Photo-Fenton treatment of water containing natural phenolic pollutants

Phenolic compounds are known to be present in high concentrations in various types of agro-industrial wastes. As they are highly biorecalcitrant, the possibility of treatment by advanced oxidation processes should be investigated. In this work, six model phenolic compounds (vanillin, protocatechuic acid, syringic acid, p-coumaric acid, gallic acid and L-tyrosine) were chosen for a demonstration of degradation by photo-Fenton reaction, under artificial light in laboratory experiments in Vienna and under sunlight in pilot-plant experiments at the Plataforma Solar de Almería in Spain. All compounds were completely mineralised. No non-degradable intermediates were produced, either in experiments with single substances or in a more complex matrix of a mixture of phenolic compounds. The expected selectivity of the photo-Fenton reaction for aromatic compounds was proven by comparison of the decrease in total organic carbon with the removal of total phenolic content.     

COP-compost: a software to study the degradation of organic pollutants in composts

Composting has been demonstrated to be effective in degrading organic pollutants (OP) whose behaviour depends on the composting conditions, the microbial populations activated and interactions with organic matters. The fate of OP during composting involves complex mechanisms and models can be helpful tools for educational and scientific purposes, as well as for industrialists who want to optimise the composting process for OP elimination. A COP-Compost model, which couples an organic carbon (OC) module and an organic pollutant (OP) module and which simulates the changes of organic matter, organic pollutants and the microbial activities during the composting process, has been proposed and calibrated for a first set of OP in a previous study. The objectives of the present work were (1) to introduce the COP-Compost model from its convenient interface to a potential panel of users, (2) to show the variety of OP that could be simulated, including the possibility of choosing between degradation through co-metabolism or specific metabolism and (3) to show the effect of the initial characteristics of organic matter quality and its microbial biomass on the simulated results of the OP dynamic. In the model, we assumed that the pollutants can be adsorbed on organic matter according to the biochemical quality of the OC and that the microorganisms can degrade the pollutants at the same time as they degrade OC (by co-metabolism). A composting experiment describing two different ¹⁴C-labelled organic pollutants, simazine and pyrene, were chosen from the literature because the four OP fractions simulated in the model were measured during the study (the mineralised, soluble, sorbed and non-extractable fractions). Except for the mineralised fraction of simazine, a good agreement was achieved between the simulated and experimental results describing the evolution of the different organic fractions. For simazine, a specific biomass had to be added. To assess the relative importance of organic matter dynamics on the organic pollutants’ behaviour, a sensitivity analysis was conducted. The sensitivity analysis demonstrated that the parameters associated with organic matter dynamics and its initial microbial biomass greatly influenced the evolution of all the OP fractions, although the initial biochemical quality of the OC did not have a significant impact on the OP evolution.     

Geosmin degradation by seasonal biofilm from a biological treatment facility

Introduction  

Initial geosmin degradation was closely related to water temperature and natural geosmin concentration of sampling environment. Here, for the first time, we evaluated the biodegradation of geosmin by microorganisms in biofilm from biological treatment unit of actual potable water treatment plant.     

Gaseous pollutants emitted from a mechanical biological treatment plant for municipal solid waste: Odor assessment and photochemical reactivity

The concentrations and chromatographic profiles of gaseous pollutants emitted from a municipal solid waste (MSW) biological treatment plant were investigated to identify the major odor substances and atmospheric photochemical reactive species (PRS). Four methods were used to measure different gaseous pollutants in this study, including colorimetric tubes, gas chromatography with mass spectrometry/flame ionization detection/pulsed flame photometric detection (GC-MS/FID/PFPD) preceded by cold trap concentration, GC-FID preceded by solid-phase microextraction (SPME), and high-performance liquid chromatography (HPLC) after derivation by 2,4-dinitrophenylhydrazine (DNPH). Seventy-five gaseous compounds belonging to nine groups (nitrogen compounds, sulfur compounds, alkanes, alkenes, aromatics, terpenes, alcohols, carbonyls, and volatile fatty acids [VFAs]) were identified. In the pre-biotreatment facility, the total concentration of the gaseous pollutants reached the maximum value on day 7 (317 ppm). During the post-biotreatment process, the total concentration of gaseous pollutants decreased from 331 ppm at the beginning to 162 ppm in the end. The group with the greatest decrease was carbonyls, from 64 to 7.4 ppm, followed by alcohols, from 40 to 4.5 ppm, which were both oxygenated compounds. The proportion of aromatics was notably high in the pre-mechanical treatment facility, accounting for 50.6% of the total, revealing the xenobiotic compounds disseminated by stirring and agitating the waste in the initial stage. The proportions of nitrogen compounds were lower in the pre- and post-mechanical treatment facilities (1.5% and 6.9%) than in the pre- and post-biotreatment facilities (11.9% and 13.8%), suggesting that their generation was closely associated with waste degradation. The major odor compounds in the facilities were acetic acid, butyric acid, valeric acid, isovaleric acid, and dimethyl sulfide. The major PRS in the facilities were aromatics, acetaldehyde, butyraldehyde, hexanal, isopentyl aldehyde, alcohol, α-pinene, limonene, and terpinene. Outside the facilities, VFAs and aromatics were the most important compounds causing an environmental impact.

Implications: The aim of this work is to assess the gaseous environmental impacts of mechanical biological treatment technology. The emission of gaseous pollutants greatly affects the living quality of nearby residents and odor complaints are becoming a major problem now. In this study, the authors utilized various pretreatment and analytical methods to obtain integrated emission information of gaseous pollutants. The results showed the transformation and fate of the gas pollutants during the treatment processes, which would help to improve the processes and to mitigate gaseous pollution.

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for information on the concentrations of the nine compound families at different sampling locations in the plant.     

GC-MS法对垃圾渗滤液生物处理前后微量有机物的研究

运用GC—MS联用技术对吴江市生活垃圾填埋场的渗滤液及生物处理曝气池出水中的微量有机物进行了检测,测得进水主要有机污染物53种,出水主要有机污染物55种。微量有机物总去除率与CODCr去除率相近。     

物理场协同作用降解有机污染物研究进展

有机污染物是环境污染物的主要类型,通过物理场外加能量的作用可实现各种有机污染物的高效降解.对微波、超声波、紫外光、电场、磁场、等离子体这几类主要物理场相互协同降解有机污染物的研究现状进行综述,重点介绍了物理场协同作用降解有机污染物的机制、效果、影响因素及污染物类型,并展望了该类研究今后的应用前景和发展趋势.     

臭氧-催化技术治理低浓度气体污染物

在对臭氧－催化技术及其发展现状评述的基础上,分别考察了铂－钯催化剂（Pt-Pd/Al2O3）对DMMP、CH4、C6H6、F22、CO催化氧化和臭氧催化 氧化的反应性能。结果表明,催化作用和臭氧催化氧化作用所要求的反应温度范围相近并低于250℃,才能很好地协同作用。臭氧－催化技术竽起燃温度低、易氧化气体污染物的处理。     

水解酸化-缺氧法处理采油废水的污染物迁移降解试验研究

水解酸化．缺氧法对采油废水有较好的处理效果，采用GC／MS技术对水解酸化-缺氧法处理采油废水过程中污染物的迁移降解进行的研究表明：水解酸化段和缺氧段对采油废水中碳原子为C6-C9、分子量为100—140的有机物均有较好的降解能力。其中，在水解酸化段中酮类、芳烃得到较好的降解，缺氧段中酚类和醚类化合物降解明显。水解酸化-缺氧工艺对于采油废水中的甲苯和二甲苯具有较好的降解能力。     

生物栅处理受污景观水体效果及机制研究

以植物、微生物为生物处理要素构建生物栅,处理污染的景观水体.选用的水生植物黄花美人蕉(Canna indica)的二级、三级根系与作为微生物载体的组合填料交织成强大的网状结构,起到固定植物、微生物附着载体及为生态系统提供氧气的作用,同时在生物栅装置运行的前期(约2 h)对污染物起到网捕、吸附作用.由网捕、吸附作用对TN、TP、NH4 -N的去除率分别为7.2%、12.5%和10.3%,对胶体态UV254的去除率为89.6%.在不进行人工曝气的条件下,生物栅主要处于微氧状态,DO维持在1.40～1.50 mg/L.生物栅的微氧状态有利于总有机碳(TOC)的去除(去除率为52.2%),特别是难降解有机物的去除(溶解态UV254去除率为27.9%),这对处理含有一定量难降解有机物的景观水体具有重要意义.由于生物栅的微氧状态及生物膜的DO浓度梯度的存在,使得微生境存在好氧、缺氧和厌氧的不同含氧状态,因而生物栅同时具有硝化、反硝化作用,并有一定的除磷效果.在水力停留时间(HRT)为72 h时,生物栅对TOC、COD、TN和TP的去除率分别为52.2%、57.6%、60.9%和82.4%.     

Coupling of solar-assisted advanced oxidative and biological treatment for degradation of agro-residue-based soda bleaching effluent

This study evaluates the effect of integrated solar-assisted advanced oxidation process (AOP) and biological treatment on the extent of degradation of effluents from chlorination (C) and first alkaline extraction (E₁) stages of soda pulp bleaching in agro-residue-based pulp and paper mill. Biodegradation of the effluents was attempted in suspended mode using activated sludge from the functional pulp and paper industry effluent treatment plant acclimatized to effluents in question. The photocatalytic treatment was employed using zinc oxide (ZnO) in slurry mode for decontamination of effluents in a batch manner and the degradation was evaluated in terms of reduction in chemical oxygen demand. The biological treatment (24?h) of C and E₁ effluent resulted in 30 and 57?% of degradation, respectively. Solar-induced AOP of C and E₁ effluents resulted in 53 and 43?% degradation under optimized conditions (2.5?g?L^?1 ZnO at pH?8.0) after 6?h of exposure. For C effluent, a short duration of solar/ZnO (1?h) prior to biological treatment reduced the time required at biological step from 24 to 12?h for almost same extent (92?%) of degradation. However, sequential biological treatment (24?h) followed by solar/ZnO (2?h) resulted in 85.5?% degradation. In contrast, in the case of E₁ effluent, sequential biological (24?h)?Csolar/ZnO (2?h) system effectively degrades effluent to 95.4?% as compared to 84.8?% degradation achieved in solar/ZnO (2?h)?Cbiological treatment (24?h) system. In the present study, the sequencing of photocatalysis with the biological treatment is observably efficient and technically viable process for the complete mineralization of the effluents.     

Anaerobic degradation of pyrrolidine and piperidine coupled with nitrate reduction

Biodegradability of secondary amines (pyrrolidine, piperidine, piperazine, morpholine, and thiomorpholine) under anaerobic conditions was examined in microbial consortia from six different environmental sites. The consortia degraded pyrrolidine and piperidine under denitrifying conditions. Enrichment cultures were established by repeatedly sub-culturing the consortia on pyrrolidine or piperidine in the presence of nitrate. The enrichments strictly required nitrate for the anaerobic degradation and utilized pyrrolidine or piperidine as a carbon, nitrogen, and energy source for their anaerobic growths. The anaerobic degradation of pyrrolidine and piperidine reduced nitrate to nitrogen gas, indicating that these anaerobic degradations were coupled with a respiratory nitrate reduction.     

Recent updates on electrochemical degradation of bio-refractory organic pollutants using BDD anode: a mini review

Boron-doped diamond (BDD) is playing an important role in environmental electrochemistry and has been successfully applied to the degradation of various bio-refractory organic pollutants. However, the review concerning recent progress in this research area is still very limited. This mini-review updated recent advances on the removal of three kinds of bio-refractory wastewaters including pharmaceuticals, pesticides, and dyes using BDD electrode. It summarized the important parameters in three electrochemical oxidation processes, i.e., anodic oxidation (AO), electro-Fenton (EF), and photoelectro-Fenton (PEF) and compared their different degradation mechanisms and behaviors. As an attractive improvement of PEF, solar photoelectro-Fenton using sunlight as UV/vis source presented cost-effectiveness, in which the energy consumption for enrofloxacin removal was 0.246 kWh/(g TOC), which was much lower than that of 0.743 and 0.467 kWh/(g TOC) by AO and EF under similar conditions. Finally the existing problems and future prospects in research were suggested.     

催化铁与生物法耦合除磷工艺特性

为了研究催化铁与生物耦合后对生物除磷特性的影响,实验采用人工配水用厌氧／好氧间歇流式富集培养聚磷微生物。对比发现,催化铁与生物耦合组中厌氧末段ORP降低了约60mV,pH值小幅度的上升（≤0．3）,整个培养过程中铁离子的浓度开始快速增加,之后趋于稳定（约40mgFe／gMLSS）。对好氧末段污泥SVI值比较发现,耦合工艺污泥沉降性能得到改善。除磷曲线比较发现,耦合组中厌氧末段磷的释放量下降,而好氧阶段磷的吸收速率增加;胞内聚合物提取表明,耦合组厌氧末段聚磷菌细胞内PHA含量有提高,好氧末段糖原含量有下降。磷形态提取分析表明,耦合组好氧末段污泥中无机态PO3 4-- P含量更高。低浓度铁离子可以起到与生物耦合同步除磷的目的,本工艺长期运行未发现耦合体系中催化铁对除磷的抑制作用。     

Including degradation products of persistent organic pollutants in a global multi-media box model

GOAL, SCOPE AND BACKGROUND: Global multi-media box models are used to calculate the fate of persistent organic chemicals in a global environment and assess long-range transport or arctic contamination. Currently, such models assume substances to degrade in one single step. In reality, however, intermediate degradation products are formed. If those degradation products have a high persistence, bioaccumulation potential and / or toxicity, they should be included in environmental fate models. The goal of this project was to gain an overview of the general importance of degradation products for environmental fate models, and to expand existing, exposure-based hazard indicators to take degradation products into account. METHODS: The environmental fate model CliMoChem was modified to simultaneously calculate a parent compound and several degradation products. The three established hazard indicators of persistence, spatial range and arctic contamination potential were extended to include degradation products. Five well-known pesticides were selected as example chemicals. For those substances, degradation pathways were calculated with CATABOL, and partition coefficients and half-lives were compiled from literature. RESULTS: Including degradation products yields a joint persistence value that is significantly higher than the persistence of the parent compound alone: in the case of heptachlor an increase of the persistence by a factor of 58 can be observed. For other substances, the increase is much smaller (4% for alpha-HCH). The spatial range and the arctic contamination potential (ACP) can increase significantly, too: for 2,4-D and heptachlor, an increase by a factor of 2.4 and 3.5 is seen for the spatial range. However, an important increase of the persistence does not always lead to a corresponding increase in the spatial range: the spatial range of aldrin increases by less than 50%, although the persistence increases by a factor of 20 if the degradation products are included in the assessment. Finally, the arctic contamination potential can increase by a factor of more than 100 in some cases. DISCUSSION: Influences of parent compounds and degradation products on persistence, spatial range and ACP are discussed. Joint persistence and joint ACP reflect similar characteristics of the total environmental exposure of a substance family (i.e., parent compound and all its degradation products). CONCLUSIONS: The present work emphasizes the importance of degradation products for exposure-based hazard indicators. It shows that the hazard of some substances is underestimated if the degradation products of these substances are not included in the assessment. The selected hazard indicators are useful to assess the importance of degradation products. RECOMMENDATIONS AND PERSPECTIVES: It is suggested that degradation products be included in hazard assessments to gain a more accurate insight into the environmental hazard of chemicals. The findings of this project could also be combined with information on the toxicity of degradation products. This would provide further insight into the importance of degradation products for environmental risk assessments.     

Peroxidative degradation of selected PCB: a mechanistic study

The enzyme-induced decomposition and biodegradation of PCB were investigated. 2,5-Dichlorobiphenyl (PCB 9) and 2,2^′,5,5^′-tetrachlorobiphenyl (PCB 52) were used as example compounds to study efficiency and mechanism of the degradation processes. It was found that the application of horseradish peroxidase (HRP) together with defined amounts of hydrogen peroxide removed 90% of the initial concentration of PCB 9 and 55% of the initial concentration of PCB 52 from an aqueous solution after a reaction period of 220 min. Dechlorination was observed as the initial step. Although the metabolites identified were mainly chlorinated hydroxybiphenyls, benzoic acids and non-substituted 1,1^′-biphenyl, some higher chlorinated biphenyl isomers also appeared. The biodegradation of PCB 9 using the white rot fungus Trametes multicolor took about four weeks and reduction was about 80% of the initial concentration. The metabolites produced (dichlorobenzenes, chlorophenols and alkylated benzenes) were not quite the same as those observed upon incubation with HRP.     

生物接触氧化处理渗滤液有机物的动力学模型研究

以重庆黑石子垃圾填埋场渗滤液生物接触氧化工艺为依托,针对其处理效果的局限性,设计了强化预处理-生物接触氧化反应器,并进行生物接触氧化反应器试验及其有机物降解动力学模型研究,旨在优化运行参数,提高渗滤液处理效果.结果表明,改进后系统比原工艺处理效果好,COD、NH4 -N、TN平均去除率分别达到95.83%、97.60%、85.60%;出水水质得到大幅度提高,出水COD、NH4 -N、TN平均质量浓度分别为235、35、199 mg/L.对生物接触氧化反应器内垃圾渗滤液有机物降解生化反应过程进行量化研究,得到微生物生长动力学模型为1/θc=0.918 7q-0.002 5;根据生物接触氧化反应器内基质消耗过程的物料平衡,得到生物接触氧化反应器处理垃圾渗滤液有机物生物降解的动力学模型为q=1.09S/(10 230 S).试验结果为生物接触氧化反应器的优化控制、设计与放大提供了参考依据.     

Impact of two chemistry mechanisms fully coupled with mesoscale model on the atmospheric pollutants distribution

Air quality models (AQM) consist of many modules (meteorology, emission, chemistry, deposition), and in some conditions such as: vicinity of clouds or aerosols plumes, complex local circulations (mountains, sea breezes), fully coupled models (online method) are necessary. In order to study the impact of lumped chemical mechanisms in AQM simulations, we examine the ability of both different chemical mechanisms: (i) simplified: Condensed Version of the MOdèle de Chimie Atmosphérique 2.2 (CV-MOCA2.2), and (ii) reference: Regional Atmospheric Chemistry Model (RACM), which are coupled online with the Regional Atmospheric Modeling Systems (RAMS) model, on the distribution of pollutants. During the ESCOMPTE experiment (Expérience sur Site pour COntraindre les Modèles de Pollution et de Transport d’Emissions) conducted over Southern France (including urban and industrial zones), Intensive observation periods (IOP) characterized by various meteorological and mixed chemical conditions are simulated. For both configurations of modeling, numerical results are compared with surface measurements (75 stations) for primary (NO_x) and secondary (O₃) species. We point out the impact of the two different chemical mechanisms on the production of species involved in the oxidizing capacity such as ozone and radicals within urban and industrial areas. We highlight that both chemical mechanisms produce very similar results for the main pollutants (NO_x and O₃) in three-dimensional (3D) distribution, despite large discrepancies in 0D modeling. For ozone concentration, we found sometimes small differences (5–10 ppb) between the mechanisms under study according to the cases (polluted or not). The relative difference between the two mechanisms over the whole domain is only −7% for ozone from CV-MOCA 2.2 versus RACM. When the order of magnitude is needed rather than an accurate estimate, a reduced mechanism is satisfactory. It has the advantage of running faster (four times less than CPU time on SGI 3800 with 30 processors). Simplified mechanisms are really important to study cases for which an online coupling is necessary between meso-scale and chemistry models (clouds or aerosols plumes impacts, highly variable meteorology).     

Coupled solar photo-Fenton and biological treatment for the degradation of diuron and linuron herbicides at pilot scale

A coupled solar photo-Fenton (chemical) and biological treatment has been used to remove biorecalcitrant diuron (42 mg l(-1)) and linuron (75 mg l(-1)) herbicides from water at pilot plant scale. The chemical process has been carried out in a 82 l solar pilot plant made up by four compound parabolic collector units, and it was followed by a biological treatment performed in a 40 l sequencing batch reactor. Two Fe(II) doses (2 and 5 mg l(-1)) and sequential additions of H2O2 (20 mg l(-1)) have been used to chemically degrade the initially polluted effluent. Next, biodegradability at different oxidation states has been assessed by means of BOD/COD ratio. A reagent dose of Fe=5 mg l(-1) and H2O2=100 mg l(-1) has been required to obtain a biodegradable effluent after 100 min of irradiation time. Finally, the organic content of the photo-treated solution has been completely assimilated by a biomass consortium in the sequencing batch reactor using a total suspended solids concentration of 0.2 g l(-1) and a hydraulic retention time of 24h. Comparison between the data obtained at pilot plant scale (specially the one corresponding to the chemical step) and previously published data from a similar system performing at laboratory scale, has been carried out.     

Photoelectrocatalytic degradation of recalcitrant organic pollutants using TiO2 film electrodes: an overview

Photoelectrocatalytic (PEC) technology involved applying an electrical bias to a TiO₂ film electrode, has been widely applied to the degradation of refractory organic pollutants, owing to its high degradation efficiency. This paper reviews recent developments in the PEC degradation of recalcitrant organic contaminants using a TiO₂ film electrode. The preparation and application of various TiO₂ film electrodes have been investigated, as well as the parameters that influence PEC activity such as the crystal structure, the film thickness and substrate material, the applied electrical bias, the solution pH and conductivity. The improvement of PEC activity by doping the TiO₂ film electrode with metal and non-metal ions has been discussed. The mechanism and kinetics for the PEC degradation of organic pollutants have also been highlighted.