Atmospheric DDTs over the North Pacific Ocean and the adjacent Arctic region: Spatial distribution,congener patterns and source implication

During the 2003 Chinese Arctic Research Expedition (CHINARE 2003) from Bohai Sea to the high Arctic (37°N–80°N), air samples were collected and analyzed for DDTs. ∑DDTs (sum of six congeners) ranged from 0.52 to 265 pg m^?3 with an average of 13.1 pg m^?3. Higher DDT concentrations were observed in Bohai Sea and near eastern Russia. The congener patterns were obviously different between the Far East Asia and the higher latitudinal regions that p,p'-DDT and o,p'-DDT were dominated in the former; while o,p'-DDT and o,p'-DDE were dominated in the latter. The source contributions of technical DDT and dicofol type DDT were estimated. Results showed that technical DDT was the dominant source (>94%) which was fresher in the Far East Asia compared to the North Pacific Ocean and the Arctic. For dicofol type DDT, the estimated contribution was minor. The “new” o,p'-DDT observed should have relatively more contribution from dicofol type DDT in the North Pacific Ocean and the Arctic.     

铁水包底粘铁所引发的一起重伤事故分析

介绍了一起铁水包底粘铁所引发的事故经过,进行了事故原因分析,指出了事故教训和预防措施。     

生物絮凝法与化学絮凝法处理洗毛废水的比较

分别采用生物絮凝法和化学絮凝法处理300 mL COD为20 000 mg/L、SS为4 000 mg/L的洗毛废水,最佳生物絮凝条件:生物絮凝剂加入量为5 mL,反应温度为30℃,先以120 r/min搅拌5 min、再以60 r/min搅拌35 min,洗毛废水pH为9.0.COD去除率达92%.最佳化学絮凝条件:化学絮凝剂加入量为30 mL,反应温度为40℃,先以120 r/min搅拌5 min、再以60 r/min搅拌25 min,洗毛废水pH为5.0.COD去除率达93%.生物絮凝剂和化学絮凝剂对洗毛废水的絮凝效果接近,但生物絮凝剂的加入量比化学絮凝剂少很多.     

酸性硫酸盐土研究现状与发展趋向

对国内外酸性硫酸盐土的研究现状进行了综述，并提出了有关今后酸性硫酸盐土研究的几个重要发展方向：（1）酸性硫酸盐土的酸释放机制；（2）酸性硫酸盐土的生态环境效应及其全球变化贡献与生态风险评价；（3）退化酸性硫酸盐土的恢复与重建的接口技术体系；（4）酸性硫酸盐土的可持续利用模式与管理。     

粉尘爆炸强度分级方法存在问题分析

介绍了目前国际上粉尘爆炸强度分级方法及分级判据，并对其存在的问题进行了分析，在此基础上提出新的等级划分及分级判据。     

Field Testing and Computer Modeling of an Oxygen Combustion System at the EPA Mobile Incinerator

The LINDE® Oxygen Combustion System has been demonstrated successfully at the EPA Denney Farm site as part of the modified EPA mobile incinerator. This paper describes the field testing results and computer modeling of the LINDE system. The oxygen system enables the EPA unit to incinerate dioxin and PCB contaminated soil at a consistent rate of 4000 lb/h—200 percent of the original maximum capacity. The pure oxygen combustion system improved the thermal efficiency of the incinerator by over 60 percent and reduced the flue gas volume dramatically. Therefore, the dust carryover problem was mitigated. The destruction and removal efficiencies of hazardous wastes exceeded EPA requirements.

The design of the proprietary burner allows the use of up to 100 percent oxygen in place of air for incineration with improvements over conventional oxy-fuel burners. As a result, the temperature distributions in the rotary kiln are uniform and NO_x emissions are low.

The oxygen combustion system, controlled by a programmable controller, provided much better response and flexibility than conventional air based systems. The system generated a stable flame and responsed well to the transient conditions of the rotary kiln. Kiln puff occurrence was virtually eliminated in the operation of the mobile incinerator.

A computer model of the incinerator was developed and used for the process design of the LINDE system. The model predicted the test results reasonably well. This model can be a useful tool in the design and operation of rotary kiln incineration systems.     

Time domain reflectometry measured moisture content of sewage sludge compost across temperatures

Time domain reflectometry (TDR) is a prospective measurement technology for moisture content of sewage sludge composting material; however, a significant dependence upon temperature has been observed. The objective of this study was to assess the impacts of temperature upon moisture content measurement and determine if TDR could be used to monitor moisture content in sewage sludge compost across a range of temperatures. We also investigated the combined effects of temperature and conductivity on moisture content measurement. The results revealed that the moisture content of composting material could be determined by TDR using coated probes, even when the measured material had a moisture content of 0.581 cm³ cm^?3, temperature of 70 °C and conductivity of 4.32 mS cm^?1. TDR probes were calibrated as a function of dielectric properties that included temperature effects. When the bulk temperature varied from 20 °C to 70 °C, composting material with 0.10–0.70 cm³ cm^?3 moisture content could be measured by TDR using coated probes, and calibrations based on different temperatures minimized the errors.     

Tar-free fuel gas production from high temperature pyrolysis of sewage sludge

Pyrolysis of sewage sludge was studied in a free-fall reactor at 1000–1400 °C. The results showed that the volatile matter in the sludge could be completely released to gaseous product at 1300 °C. The high temperature was in favor of H₂ and CO in the produced gas. However, the low heating value (LHV) of the gas decreased from 15.68 MJ/N m³ to 9.10 MJ/N m³ with temperature increasing from 1000 °C to 1400 °C. The obtained residual solid was characterized by high ash content. The energy balance indicated that the most heating value in the sludge was in the gaseous product.