum and zinc. Iron and sulfate were very high and the pH ranged from 1.4 to 3.1. Georges Creek water had much lower concentrations of metals, iron and sulfate and a pH of about 7.0. The distribution of macrobenthos in Georges Creek showed the effects of both runoff from coal storage piles and periodic drought. Brillouin's diversity index values were low even in areas which did not dry. Densities of tubificid worms and chironomid larvae were very high above the coal storage areas where organic inputs were high. At all the rest of the sampling stations, macroinvertebrate densities were very low. Where coal pile runoff enters Georges Creek, it compounds the effects of periodic drought and further stresses the aquatic community.     

EFFECTS OF INITIAL ABSTRACTION AND URBANIZATION ON ESTIMATED RUNOFF USING CN TECHNOLOGY1

ABSTRACT: Few studies have been conducted to explore the effects of initial abstraction on estimated direct runoff despite the widespread use of the curve number (CN) method in many hydrologic models to estimate direct runoff. In this study, use of a 5 percent ratio of initial abstraction (I_a) to storage (S) to estimate daily direct runoff with modified CN values for a 5 percent I_a/S value was investigated using the Long‐Term Hydrologic Impact Assessment (L‐THIA) geographic information system (GIS). In addition, the effects on estimated runoff of altering the hydrologic soil group due to urbanization were investigated. The L‐THIA model was applied to the Indiana Little Eagle Creek watershed with 5 percent and 20 percent I_a/S values, considering hydrologic soil group alteration due to urbanization. The results indicate that uses of a 5 percent l_a/S and modified CN values and Hydrologic Soil Group D for urbanized areas in model runs can improve long term direct runoff prediction.     

垃圾填埋二次污染的危害与防治

介绍了垃圾卫生填埋中二次污染的危害,指出垃圾卫生填埋场建设和填埋操作中为防止填埋释放物对周围环境的二次污染所应采取的防渗、收集、处理和利用等措施,探讨了在垃圾卫生填埋场建设和填埋操作中应注意的问题及应着重考虑的方面.     

Evaluation of leachate composition by multivariate data analysis (MVDA)

Landfills generate emissions in the form of gas and leachate. The emissions are often measured within monitoring programmes. It is likely that the requirements of such monitoring programmes can be extended in the future, particularly in light of the increased interest in specific organic substances. Multivariate data analyses (MVDA) have been used to evaluate the possibility of predicting the content of specific organic substances from more common analyses. The results indicate that this is possible for a specific leachate. MVDA can also be used to reduce the number of analyses performed within existing monitoring programmes while retaining information about all the variables formerly included in the programmes.     

我国城市生活垃圾的处理和发展趋势

城市生活垃圾给城市环境造成了严重污染，威胁了城市居民的生存环境和经济、社会的可持续发展。目前，国内采取的垃圾处理技术主要有卫生填埋、焚烧、堆肥等，热解技术由于具有资源回收率高、二次污染小、综合效益好等优点，越来越适合我国中小城市的垃圾处理。垃圾气化技术的研究成为当今世界的热点。此外，我国对垃圾衍生燃料的研究也刚刚起步。为促进城市持续、稳定的发展，提出了垃圾分类收集、分拣、综合利用垃圾处理技术的措施。     

微波消解法快速测定渗滤液化学需氧量

针对国标回流法测定化学需氧量消耗时间长,分析费用高等不足,研究了微波消解法测定垃圾渗滤液的试验方法.通过微波消解功率、消解时间、催化剂用量等试验,确定了微波消解测定渗滤液CODCr的最佳条件.该方法具有省时间、省试剂、准确度高等优点.     

生活垃圾卫生填埋场安全运行问题探讨

分析总结了垃圾填埋场的安全运行中常出现的4个安全问题,即沼气爆炸和火灾事故、边坡和大坝不稳定性造成滑坡、填埋区作业时存在较大的安全隐患、填埋场周边环境污染等。笔者以建设部科技示范工程广州市兴丰生活垃圾卫生填埋场成功的运行经验为例进行了探讨,提出了针对垃圾填埋场常见安全问题相应的解决办法,即科学的填埋场设计、完善的安全运行制度、规范的营运管理和营运监管相结合的管理模式等。     

生活垃圾填埋产沼的提取净化利用

垃圾填埋是目前我国各城市广为采用的垃圾处理方式，但垃圾填埋产沼以后对沼气的回收利用却不被人们所熟知和重视。由此造成了对可开发利用的二次能源的极大浪费，而沼气对周围环境也造成了严重的污染并对大气臭氧层造成了破坏。本文阐述了垃圾填埋产沼回收的必要性和经济性，对垃圾填埋产沼提取利用、制取汽车压缩气的可行性及工艺流程进行了分析和介绍。