Efficient degradation of semi-coking wastewater in three-dimensional electro-Fenton by CuFe2O4 heterocatalyst

Semi-coking wastewater contains a rich source of toxic and refractory compounds. Three-dimensional electro-Fenton (3D/EF) process used CuFe₂O₄ as heterocatalyst and activated carbon (AC) as particle electrode was constructed for degrading semi-coking wastewater greenly and efficiently. CuFe₂O₄ nanoparticles were prepared by coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy disperse spectroscopy (EDS). Factors like dosage of CuFe₂O₄, applied voltage, dosage of AC and pH, which effect COD removal rate of semi-coking waste water were studied. The results showed that COD removal rate reached to 80.9% by 3D/EF process at the optimum condition: 4 V, 0.3 g of CuFe₂O₄, 1 g of AC and pH?=?3. Trapping experiment suggesting that hydroxyl radical (?OH) is the main active radical. The surface composition and chemical states of the fresh and used CuFe₂O₄ were analyzed by XPS indicating that Fe, Cu, and O species are involved into the 3D/EF process. Additionally, anode oxidation and the adsorption and catalysis of AC are also contributed to the bleaching of semi-coking waste water. The possible mechanisms of 3D/EF for degrading semi-coking waste water by CuFe₂O₄ heterocatalyst were proposed.

     

低接种量条件下实现厌氧氨氧化快速启动的策略

厌氧氨氧化(Anaerobic ammonia oxidation, anammox)是目前最高效节能的脱氮方式,可以在不加碳源的条件下实现自养高负荷脱氮。然而,厌氧氨氧化菌(Anaerobic ammonia oxidizing bacterial, anAOB)因其生长缓慢,会导致污水处理工艺的启动周期较长。因此,为缩短anammox的启动周期,设置了3种不同污泥接种方式(A：接种500 mg·L⁻¹ anAOB; B：接种500 mg·L⁻¹ anAOB+5 000 mg·L⁻¹反硝化菌;C：接种500 mg·L⁻¹ anAOB+5 000 mg·L⁻¹硝化菌)开展anammox启动实验,分析了底物浓度对脱氮效果的影响以及不同接种条件下微生物群落的差异。结果表明,采用向反应器投加500 mg·L⁻¹ anAOB+5 000 mg·L⁻¹反硝化菌的接种方式,可以实现anammox的快速启动;启动30 d后,总氮去除效率(nitrogen removal rate, NRR)可达1.41 kg·(m³·d)⁻¹以上。微生物群落分析结果表明,反应器中主要存在的anAOB为Candaditue Kuenenia;与单独接种anammox污泥相比,接种反硝化污泥和anammox污泥会使Candaditue Kuenenia的相对丰度提高了40.0%,从而使脱氮效率提高了31.2%。底物浓度对anammox过程的影响结果表明,进水${\rm{NO}}_2^{-} $-N质量浓度达到500 mg·L⁻¹时会导致游离亚硝酸(FNA)浓度升高,而当FNA质量超过0.05 mg·L⁻¹时,会严重影响anAOB活性,导致反应器出水水质波动;通过降低进水${\rm{NO}}_2^{-} $-N浓度,可以使系统恢复。以上研究结果说明,通过接种反硝化菌和anAOB的方式可实现anammox的快速启动,加速实现anammox工艺在污水处理中大规模应用。     

Emissions of intermediate volatility organic compound from waste cooking oil biodiesel and marine gas oil on a ship auxiliary engine

Ship auxiliary engines contribute large amounts of air pollutants when at berth.Biodiesel,including that from waste cooking oil(WCO),can favor a reduction in the emission of primary pollutant when used with internal combustion engines.This study investigated the emissions of gaseous intermediate-volatile organic compounds(IVOCs) between WCO biodiesel and marine gas oil(MGO) to further understand the differences in secondary organic aerosol(SOA) production of exhausts.Results revealed that WCO ex...     

Influence of metal ions on sulfonamide antibiotics biochemical behavior in fiber coexisting system

Metal ions and fiber are common compounds in the livestock and poultry manure,which will affect the fate of organic compounds in aqueous environment. However,limited research has addressed the effect of coexisting metal ions and fiber on the biodegradation of sulfonamide antibiotics. Accordingly, a compositing study was performed to assess the effect of metal ions(Fe3+and Cu2+) on the biodegradation of sulfadimethoxine sodium salt(SDM) in the presence of fiber. The enhanced adsorption of SDM onto fiber in the presence of metal ions can be attributed to the π+–π electron donor acceptor(EDA) interaction. The microbial(Phanerochaete chrysosprium) could easily attach onto fiber forming attached microbial, and the degradation rates of SDM of immobilized bacteria in the presence of Fe3 +were 100%, which were significantly higher than those of free bacteria(45%). This study indicates that Fe3 +and fiber could enhance the biodegradation of SDM. Fiber acts as adsorbent, carrier, and substrate which enhanced the removal of SDM.     

Exploring the abundance and influencing factors of antimicrobial resistance genes in manure plasmidome from swine farms

Plasmids play a critical role in the dissemination of antimicrobial resistance genes (ARGs), however, a systematical understanding of ARGs originated from plasmids in swine production is currently lacking. Herein, quantitative polymerase chain reaction was applied to determine the prevalence of ten ARGs and the class1 integron gene intI1 of plasmid source in swine manure from 44 farms in Sichuan, Hubei and Hebei provinces, China. All assayed ARGs were observed in plasmid DNA samples, and the average absolute abundance of aac(6’)-Ib-cr, bla_NDM, bla_CTX-M, optrA, ermB, floR, mcr-1, qnrS, tetM, sul1 and intI1 were 7.09, 2.90, 4.67, 6.62, 7.55, 7.14, 4.08, 4.85, 7.16, 7.11 and 8.07 of 10 log copies/gram, respectively. IntI1 showed a high correlation (r > 0.8, P < 0.01) with the abundance of aac(6’)-Ib-cr and sul1 in swine manure. Moreover, the farm scale (i.e., herd population) and geographical location were not found to be critical factors influencing the absolute abundance of ARGs of plasmid DNA in swine farms. However, the concentrations of florfenicol, Cu, Zn, Fe, total phosphorus (TP) and total potassium (TK) demonstrated a significant correlation with the abundance of several ARGs. Particularly, Cu and Zn had high correlations with optrA and bla_CTX-M, respectively. Our results demonstrated that antibiotics, heavy metals and environmental nutrients are likely jointly contributing to the long-term persistence of ARGs in swine production. This study provides insights into the abundance and influencing factors of ARGs from swine manure, which is of significance for assessing and reducing the public health risks in livestock production.     

Lignin-Based Magnetic Nanoparticle Adsorbent for Diclofenac Sodium Removal: Adsorption Behavior and Mechanisms

Journal of Polymers and the Environment - Diclofenac sodium, as a typical deputation of non-steroidal anti-inflammatory drugs, is widely used in clinical treatment. Due to the heavy use, diclofenac...     

中国医院污水处理现状及前景分析

医院污水具有空间污染、急性传染和潜伏性传染等特征,不有效处理会成为一条疫病扩散的重要途径,并严重污染环境.本文首先提出了中国医院污水的处理现状,找出与发达国家之间的差距,进而对中国医院污水处理的前景进行了分析,提出中国医院污水处理中应改善的几个方面.     

稻壳基活性炭催化剂的低温NH3-SCR抗硫性能

以稻壳基活性炭（DAC）为载体,利用等体积浸渍法制备了DAC负载Mn、Ce氧化物的Mn-Ce/DAC脱硝催化剂,并用于氨法SCR反应.采用N₂吸附、X射线衍射（XRD）、X射线光电子能谱（XPS）和程序升温吸附脱附（TPR/TPD）等手段对催化剂的物理化学性能进行了表征.结果发现与商业木屑基活性炭负载Mn、Ce氧化物催化剂（Mn-Ce/MAC）相比,Mn-Ce/DAC具有更高的Ce³⁺/Ce⁴⁺比率、表面化学吸附氧含量以及表面Brønsted酸性位点,这与其优良的低温SCR活性及抗硫抗水性能直接相关.原位红外光谱结果显示在含硫气氛中Mn-Ce/DAC表面的硫酸盐含量明显低于Mn-Ce/MAC,表明前者具有优良抗硫性能.     

兰州市大气降尘中正构烷烃的分布特征及源解析

采集了2005年春季兰州市不同功能区大气降尘样品,采用气相色谱/质谱法测定样品中的正构烷烃。结果表明,降尘中正构烷烃主要有2种类型,一种是后峰型,以C29为主峰碳,大于C25正构烷烃具有明显的奇偶优势,碳优势指数(CPI)为1.25~1.40;另一种是双峰型,分别以C29,C20,C19,C15为主峰碳,在C25或C27后有明显的奇碳数优势,CPI为1.26~2.35。研究区内不同区域降尘中正构烷烃分布有明显的变化,相对清洁区正构烷烃分布为后峰型,主要来源于燃煤、高等植物的不完全燃烧。工业区、商业区、商业居民混合区正构烷烃分布属于双峰型,既有高等植物蜡的输入,也有汽车尾气、石油化工的输入,且人为源的贡献较大。     

Size-resolved carbonaceous components and water-soluble ions measurements of ambient aerosol in Beijing

A MOUDI-120 sampler was used in Beijing to collect multi-stage samples in the summer and winter of 2013 to 2015. Thirty-three sample sets were collected during the daytime,nighttime, and different pollution levels. The actual relative humidity in the impactors was calculated for the first time. The carbonaceous components(organic and elemental carbon,OC and EC, respectively) and water-soluble inorganic ions(Na~+, NH_4~+, K~+, Mg~(2+), Ca~(2+), Cl~-, NO_3~-,and SO_4~(2-)) were analyzed in each sample. The characteristics of the mass concentration distribution and charge balance were discussed. On the basis of relative humidity in the impactors, aerosols less than 1.0 μm were sampled under relatively dry conditions in most cases. The concentration levels for the chemical species were higher in the winter than in the summer. Three modes(condensation mode, droplet mode, and coarse mode) could be identified from the distributions of NH_4~+, NO_3~-, SO_4~(2-), Cl~-, K~+, OC and EC. The distribution characteristics for the pollution dissipation process were different from the pollution accumulation process. NO_3~-and NO_2~-contributed most of the negative electric charges in the stage below 0.1 μm. In the condensation mode, the cations were dominated by NH_4~+, which was sufficient to balance the anions. In the droplet mode of the heavily polluted samples,the ammonium was not sufficient to balance the anions. In the coarse mode, the positive electric charges were primarily composed of metal cations. The analyzed anions were not sufficient to neutralize the measured cations.