The treatment of black-odorous water using tower bipolar electro-flocculation including the removal of phosphorus,turbidity, sulfion,and oxygen enrichment

• An innovative bubble column tower BPE was designed to treat the black-odorous water. • PO₄³⁻, S²⁻ and turbidity were removed, and dissolved oxygen was enriched in the BPE. • An aluminum bipolar electrode gave the best oxygen enrichment and pollutant removal. • Changes of microorganisms confirmed the improvement in water quality achieved. The large amount of municipal wastewater discharged into urban rivers sometimes exceeds the rivers’ self-purification capacity leading to black-odorous polluted water. Electro-flocculation has emerged as a powerful remediation technology. Electro-flocculation in a bubble column tower with a bipolar electrode (BPE) was tested in an attempt to overcome the high resistance and weak gas-floatation observed with a monopolar electrode (MPE) in treating such water. The BPE reactor tested had a Ti/Ta₂O₅-IrO₂ anode and a graphite cathode with an iron or aluminum bipolar electrode suspended between them. It was tested for its ability to reduce turbidity, phosphate and sulphion and to increase the concentration of dissolved oxygen. The inclusion of the bipolar electrode was found to distinctly improved the system’s conductivity. The system’s electro-flocculation and electrical floatation removed turbidity, phosphate and sulphion completely, and the dissolved oxygen level improved from 0.29 to 6.28 mg/L. An aluminum bipolar electrode performed better than an iron one. Changes in the structure of the microbial community confirmed a significant improvement in water quality.     

The transport and retention of CQDs-doped TiO2 in packed columns and 3D printed micromodels

CQDs-doped TiO₂（C-TiO₂） has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO₂ in porous media is necessary for evaluating the environmental process of this new nanomaterial.Column experiments were used in this study to investigate ionic strength（IS）,dissolved organic matter（DOM）and sand grain size on the transport of C-TiO₂.The mobility of C-TiO₂ was inhibited by the incr...     

连续紫外扫描光谱法快速测定废水的化学需氧量

探讨了紫外扫描光谱最佳吸收波段内的吸光度集合所组成的峰面积与被测定废水的COD含量的相关性,同时进行了精密度和标准方法的比对实验,取得较好效果.该方法适用于多成分有机混合物的快速测定.     

Flame propagation through dust clouds of nano and micron scale aluminum particles

Temperature measurement on propagating flame and minimum explosible concentration are investigated. The dust explosion experiments of nano-particle dust clouds exhibit higher temperature gradient in preheat zone and lower MEC than those of micron particle dust clouds. A heterogeneous model is proposed to describe the oxidation process under two extreme conditions: whether the alumina film is involved in the reaction or not. The new methodology allows the estimation of oxidation kinetics of growing alumina. For micron particle, the model clarifies that the activation energy which has been wrongly considered to be for aluminum oxidation should be for lattice diffusion, and the initial reaction rate is proved to be dominated by the diffusion rate of oxygen through alumina shell as diffusion controlled reaction. For nano-particle, the model explained that why the reported activation energy shows significantly lower than that for micron particle, due to initially ignorable alumina film or considered as kinetically controlled reaction. However, as reaction occurs and alumina builds up on the surface, the interference of alumina somewhat increases the activation energy.     

Different stabilities of multiwalled carbon nanotubes in fresh surface water samples

The stability of multiwalled carbon nanotubes (MWNTs) in particulate aggregates and surfactant-facilitated suspensions after being mixed into eight types of fresh surface water samples was investigated. MWNTs in particulate aggregates could not be stabilized in any of the water samples except for the one having relatively high content of dissolved organic matter with the aid of sonication. Sodium dodecyl benzenesulfonate (SDBS), polyethylene glycol octylphenyl ether (TX100) and cetyltrimethyl ammonium bromide (CTAB) were used to prepare MWNT suspensions. SDBS- and TX100-stabilized MWNTs could partly remain suspending after being mixed into the water samples, whereas CTAB-stabilized MWNTs readily sedimentated due to the surface charge neutralization by the surface water contained negatively-charged anions and colloids. This is a first systematic study examining the stability of carbon nanotubes in natural surface waters, the results from which will be useful for understanding the transport, fate and ecological effect of carbon nanotubes in the aqueous environment.     

Arsenic mobility and speciation in a contaminated urban soil are affected by different methods of green waste compost application

Application of green waste compost (GWC) to brownfield land is now common practice in soil restoration. However, previous studies have demonstrated both beneficial and detrimental effects on arsenic and metal mobility. In this paper, trace element behaviour was investigated following GWC application, either as surface mulch to, or mixed into soil from a previously described brownfield site in the U.K. Significant differences in arsenic mobility were observed between treatments. Mulching caused most disturbance, significantly increasing soil pore water As, together with Fe, P, Cr, Ni and dissolved organic carbon, the latter was a critical factor enhancing As mobilization. Arsenate was the main inorganic As species in soil pore water, increasing in concentration over time. An initial flush of potentially more toxic arsenite decreased 4 weeks after compost application. Biological processes appeared to play an important role in influencing As mobility. The results point to the necessity for careful management of As-contaminated soils.     

Fenton试剂去除钻井污水CODCr技术研究

以钻井污水为研究对象初步研究了Fenton试剂处理污水各影响因素的作用机理,通过实验确定了Fenton反应的各种影响因素最佳工艺条件为:H2O2/CODCr为1.5,pH值为3,氧化反应时间3h,处理后水质达到综合污水排放一级标准(GB8978-1996),钻井污水中CODCr的去除率达95.2%,该工艺具有能耗低、运行成本低和操作简单等特点。     

Toxicity measurements in aqueous solution during ozonation of mono-chlorophenols

The Microtox toxicity and Oxygen Uptake Rate (OUR) inhibition tests were conducted to monitor the variation of toxicity during ozonation of 2-chlorophenol (2-CP), 3-chlorophenol (3-CP) and 4-chlorophenol (4-CP) under neutral conditions. The results revealed that the oxidized 2-CP solution exhibited new toxicity to pure bacteria and mixed microorganisms in the early stage of ozonation. The largest inhibition of OUR appeared at one mol of applied ozone dosage per mol of initial 2-CP, and the percentage of inhibition was 63.8%. In addition, ozonated 3-CP and 4-CP also significantly induced new aqueous toxicity, if these toxic intermediates were not further ozonated. Comparing the variation of toxicity and the hydroxylated/chlorinated intermediates formed, 3-chloro-catechol, 2-chloro-2, 4-hexadienedioic acid and the dimmer compounds may be related to the sources of toxicity during the ozonation of 2-CP.     

Characterization of haloacetic acid precursors in source water

Raw water from the Bangkok (Thailand) main municipal water supply canal was examined for its natural organic composition by fractionation with adsorption resins. DAX-8 resin was the first resin employed to fractionate the hydrophobic fractions. Fractionation at neutral pH resulted in the separation of the hydrophobic neutral components; at a high pH level (approx. 10) separation of the hydrophobic base components occurred; and at a low pH level (approx. 2) the hydrophobic acid components were separated. AG-MP-50 cationic resin was then used to separate the hydrophilic base components, and WA-10, a weak anionic resin, was applied finally to fractionate the hydrophilic acid and neutral components. Subsequently, each fraction was tested for its chlorine disinfection by-product (DBP) formation potential. The HAA formation tests demonstrated that the various organic fractions had different reactivity levels for the formation of haloacetic acids (HAAs). For this source water, the hydrophilic neutral fraction dominated over the other five fractions in being the main organic component and the most significant precursor of HAAs formation. On the other hand, in terms of specific HAA formation potential (FP), the hydrophobic and hydrophilic base fractions were the most reactive precursors to the formation of HAAs. In all cases, the quantity of HAAs formed depended linearly upon the amount of organic constituents in the water sample.     

松花江哨口至松花江村段浮游植物光合作用产氧模型研究

为研究松花江哨口至松花江村江段的水环境容量,本文从浮游植物光合作用机理出发,利用连续３年多项指标实测资料,采用外包线法,初步确定一种浮游植物光合作用产氧率计算关系式。将这种方法应用于研究江段效果较好,经相关性检验,r＝0.90,r＞r_0.01,相关性极显著。该计算式能否用于哨口至松花江村以外的江段,尚需进一步验证。