Numerical approach to modelling pulse mode soil flushing on a Pb-contaminated soil

4noPurpose: Soil flushing can represent a suitable technology in remediation of soils, sediments and sludge contaminated by persistent species (e.g. toxic metal). This paper presents a model specifically developed to evaluate the feasibility of chelating agent-enhanced flushing. The model, here applied to the remediation of real Pb-contaminated soils, was conceived also to simulate an innovative pulse-mode soil flushing technique. Materials and methods: The soil flushing application was firstly carried out through columns laboratory experiments. Columns were filled with a real Pb-contaminated soil (3,000 mg kg−1 of dry soil) and flushing was operated in a pulse mode with different chelating agent dosages (3 and 4.3 mmol kg−1soil). Experimental results were used to calibrate and validate the developed reactive transport model that accounts for transport of ethylenediamine tetraacetic acid (EDTA) and EDTA–Pb chelate complexes, Pb residual concentration on soil and the reduction in permeability by soil dissolution. Determination of hydrodynamic and hydrodispersive parameters was carried out through a numerical approach incorporating the use of neural network as interpolating function of breakthrough data obtained by a tracer test. Results and discussion: The EDTA dosage strongly influenced the efficiency in Pb extraction and soil permeability. Cumulative extractions of Pb were found to be 20 and 29 % for the EDTA concentrations of 3 and 4.3 mmol/kg of dry soil, respectively. The soil dissolution caused a significant flow rate decrease, as a consequence of the increase in chelating agent concentration. Therefore the recovery phase duration increased from 738 to 2,080 h. The ability of the model in simulating all the examined phenomena is confirmed by a good fit with experimental results in terms of (a) soil permeability reduction, (b) eluted Pb and (c) residual Pb in the soil. Conclusions: Results highlighted as the model, supported by a preliminary and careful characterization of the soil, can be useful to assess the feasibility of the flushing treatment (avoiding soil clogging) and to address the choice of the operating parameters (flow rate, chelating agent dosage and application method). On the basis of the present research results, a protocol is suggested for in situ soil pulse–flushing application.openLuciano, A.; Viotti, P.; Torretta, V.; Mancini, G.Luciano, A.; Viotti, P.; Torretta, Vincenzo; Mancini, G

Comparison between two cases study on water kiosks

Bottled water consumption in Europe began in the 70s. Environmental impact derived from water production chain is very significant: for example plastic bottles use, oil consumption for bottle production, air emission from vehicles transporting bottles, not recycled plastic packages, etc. In this research an environmental and economic impact evaluation was presented for two case studies, regarding water kiosk design with the aim of supplying controlled natural and sparkling water with better organoleptic quality compared to water directly supplied from aqueduct

Incineration of Pre-Treated Municipal Solid Waste (MSW) for Energy Co-Generation in a Non-Densely Populated Area

Abstract: The planning actions in municipal solid waste (MSW) management must follow strategies aimed at obtaining economies of scale. At the regional basin, a proper feasibility analysis of treatment and disposal plants should be based on the collection and analysis of data available on production rate and technological characteristics of waste. Considering the regulations constraint, the energy recovery is limited by the creation of small or medium-sized incineration plants, while separated collection strongly influences the heating value of the residual MSW. Moreover, separated collection of organic fraction in non-densely populated area is burdensome and difficult to manage. The paper shows the results of the analysis carried out to evaluate the potential energy recovery using a combined cycle for the incineration of mechanically pre-treated MSW in Basilicata, a non-densely populated region in Southern Italy. In order to focalize the role of sieving as pre-treatment, the evaluation on the MSW sieved fraction heating value was presented. Co-generative (heat and power production) plant was compared to other MSW management solutions (e.g., direct landfilling), also considering the environmental impact in terms of greenhouse gases (GHGs) emissions

Organic waste valorization in remote islands: analysis of economic and environmental benefits of onsite treatment options

Solid waste management (SWM) represents an important issue for small islands. This research evaluates the municipal SWM system of the Pelagian archipelago, in Italy. The research aims to evaluate environmental and econoemic benefits of onsite treatment plants for the valorization of the organic fraction of municipal solid waste. The sizing of the anaerobic digestion (AD) and composting plant was developed, and the characteristics of the plant were used to conduct a cost analysis and an environmental life cycle assessment. The current waste management system (S0) has been compared with the new strategy proposed (S1). Results showed that S1 leads to save more than 250,000 € y−1 due to the avoidance of organic waste final disposal and shipping, determining a payback time of about 7 years. Environmental benefits include a lowering of CO2-eq emission of more than 1100 tonnes per year and a reduction of all the six environmental impacts analysed. The outcomes represent a novel contribution to the scientific literature since the research provides the first comparison of quantitative data about environmental and cost benefits of onsite AD plants in small islands. The research underlines that onsite waste treatment systems are viable options to improve SWM systems in isolated regions

Poultry manure gasification and its energy yield

The disposal of poultry manure is one of the main problems of the poultry sector. The results of some tests developed in a gasification pilot plant are presented in this paper. The aim was to preliminarily analyze the energy generation from poultry manure treated by gasification. The level of energy yields and the quantification of the produced syngas are also reported. The good results suggests an possible application at full scale

Thermal behavior of a semibatch reactor during upset conditions as a function of dosing and temperature controller type

In fine chemical industries, potentially runaway reactions are often carried out in semibatch reactors to better control the heat evolution. For such processes, an uncontrolled temperature increase can trigger secondary undesired reactions or, worse, decompositions of the reacting mixture with consequent reactor pressurization and, eventually, physical explosion. For this reason, during years, it has been tried to simulate how a runaway phenomenon evolves as a consequence of a number of upset operating conditions: e.g. dosing errors, cooling system failure or external fire. In this work, a dedicated software has been developed and used to simulate a dosing error occurring during an industrial synthesis. Particularly, it has been analyzed the effect of the different industrial temperature control modes (isoperibolic and isothermal) and their related controller parameters onto the time evolution of the main process variables. Theoretical simulations have shown that dif-ferent scenarios can arise as a function of these control features

Public attitude towards nuclear and renewable energy as a factor of their development in a circular economy frame: two case studies

5siThe energy sector is one of the most important sectors of the economy and one of the polluters of the environment. Therefore, in order to achieve the Sustainable Development Goals and the climate goal stated in the Paris Agreement, many countries need to carry out a full-scale eco-modernization of the energy sector and develop green energy. Nuclear and renewable energy may become key areas of global energy development in the near future, in agreement also with Circular economy concepts, but public opinion (and other controversial visions/aspects) is one of the barriers to their development. The purpose of this study is to analyze the relationship between attitudes towards nuclear and renewable energy in two countries: EU and non-EU, considering the level of their development. The authors conducted a survey among residents regarding their attitude towards nuclear and renewable energy, as well as their attitude to the present energy policy. The cluster analysis technique was used to analyze the results. The obtained results confirmed the dependence between the level of development of nuclear and renewable energy and the public attitude towards it. The authors identified the public attitude as one of the key factors in the development of energy and the achievement of environmental and social sustainability.openopenKaraeva, Anzhelika; Magaril, Elena; Torretta, Vincenzo; Viotti, Paolo; Rada, Elena CristinaKaraeva, Anzhelika; Magaril, Elena; Torretta, Vincenzo; Viotti, Paolo; Rada, Elena Cristin

the future of biofuels for a sustainable mobility

Biofuels production is strongly supported all over the world as a renewable energy source for reducing the dependence with respect to the unstable market of oil import. Bioethanol, the main biofuel produced in the world, is widely used for mobility in Brazil, and also in USA, but with little differences with respect to its sustainability. In Brazil it is produced from a by-product of the sugarcane industry; while, in USA it is manufactured from food crops. Biogas and biodiesel productions are growing fast but lesser than that of bioethanol. The European Union is looking at this issue with great interest and, in 2011, it adopted an extensive strategy to reduce carbon dioxide emissions related to transport by 60% within 2050. In order to achieve this result, a transformation of the current European transport system will be necessary. The ambitious goal will imply complex measures including the fossil fuels limitation in favor of renewable fuels. This program opens several possibilities concerning the development of biofuels (i.e. biogas, bioethanol and biodiesel) and their related technologies, which are still on trial (mainly regarding the bioethanol production) as well as object of economic and social sustainability analysis. The paper deals with the use of biofuels for transport in the European framework, showing that its sustainability could raise relevant negative social effects mainly due to the use of land for energy crops (e.g. change of food price and world food shortage)

Microbial Enzyme Biotechnology to Reach Plastic Waste Circularity: Current Status, Problems and Perspectives

The accumulation of synthetic plastic waste in the environment has become a global concern. Microbial enzymes (purified or as whole-cell biocatalysts) represent emerging biotechnological tools for waste circularity; they can depolymerize materials into reusable building blocks, but their contribution must be considered within the context of present waste management practices. This review reports on the prospective of biotechnological tools for plastic bio-recycling within the framework of plastic waste management in Europe. Available biotechnology tools can support polyethylene terephthalate (PET) recycling. However, PET represents only ≈7% of unrecycled plastic waste. Polyurethanes, the principal unrecycled waste fraction, together with other thermosets and more recalcitrant thermoplastics (e.g., polyolefins) are the next plausible target for enzyme-based depolymerization, even if this process is currently effective only on ideal polyester-based polymers. To extend the contribution of biotechnology to plastic circularity, optimization of collection and sorting systems should be considered to feed chemoenzymatic technologies for the treatment of more recalcitrant and mixed polymers. In addition, new bio-based technologies with a lower environmental impact in comparison with the present approaches should be developed to depolymerize (available or new) plastic materials, that should be designed for the required durability and for being susceptible to the action of enzymes

Removal of Arsenic (III) from water with a combination of Graphene Oxide (GO) and Granular Ferric Hydroxide (GFH) at the optimum molecular ratio

The occurrence of arsenic in water is a global problem for public health. Several removal technologies have been developed for arsenic removal from water, and adsorption onto iron oxyhydroxides is the most widely used technique. Granular ferric hydroxide (GFH) has been used mainly for As(V) removal, but it has the disadvantage that it can create a problem with the residual concentration of iron in the water. Moreover, graphene oxide (GO), which contains a large amount of reactive oxygen, exhibits high adsorbing capacity. In this study, the combined use of GO and GFH as adsorbent materials in different molar ratios was investigated in order to achieve the maximum As(III) removal from aqueous solutions. The effect of the adsorbent’s dosage, pH value, contact time, initial As(III), and different molar ratios of GO/GFH was examined. As depicted, the presence of GFH enhances the use of GO. In particular, the molar ratio of GO/GFH 2:1 (i.e., 0.2 g/L GO and 0.1 g/L GFH) is chosen as optimal at pH value 7.0 ± 0.1, while the removal percentage increased from 10% (absence of GFH) to 90% with the simultaneous addition of GFH. Freundlich isotherm and pseudo-second-order kinetic models described the experimental data adequately and the highest adsorption capacity that was achieved was 22.62 µg/g