Electrochemical oxidation of bisphenol A. Application to the removal of bisphenol A using a carbon fiber electrode

Leachate samples with a high strength of ammonium-nitrogen (NH4+-N) were collected from a local landfill site in Hong Kong. Two experiments were carried out to study (1) the inhibition of microbial activity of activated sludge by NH4+-N and (2) the chemical precipitation of NH4+-N from leachate as a preliminary treatment prior to the activated sludge process. The experimental results demonstrated that the efficiency of COD removal decreased from 97.7% to 78.1%, and the dehydrogenase activity of activated sludge decreased from 9.29 to 4.93 microg TF/mg MLSS, respectively, when the NH4+-N concentration increased from 53 to 800 mg/l. The experiment also demonstrated that the NH4+-N in the leachate can be quickly precipitated as MgNH4PO4 x 6H2O after addition of MgCl2 x 6H2O + Na2HPO4 x 12H2O. The NH4+-N concentration was reduced from 5618 to 112 mg/l within 15 min when a molar ratio of Mg2+:NH+:PO4(3-) = 1:1:1 was used. The optimum pH to reach the minimum solubility of MgNH4PO4 x 6H2O was found to be in the range of 8.5-9.0. Attention should be given to the high salinity formed in the treated leachate by using MgCl2 x 6H2O + Na2HPO4 x 12H2O, which may affect microbial activity in the following biological treatment processes. Using two other combinations of chemicals [MgO + 85%H3PO4 and Ca(H2PO4)2 x H2O + MgSO4 x 7H2O] could minimise salinity generation after precipitation, while they were less efficient for NH4+-N removal.     

Recovery of zinc and lead from fly ash from ash-melting and gasification-melting processes of MSW--comparison and applicability of chemical leaching methods

Fly ash generated from MSW ash-melting and gasification-melting plants, known as Melting Furnace Fly Ash (MFA), contains considerable amounts of heavy metals such as Pb and Zn. These metals can be recovered using a smelting furnace after "pre-treatment" for removal of unnecessary elements such as Cl, Sn and Si. Chemical methods have been studied for pretreatment in the past. However, they have been discussed only with regard to treatment cost and the concentration of Pb and Zn recovered, but neither applicability to various types of MFA nor the environmental impact have been considered. In this study, acid, alkaline and ammonia/chloride leaching methods were compared from the standpoints of: (1) applicability to MFA, (2) concentration of Pb and Zn recovered, (3) treatment cost, and (4) environmental impact. Twenty-three samples of MFAs were collected and classified into 4 types based on element contents. A Pb and Zn recovery experiment was conducted for the representative MFA of those types. The results showed: (1) MFA from gasification-melting plants cannot be treated by chemical methods; (2) the other MFA can be treated to an acceptable quality by existing smelting furnaces; (3) only MFA from electric resistance ash-melting plants can be treated easily by the water washing method; and (4) alkaline and ammonia/chloride leaching methods were more effective than acid leaching.     

2001～2003年间北京大气降水的化学特征

为了了解北京大气降水的化学组成与时间变化特征,连续进行了2年的降雨采样与分析.在65个降雨样品中,12%的降水呈酸性;全年降水的酸度主要取决于夏季的降水.SO₄^2-、NH₄⁺与Ca²⁺是含量最丰富的组分,其平均浓度均接近或超过200礶q/L.比较分析表明,在近几年,SO₄^2-对降水酸度的贡献显著降低,降水的硫污染特征减弱,而No₃^-的贡献显著增加.人为污染元素和地壳元素的浓度均在冬春季较高,在夏季最低.     

Sorption of biodegradation end products of nonylphenol polyethoxylates onto activated sludge

IntroductionRecently ,nonylphenolpolyethoxylates (NPnEO (n :numberofethoxyunits(EOs) )havebecomeaproblematicissueforthereasonthatthesecompounds,animportantgroupofnonionicsurfactants ,havebeenusedwidelyinvariousindustriesasflocculants,dispersants,emulsifie…     

北京城区大气干沉降的水溶性离子特征

为了解北京城区大气干沉降中水溶性离子的化学组成与时间变化特征,连续进行了4年多的干沉降采样与分析.结果表明,在222个有效干沉降样品中,存在不同程度的阴离子缺失. SO42-与Ca2+分别是含量最丰富的阴、阳离子组分,其次是NO3-和NH4+. SO42-、NO3-和NH4+呈现相似的季节变化特征,即其浓度在夏季最高,冬季最低. 干沉降基本呈中性,其pH值月变化幅度小,但季节变化明显,夏季低而春季高.     

Characteristics of fear of crime in evacuation shelters after the Great East Japan Earthquake

After the Great East Japan Earthquake in March 2011, numerous evacuees had to stay in evacuation shelters such as school gymnasiums. In general, after a disaster, ensuring the safety and security of evacuees in evacuation shelters is a serious problem. Consequently, many of these evacuees feared that they would be victims of crime in the shelters or that their evacuated homes would be burgled. To examine what factors evoke a general fear of crime in shelters and burglary of evacuated homes, we conducted an online questionnaire on 300 evacuees in Miyagi Prefecture who had stayed at such shelters. From a factor analysis of fear of 16 specific kinds of crime in shelters, we extracted two factors representing fear of property and female-related crime. We then found that a general fear of crime in shelters was associated with being young and a fear of female-related crime, while a fear of burglary of evacuated homes was associated with being female, owning a detached house, and fear of property crime. Based on these results, we provide recommendations aiming to help reduce the fear of crime in shelters and burglary of evacuated homes.     

Sequential Determination of Trace Metals in Sea Water by Inductively Coupled Plasma Mass Spectrometry After Electrothermal Vaporization of their Dithiocarmabamate Complexes in Methyl Isobutyl Ketone

A sensitive method for sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water using an inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone (MIBK) has been investigated. All analyte elements were simultaneously concentrated 20 fold in a single extract and introduced into the plasma using a graphite rod electrothermal vaporizer (ETV). A sensitivity enhancement due to a chemical modification using a mixed modifier of palladium nitrate and magnesium nitrate was observed for all analyte elements. The limits of detection of the method ranged from 2 ng l-1 for Co to 329 ng l-1 for V. For the replicate determinations of the analyte elements in a sea water sample, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery test performed on a sea water sample resulted in values ranging from 87% for Sb to 119% for V. With the exception of Mo, the application of this method for the determination of the analyte elements in sea water samples collected from the surface to the depth of 5000 m at the sampling station of 34°12.08N, 141°57.50E (Oct. 12, 1994) in the northwest Pacific Ocean resulted in vertical distributions and concentration ranges which were in a good agreement with those reported in literatures.     

Use of a seeder reactor to manage crystal growth in the fluidized bed reactor for phosphorus recovery.

The authors have been engaged in the development of a phosphorus recovery system capable of maintaining high recovery efficiencies, with the chemical cost suppressed. This time, they conducted demonstration tests of a fluidized bed magnesium ammonium phosphate reactor provided with a seeder reactor for the supernatant from anaerobic digestion using a pilot experimental plant with a wastewater treatment capacity of 20 m3/d. For the digestion supernatant with a phosphorus concentration of approximately 300 mg/L, the treated water phosphorus concentration was 10 to 25 mg/L, and the phosphorus recovery efficiency was more than 90%. Relative to the chemical cost in the case of magnesium chloride, the chemical cost in the case of magnesium hydroxide is approximately 40%. Thus, with the new system, it was possible to reduce the running cost while maintaining high recovery efficiencies.     

Strontium isotope constraints on the seasonal variation of the provenance of base cations in rain water at Kawakami, Central Japan

The ⁸⁷Sr/⁸⁶Sr ratios in monthly precipitation in the forested basin at Kawakami, central Japan, varied seasonally from 0.709 to 0.711 in spring to as low as 0.7062 ± 0.0004 in autumn over nine years from 1987 to 1995. The seasonal variation can be explained in terms of the mixing of three sources of Sr: sea salt (⁸⁷Sr/⁸⁶Sr 0.70917), soluble eolian minerals originating from deserts in continental Asia ( 0.711), and biogenic materials growing on soils derived from the volcanic rock substrates in the vicinity ( 0.706). It is estimated that the contribution of sea-salt Sr into the Kawakami rain Sr is relatively constant (10 ± 5%) and that more than half of the Sr is of biogenic origin throughout the year except during spring rains when 50% of the Sr is due to the dissolution of Ca-minerals from Asian dusts. The dominant contribution of eolian components to spring rains is consistent with the high concentration of ³H, which is typical of air masses from Asia.