A root exudates based approach to assess the long-term phytoavailability of metals in biosolids-amended soils

Organic acids present in the rhizosphere of growing plants are widely recognized to be responsible for dissolving the solid phase metals in the soil and making them available for plant absorption. We proposed a root exudates-based model to assess the long-term phytoavailability of metals in biosolids-amended soils. The phytoavailability of biosolids-borne metals was defined in terms of a capacity factor and an intensity factor. The plant available metal pool, C₀ (capacity factor, mg kg⁻¹), can be estimated by fitting the successive organic acids extraction data to an exponential decay kinetic equation. The field metal removal rate, k (intensity factor, yr⁻¹), can be estimated from the successive extraction-based metal release rate through an effective annual organic acid production in the rhizosphere which was found to be characteristic of plant species. The protocol was successfully used to assess the long-term phytoavailability of metals in biosolids-amended soil from two biosolids land application sites.     

Influence of plants on the reduction of hexavalent chromium in wetland sediments

This work addresses the effect that plants (Typha latifolia and Carex lurida) have on the reduction of Cr(VI) in wetland sediments. Experiments were carried out using tubular microcosms, where chemical species were monitored along the longitudinal flow axis. Cr(VI) removal was enhanced by the presence of plants. This is explained by a decrease in the redox potential promoted by organic root exudates released by plants. Under these conditions sulfate reduction is enhanced, increasing the concentration of sulfide species in the sediment pore water, which reduce Cr(VI). Evapotranspiration induced by plants also contributed to enhance the reduction of Cr(VI) by concentrating all chemical species in the sediment pore water. Both exudates release and evapotranspiration have a diurnal component that affects Cr(VI) reduction. Concentration profiles were fitted to a kinetic model linking sulfide and Cr(VI) concentrations corrected for evapotranspiration. This expression captures both the longitudinal as well as the diurnal Cr(VI) concentration profiles.     

养猪废水的吸附-过滤法初级处理试验研究

以实际养猪废水为对象,采用吸附-过滤法进行预处理,研究稻草滤料和稻草-沸石双层滤料在不同滤速下对养猪废水中CODCr、氨氮和磷的去除效果.结果表明,稻草-沸石双层滤料对CODCr、氨氮和磷的去除效果明显优于稻草滤料.以稻草-沸石双层滤料为过滤介质时,5 m/h的滤速下,CODCr、氨氮和磷的最大去除率分别达47 9%、72 9%和50 1%.研究表明,吸附-过滤预处理不仅能去除养猪废水中的CODCr、氨氮和磷,还能去除一定量的小分子有机物和臭味,同时附着大量固体有机物的稻草和吸附有氨氮、磷的沸石经过处理后可作为土壤改良剂或肥料,从而实现了农业固体废物的资源化利用.     

具有超压/负压防护功能的急救车防生物污染的安全性试验研究

采用粘质沙雷菌气溶胶,对具有超压/负压防护功能的急救车防生物污染的安全性进行试验考核。分别测试气溶胶发生后30s,1min,5min,10min时,车厢在超压防护和负压防护下的过滤效率,其结果表明:急救车在超压防护状态下开启空调时的平均过滤效率能达到99.99%,不开空调时的平均过滤效率能达到99.95%;在负压防护状态下开启空调时的平均过滤效率能达到99.93%,不开空调时的平均过滤效率能达到99.95%。证明急救车能够通过生物污染区域安全运送、急救伤病员,也能够运送、急救生物污染伤病员或烈性传染病员确保沿途环境不受污染,该研究成果为应对生物恐怖袭击和突发公共卫生事件(烈性传染病)提供了一种安全可靠的机动医疗救治平台。     

水处理技术发展对电力工业水循环利用的经济性影响

讨论了一些为提高生产力和降低成本而发展起来的废水零排放或水回收循环利用前沿技术,并将这些技术的经济性与原有的水循环利用系统进行比较.     

油田采出水过滤进水中不同粒径悬浮物的质量分布

采用已知孔径的微孔过滤器,对油田采出水的过滤进水进行了筛分,分析了悬浮物的质量浓度,并同步测定了颗粒体积浓度和几何特征值。除了D[v,0.5]具有指标性意义外,粒度分析结果并不能完全代表过滤等工艺的分离精度。悬浮物几何特征值、体积浓度和质量含量降低率不是同步的,其中质量浓度降低幅度最小。当粒径小于4μm的悬浮物质含量超过3mg/L时,难以被目前普遍采用的过滤工艺去除。应选择与膜过滤类似的更精密的工艺技术,才能最终达到采出水回用标准。     

土壤过滤净化氮氧化物实验研究

实验考察了土壤类型、进口浓度、温度和过滤气速对净化氮氧化物废气效果的影响。结果表明 ,土壤过滤能够有效削减NOx 污染 ,对NO2 的净化效率可达 90 %以上 :肥沃土壤的净化效率明显高于贫瘠土壤 ,适宜作为过滤介质 ;在实验浓度范围内 ,净化效率基本随着进口浓度的提高而提高。当进口浓度高于 2mg m3时 ,净化效率基本稳定在95 %左右 ;温度的升高对提高去除率是有利的 ,而且对延长土壤滤池有效使用时间有很大帮助 ;在实验范围内气速的提高对NO2 去除率影响不明显。     

生物过滤氧化反应器处理焦化废水

针对钢铁厂焦化车间采用普通活性污泥工艺处理焦化废水 ,出水水质经常超标 ,且对冲击负荷适应力差的情况 ,使用生物过滤氧化反应器 (BIOFOR)工艺对废水进一步进行处理 ,运行结果表明 ,BIOFOR表现出良好的抗冲击负荷能力 ,对CODCr、NH3 N、SS、油类、酚、氰化物等主要污染物的去除率都分别为 6 4 7%、79 8%、76 6 %、5 2 1%、95 4 %、6 1 4 % ,出水水质高于GB8978 1996第二类污染物二级排放标准。     

垃圾渗滤液预处理实验研究

在总结以往研究成果的基础上,选用絮凝沉淀和沙滤方法对垃圾渗滤液进行预处理,实验得出了各自最佳的处理条件,并提出了一个成本低效果好的处理方案。     

Comprehensive alarm information processing technology with application in petrochemical plant

During the abnormal plant conditions, too much information is produced due to momentary plant excursions above alarm limits. This flood of information impedes correct interpretation and correction of plant conditions by the operator. Existing techniques for the design of alarm systems mostly have weak ability to handle complex hazard scenarios and increase the probability of larger safety issues. In this paper, a comprehensive alarm information processing (AIP) technology is introduced, called multi-round alarm management system (MRAMS), including several processing strategies: AIP based on single sensor, AIP based on sensor group, root cause diagnosis based on Bayesian network, sensor fault judgment method and false alarm inhibition method. In case studies, both simulation experiment and pilot application on a real petrochemical plant are presented. Results indicate the MRAMS is helpful in improving the accuracy of correctly diagnosing the root causes and hence avoiding false and redundant alarms. By adopting this new technology, the safe and reliable operation of the plant can be achieved, and the economic loss brought by improper alarms can be reduced.