如何掌握湿球溶冰及溶冰不当的处理方法

如何掌握湿球溶冰及溶冰不当的处理方法王国贵在秋冬交替的季节中常常因湿球纱布结冰而影响大气的湿度测量。如何获得准确的湿球温度，对于提高湿度的准确度至关重要。正确掌握湿球溶冰时机又是获得准确湿球湿度的关键所在。ｌ如何掌握溶冰时间在北方进入冬季，气温降至使...

治理深圳河工程河道污染土处理方案及设计优化

治理深圳河工程的河道开挖项目,需按污染土和非污染土分别进行施工,对污染土进行大规模的处理在国内的水利工程中尚属首次。本文介绍了深圳河污染土的分层开挖、弃置、淋溶水处理、水质的监测以及所取得的工程实践经验,供大家参考借鉴。

Removal of cadmium from aqueous solutions using red mud granulated with cement

A novel adsorbent was prepared from granular red mud mixed with cement and its potential to be a suitable adsorbent for the removal of cadmium ions from aqueous solutions was evaluated. The wet red mud was directly mixed up with cement at different mass fractions of 2%-8% and their properties were investigated. Based on the textural characteristics and strength, the granular red mud with 2% addition of cement maintaining for 6 d is identified to have better properties. The batch adsorption experiments for adsorption of Cd2+ ions from solution were performed at 30, 40 and 50 °C at different initial concentrations under the condition of constant pH of 6.5. The equilibrium adsorption was found to increase with the increase of temperature during the adsorption process. Langmuir adsorption isotherm model was found to match the experimental adsorption isotherm better. The kinetics of adsorption was modeled using a pseudo second order kinetic model and the model parameters were estimated.

Ozonation and Biodegradability of Lignin in Water

To convert the non biodegradable sodium lignin sulfonate into biodegradable substances, the sodium lignin sulfonate in the water was ozonized and the pH value, dissolved organic carbon(DOC), ultraviolet absorbency at λ =254 nm(UVA) and the biodegradability of the ozonation effluent were measured. The non biodegradable sodium lignin sulfonate can be partly converted into biodegradable substances by ozonation (about 38 76%). In the ozonation process, there is little DOC decrease, but much UVA decrease and obvious pH drop.

Synthesis of ZnO whiskers via hydrothermal decomposition route

ZnO whiskers with a length of 30-40μm and a diameter of about 1μm were synthesized by co-precipitation of ZnSO 4 and Na2CO3 solution at room temperature followed by hydrothermal treatment of the as-prepared Zn5(CO3)2(OH)6 precursor at 160 ℃for 6 h.The increase of the initial solution pH promotes the hydrothermal conversion of the particulate Zn5(CO3)2(OH)6 to ZnO whiskers.The presence of minor amount of EDTA in the hydrothermal solution promotes the one dimensional growth of ZnO whiskers,leading to the formation of ZnO whiskers with a length of 50-60μm and a diameter of 1-2μm.

Recovery of copper sulfate after treating As-containing wastewater by precipitation method

The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2：1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4：1 and copper arsenite was reduced by SO2 at 60℃ for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H2SO4 solution under the action of air. The results show that red residue is Cu3（SO3）2·2H2O and the white powder is As2O3. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H2SO4 to Cu is 1.70, H2SO4 concentration is 24% and the leaching temperature is 80 ℃. The direct recovery rate of copper sulfate is 79.11% and the content of CuSOa·5H2O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.

Promotion of conversion activity of flue gas desulfurization gypsum into α-hemihydrate gypsum by calcination-hydration treatment

The massive accumulation of flue gas desulfurization(FGD)gypsum produced in the wet limestone-gypsum flue gas desulfurization process not only encroaches on lands but also causes serious environmental pollution.The preparation ofα-hemihydrate gypsum(α-HH)is an important way to achieve high-value utilization of FGD gypsum.Although the glycerol-water solution approach can be used to produceα-HH from FGD gypsum under mild conditions,the transition is kinetically unfavorable in the mixed solution.Here,an easy pretreatment was used to activate FGD gypsum by calcination and hydration to readily complete the transition.The pretreatment deteriorated the crystallinity of FGD gypsum and caused it to form small irregular flaky crystals,which dramatically increased the specific surface area.Additionally,most of the organics adsorbed onto FGD gypsum surfaces were removed after pretreatment.The poor crystallinity,increased specific surface area,and elimination of organics adsorbed onto crystal surfaces effectively improved the conversion activity of FGD gypsum,thereby promoting dihydrate gypsum(DH)dissolution andα-HH nucleation.Overall,the phase transition of FGD gypsum toα-HH is facilitated.

Adsorption of Pb^(2+) on macroporous weak acid adsorbent resin from aqueous solutions: Batch and column studies

The adsorption properties of a novel macroporous weak acid resin （D152） for Pb^2＋ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb^2＋ is at pH 6.00 in HAc-NaAc medium. The statically saturated adsorption capacity is 527 mg/g at 298 K. Pb^2＋ adsorbed on D152 resin can be eluted with 0.05 mol/L HCI quantitatively. The adsorption rate constants determined under various temperatures are k288 n=2.22×10-5 s^-1, k298 K=2.51 × 10^-5 s^-1, and k308 K= 2.95 × 10^-5 s^-1, respectively. The apparent activation energy, Ea is 10.5 kJ/mol, and the adsorption parameters of thermodynamics are ΔH^Θ=13.3 kJ/mol, ΔS^Θ=119 J/（mol·K）, and ΔG^Θ298 K =-22.2 kJ/mol, respectively. The adsorption behavior of D152 resin for Pb^2＋ follows Langmuir model.

Removal and transformation of dissolved organic matter in secondary effluent during granular activated carbon treatment

This paper focused on the removal and transformation of the dissolved organic matter （DOM） in secondary effluent during the granular activated carbon （GAC） treatment. Using XAD-8/XAD-4 resins, DOM was fractionated into five classes： hydrophobic acid （HPO-A）, hydrophobic neutral （HPO-N）, transphilic acid （TPI-A）, transphilic neutral （TPI-N） and hydrophilic fraction （HPI）. Subsequently, the water quality parameters of dissolved organic carbon （DOC）, absorbance of ultraviolet light at 254 nm （UV-254）, specific ultraviolet light absorbance （SUVA） and trihalomethane formation potential （THMFP） were analyzed for the unfractionated and fractionated water samples. The results showed that the order of the DOC removal with respect to DOM fractions was observed to be HPI〉HPO-A〉HPO-N〉TPI-A〉TPI-N. During the GAC treatment, the THMFP of the unfractionated water samples decreased from 397.4 μg/L to 176.5 μg/L, resulting in a removal efficiency of 55.6%. The removal order of the trilaalomethanes （THMs） precursor was as follows： HPO-A〉TPI-A〉TPI-N〉HPO-N〉HPI. By the GAC treatment, the specific THMFP of HPO-A, TPI-A, TPI-N and the original unfractionated water samples had a noticeable decrease, while that of HPO-N and HPI showed a converse trend. The Fourier transform infrared （FTIR） results showed that the hydroxide groups, carboxylic acids, aliphatic C-H were significantly reduced by GAC treatment.

Easy removing of phenol from wastewater using vegetable oil-based organic solvent in emulsion liquid membrane process

Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10^(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min^(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min^(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L^(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.

Advanced sludge reduction and phosphorous removal process

An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.

Experimental Study of Osmotic Dehydration of Date （Phoenix dactylifera L,）： Application for Lemsi Cultivars

The cultivar date Lemsi is well known in the coastal oasis of Tunisia for both its quality stage ＂blah＂ and its earliness. This variety is characterized by its astringent taste and has never been studied extensively. An osmotic dehydration treatment is necessary to improve the quality of the final product for maintaining its integrity. Thus, it is a preservation technique that is often used as pretreatment to obtain partially dehydrated fruit. In this experimental study, the cultivar date Lemsi were cut into cubes of 1 cm3 and were immersed in sucrose solutions of 50%, 60% and 70% at 20℃ for 0-240 min. The moisture content, the solute gain, the water loss and the ratio WL/SG are determined and discussed. The results deduced from this work have showed that sugar gain SG, water loss WL and the ratio WL/SG are increased with concentration of osmotic solution. Likewise, the osmotic dehydration treatment need to be followed of a convective drying to ensure the quality of the final product.

Global Solution for Preserving Citrus Fruit Using Natural Treatments

Different tests were carried out to assess the efficiency of replacing plant protection products used at the main application points in citrus fruit packinghouses with natural treatments. The efficiency of an aqueous treatment containing potassium sorbate was found to significantly reduce decaying in Marisol mandarins previously inoculated with Penicillium digitatum and Penicillium italicum. The same food preservative was used in conjunction with a fruit detergent and was applied on Washington Navel oranges and the reduction in the appearance of decaying was similar to that obtained using Guazatine. Finally, two different essential oils were tested. One was combined with a coating and the KS, whilst the other was applied as a fumigant. In the case of wax treatments, it was found that the combination of essential oil or KS with Imazalil at half the dose （0.1%） was equivalent to treatment with a higher dose of Imazalil （0.2%） thus making it possible to reduce the dose of plant protection products used without reducing decay control effectiveness. The treatment with a fumigant with essential oil has a level of efficiency similar to Imazalil against PI. These treatments can be considered a viable alternative to the use of plant protection products.

Research on the Critical Conditions for Clay Particle Release During Saline Aquifer Freshening Process

Water sensitivity phenomenon occurs during saline aquifer freshening process in seawater intrusion area, and clay particles released in the phenomenon can damage the infiltration capacity of the aquifer. In order to find out the factors and mechanisms for clay particle release, laboratory column infiltration experiments simulating saline aquifer freshening process were designed to measure the critical conditions(critical flow velocity, critical salt concentration and critical ionic strength) and force analysis for clay particle according to DLVO electric double layer theory was employed to illustrate the mechanisms for particle release. The research results showed that critical flow velocity for clay particle release is influenced by salt concentration of injecting solution. When salt concentration of injecting solution is very high, clay particles are not released, indicating that there does not exist a critical flow velocity in this situation. As salt concentration of injecting solution decreases, particles start to be released. The critical salt concentration for clay particle release is 0.052 mol L-1 in our work, which was determined by a constant-flux experiment for stepwise displacement of high concentration Na Cl solution. The critical ionic strength for clay particle release decreases as Ca2+ molar content percentage of the mixed solution of Na Cl and Ca Cl2 increases following the first-order exponential decay equation y = 0.0391e-0.266 x + 0.0015.

A pilot study on wastewater treatment by constructed wetlands with high dissolved oxygen vegetated submerged bed

It is necessary to treat wastewater in a more environment-friendly fashion.Vegetated submerge bed constructed wetlands (CWs) has become the focus of the research in this field. In this paper, the overall capacity of vertical subsurface flow CWs in the removal of pollutants from municipal wastewater effluent and the effects of the depth of vegetated submerged bed on the removal efficiency were studied. The results showed that the COD, NH+4-N and TN could be removed effectively in the vertical subsurface flow CWs and the best efficiency was obtained from the 10 cm run. However, the TP removal was not effective in all vertical CWs. A shallow depth of vegetated submerged bed may avoid the risk of substrate plugging effectively, and may keep a stable operation of CWs in long term. Decreasing the depth of vegetated submerged bed could create a sufficient aerobic circumstance in which the concentration of DO (dissolved oxygen) in bed was super saturation.

Solvent switching and purification of colloidal nano- particles through water/oil Interfaces within a density gradient

Traditional post-treatment of colloidal nanoparticles （NPs） usually involves repeated centrifugation-wash-sonication processes to separate NPs from the original synthetic environment; however, such separation processes have either high energy cost or low efficiency and tend to cause aggregation. Here we show a general and scalable colloid post-processing technique based on density gradient centrifugation through water/oil interfaces. Such a one-step technique can switch the solvent in a colloid at almost any concentration without aggregation, and meanwhile purify colloidal nanoparticles by separating them from by-products and environmental impurities. Droplet sedimentation was shown to be the mechanism of this one-step concentration/purification process, and mathematical modeling was established to quantify the accumulation and sedimentation velocities of different NPs.

Excellent long-term reactivity of inhomogeneous nanoscale Fe-based metallic glass in wastewater purification

Metallic glasses(MGs)have attracted great attention in wastewater treatment because of their high reactivity arising from amorphous structure,large residual stress and high density of low coordination sites.However,the reactivity of MGs would gradually slow down with time due to the passivation of active sites by corrosion products,resulting in limited long-term reactivity,which is also an unsolved key issue for established crystalline zero valent iron(ZVI)technology.Here,such problems are successfully overcome by introducing nanoscale chemical inhomogeneities in Fe-based MG(Fe-MGI),which apparently contributes to local galvanic cell effect and accelerates electron transfer during degradation process.More importantly,the selective depletion of Fe0 causes local volume shrinkage and crack formation,leading to self-peeling of precipitated corrosion products and reacted regions.Thereby fresh low coordination sites could be continuously provided,counteracting the mass transport and reactivity deteriorating problem.Consequently,Fe-MGI demonstrates excellent long-term reactivity and self-refreshing properties even in neutral solution.The present results provide not only a new candidate but also a new route of designing ZVI materials for wastewater treatment.

A multistep attachment process:Transformation of titanate nanotubes into nanoribbons

The mechanism of the conversion of titanate nanotubes into nanoribbons is of considerable interest.The details of the transformation processes involved when nanoribbons are produced from a P25 TiO 2 powder precursor by alkaline hydrothermal treatment have been investigated systematically by transmission electron microscopy.A multistep attachment model is proposed for the growth at the early stage of coarsening.The treatment duration has a strong effect on the change in product morphology from hollow nanotubes into nanoribbons,since the nanotubes cannot retain their morphology in the strong alkaline solution for extended periods of time.Most of the nanotubes were etched and dissolved,providing the nutrients for subsequent nanoribbon growth.Some stable nanotubes grew spirally internally to form nanowires or became connected together to form rafts which acted as the grains for nanoribbon growth.With increasing hydrothermal time,a large number of nanotubes and other fragments became attached to the grains which began to grow larger and eventually formed the nanoribbons,in a process in which the stepped faces and kinked faces became fused and were eliminated while the flat faces were retained in the nanoribbon morphology.