Elena Cristina Rada

Lower Heating Value Dynamics during Municipal Solid Waste Bio-Drying

In agreement with the new European Union directives concerning the valorization of materials and energy recovery, Municipal Solid Waste (MSW) management is, in general based on an integrated approach characterized by a combination of different treatment processes. The bio-mechanical treatment (BMT) of MSW is an increasing option in Europe either as a pre-treatment before landfilling or as a pre-treatment before combustion. In this context the research on the bio-drying process is not fully developed. In the present paper the Lower Heating Value (LHV) dynamics during MSW bio-drying has been assessed. Measurements were made using a pilot scale bio-dryer that allows the recording of data as air flow, temperature (at the entrance, at the exit and inside the waste), and weight loss. An initial characterization of the MSW completes the input data. Results give information on the dynamics of the main process parameters (humidity, volatile solids, ammonia, Lower Heating Value) and also of additional parameters.

Some Research Perspectives on Emissions from Bio-Mechanical Treatments of Municipal Solid Waste in Europe

The bio-mechanical treatment of Municipal Solid Waste is an increasing option in Europe either as a pre-treatment before landfilling or as a pre-treatment before combustion. The present work deals with the problem of assessment of significant data related to emissions to air from bio-mechanical treatments. Reliable data are necessary for the development of: a) Life Cycle Assessment studies; b) verification of compliance with existing regulations; c) environmental impact studies assessment. In order to point out some lack of knowledge about bio-mechanical treatments, some results of a Life Cycle Assessment study on Municipal Solid Waste bio-stabilization treatment have been reported and analysed. Indeed, during the development of that Life Cycle Assessment, some problems were found regarding the availability and the quality of emission data from Municipal Solid Waste mechanical biological treatment. Concerning existing regulations, in Europe we can find both countries with enhanced approaches, and countries with a soft approach. In the second case, for instance, a few Italian regions adopted local regulations in order to improve the quality of the environmental regulation as the national one has been considered inadequate. The environmental impact assessment of bio-mechanical treatments is not still as developed as options such as incineration. The reason is that the impact of a bio-mechanical treatment plant is considered low. On the contrary it can be demonstrated that a greater attention must be paid in the case of non optimised technologies and large plants.

Air pollution control through biotrickling filters: a review considering operational aspects and expected performance

Abstract The biological removal of pollutants, especially through biotrickling filters (BTFs), has recently become attractive for the low investment and operational costs and the low secondary pollution. This paper is intended to investigate the state of the art on BTF applications. After an overview on the biodegradation process and the typical parameters involved, this paper presents the analysis of a group of 16 literature studies chosen as the references for this sector. The reference studies differ from one another by the pollutants treated (volatile organic compounds [VOC], hydrogen sulphide, nitrogen oxides and trimethylamine), the geometry and size of the BTFs, and the procedures of the tests. The reference studies are analyzed and discussed in terms of the operational conditions and the results obtained, especially with respect to the removal efficiencies (REs) and the elimination capacities (ECs) of the pollutants considered. Empty bed residence time (EBRT), pollutant loading rate, temperature, pH, oxygen availability, trickling liquid flow rate, inoculum selection and biomass control strategies revealed to be the most important operational factors influencing the removal performance of a BTF.

Comparison between conventional biofilters and biotrickling filters applied to waste bio-drying in terms of atmospheric dispersion and air quality

ABSTRACT Biofiltration has been widely applied to remove odours and volatile organic compounds (VOCs) from industrial off-gas and mechanical-biological waste treatments. However, conventional open biofilters cannot guarantee an efficient dispersion of air pollutants emitted into the atmosphere. The aim of this paper is to compare conventional open biofilters with biotrickling filters (BTFs) in terms of VOC dispersion in the atmosphere and air quality in the vicinity of a hypothetical municipal solid waste bio-drying plant. Simulations of dispersion were carried out regarding two VOCs of interest due to their impact in terms of odours and cancer risk: dimethyl disulphide and benzene, respectively. The use of BTFs, instead of conventional biofilters, led to significant improvements in the odour impact and the cancer risk: when adopting BTFs instead of an open biofilter, the area with an odour concentrationu2009>u20091 OUu2005m−3 and a cancer risku2009>u200910−6 was reduced by 91.6% and 95.2%, respectively. When replacing the biofilter with BTFs, the annual mean concentrations of odorants and benzene decreased by more than 90% in the vicinity of the plant. These improvements are achieved above all because of the higher release height of BTFs and the higher velocity of the outgoing air flow.

Noise and Air Pollution from Urban Traffic

Together with the atmospheric emission of pollutants, noise can affect the health of the population. In particular, urban traffic is important when considering population health, because of its proximity to the receptors. In comparison with other pollutants, the control of environmental noise has been hampered by insufficient knowledge of its effects on people and of dose-response relationships, as well as by a lack of defined criteria. Due to the high levels of external noise and interior noise, the difficulties are in communication and a series of nonspecific symptoms: irritability, headache, palpitations, sleep disorders, stress. Concerning air pollution, the health of the population is directly influenced by primary emissions or atmospheric transformation from motor vehicles. Few studies have characterized the spatial correlation between both factors, air pollutants and noise, thus this paper, based on urban noise measurements, presents preliminary data on noise levels in a European capital and a discussion where interactions with air quality are dealt with. Data demonstrates that the urban structure of the analysed city cannot guarantee an adequate protection of the population against noise, because of the interactions between neighbouring areas.

DOMESTIC ACTIVITIES AND PM GENERATION: A CONTRIBUTION TO THE UNDERSTANDING OF INDOOR SOURCES OF AIR POLLUTION

Few researches on domestic indoor air pollution have given quantitative information on the variation of the characteristics of the indoor source of particulate matter (PM). The purpose of this work was to investigate the emission characteristics of the common indoor particle sources. More specifically, this paper is intended to contribute to the understanding of how normal domestic activities could affect the human health. The emission sources of PM studied in this work was cooking, vacuuming, ironing and the use of deodorant spray.Cooking activities were expected to be one of the major sources of indoor particles and the features of the cookers may affect the characteristics of emissions resulting from cooking. For this reason, the results of a previous study based on the variability of the power of the cooker were reported, to study the sustainability of natural gas from the point of view of the induced indoor human exposure to PM. Measurements were performed by a GRIMM analyser, able to measure 16 granulometric classes from 0.3 to 20 µm. The study found that the activity of cooking and the use of deodorant spray are the sources that produce the higher indoor concentration levels compared with the other sources studied.

Assessment of arsenic removal efficiency by an iron oxide-coated sand filter process

Arsenic is among the most dangerous contaminants which can limit groundwater use for drinking water consumption. Among the most diffused As-removal technologies around the world, adsorptive media systems are usually favored for relatively low cost and simplicity of operation. This study examines the performance of a laboratory-scale iron oxide-coated sand (IOCS) column filter, to remove arsenic (arsenate (As[V]) and arsenite (As[III])) from groundwater. This technology could be adopted in small communities, as it showed consistent removal rates of 99% with an easy-to-operate process. Some considerations about the possible introduction of such technology in developing countries are provided, highlighting the general impacts to human health related to high arsenic concentrations in groundwater. This, among other adsorption processes, could be recommended as a sustainable mean of ensuring good drinking water quality in developing regions, reducing human health impacts.

Biofiltration Combined With Non-thermal Plasma For Air Pollution Control: A Preliminary Investigation

Biological technologies have been often employed to remove volatile organic compounds (VOCs) at low concentrations from air streams. However, biodegradation is very sensitive to variations of inlet concentrations and flow rate that usually occurs in real industrial processes; furthermore, an acclimation period is required by microorganisms to adapt to new conditions of flow rate and concentration. A possible solution to overcome these issues is represented by a pre-treatment with non-thermal plasma (NTP). The synergy between an NTP reactor and a biofilter in removing a mixture of VOCs from air is the object of this paper. A mixture of five VOCs (benzene, ethylbenzene, p-xylene, n-heptane and toluene) and humid air was chosen to represent the gaseous effluent stripped from an industrial wastewater treatment plant. A sudden increase in the VOC concentrations was intentionally induced to understand if NTP can manage peaks of the inlet concentration of pollutants and help the biodegradation carried out in the biofilter. NTP revealed to be capable of both pre-treating concentrations peaks and converting the initial VOCs in more soluble compounds; in conclusion, NTP is able to help biodegradation, allows controlling unsteady conditions and prevents stress to bacteria.

An Example Of The Removal Of Organic Pollutants From Off-gas Generated From Small Activities In The Proximity Of Urban Areas

This article describes a theoretical application aimed at the potential recovery of organic pollutants poorly soluble in water and with a molecular weight higher than that of water. The organic pollutants must be present in the gas stream to be treated only in low concentrations. A case study was considered in which chlorobenzene was taken as the organic pollutant of reference. The application can be interesting when applied to industrial off-gases, especially if generated in the proximity of urban areas. Indeed, often in most industrialized regions of northern Italy, urban/industrial planning has not adequately separated the residential and productive areas: the presence of a number of small polluting activities can create critical conditions of human exposure even in the absence of large emitters. The system is developed according to two alternative process schemes (liquid–liquid separator equipped with a coalescer and separation using membrane process). The goal is twofold: from an environmental point of view, the aim is to treat the gas flow, limiting the dispersion into the atmosphere of hazardous pollutants; to this, an economic target should be added, with the opportunity to simultaneously retrieve reusable substances in industrial production cycles.

Circular economy and waste to energy

Waste management in European Union has long being regulated by the 4Rs principle, i.e. reduction, reuse, recycling, recovery, with landfill disposal as the last option. This vision recently led the European Union (especially since 2015) to the introduction of virtuous goals based on the rejection of linear economy in favour of circular economy strongly founded on materials recovery. In this scenario, landfill disposal option will disappear, while energy recovery may appear controversial when not applied to biogas production from anaerobic digestion. The present work aims to analyse the effects that circular economy principles introduced in the European Union context will have on the thermochemical waste treatment plants design. Results demonstrate that indirect combustion (gasification + combustion) along with integrated vitrification of the non-combustible fraction of treated waste will have a more relevant role in the field of waste treatment than in the past, thanks to the compliance of this option with the principles of circular economy.Waste management in European Union has long being regulated by the 4Rs principle, i.e. reduction, reuse, recycling, recovery, with landfill disposal as the last option. This vision recently led the European Union (especially since 2015) to the introduction of virtuous goals based on the rejection of linear economy in favour of circular economy strongly founded on materials recovery. In this scenario, landfill disposal option will disappear, while energy recovery may appear controversial when not applied to biogas production from anaerobic digestion. The present work aims to analyse the effects that circular economy principles introduced in the European Union context will have on the thermochemical waste treatment plants design. Results demonstrate that indirect combustion (gasification + combustion) along with integrated vitrification of the non-combustible fraction of treated waste will have a more relevant role in the field of waste treatment than in the past, thanks to the compliance of this option wit...