微好氧颗粒污泥工艺降解五氯酚的实验研究

微好氧颗粒污泥工艺能够同时进行好氧氧化和厌氧还原过程，是处理五氯酚（PCP）的理想方法。对影响好氧颗粒污泥降解PCP的因素水力学上升流速、碱加入量以及水力停留时间进行考察。结果表明，水力学上升流速为4.58m／h，进水NaHCO3浓度为900mg／L，水力停留时间为24h时，处理效果比较好。     

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.     

Tributyltin partitioning in sediments: effect of aging

The effect of aging on the solid/pore-water partitioning and desorption behaviour of tributyltin (TBT) in sediments was examined. Three sediment samples with contrasting physical and chemical properties were spiked with 10 mg/kg TBT and aged under sterile conditions for periods of time ranging from 1 to 84 days. Aging had a negligible effect on partitioning and desorption behaviour in a sandy sample with very low organic carbon content (0.2% w/w). In contrast, for samples with larger amounts of organic carbon (2.6% and 4.8% w/w), aging caused substantial increases in TBT sorption. For these samples, apparent distribution coefficients (KD,app) obtained from sequential 2 h desorption experiments also exhibited a twofold increase between spiked sediments subjected to aging for 1 day and 84 days. This study demonstrates that aging effects may be an important aspect of TBT fate in contaminated sediments.     

Factors influencing arsenic accumulation by Pteris vittata: a comparative field study at two sites

This study compared the factors influencing arsenic (As) accumulation by Pteris vittata at two sites, one containing As along with Au mineralization and the other containing Hg/Tl mineralization. The soils above these two sites contained high As concentrations (26.8-2955 mg kg(-1)). Although the As concentration, pH, soil cation exchange capacity and plant biomass differed significantly between the two sites, no differences were observed in the As concentrations in the fronds and roots, or the translocation factors, of P. vittata, suggesting that this species has consistent As hyperaccumulation properties in the field. The As concentration in the fronds was positively related to phosphorus (P) and potassium (K), but negatively related to calcium (Ca), at one site. This suggested that P, K and Ca influenced As accumulation by P. vittata in the field.     

混凝-生物接触氧化法处理城市污水的研究

采用混凝-生物接触氧化法处理生活小区废水,考察了不同混凝剂用量对COD、NH4-N、SS、TP的去除效果,同时研究了生物接触氧化法对COD、NH4-N等的去除以及耐冲击负荷能力.结果表明,随混凝剂用量的增加,COD、SS、TP的去除率随之增加,生物接触氧化法具有较高的抗冲击负荷能力,最大NH4-N去除负荷达到0.55 kg/(m3·d),最大有机去除负荷达到4.32 kg/(m3·d)     

L-半胱氨酸改性甲壳素处理含铅、镉工业废水

研究了L 半胱氨酸改性甲壳素作为吸附剂对Pb2 + 、Cd2 + 的动态吸附性能 ,同时考察了流速、溶液中离子的含量、吸附剂的相对用量等因素对吸附效果的影响 ,以及洗脱液的种类和酸度、洗脱速度、洗脱液体积等因素对解吸率的影响。结果表明 ,用该吸附剂填装的吸附柱对含Pb2 + 、Cd2 + 工业废水直接进行处理 ,处理后的水达到了排放标准。     

Trace metal behaviour in the Conwy estuary,North Wales

The distribution of trace metals Zn, Ni, Mn, Fe, Cu, Pb, Cd and Cr between suspended particulate matter (SPM) and water in the Conwy estuary, North Wales, has been studied in three surveys in 1998. Dissolved Cu and Mn showed some monthly variations. Most of the dissolved trace metals displayed a negative association with salinity, indicating rivers as a major source of inputs for them. Particulate Zn, Mn and Fe showed a decreasing concentration seaward, whilst the levels of Ni, Cu, Cr and Pb increased with salinity. SPM concentration was the most important variable significantly related to trace metal concentrations in SPM, with an inverse relationship between the two parameters. This was explained by the relative enrichment of trace metals in fine particles at low SPM concentrations and relative depletion of trace metals in coarse particles at high SPM concentrations. Particulate Zn, Mn and Pb were dominated by the fraction available to acetic acid (non-detrital), whilst particulate Ni, Fe and Cr were dominated by the fraction available to nitric acid (detrital). The partition coefficient of trace metals between SPM and water declined with increasing SPM concentration, consistent with the so-called "particle concentration effect". Such a phenomenon may be explained by the presence of fine particles (including colloids) enriched with trace metals at low SPM concentrations, and the salinity-induced desorption.     

Combined glassification of EAF dust and incinerator fly ash

Stainless steelmaking dust contains large amount of heavy metals, such as Cr and Ni. If these hazardous materials are not treated properly, they will cause detrimental secondary contamination. Preliminary study on recycling stainless steelmaking dust employed the thermal molten technology. Glass-ceramics were formed by combination stainless steel dust and incinerator fly ash with the ratio of 1:9. The major phases were Augite, Akermanite, and Donathite. It was found that the glass-ceramics shows the best characteristic at 900 degrees C after 5 h of heat treatment. This product can be used as building materials or refractory materials.     

Multivariate statistical study of heavy metal enrichment in sediments of the Pearl River Estuary

The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.     

Modeling of flow and contaminant transport in coupled stream-aquifer systems

This paper describes an integrated approach for modeling flow and contaminant transport in hydraulically connected stream-aquifer systems. The code, FTSTREAM, extended the capabilities of the ground-water model, FTWORK, to incorporate chemical fate and transport in streams. Flow in the stream network is modeled as an unsteady, spatially varying flow, while transport modeling is based on a one-dimensional advection-dispersion equation. In addition to sorption and decay during transport in ground water, the model incorporates volatilization, settling and decay during transport in surface water. The interaction between surface water and ground water is accommodated by a leakage term and is implemented in the model using an iterative Picard-type procedure to ensure mass conservation across the interface between the two systems. The modeling approach is used to simulate contaminant transport in the Mad River, Ohio, which is hydraulically connected to a buried valley aquifer of sand and gravel outwash. The river is a receiving stream in the upstream part of the modeled area. Downstream, heavy pumping from a municipal well field causes the river to become a loosing stream. Induced infiltration from the river is responsible for a considerable portion of the well yield. The flow and transport model, developed for this study, simulates coupling between flow in the aquifer and the river. Hypothetical sources of contamination are introduced at selected locations in the upstream portion of the aquifer. The model is then used to simulate the expected transport in both the aquifer and the stream. A series of simulations elucidates the role of the river in facilitating the transport of the hypothetical contaminants in ground water and surface water. Effect of sorption, retardation and volatilization on contaminant transport is also examined for the case of the volatile organic compounds.