Effects of inorganic chlorine source on dioxin formation using fly ash from a fluidized bed incinerator

Chlorine source is indispensable for polychlorinated dibenzo-p-dioxin and furan (PCDD/F) formation during municipal solid waste (MSW) incineration. Inorganic chlorine compounds were employed in this study to investigate their effects on PCDD/F formation through heterogeneous synthesis on fly ash surfaces. A fly ash sample obtained from a fluidized bed incinerator was sieved to different size fractions which served as the PCDD/F formation sources. The capability of different metal chlorides which facilitate the formation of PCDDs/Fs was found to follow the trends: Na ＜ Mg ＜ K ＜ Al ＜ Ca, when two particle fractions of ＞177 μm and 104-125 μm were used in the experiments. However, the capability of NaCl, MgCl2 and KCl did not seem much different from each other, whereas CaCl2 and AlCl3 were much more active in PCDD/F formation. NaCl and MgCl2 were relatively effective to produce more PCDDs, while KCl, AlCl3 and CaCl2 generated more PCDFs during heterogeneous reactions occurring on fly ash. 2,3,7,8-TCDF was the most significant contributor to the toxicity of the PCDDs/Fs formed from inorganic chlorine sources. Decreasing the sizes of fly ash particles led to more active formation of PCDDs/Fs when NaCl was used as inorganic chlorine in the experiment. The highest PCDDs/Fs produced from particles with size ＜37 μm, while the lowest PCDDs/Fs produced from particles with size ＞177 μm. The toxicity generally increased with decreasing size of the fly ash particles. The formation of PCDDs was mainly facilitated by the two size fractions, 104-125 μm and ＜37 μm, while formation of PCDFs was favored by the two other size fractions, ＞177 μm and 53-104 μm.     

模拟及河道实验浮床水芹根系生长及生物量分配对比研究

为了对比研究浮床植物水芹菜在模拟及野外河道实验中根系生长及生物量分配的差异性,探索水芹浮床模拟实验与实际应用中的差异性,我们在实验河道边放置水箱,通过抽取河水到水箱中设置水芹浮床水箱模拟实验,并且与河道中水芹浮床实验作对比。结果发现:河道和水箱中植物根系指标除了平均根直径外其他指标随着水芹的生长以指数方式增长,平均根直径随着水芹的生长以指数方式下降;在根系总长度、根系总表面积、根系分叉数、根系交叠数方面,水箱中的水芹显著大于河道中的水芹(p0.05);水箱浮床水芹根系指标的增长速度大于地上部分的增长速度,河道中水芹地上部分增长速度要大于地下部分;水芹冠根比随时间的变化呈现出先下降后上升趋势,水箱中水芹冠根比的变化速率更小。水箱中的水芹受到了营养条件的限制,用模拟水芹浮床来研究其净化效率时,在一定程度上(与实际应用相比)高估了河道水芹浮床根系部分的作用。     

Grazed Riparian Management and Stream Channel Response in Southeastern Minnesota (USA) Streams

The U.S. Department of Agriculture-Natural Resources Conservation Service has recommended domestic cattle grazing exclusion from riparian corridors for decades. This recommendation was based on a belief that domestic cattle grazing would typically destroy stream bank vegetation and in-channel habitat. Continuous grazing (CG) has caused adverse environmental damage, but along cohesive-sediment stream banks of disturbed catchments in southeastern Minnesota, short-duration grazing (SDG), a rotational grazing system, may offer a better riparian management practice than CG. Over 30 physical and biological metrics were gathered at 26 sites to evaluate differences between SDG, CG, and nongrazed sites (NG). Ordinations produced with nonmetric multidimensional scaling (NMS) indicated a gradient with a benthic macroinvertebrate index of biotic integrity (IBI) and riparian site management; low IBI scores associated with CG sites and higher IBI scores associated with NG sites. Nongrazed sites were associated with reduced soil compaction and higher bank stability, as measured by the Pfankuch stability index; whereas CG sites were associated with increased soil compaction and lower bank stability, SDG sites were intermediate. Bedrock geology influenced NMS results: sites with carbonate derived cobble were associated with more stable channels and higher IBI scores. Though current riparian grazing practices in southeastern Minnesota present pollution problems, short duration grazing could reduce sediment pollution if managed in an environmentally sustainable fashion that considers stream channel response.     

高氨氮化工废水MBBR—AMBBR—MBBR组合工艺处理

采用移动床生物膜反应器（MBBR）—厌氧移动床生物膜反应器（AMBBR）—MBBR组合工艺处理高氨氮化工废水。反应器采用几何构型优化、比表面积大的新型YD-25生物载体和DNF-203硝化细菌,实现了同步硝化和反硝化,强化了脱氮能力。采用投加菌种和排泥的方式,经27 d的驯化培养即完成了反应器的挂膜启动。试验结果表明：最佳操作条件为HRT 8 d、MBBR中DO 3 mg/L、进水pH 8.0;在进水COD 2 840~7 437 mg/L、ρ（氨氮）92~179 mg/L、TN 148~258 mg/L、pH 6~8的条件下,出水指标均值为COD 352 mg/L、ρ（氨氮）21.2 mg/L、TN 36 mg/L、pH 7.4,满足排放要求。     

Fenton流化床陶瓷膜反应器处理造纸废水的膜污染与清洗

采用Fenton流化床陶瓷膜反应器处理造纸废水二级出水,研究了陶瓷膜膜污染的机理,提出了相应的清洗再生方案。实验结果表明:Fenton流化床陶瓷膜反应器处理后废水的溶解性有机碳和色度去除率分别达到84.2%和94.1%。通过Darcy定律模型计算,过滤阻力主要来自于滤饼层阻力,约占总阻力的62.1%;滤饼层中主要污染物为悬浮固体,约占滤饼层总质量的75.4%;疏水性有机物是造成滤饼层污染的主要溶解性有机物,而亲水性有机物更易造成膜孔堵塞;腐殖酸对滤饼层和膜孔堵塞影响较大,而蛋白质比多糖更易引起膜孔堵塞。采用HNO_3清洗污染膜效果最佳,在HNO_3质量分数1.00%、反应时间15 min时,膜通量恢复率达73.6%。     

并流旋转床气相压降数值模拟与实验研究

旋转床气相压降是设计旋转床的重要技术指标之一。通过分析并流旋转床结构与工作原理,建立气相压降的理论模型。采用Eulerian多相流模型和k-ε模型对并流旋转床气相压降进行数值模拟,探索液体分布器结构对气相压降的影响。实验表明所建立的压降模型较好地解释了实验现象,孔型分布器有利于减小气相压降。     

A^2/O-MBR组合工艺运行优化与氮磷深度控制的分析

为了遏制水环境不断恶化的趋势,应加强对氮、磷超标的治理工作,促进水生态环境平衡发展。本文采用A^2/O-MBR作为主体工艺,后续辅以化学除磷和以深床滤池为反硝化单元的组合工艺,确保最终出水满足天津市《城镇污水处理厂污染物排放标准》(DB12/599-2015)A标准排放要求。     

不同填充率对移动床生物膜反应器的产泥性能影响研究

研究了不同填充率下（10%～70%）移动床生物膜反应器的生物膜特征和处理效果,以及填充率与污泥产率的关系。结果表明：随着填充率的增加,填料上生物膜厚度逐渐减少,反应器中附着微生物浓度逐渐增加;污泥产率因填充率不同而有很大差异,同一个反应器内污泥产率随填充率的增加而减少;在进水COD为400 mg/L、NH⁺₄-N为40 mg/L、水力停留时间为12 h条件下,不同填充率下COD去除率均可达到94%以上,NH⁺₄-N去除率达到97%以上。     

生态浮床及辅助技术治理汇丰河黑臭水体

采用生态浮床为核心,辅以微曝气复氧、纳污减污栅和人工介质等多项技术,对上海市汇丰河黑臭水体进行治理,工程取得了预期效果,水体透明度由原来的平均小于20cm增加到平均50cm以上,主要水质指标NH3-N、TP、CODMn的最大净化率平均分别达到了69．9％、80．7％和63．5％,河道生物多样性显著提高。     

煤层气采出水中重金属含量分析

概述了国内外煤层气的开发利用现状,针对煤层气开发过程中采出水的利用价值,结合多个井场采出水的样品实测数据,详细讨论了重金属及其他污染物含量对煤层气采出水利用价值的影响,对其中所含各类污染物质及重金属进行了分类对比分析,提出了煤层气采出水综合利用的处理建议。