污染地下水原位处理方法:可渗透反应墙

可渗透反应墙法是 2 0世纪 90年代新兴的一种地下水污染原位处理方法 ,该方法目前在欧美已开始进入广泛的工程应用阶段。该方法与早期的一些处理方法相比 ,具有能持续原位处理、处理组分多、价格相对便宜等特点。本文系统介绍了该处理方法的基本原理、系统的结构构造和类型、处理机理和反应材料以及设计与施工等 ,为在我国开展该方法的研究和应用打下基础。     

TCE/PCE的DNAPL污染及零价铁墙防治技术

介绍了一种国内环保领域鲜有提及的土壤及地下水中的重非水相液体污染即:DNAPL污染,并以三氯乙烯(TCE)和四氯乙烯(PCE)为例阐述了其产生来源、危害及污染行为.针对DNAPL污染,详细论述了零价铁墙防治原理、降解途径及其主要的影响因素.     

Hydraulic constraints on the performance of a groundwater denitrification wall for nitrate removal from shallow groundwater

Denitrification walls are a practical approach for decreasing non-point source pollution of surface waters. They are constructed by digging a trench perpendicular to groundwater flow and mixing the aquifer material with organic matter, such as sawdust, which acts as a carbon source to stimulate denitrification. For efficient functioning, walls need to be permeable to groundwater flow. We examined the functioning of a denitrification wall constructed in an aquifer consisting of coarse sands. Wells were monitored for changes in nitrate concentration as groundwater passed through the wall and soil samples were taken to measure microbial parameters inside the wall. Nitrate concentrations upstream of the wall ranged from 21 to 39 g N m(-3), in the wall from 0 to 2 g N m(-3) and downstream from 19 to 44 g N m(-3). An initial groundwater flow investigation using a salt tracer dilution technique showed that the flow through the wall was less than 4% of the flow occurring in the aquifer. Natural gradient tracer tests using bromide and Rhodamine-WT confirmed groundwater bypass under the wall. Hydraulic conductivity of 0.48 m day(-1) was measured inside the wall, whereas the surrounding aquifer had a hydraulic conductivity of 65.4 m day(-1). This indicated that during construction of the wall, hydraulic conductivity of the aquifer had been greatly reduced, so that most of the groundwater flowed under rather than through the wall. Denitrification rates measured in the center of the wall ranged from 0.020 to 0.13 g N m(-3) day(-1), which did not account for the rates of nitrate removal (0.16-0.29 g N m(-3) day(-1)) calculated from monitoring of groundwater nitrate concentrations. This suggested that the rate of denitrification was greater at the upstream face of the wall than in its center where it was limited by low nitrate concentrations. While denitrification walls can be an inexpensive tool for removing nitrate from groundwater, they may not be suitable in aquifers with coarse textured subsoils where simple inexpensive construction techniques result in major decreases in hydraulic conductivity.     

郴州市王仙岭尾砂库重金属污染治理工程实例

介绍了湖南省郴州市王仙岭旅游度假区尾砂重金属污染治理工程,包括该场地重金属污染的现状调查与分析,修复技术的分析和选用以及实施工艺。为防止尾砂污染扩散,该工程主要采用重金属稳定化和阻隔防渗组合技术。该工程的成功实施证明其所采用的调查方法、工程技术和施工工艺的有效性,可为同类项目的调查、设计与施工提供参考借鉴。     

Experimental studies of removing typical VOCs by dielectric barrier discharge reactor of different sizes

This research conducted both lab-scale and pilot-scale tests by selecting toluene as the typical volatile organic compounds (VOCs) and by using the promising non-thermal plasma oxidation technology – dielectric barrier discharge (DBD). To develop baseline engineering data to demonstrate the feasibility of application of self-made DBD reactors, the peak voltage, gas flow speed, initial toluene concentration, discharge frequency and duty ratio were studied. The results showed that toluene removal efficiency improves with increase of electrical voltage, frequency and duty ratio, and declines with increase of polar distance, gas flow speed and toluene initial concentration. When the voltage increases, the energy efficiency rises first and then drops. The energy efficiency reaches the climax when the energy density reaches 150.8 J/L and 101.7 J/L in the lab-scale experiment and pilot-scale experiment respectively.     

The influence of hyperbaric oxygen therapy on intestinal mucosal barrier function in rats with acute carbon monoxide poisoning

Hyperbaric oxygen increases the partial pressure of O₂ in arterial blood and tissues and thereby relieves cellular hypoxia. We investigated whether this treatment changes biochemical parameters and intestinal mucosal barrier function in rats exposed to toxic levels of CO. Groups of ten Sprague–Dawley rats were treated with CO, with hyperbaric oxygen, or with CO followed by hyperbaric oxygen. A fourth group maintained under normal atmospheric conditions served as a control. CO poisoning increased red blood cell distribution width and the amount of alanine aminotransferase, urea nitrogen, and tight junction creatine kinase but decreased the mean corpuscular hemoglobin (Hb). These changes were reversed after hyperbaric oxygen therapy, which increased the number of red blood cells, hematocrit level, total protein, and Hb level. Hyperbaric oxygen therapy also increased tight junction protein 1 expression and reduced toll-like receptor 4 expression in the rat colon. In conclusion, hyperbaric oxygen resulted in an improved oxic condition in CO-poisoned rats and restored energy metabolism by repairing, to some extent, the organs injured by CO. The therapy may also improve the function of the intestinal mucosal barrier.     

傍河型水源井氨氮阻断与去除工程设计案例分析

针对沈阳市傍河型水源地的氨氮(NH+4-N)污染问题,通过野外研究区的水文地质调查,在查明研究区NH+4-N污染特征的基础上,结合室内批试验、柱实验和数值模拟,筛选出最佳的NH+4-N去除方案,提出了研究区渗透反应格栅(PRB)构建方案,并成功构建了示范工程尺度的PRB,用以去除地下水中的NH+4-N污染.室内批实验和柱实验表明,利用微生物硝化作用结合沸石的吸附作用去除地下水中NH+4-N是可行的.通过对研究区水质数值模拟,发现构建有一定弧度的PRB能最大限度的保护水源井.在PRB的构建过程中,利用高压旋喷技术和旋挖技术解决了大深度(30 m)PRB的构建问题,且PRB建成运行监测表明,示范工程尺度的PRB能有效阻断和去除地下水中NH+4-N.     

介质阻挡放电等离子协同TiO_2-GAC降解甲基橙的研究

采用介质阻挡放电(DBD)等离子协同颗粒活性炭负载TiO2(TiO2-GAC)对甲基橙进行降解,研究了该体系的协同处理效果,探讨了放电电压、初始pH、初始电导率、初始浓度和TiO2-GAC投加量等操作参数的影响,并建立了协同体系的表观反应动力学模型.实验结果表明,DBD与TiO2-GAC联合处理表现出明显的协同效应,处理25min后,协同体系对甲基橙的降解率和COD去除率分别为96.2%和90%,与单独DBD体系相比,分别提高了52.7%和50.4%;协同体系降解甲基橙的过程符合表观反应动力学模型,模型值与实验值吻合良好,总级数为2.352;体系中H2O2、O3浓度测定结果表明,与单独DBD体系对比,协同体系的H2O2浓度增高,而O3浓度降低,说明TiO2-GAC起到了催化作用;TiO2-GAC在DBD体系中获得了原位再生,五次再生循环后再生率达80%.     

国内道路声屏障行业发展中的几个问题浅析

随着国内交通的发展,铁路、公路、桥梁、地铁、轻轨、高架路越来越多,车速越来越快,人们在享受便捷交通的同时也越来越受到交通噪声的困扰,声屏障作为交通噪声治理的主要手段,已得到大规模使用,本文根据作者个人的经验和体会,总结了行业的现状和存在的问题,得出门槛低、预算低、标准落后是目前阻碍声屏障行业发展和水平提高的关键。     

HCl改性沸石和方解石复合覆盖层控制底泥氮磷释放的效果及机理研究

提出了HCl改性沸石和方解石复合覆盖控制底泥氮磷释放的新方法,利用摇床振荡试验和底泥氮磷释放控制模拟试验,设计了5种底泥处理方案,重点针对HCl改性沸石和方解石复合覆盖技术研究了其抑制底泥氮磷释放的效果及机理.结果表明,方解石覆盖层可以较好地抑制底泥磷的释放,而对底泥氨氮释放的抑制效果较差.天然沸石和方解石复合覆盖层不仅可以有效地抑制底泥氨氮的释放,而且可以有效地抑制底泥磷的释放.采用HCl对沸石进行改性,可以提高沸石和方解石复合覆盖层抑制底泥磷释放的效率,模拟期间复合覆盖层对底泥磷释放通量的抑制率由天然沸石的84%提高到HCl改性沸石的91%.采用HCl对沸石进行改性,降低了沸石和方解石复合覆盖系统有效控制底泥氨氮释放的持续时间,与天然沸石相比,相同投加量条件下HCl改性沸石有效控制底泥氨氮释放的持续时间缩短了1/3左右.采用HCl对沸石进行改性增强了复合覆盖系统抑制底泥磷释放效率的机理与HCl改性降低了沸石Na⁺的交换量并提高了沸石H⁺的交换量相关.