夏季潮滩对上海老港垃圾填埋场渗滤液氮、磷净化效果研究

垃圾填埋产生的渗滤液造成的环境污染问题El益严重。采用自然湿地对垃圾渗滤液净化有诸多优点,而相关的研究较少。根据渗滤液的不同浓度和不同滞留时间的净化效果不同,采用实验室模拟和培养的方法来研究老港垃圾填埋场附近潮滩对垃圾渗滤液营养盐N、P的净化效果。研究发现：夏季老港中、低潮滩在较短滞留时间（6h）内对各浓度渗滤液中N、P的净化效果不明显,而在较长滞留时间内（96h）中、低潮滩对各浓度渗滤液净化效果明显,净化后污水中N、P含量可达到排放标准;垃圾渗滤液质量分数为5％时,潮滩对N、P的净化效果最为明显。     

生物脱氮工艺控制优化策略的研究进展

针对传统的单污泥生物脱氮系统具有所需反应器体积大、硝化反硝化效率低及对进水COD利用率低等一系列问题 ,总结了提高生物脱氮工艺效率的在线控制策略 ,如曝气控制、外投碳源控制和污泥龄控制 (SRT) ,为当前污水厂在工艺设计一定的限制性条件下进行在线优化以满足日益严格的排放标准提供了重要保证。     

膜生物反应器处理城市污水的影响因素研究

采用缺氧/好氧一体式膜生物反应器(A/O-MBR)处理城市污水,试验结果表明:系统处理效果稳定,出水COD、NH3-N、TN的平均去除率分别达到92%、95%和80%以上,各项出水水质优于《城市杂用水水质》(GB/T18920-2002)标准。当水力停留时间在6~18 h、曝气强度(气水比)在20∶1~60∶1之间变化时,水力停留时间和曝气强度对MBR运行效果的影响不甚显著;温度对COD去除的影响不大,但温度对NH3-N、TN有显著的影响,温度由9.5℃升至30℃时,NH3-N、TN去除率分别由6.2%、7.9%提高到99.0%、83.3%。     

粪便与生活垃圾混合堆肥氮转化与腐熟度

采用静态仓强制通风进行粪便和生活垃圾混合堆肥,以玉米秸和石灰为调理剂,考察堆肥过程的氮转化与腐熟度。试验结果表明:堆肥中氮的损失量为26%～49%,堆体高温期持续时间长,导致氮的损失增加。添加石灰使堆肥前期的氮损失率增加,但加快了堆肥过程,总氮的损失没有加大。水溶性氨氮含量在堆肥升温期出现峰值5.61mg/gdw,堆肥结束时氨氮含量小于0.34mg/gdw;堆肥中硝态氮主要在降温期和腐熟期形成,达到1.84～4.05mg/gdw。氨氮和硝态氮之比小于0.16和水溶态有机碳与总氮之比小于1.10,较适合作为粪便与垃圾的混合堆肥腐熟指标。     

反应器理论在复合垂直流构建湿地水流流态研究中的应用

运用反应器理论研究了一种新型的复合垂直流构建湿地系统(IVCW)的水流流态,由示踪剂试验得到水流停留时间分布(RTD),从而确定了IVCW在水力负荷为200～800mm/d时,停留时间为19～35h,并由RTD曲线的特征值确定IVCW的水流流态介于理想推流与完全混合流之间,同时应用离散流模型,不仅较好地模拟了IVCW的实际水流流态,还得到了水流的Peclect准数在11～19之间.通过有植物与无植物系统的对照发现植物根系有利于IVCW的水流流态接近理想推流状态.     

不同植物人工湿地净化效果及基质微生物状况差异分析

为研究不同植物对人工湿地污染物净化效果和基质微生物状况的影响,采用序批式运行的沙培模拟人工湿地,探讨了菖蒲、香蒲、千屈菜、芦苇和白鹤芋5种湿地植物在不同HRT(水力停留时间,分别为1,3和5 d)下对模拟废水中TP,NH₄+-N和COD_Cr去除效果的影响,比较了不同植物类型模拟人工湿地中基质微生物的数量差异. 结果表明,不同植物系统对污染物的去除随HRT延长逐渐提高,HRT为5 d时各植物系统对污染物的去除效果最佳.TP,NH₄+-N和COD_Cr的最高去除率分别达90.4%,61.7%和96.4%.相对于其他试验系统,菖蒲系统对各污染指标均具有最优的去除效果. 植物种类对基质微生物数量的影响无显著差异.研究还发现,各系统中亚硝酸细菌数量与NH₄+-N去除率之间呈显著相关.      

藻类有机物对纳滤膜去除萘普生效果影响研究

研究了2种藻类(鱼腥藻/小环藻)有机物(AOM)对纳滤膜去除萘普生(NPX)的影响效果.结果表明,在藻类AOM存在的情况下HL纳滤膜对NPX的去除率由63%增加至64.7%(小环藻)和72.7%(鱼腥藻);但同时造成了严重的膜污染,比通量由99.7%下降至89.6%(小环藻)和86.3%(鱼腥藻).研究发现,藻类AOM的中等分子量(1.5~5kDa)发挥了重要的作用,它们主要由疏水性有机物构成,紧密地黏附在膜表面形成滤饼层,使膜表面的疏水性增强.滤饼层的疏水性造成膜通量衰减并提高NPX去除率.研究还表明,鱼腥藻AOM在中等分子的疏水性明显比小环藻的强,造成的膜污染更严重以及更高的NPX去除效果.     

Metabolism and excretion of orally and intraperitoneally administered trimethylarsine oxide in the hamster

When trimethylarsine oxide (TMAO) was administered orally to hamsters once only, 86.9±11.1% of the administered dose of the compound was exreted in the urine during the following 24 hours: TMAO proved to be an arsenic compound eliminated extremely rapidly. The unchanged form of TMAO was the one and only trimethylarsenic compound (TMA) detected in the urine: in othe words, TMAO proved neither to be demethylated nor to be converted to arsenobetaine. It was shown, on the other hand, that TMAO is partly reduced in vivo and that only trimethylarsine was detected in expired air.     

Release of Cd immobilized by soil constituents and its bioavailability

Release of Cd immobilized by soil constituents (clay, humic acids, bacterial cells) in vitro and under soil conditions and its bioavailability to lettuce were studied. The most resistant to extraction with 0.02 M EDTA in vitro as well as under soil conditions was cadmium immobilized by humic acids during decomposition of contaminated plant residues but Cd‐dead cells when 0.1 M NaNO₃ was the extractant.

Cadmium addition (3 mg kg^‐1) to soil and its form were without effect on plant growth and amount of metal accumulated in roots. Tops of plants grown in soil supplemented with Cd‐resting cells contained significantly less metal then other ones.     

Nitrogen dynamics in the sediments of a wetland coastal ecosystem of southern India

The study area, Kuttanad Waters is a part of the Cochin estuarine system on the west coast of India. Kuttanad is well known for its agricultural activity and so the major contribution to the inorganic ions of nitrogen will be from fertilisers applied in agriculture. Based on observed salinity the stations have been divided into three zones. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. The chemical speciation scheme applied here distinguishes three forms of ammoniacal nitrogen species: exchangeable, fixed, and organic ammoniacal nitrogen. No significant trends were observed in the seasonal distribution of total, exchangeable, fixed and organic nitrogen. A significant concentration of exchangeable ammonia was observed in the sediment due to their predominantly reducing environment, which restricts nitrification. High NH₄-N concentrations in the pore waters, along with the sedimentary composition leads to a significantly high quantity of fixed NH₄-N. The low values for N org is due to high mineralisation or deamination of organic nitrogen