Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

The hydrolysis/precipitation behaviors of Al³⁺, Al₁₃ and Al₃₀ under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl₃, PAC_Al13 and PAC_Al30 were 6.5–7.5, 8.5–9.5, and 7.5–9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl₃ ? PAC_Al30 > PAC_Al13. The precipitates' size increased when the dosage increased from 50 μM to 200 μM, but it decreased when the dosage increased to 800 μM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The iso-electric points of the freshly formed precipitates for AlCl₃, PAC_Al13 and PAC_Al30 were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl₃ hydrolysis precipitates were lower than those of PAC_Al13 and PAC_Al30 when pH > 5.0. The Zeta potential of PAC_Al30 hydrolysis precipitates was higher than that of PAC_Al13 at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al–Ferron research indicated that the hydrolysis precipitates of AlCl₃ were composed of amorphous Al(OH)₃ precipitates, but those of PAC_Al13 and PAC_Al30 were composed of aggregates of Al₁₃ and Al₃₀, respectively. Al³⁺ was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al₁₃ and Al₃₀ species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al–Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al–Ferron method. The chemical composition of Al_a, Al_b and Al_c depended on coagulant and solution pH. The Al_b measured in the current case was different from Keggin Al₁₃, and the high Al_b content in the AlCl₃ hydrolysis precipitates could not used as testimony that most of the Al³⁺ was converted to highly charged Al₁₃ species during AlCl₃ coagulation.     

Community participatory landscape classification and biodiversity assessment and monitoring of grazing lands in northern Kenya

In this study, we asked the Ariaal herders of northern Kenya to answer "why, what and how" they classified landscape, and assessed and monitored the biodiversity of 10 km(2) of grazing land. To answer the "why question" the herders classified grazing resources into 39 landscape patches grouped into six landscape types and classified soil as 'warm', 'intermediate' or 'cold' for the purpose of land use. For the "what question" the herders used soil conditions and vegetation characteristics to assess biodiversity. Plant species were described as 'increasers', 'decreasers' or 'stable'. The decreaser species were mostly grasses and forbs preferred for cattle and sheep grazing and the increasers were mostly woody species preferred by goats. The herders evaluated biodiversity in terms of key forage species and used absence or presence of the preferred species from individual landscapes for monitoring change in biodiversity. For the "how question" the herders used anthropogenic indicators concerned with livestock management for assessing landscape potential and suitability for grazing. The anthropogenic indicators were related to soils and biodiversity. The herders used plant species grazing preferences to determine the links between livestock production and biodiversity. By addressing these three questions, the study shows the value of incorporating the indigenous knowledge of herders into classification of landscape and assessment and monitoring of biodiversity in the grazing lands. We conclude that herder knowledge of biodiversity is related to the use as opposed to exclusive conservation practices. This type of knowledge is extremely valuable to conservation agencies for establishing a baseline for monitoring changes in biodiversity in the future.     

Long-term evaluation of coal fly ash and mine tailings co-placement: A site-specific study

This study presents the results of a laboratory investigation conducted to evaluate the efficiency of coal fly ash to control the formation of acid mine drainage (AMD) from mine waste. Site-specific materials, coal fly ash from Atikokan Thermal Generating Station and mine tailings from Musselwhite mine, were mixed at different proportions for the investigation of the drainage chemistry and the optimal mix using static testing (acid–base accounting) and kinetic (column) testing. The acid–base accounting (ABA) results indicated that the fly ash possessed strong alkaline (neutralization) potential (NP) and could be used in the management of reactive mine tailings, thus ensuring prevention of AMD in the long-term. Column tests conducted in the laboratory to further investigate long-term performance of fly ash in the neutralization and prevention of acid mine drainage from tailings similarly showed that mixing fly ash with mine tailings reduces dissolution of many heavy metals from tailings by providing alkalinity to the system. It was found that a fly ash to tailings mass ratio equal to or greater than 15% can effectively prevent AMD generation from Musselwhite mine tailings in the co-placement approach.     

Assessment Tools for Urban Catchments: Defining Observable Biological Potential1

Abstract: Urbanization represents a strong and increasingly more prevalent impact on stream quality worldwide. One of the characteristic effects of increased urbanization is a consistent decline in biological stream condition. The characterization of this biological degradation with increasing urbanization presents a number of advantages for the study and management of urban streams and catchments. In this paper, the limitation of biological condition with urbanization, called observed biological potential, is characterized. Using an urban intensity index and a biological index developed specifically for urban systems in the Baltimore, Maryland; Cleveland, Ohio; and San Jose, California regions, two principal techniques were compared (quantile regression and bin regression) to define observed biological potential along urban gradients. Quantile regression was selected as the preferable tool for describing observed biological potential given the consistency with which it can be applied and its statistical efficiency, however, bin quantile regression performed similarly. Having identified a numeric approximation of observed biological potential, two methods for identifying factors related to distance from potential as a way of identifying critical environmental factors affecting biological condition in urban areas were explored. The results of this work can be used for identifying benchmarks for urban stream biological condition, identifying limiting catchment characteristics, and prioritizing urban stream management efforts.     

浅谈新疆风电场水土保持措施配置——以新疆华电小草湖风电场二场一期工程为例

风能作为一种清洁无污染的可再生能源,已经被广泛运用到电力事业的发展中来。近年来,新疆的风力发电发展迅速,风电场建设过程中不可避免地会对土壤及植被造成一定的破坏,人为地加剧了水土流失。概述了风电项目水土流失特点,以新疆华电小草湖风电场工程为例,结合项目区具体特点,分区设置防治措施。通过工程措施、植物措施与临时措施的有机结合,有效地防止水土流失。     

双区电除尘器降低锅炉烟尘排放浓度

粉尘在传统结构的荷电区荷电之后,一部分尘粒被阳极板捕集,大部分带有正、负电荷的尘粒再分别被收尘区的管式辅助电极和阳极板捕集.模拟试验数据表明,收尘区具有高电压、低电流和板电流密度分布均匀的特性.工业性试验结果显示,应用双区电除尘技术设计或改造电除尘器,不仅可以较好地防止发生反电晕,而且能够将锅炉烟尘排放质量浓度降低到50 mg/m3以下.与传统的卧式电除尘器相比,还可节省10%左右的占地面积和钢材用量.     

1.5t、3t电弧炉烟尘治理

针对1.5 t、3 t电弧炉在烟尘治理时场地狭小的特点,采用可折叠式收尘罩与低压长袋脉冲袋式除尘器技术进行治理.测试表明,系统运行可靠,烟尘治理效果良好,工厂车间环境取得显著改善,岗位粉尘浓度、烟尘排放浓度均达到国家规定的标准.     

基于人工免疫原理的事故预防研究

介绍生物免疫识别模式,分析事故预防过程的实质是抑制潜在危险转化成事故的控制过程,分析比较事故预防与生物免疫识别模式在作用、生存环境、动作触发源等的共性,构建了基于免疫识别模式的事故预防系统并建立了事故预防数学模型;定义事故预防系统的识别率、失效率、误判率并给出了数学表达式,指出监测生产系统各环节状态信息是否符合系统的安全要求就是识别潜在危险的过程,是事故预防的关键,基于人工免疫原理的事故预防数学模型具有较强的健壮性、自适应性和动态防护性等特点。     

Impact of Bioaugmentation with a Consortium of Bacteria on the Remediation of Wastewater-Containing Hydrocarbons (5 pp)

Goals, Scope and Background It has been observed that hydrocarbon treated wastewaters still contain high COD and a number of intermediates. This suggests that the required catabolic gene pool for further degradation might be absent in the system or, that its titer value is not significant enough. By providing the desired catabolic potential, the overall efficiency of the treatment system can be improved. This study aims to demonstrate this concept by bioaugmentation of a lab-scale reactor treating refinery wastewater with a consortium having the capacity to complement the alkB genotype to the available microbial population. Methods Two reactors were set up using activated biomass collected from a refinery treatment plant and operated at a continuous mode for a period of 8 weeks. The feed to both reactors was kept constant. Crude oil was spiked regularly. One reactor was bioaugmented with a consortium previously described for crude oil spill remediation. The efficiency of the bioaugmented reactor was demonstrated by reduced COD. The changes in the microbial population over a period of time were analyzed by RAPD. Catabolic activity of the biomass in both reactors was monitored by PCR. The presence of the catabolic loci was confirmed by Southern Hybridization. Results and Discussion 52.2% removal of COD was observed in the bioaugmented reactor while only 15.1% reduction of COD was observed in the reactor without bioaugmentation. The change in microbial population can be seen from the 4th week, which also corresponds to improved catabolic activity. The presence of the bedA locus was seen in all samples, which indicates the presence of aromatic degraders, but the appearance of the alkB locus, from the 6th week onwards, which was observed only in the samples from the bioaugmented reactor. The results suggest that the gene pool of the bioaugmented reactor has catabolic loci that can degrade accumulated intermediates, thus improving the efficiency of the system. Conclusions In this study, improvement of efficiency of bioremediation was demonstrated by addition of catabolic loci that are responsible for degradation. Bioaugmentation was carried out in biomass that was collected from an ETP (effluent treatment plant) treating hydrocarbon containing wastewater to study the strategies for improvement of the treatment system. Biostimulation, only marginally improved the efficiency, when compared to bioaugmentation. The improved efficiency was demonstrated by COD removal. The presence of the alkB locus suggests the importance of a catabolic gene pool that acts on accumulated intermediates. It is well documented that straight chain aliphatics and intermediates of aromatic compounds after ring cleavage, accumulate in refinery wastewater systems, thereby hindering further degradation of the wastewater. Supplementation of a catabolic gene pool that treats the lower pathway compounds and alkanes will improve the overall efficiency. In this study, results suggest that the alkB locus can also be used to monitor the degradative mode of the activated biomass. Recommendations and Perspective . Pollution from petroleum and petroleum products around the globe are known to have grave consequences on the environment. Bioremediation, using activated sludge, is one option for the treatment of such wastes. Effluent treatment plants are usually unable to completely degrade the wastewater being treated in the biological unit (the aerator chambers). The efficiency of degradation can be improved by biostimulation and bioaugmentation. This study demonstrates the improved efficiency of a treatment system for wastewater containing hydrocarbons by bioaugmentation of a consortium that supports degradation. Further experiments on a pilot scale are recommended to assess the use of bioaugmentation on a large scale. The use of molecular tools, like DNA probes for alkB, to monitor the system also needs to be explored.     

河北省钢铁工业主要大气污染物减排潜力分析

通过对河北省钢铁工业存在问题的分析,得出我省钢铁行业主要大气污染物为二氧化硫和粉尘.结合我省钢铁企业的实际情况,从工程技术、政策管理等方面提出相应治理措施,并对"十一五"期间我省钢铁行业二氧化硫和粉尘减排效益进行预测.预测结果显示:采用所建议的减排措施后,我省钢铁工业二氧化硫减排量对全省"十一五"减排计划的贡献率为81.4%;粉尘可减排60%.