Performance evaluation of a full-scale natural treatment system for nonpoint source and point source pollution removal

This study presents a full-scale performance of a natural treatment system (NTS) facility in Taiwan with nearly 2 years of observations. The study site, composed of several treatment ponds in series, was designed primarily to reduce polluted stormwater runoff from tea gardens and partially to untreated domestic wastewater from nearby villages. Thus, both nonpoint source and point source pollution are treated in this system. From 28 field samplings in 2006-2007, the NTS site shows satisfactory treatment performance and the effluent water quality is significantly improved. Seven of the 28 sampling events are storm events (nonpoint source pollution) and the remainder are from regular monitoring (point source pollution). The average volume of influent and effluent is 533 CMD and 196 CMD, respectively. In order to determine the removal efficiency, several assessment measures are employed in an attempt to obtain unbiased conclusions. They are removal rate (RR), efficiency rate (ER), summation of loads (SOL), flux rate (FR), and effluent probability method (EPM). The average percent removal efficiency of NH(3)-N is 53.5-75.2% and of TP is 59.0-84.7%, in which the highest result is calculated by SOL method and the lowest rate is obtained from RR. In FR evaluation, larger treatment capacity for NH(3)-N than for TP is provided in the site and the average FR is respectively 0.230 g/m(2) day and 0.017 g/m(2) day. Of the methods examined, EPM is the only method capable of illustrating data distribution. Finally, recommendations on the usefulness of these measures are summarized to facilitate the understandings of NTS performance evaluations.     

Vegetation recovery patterns assessment at landslides caused by catastrophic earthquake: A case study in central Taiwan

The catastrophic earthquake, 7.3 on the Richter scale, occurred on September 21, 1999 in Central Taiwan. Much of standing vegetation on slopes was eliminated and massive, scattered landslides were induced at the Jou-Jou Mountain area of the Wu-Chi basin in Nantou County. We evaluated three methods for assessing landslide hazard and vegetation recovery conditions. (1) Self-organizing map (SOM) neural network coupled with fuzzy technique was used to quickly extract the landslide. (2) The NDVI-based vegetation recovery index derived from multi-temporal SPOT satellite images was used to evaluate vegetation recovery rate in the denudation sites. (3) The spatial distribution index (SDI) based on land-cover topographic location was employed to analyze vegetation recovery patterns, including the invading, surviving and mixed patterns at the Jou-Jou Mountain area. On September 27, 1999, there were 849.20 ha of landslide area extracted using the self-organizing map and fuzzy technique combined model. After six years of natural vegetation succession, the landslide has gradually restored, and vegetation recovery rate reached up to 86%. On-site observation shows that many native pioneer plants have invaded onto the denudation sites even if disturbed by several typhoons. Two native surviving plants, Arundo formosana Hack and Pinus taiwanensis Hayata, play a vital role in natural vegetation succession in this area, especially for the sites on ridgeline and steep slopes.     

盲样考核浓度预判及稀释方法——以原子荧光法测定水中砷为例

以原子荧光法测定水中砷为例,探讨了实验室盲样考核浓度预判及稀释方法.分析了3个砷盲样考核实例,归纳了“直接稀释法”“系列稀释法”“最大稀释法”3种方法,分别适用于盲样浓度范围窄、适中、宽3种情况,检测人员可根据考核机构给定的浓度范围合理选用.     

环境监测技术培训需求分析——应用OTP模型

简述了环境监测技术培训需求分析的重要性及OTP模型的概念.针对环境监测技术培训的现状和特点,设计了符合环境监测技术培训特点的OTP模型,提出了系统分析环境监测技术培训需求的方法,以及根据实际情况科学设置输入项的不同权重,充分考虑影响模型输出的各种因素,加强研究模型输入项的量化表征,动态调整模型的输入项的建议.     

Effect of air-drying and oven-drying treatment on Cr(VI) content and Cr bond forms in soil

Air-drying and oven-drying are pretreatment processes often used before testing and analyzing various soil characteristics in the laboratory. This study selected three kinds of soil, including red soil, entisol, and alluvial soil, and examined the variation of the Cr(VI) content and Cr bond forms in these soils during air-drying and oven-drying. The results show that when the soil is air-dried in natural environment, the Cr(VI) content decreases with air-drying time. On day 10 of air-drying, the Cr(VI) content in these soils is 22.8～47.9 % of the initial value. When the soil is oven-dried, the Cr(VI) concentration decays faster; on day 8, the Cr(VI) is no longer detected in these soil samples. When the Cr(VI)-contaminated soil is treated by air-drying and oven-drying, the Cr bond form converts into a more stable form. After oven-drying, the Cr mainly exists in Fe–Mn oxide form, organic bond form, and residual form. The air-drying and oven-drying pretreatment processes of soil reduce the Cr(VI) content and stabilize the Cr bond form. If the laboratory analytic results are applied to risk analysis or remediation strategy planning for chromium-contaminated soil, the toxicity, bioavailability, and mobility of Cr in soil may be underrated.     

建设项目竣工验收现场平行样控制指标研究

依据建设项目竣工环境保护验收中污水监测的要求,通过积累大量验收监测质量检查的实验数据,运用数理统计的方法,以化学需氧量和氨氮两个项目为例,建立了质控数据的评价方法,并确定了现场平行样偏差指标的限値。     

挥发性有机物污染土壤样品采样方法比较

以苯系物污染土壤样品的采集为例,比较了4种不同采样方法导致样品检测结果的差异。其中,方法 1将样品装填至广口瓶内并压实密封,方法2采用非扰动采样器采集10 g样品后转移至加有10 mL甲醇保护剂的Vial瓶中密封,方法 3用非扰动采样器采集10 g样品后直接将其密封于采样器内,方法 4用Encore采样器采样后将其密封于采样器内。结果表明,方法 2采集样品的检出率最高,其余3种方法的差异不明显,方法 2采集样品的检出结果 71%以上都大于其余3种方法。而且,对于挥发性较强的苯与甲苯,以方法 2采集的样品91%以上都大于其余3种方法,最大及平均检出浓度高出2~3个数量级。5种不同土质样品检测结果表明,对于有机质含量较低的细砂,方法2的最高及平均检出浓度均高于其余3种方法 1~3个数量级,差异随土壤有机质含量的升高而降低。可见,对于苯系物及挥发性强于苯系物的其他挥发性有机物污染土壤样品的采集,方法 2效果最优,可指定为VOCs污染场地土壤样品的采样方法。     

过硫酸盐去除石灰土介质中汽油BTEX的效果及乙醇的影响

为了认识岩溶区石灰土含水介质中化学氧化联合生物降解去除燃油苯系物的效果,以汽油中的苯、甲苯、乙苯和二甲苯(BTEX)作为污染物,通过批实验研究过硫酸盐(PS)联合硝酸盐去除汽油BTEX的效果,并认识不同浓度乙醇(EtOH)存在时带来的影响及化学氧化与反硝化联合修复的可能性.结果表明,在35 d内各组的BTEX去除率均达到91.00%以上,PS化学氧化能有效地去除BTEX.在不含EtOH及含EtOH初始浓度为500和5000 mg·L^-1的情况下,BTEX浓度在第65 d时分别为未检出、0.226 mg·L^-1、0.243 mg·L^-1,去除率分别为99.98%、99.00%、98.70%,其中,苯的去除率分别为99.98%、97.01%、93.32%.随着EtOH浓度的增加,苯的去除受到抑制,EtOH对BTEX的化学氧化具有阻碍作用.石灰土介质中高铁含量对PS具有活化能力,高含量有机质能促进PS分解,并导致pH值回升,出现反硝化作用和硫酸盐还原作用,有利于生物降解作用的恢复.     

间歇-阶段性酸雨入侵对填埋稳定化飞灰中重金属浸出行为影响

以间歇-分阶段进水方式进行了模拟酸雨柱式动态淋溶实验.结果表明,间歇-阶段性酸雨入侵会影响填埋飞灰中Pb、Zn、Cu、Cr和Ni的浸出行为;尤其间歇停滞期后的初期酸雨入侵会增加多数重金属的再浸出水平,且该部分重金属的释放主要源于前阶段酸雨侵蚀过程中所形成的非稳定性(弱酸态)重金属.各酸雨侵蚀阶段,部分重金属(如Pb-Zn)的浸出行为具有相关性,这与各重金属在飞灰基质内的赋存形态、矿物相稳定性及酸性侵蚀程度等有关.各阶段酸雨入侵会相继溶出飞灰中的可溶性(NaCl、KCl等)、难溶性氯盐(CaClOH)以及微溶性钙盐(CaSO₄),并增加CaCO₃和Ca-Al-Si-O等矿物的峰强.各阶段酸雨入侵会使初始飞灰表面的团簇状结构逐渐被酸性(H⁺)侵蚀作用破坏,并暴露出大量棒状或条形状CaCO₃晶体,且随着酸雨入侵次数的增加,CaCO₃也将逐渐被侵蚀破坏.本研究为非连续酸性降雨条件下填埋稳定化飞灰的重金属浸出行为评价及风险管控提供了科学依据.     

The general utilization of scrapped PC board

The traditional burning process is used to recover copper from scrapped PC board (printed circuit board) but it causes serious environmental problems. In this research a new process was developed which not only prevents pollution problems, but also maximizes the utility of all the materials on the waste board. First, the scrapped PC board was crushed and grounded, then placed in the NH₃/NH₅CO₃ solution with aeration in order to dissolve copper. After distilling the copper NH₃/NH₅CO₃ solution and then heating the distilled residue of copper carbonate, pure copper oxide was obtained with particle size of about 0.2 μm and the shape elliptical. The remaining solid residue after copper removal was then leached with 6 N hydrochloric acid to remove tin and lead. The last residue was used as a filler in PVC plastics. The PVC plastics with PC board powder as filling material was found to have the same tensile strength as unfilled plastics, but had higher elastic modulus, higher abrasion resistance, and was cheaper.