Hundreds of tons of pharmaceutical compounds are annually dispensed and consumed worldwide. Pharmaceuticals are an important class of emerging environmental micropollutants: their presence in water ...bodies is an increasing environmental concern. The aim of this review paper is to provide a comprehensive review of the occurrence of pharmaceuticals in freshwater aquatic environments in the African and European context. A literature survey has been performed, resulting in 3024 data points related to environmental occurrence. The concentration levels of 71 pharmaceuticals were assessed. The top ten most frequently detected and quantified compounds in both continents were sulfamethoxazole, carbamazepine, diclofenac, trimethoprim, ibuprofen, naproxen, paracetamol (acetaminophen), ketoprofen, venlafaxine and clarithromycin. The maximum concentrations of 17β-estradiol, estriol, ciprofloxacin, sulfamethoxazole, paracetamol, naproxen reported in African aquatic environments were ~3140, ~20,000, ~125, ~100, ~215 and ~171 times higher, respectively, than the concentrations reported in European based studies.
The variation in pharmaceutical consumption, partial removal of pharmaceuticals in wastewater treatment processes, and the direct discharge of livestock animal farm wastewater were identified among the major reasons for the observed differences. Several pharmaceuticals were found in aquatic environments of both continents in concentration levels higher than their ecotoxicity endpoints. In Europe, compounds such as diclofenac, ibuprofen, triclosan, sulfadimidine, carbamazepine and fluoxetine were reported in a concentration higher than the available ecotoxicity endpoints. In Africa, much more compounds reached concentrations more than the ecotoxicity endpoints, including diclofenac, ibuprofen, paracetamol, naproxen, ciprofloxacin, triclosan, trimethoprim, sulfamethoxazole, carbamazepine and fluoxetine, estriol and 17β-estradiol. Details for each therapeutic group are presented in this review.
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•Large variation in pharmaceuticals concentration in surface waters in Africa and Europe was observed.•The maximum concentrations reported in Africa were nearly 20,000 times higher than in Europe.•Partial removal in WWTP and high pharmaceutical consumption were among the major factors.•Sulfamethoxazole and carbamazepine were the most detected compounds.•Measured concentrations were up to 7850 times higher than ecotoxicity endpoints in Africa.
New perspectives for Advanced Oxidation Processes Dewil, Raf; Mantzavinos, Dionissios; Poulios, Ioannis ...
Journal of environmental management,
06/2017, Letnik:
195, Številka:
Pt 2
Journal Article
Recenzirano
Odprti dostop
Advanced Oxidation Processes (AOPs) are called to fill the gap between the treatability attained by conventional physico-chemical and biological treatments and the day-to-day more exigent limits ...fixed by environmental regulations. They are particularly important for the removal of anthropogenic pollutants and for this reason, they have been widely investigated in the last decades and even applied in the treatment of many industrial wastewater flows. However, despite the great development reached, AOPs cannot be considered mature yet and there are many new fields worthy of research. Some of them are going to be briefly introduced in this paper, including hybrid processes, heterogeneous semiconductor photocatalysis, sulphate-radical oxidation and electrochemical advanced oxidation for water/wastewater treatment. Moreover, the use of photoelectrochemical processes for energy production is discussed. The work ends with some perspectives that can be of interest for the ongoing and future research.
Hydrogen is a common reactant in the petro-chemical industry and moreover recognized as a potential fuel within the next 20 years. The production of hydrogen from biomass and carbohydrate feedstock, ...though undoubtedly desirable and favored, is still at the level of laboratory or pilot scale. The present work reviews the current researched pathways. Different types of carbohydrates, and waste biomass are identified as feedstock for the fermentative bio-hydrogen production. Although all techniques suffer from drawbacks of a low H2 yield and the production of a liquid waste stream rich in VFAs that needs further treatment, the technical advances foster the commercial utilization. Bacterial strains capable of high hydrogen yield are assessed, together with advanced techniques of co-culture fermentation and metabolic engineering. Residual VFAs can be converted. The review provides an insight on how fermentation can be conducted for a wide spectrum of feedstock and how fermentation effluent can be valorized by integrating fermentation with other systems, leading to an improved industrial potential of the technique. To boost the fermentation potential, additional research should firstly target its demonstration on pilot or industrial scale to prove the process efficiency, production costs and method reliability. It should secondly focus on optimizing the micro-organism functionality, and should finally develop and demonstrate a viable valorization of the residual VFA-rich waste streams.
•Hydrogen is a common reactant in the chemical industry and a potential fuel.•Review of the current researched fermentation bio-hydrogen pathways.•New developments (e.g. metabolic engineering, H2 separation) are assessed.•Fermentation has low H2 production yields. The fermentation effluent, rich in VFAs, needs further treatment.
In this study, a biphasic reaction system was developed for the microwave-assisted production of 5-hydroxymethylfurfural (HMF) and furfural. The proposed biphasic reaction system is a possible ...solution in the transition of current industrially state-of-the-art technologies which use C6 carbohydrates to an industrial process where lignocellulosic biomass can be processed, thus being a true sustainable process. In this respect, cellulose and xylan were chosen as model compounds since they are considered as the major building blocks of lignocellulosic polysaccharides. The reaction system consisted of an acidified aqueous phase and methyl isobutyl ketone (MIBK) as the organic phase. Upon the formation of HMF and furfural in the water phase, an instantaneous extraction into MIBK took place. The proposed biphasic reaction system offers many advantages over a monophasic reaction system, including (i) upon formation, furfural and HMF are continuously extracted into the MIBK layer, leading to the suppression of unwanted rehydration reactions, (ii) no unwanted solid particles are formed, and (iii) HMF and furfural can more easily be recovered from the reaction mixture. The goal of this study was to develop the microwave-assisted process in such a way that both cellulose and xylan were simultaneously converted. To this end, optimum process parameters in terms of HCl concentration (cHCl), temperature (T) and reaction time (t) were determined. A maximum HMF yield of 33.65 ± 0.46 w% (or 43.27 mol%) and a maximal furfural yield of 33.30 ± 1.30 w% (or 45.79 mol%) were achieved. To validate the proposed biphasic system, bamboo (Phyllostachys aureosulcata) was applied as a lignocellulosic feedstock, which resulted in a HMF yield of 42.44 mol% and a furfural yield of 48.90 mol%, based upon the cellulose and hemicellulose fraction of the bamboo particles. Since similar yields are observed compared to the model compounds, it is concluded that the lignocellulosic structure does not influence the reaction pathway. This means that the proposed biphasic system can be generalized for a wide variety of lignocellulosic feedstocks.
•Simultaneous formation of HMF and furfural via a microwave-assisted process.•RSM for the optimization of reaction time, temperature and acid concentration.•The measured data show a good agreement with the predicted RSM model.•The biphasic system shows advantages over a monophasic reaction system.
In this study, the effect of microwaves on the production of 5-hydroxymethylfurfural (HMF) in a biphasic system was evaluated via a kinetic analysis. The reaction system consisted of an acidified ...aqueous phase and methyl isobutyl ketone (MIBK) as an organic phase, in which HMF is extracted directly upon formation during the reaction. Two identically shaped reactors were used to assess the influence of microwaves on the production of HMF. A borosilicate glass reactor was used to heat the reaction mixture via microwaves directly, whereas the silicon carbide (SiC) wall of the second reactor absorbed all microwaves and hence the reactor content was heated via convective heat transfer. An identical temperature profile was imposed on both reactors. Cellulose, glucose and fructose were chosen as feedstocks for the conversion to HMF. It was observed that microwaves have a significant effect on the reactions. The hydrolysis of cellulose to glucose was a 2.3 folds faster in the presence of microwaves at the process conditions (0.046 M HCl, 177 °C). The isomerization of glucose to fructose showed a similar increase (factor 2.5). The required energy input for the reaction was systematically higher for the SiC reactor.
“Second generation” bioethanol, with lignocellulose material as feedstock, is a promising alternative for first generation bioethanol. This paper provides an overview of the current status and ...reveals the bottlenecks that hamper its implementation. The current literature specifies a conversion of biomass to bioethanol of 30 to ~50% only. Novel processes increase the conversion yield to about 92% of the theoretical yield. New combined processes reduce both the number of operational steps and the production of inhibitors. Recent advances in genetically engineered microorganisms are promising for higher alcohol tolerance and conversion efficiency. By combining advanced systems and by intensive additional research to eliminate current bottlenecks, second generation bioethanol could surpass the traditional first generation processes.
Soil with heavy metals contamination, mainly lead (Pb), cadmium (Cd), and chromium (Cr) is a progressively worldwide alarming environmental problem. Recently, biochar has been used as a soil ...amendment to remediate contaminated soils, but little work has been done to compare with other organic amendments like compost. We investigated biochar and compost's comparative effect on Pb, Cd, and Cr immobilization in soil, photosynthesis, and growth of maize plants. Ten kg soil was placed in pots and were spiked with Pb, Cd, and Cr at concentrations 20, 10, 20 mg kg
. The biochar and compost treatments included 0, 0.5, 1, 2, and 4% were separately applied to the soil. The crop from pots was harvested after 60 days. The results show that the highest reduction of AB-DTPA extractable Pb, Cd, and Cr in soil was 79%, 61% and 78% with 4% biochar, followed by 61%, 43% and 60% with 4% compost compared to the control, respectively. Similarly, the highest reduction in shoot Pb, Cd, and Cr concentration was 71%, 63% and 78%with 4% biochar, followed by 50%, 50% and 71% with 4% compost than the control, respectively. The maximum increase in shoot and dry root weight, total chlorophyll contents, and gas exchange characteristics were recorded with 4% biochar, followed by 4% compost than the control. The maximum increase in soil organic matter and total nitrogen (N) was recorded at 4% biochar application while available phosphorus and potassium in the soil at 4% compost application. It is concluded that both biochar and compost decreased heavy metals availability in the soil, reducing toxicity in the plant. However, biochar was most effective in reducing heavy metals content in soil and plant compared to compost. In the future, more low-cost, eco-friendly soil remediation methods should be developed for better soil health and plant productivity.
It is clear that renewable resources will play a crucial role in limiting the CO2 emissions. Energy from biomass and waste is regarded as one of the most dominant future renewable energy sources, ...since it can provide a continuous power generation. In this regard, the application of anaerobic digestion is emerging spectacularly. This manuscript lists and discusses the main beneficial properties of anaerobic digestion. Different types of biomass and waste are suitable for anaerobic digestion: the organic fraction of municipal solid waste, waste oils and animal fat, energy crops and agricultural waste, manure and sewage sludge. The potential, opportunities and challenges of these biomasses are discussed. Typical biogas yield and points of attention are included. The manuscript concludes with an overview and discussion of the major research trends in anaerobic digestion, including the analysis of microbial community development, the extension of anaerobic digestion models, the development of pre-treatment techniques and upgrading of the biogas produced.
The discharge of dye-contaminated wastewater into natural waterways presents a substantial risk to human and environmental health, therefore necessitating the treatment and removal of toxic dyes from ...colored wastewaters before their release into the ecosystem. The aim of this study was to isolate and characterize bacterial strains capable of decolorizing and/or degrading azo dyes commonly applied in textile production (monoazo dye Reactive Orange 16 and diazo dye Reactive Green 19) from activated sludge systems used in the treatment of (textile) wastewater. Following a prescreening of 125 isolates for their decolorization potential five strains were retained for further evaluation of decolorization rate and effects of physicochemical parameters using a microtiter plate method. Of those five strains, one strain belonging to the genus Acinetobacter (ST16.16/164) and another belonging to Klebsiella (ST16.16/034) outperformed the other tested strains. Both strains exhibited strong decolorization ability (>80%) within a wide temperature range (20 °C–40 °C) and retained good decolorization activity at temperatures as low as 10 °C (especially strain ST16.16/034). Among the different pH values tested (pH 4, 7 and 10), highest dye removal for both strains occurred at pH 7, with decolorization efficiency remaining relatively high under alkaline conditions (pH 10), and neither isolates decolorization efficiency was negatively impacted by high salt or high dye concentration. Furthermore, both strains displayed the highest rate of decolorization and were able to completely (ST16.16/034) or partly (ST16.16/164) degrade the azo dyes. Altogether, our results support the use of these bacteria in the treatment of industrial wastewaters containing azo dyes.
The paper reviews the pyrolysis of biomass constituents and possible secondary reactions. Biomass pyrolysis yields mostly liquid and solid fuel, easy to store and transport.
Relevant working ...conditions for experiments and large-scale operation are: (i) biomass particles
<
200
μm, (ii) a particle heating rate of at least about 80
K
min
−1 and (iii) a reactor environment where the internal resistance to heat penetration is smaller than the external resistance to heat transfer (Biot-number, Bi
<
1).
The circumstances of TGA and DSC experiments meet these requirements and fully determine the reaction kinetics and endothermicity of the pyrolysis reaction. The reaction rate constant and the heat of reaction are essential parameters in the design of a pyrolysis reactor. For most of the biomass species tested, the first order reaction rate constant is large and >0.5
s
−1. The heat of reaction ranges from 207 to 434
kJ
kg
−1. All results tie in with literature data, although the reader is cautioned in using literature data since experiments were not always performed under relevant testing conditions.
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