Environmental control and sustainability management.PDF

Environmental Control: What is a possible definition of pollution? “Unwanted, often dangerous, material that is introduced into the Earth’s environment as the result of human activity, that threatens human health, and that harms ecosystems”; Or “A pollutant is a substance or energy introduced into t...

Environmental Control: What is a possible definition of pollution? “Unwanted, often dangerous, material that is introduced into the Earth’s environment as the result of human activity, that threatens human health, and that harms ecosystems”; Or “A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values. Three main environmental phases: Gas (AIR) Liquid (WATER) Solid (SOIL)” What is a possible definition of environmental control? Environmental monitoring is a tool to assess environmental conditions and trends, support policy development and its implementation, and develop information for reporting to national policymakers, international forums and the public. It describes the processes and activities that need to take place to characterize and monitor the quality of the environment and refers to the tools and techniques designed to observe an environment, characterize its quality, and establish environmental parameters; for the purpose of accurately quantifying the impact an activity has on an environment What is the link between pollution and death? POLLUTION is the largest environmental cause of DISEASE and PREMATURE DEATH in the world today. Forms of pollution produces by industry, mining, electricity generation, mechanized agriculture and petroleum- powered vehicles (Ambient air pollution, Chemical pollution and Soil pollution are all on the rise res What is the link between pollution and poverty? Poverty is not simply a lack of money but also a reduced access to education, health care, nutrition and sanitation. It impedes the participation in legal and political processes and civil society What is the economic cost of pollution? The costs of pollution-related disease are overlooked and undercounted because they are associated with non- communicable diseases of long latency that: extend over many years; are spread across large population; are not captured by standard economic indicators However, these costs include direct medical expenditures, indirect health-related expenditures (time lost from school or work), diminished economic productivity in persons damaged by pollution and losses in output resulting from premature death. In addition to them, there are also intangible costs aa poor health in people made ill by pollution, disruption of family stability and loss in year of life. Describe the macro classes into which pollution can be divided Pollution can be divided into 4 MACRO CLASSES: AIR POLLUTION (household, ambient fine particulate, and tropospheric ozone) which is associated with several risk factors for cardiovascular disease and with several highly prevalent non-communicable disease; WATER POLLUTION (unsafe sanitation, unsafe water resources) which is associated to acute and chronic gastrointestinal diseases (diarrheal diseases 70 % of deaths attributed to water pollution); SOIL, CHEMICAL AND HEAVY METAL POLLUTION (including contaminated sites) to which a comprehensive assessment of the health effects has not yet been published and OCCUPATIONAL POLLUTION (carcinogens, occupational particulate, gases and fumes) which has a recent origin and is due to a rapid, largely, uncontrolled industrialization. Nowadays, high-income countries are controlled by legislation and regulation, but it is still highly prevalent in low-income and middle-income countries. What is the concept of environmental injustice? ENVIRONMENTAL INJUSTICE is the inequitable exposure of poor and minorities to toxic chemicals, contaminated air and water, unsafe workplaces, and other forms of pollution. Indeed, pollution threatens fundamental human rights: the rights to life, to health and to well be in. This phenomenon exists in countries at all levels. Describe one of the possible classification of pollutants NUTRIENTS: Negative impacts of nitrogen (N) and phosphorus (P) at high relative concentrations and Eutrophication (phytoplankton growth) PESTICIDES: Wide range of mostly organically based chemicals used to control pests and released intentionally HAZARDOUS ORGANIC CHEMICALS: Commonly used as fuels and as materials for a variety of industrial processes and not intentionally released HAZARDOUS MATERIALS: generally, fit the definition of hazardous waste ACIDIFICATION: result of the conversion of the oxides of N and S into their respective acids in the atmosphere, acid mine drainage (pyrite) and heavy use of ammoniacal fertilizers SALINITY and SODICITY: reduction in plant productivity due to increased osmotic potential and changes in soil physical properties and irrigation TRACE ELEMENTS: present in relatively low concentrations and cause acute or chronic health problems (Cd, Cu, Pb, Mn, Zn) SEDIMENTS: soil particles that have eroded from the landscape and have been carried to surface waters, block light transmission, can be enriched in P and can be source or sink for water pollutants PARTICULATES: move deep into lung tissue GREENHOUSE GASES: anthropogenic or naturally occurring SMOG-FORMING COMPOUNDS: ingredients for process of smog production What are the parameters to consider when describing a pollutant? PERSISTANCE: tendency of a substance to degrade in the environment (ex. Halogenated organic chemicals). RESIDENCE TIME: length of time a substance remains in a particular environmental compartment (S and N oxides in the atmosphere) BIOAVAILABILITY OF A SUBSTANCE: the possibility of it causing an effect, positive or negative, on an organism (strictly correlated to remediation) Produce a risk assessment plan for a “pollutant”. This process is generally applied to INDIVIDUAL STRESSORS and POTENTIAL ADVERSE EFFECTS on single organism or small group of organisms. The formal ecological risk assessment process takes a broader view of the ecosystem and includes steps beyond the four listed above. Risk assessments span many areas of expertise and invariably involve the use of assumptions and seemingly arbitrary safety factors that are sources of criticism. The goals for a risk assessment plan are: Considering existing or possible contamination of soil, air, water, or sediments; Tracing all possible routes of exposure for organisms of concern; Determining the dose received by organisms of concern; Determining the potential negative impacts of that dose on the organisms of concern. The risk assessment plan is composed by: 1. HAZARD IDENTIFICATION, which is the qualitative assessment of a substance that determines whether exposure to a specific substance causes harm 2. EXPOSURE ASSESSMENT, i.e., the process by which the identity of the organisms exposed to a contaminant and the dose received are determined. During this step, all possible means of exposure to a contaminant and the relative contribution of each route of exposure to the dose of the recipient are investigated. Specific parameters investigated are the “STARTING POINT”, which is how the organism can receive a dose, the “HEIs” (Highly Exposed Individuals), which represents persons with exposure greater than that of 95% of the population and with the greatest likelihood of suffering the greatest harm at the lowest dose of the pollutant and “HEEE”, which stands for high end exposure estimate and represents fraction of population receiving the dose greater than the 90th percentile of all individuals in the population. 3. DOSE-RESPONSE ASSESSMENT, where the relationship between the amount of a substance that an organism receives (the dose) and the effects on that organism (the response) are investigated. Responses can be favorable or unfavorable. For the risk assessment process, dose–response assessment may take information from the exposure assessment and determine the effects on the exposed organisms. An important parameter is the NOAEL (No Observable Adverse Effect Level), which is the highest dose that can be administered without a statistically significant increase in adverse response Few experiments use doses near the NOAEL (ex. animal), but however in many cases there are problems of extrapolation: passing from high doses to low doses and from animal to human, 4. RISK CHARACTERIZATION, the step in which the results from exposure assessment and dose response assessment for determining the management practices or cleanup procedures that produce acceptable exposures to the receptor organisms are combined. Back-calculation, starting with an acceptable exposure to an organism and working back to the management practices or media concentrations (e.g., levels in soil or water) that produce the maximum acceptable exposures. The bases of regulatory action are put in this step. A very important parameter is the “RfD” (Reference Dose), which is the daily intake of a chemical that, if taken during an entire lifetime, will be without appreciable risk. This parameter is calculated as NOAEL divided by a safety factor (10 to 1000) An ecological risk assessment is exploited to predict future adverse effects from an ecological stressor (prospective, e.g., the release of a new pesticide), to determine whether a stressor has caused (retrospective) an effect and to characterize an ecological resource. This kind of assessment is similar to exposure assessment and dose-response assessment of hazard identification. An assessment end points is performed in order to overcome the difficulty in dealing with numerous species in an ecological risk assessment. Indeed, there are some species that are selected to represent the net effect of a stressor on different ecological organizational levels and, even though simplification, a considerable amount of effort is spent. Risk characterization is the final phase and generally involves some attempt to quantify the risk realized from the stressors. Once finished with the assessment, we may approach it differently in the future process (FEEDBACK LOOP). Both the general public and the scientific community can be critical of the risk assessment process and the resulting regulations: a social–political issue and not necessarily a scientific decision. What is the difference between the conventional risk assessment and the ecological risk assessment? A CONVENTIONAL RISK (=the chance of injury, loss, or damage) ASSESSMENT is a process used to estimate quantitatively * the risks associated to the exposure of any organism to various substances in the environment (the tendency is to focus on human health). An ECOLOGICAL RISK ASSESSMENT, instead, addresses the effects of contaminants on all organisms besides humans. The latter is indeed exploited to predict future adverse effects from an ecological stressor (prospective, e.g., the release of a new pesticide), to determine whether a stressor has caused (retrospective) an effect and to characterize an ecological resource. * Quantification of a risk: number of negative outcomes divided by the number of organisms exposed to the risk or by some other measure of exposure to the risk. What is the meaning of residence time and what is its use? MEAN RESIDENCE TIME (MRT) is the measure of the time it takes a substance to cycle through a particular pool. It is usually exploited to monitor CO2 and O2 (Atmospheric oxygen = 3000 years Carbon dioxide = 5 year) due to the fact that biogeochemical cycles of nutrients and trace elements are extremely complex: Specific transfer rates; MRTs; Fates in the ecosystems. Atmospheric processes influence their cycling. What characteristics of the atmosphere can influence the distribution of pollutants? The dispersion of the pollutants depends both on the speed and direction of winds and on the differences in T with altitude (expressed by the dry adiabatic lapse rate ) What is the chemical composition of the atmosphere and what are the major pollutants? The atmosphere is mostly composed of a high relative concentration of N2 and O2 = no significant perturbation. The presence of other components (such as Methane, Carbon dioxide, Nitrous oxide Hydrogen sulfide, CFCs, Carbonyl sulfide and Carbon monoxide) is due to natural emissions and/or anthropogenic emission. What is the main cause of the ozone hole? The main cause of ozone holes is CFCs. Indeed, one Cl atom photo-dissociated from a CFC molecule can catalyze thousands of O3 destroying cycles, resulting in the degradation of about 100,000 O3 molecules. What are the major pollutants of water? The contamination of groundwaters is due to the downward leaching of chemicals, the intentional discharge of wastes and the contaminant spills. The magnitude is influenced by sorption, biodegradation, hydrolysis, solubility, volatilization, climatic parameters (precipitation and evapotranspiration). What are the major potential problems for water? The pollution potential of a substance is related to its water-soluble characteristics, harmful nature, and the MRT (mass rapid transit) of a particular aquatic system. The major potential problems for water are acidity, eutrophication, surface runoff and sediments. ACIDITY: The acidity of water bodies has important consequences on the survival of aquatic organisms. High levels of H+ ions can result in lakes, streams, and rivers that no longer support aquatic life. When acids are added to aquatic ecosystems, the decrease in pH that occurs depends greatly on the buffering capacity o f the system EUTROPHICATION: The excessive amounts of nutrients, such as N and P, are added to the ecosystem leads to enhanced algal growth, decreased dissolved O2 and reduced water transparency. SURFACE RUNOFF: it is a precipitation event–driven process SEDIMENT LOADING: it is a major water quality problem due to siltation phenomena, the absorption of potential nutrients, pesticides, and organic matter, the decrease of light penetration which reduces the growth of benthic plants, the buildup of materials which entails the loss of water-storage capacity in reservoirs, lakes, and wetlands. ENRICHMENT RATIO: reflects the importance of sorbed chemicals in the eroding sediments and is dependent on soil type, erosion mechanism and total mass of soil eroded. RUNOFF COEFFICIENT: It is influenced by inherent infiltration rate of the soil, slope, rainfall intensity and antecedent moisture conditions. What are the most important features to be considered for soil pollution? The soil is a natural, three-dimensional array of vertically differentiated material at the surface of the Earth’s crust. Its pollution could be caused by chemical or biological issues, by erosion, by erosion, by compaction and/or by salination. The most important feature we must consider are its physical, chemical and biological properties (with their specific processes annexed). As regard to the PHYSICAL PROPERTIES we consider: PARTICLE SIZE and SOIL TEXTURAL classes and the AGGREGATES and SOIL STRUCTURE (the latter influences the infiltration of water and gas diffusion) SOIL DENSITY (it allows the estimation of the type of soil minerals present and the degree of soil compaction, respectively) SOIL SOLIDS which are divided into primary, formed during the cooling of molten rock, predominately silicate minerals, and secondary, formed in soils from soluble products derived from the WEATHERING OF ROCKS (slow physical and chemical process, loss of soluble constituents and formation of secondary minerals), minerals. SOIL ORGANIC and INORGANIC CARBON (the organic one influences physical, chemical and biological properties whereas inorganic one includes carbonate species (buffering)). SOIL WATER expressed through cohesion (water-water) and adhesion (water-soil) forces and water content and water potential (measure of the strength, or energy, with which water is held by the soil). Also, its MOVEMENT is considered as saturated flow (water) and/or unsaturated flow (air). SOIL CLIMATE i.e. influences of precipitation and temperature on weathering and degradation rates, and translocation processes. GAS TRANSFER due to the fact that the soil atmosphere is influenced by the atmosphere because gases flow into and out of soil depending on concentration gradients. This parameter is influenced by soil porosity, soil water contents, biological activity, and the partial pressures of soil gases. EROSION where we could have onsite and offsite problems. As regard to the CHEMICAL PROPERTIES we consider: The PRESENCE OF ORGANIC MATTER which has effects on: Structure Cation exchange capacity Macro/Micronutrients pH buffering ACIDITY which is caused by natural rainfalls (leaching of basic cations, leaving Al3+), plant and microbial respiration, mineralization, and nitrification of organic N and eventually oxidation of pyrite. It leads to phytotoxicity and less fertility. SALINITY and SODICITY caused by excessive amounts of salts and Exchangeable Na. It has a high Influence on soil structure. REDOX PROPERTIES which are controlled by abiotic and biotic processes (the sequence of reduction is well understood). We mainly consider transformations that occur when soil is saturate with water and the others are less studied. Typical chemical processes are: CATION AND ANION EXCHANGE: Ion exchange (ionization or protonation of Isomorphic substitution (element uncharged sites, pH dependent substitution) phenomenon) SORPTION: Clay type and content Soil organic matter Oxides and hydroxides of Al and Fe Function of pH Carbonates As regard to the BIOLOGICAL PROPERTIES we consider: The ROLE that each component has in formation of soil Plants→ Plant cycle nutrients Soil animals → Decomposition Soil microorganisms → Physical mixing. Influenced by rainfall, temperature, vegetation, and physical and chemical properties of soil What is soil quality? A universal definition has not been defined yet. Indeed, the concept of “clean soils” and soil quality is rather new, often highly controversial, and not as well defined from a scientific perspective, unlike “clean water” and “clean air”. However, the process to assess it entails to: Identify symptoms Make a provisional Make a prognosis Identify and measure diagnosis Prescribe a treatment vital signs Conduct tests to verify the diagnosis We need a mimimum data set (MDS) to develop a «soil quality index» using pedotransfer functions What is environmental testing? Environmental testing is an ensemble of analysis related to the concentration of contaminants, chemical, physical and biological properties. The results give us back the indicator of the quality of tested matrix. Analysis could be either integral where all the elements are analyzed (simple but often the results give back results with little value) or fractional (more complicated but useful). Soil testing It is a quantitative analysis of soils to determine if environmentally unacceptable levels of nutrients, nonessential elements or organic compounds are present. The process consists in three phases: 1) sample collection and handling (which in many cases depends on the type of test→ understanding of the nature of the risk for the correct soil sampling is pivotal); 2) method of analysis in which at first there is a pretreatment procedure of the sample (drying, grounding, mixing and sieving) and then the wanted analysis is performed (soil water pH, lime requirement, organic matter content and available nutrients (K, Ca, Mg, Mn, Zn)); 3) Interpretations and recommendations There are many difficulties when we want to establish a relationship between the environmental risk and the amount of an element. Risk assessment models = target organism, most sensitive pathway, regulatory upper limit Water testing The aim is the determination of water quality in terms of organic, inorganic and physical properties and biological organisms. A representative water sample (temporal and spatial) is exploited. For surface water, the sampling specifics (such as location, depth and frequency) are very important. Recommendations related to the ultimate use of water and based on a complete evaluation of water properties (physical, chemical and biological). As regard to the interpretation of interaction between pollutants and water environment, it really depends on the type of source: if we are dealing with a point source the interpretation is simple whereas if the source is nonpoint it becomes very complicated due to the need to characterize all potential sources, the pathways, the channel processes and the sediments. Air testing When dealing with air quality we need to consider either we are checking an indoor where concentrations depend on height, ventilation, heating and cooling and an outdoor environment where they depend on wind action, precipitation, and sunlight (here we highlight six principal pollutant). In this matrix, the particulate matter is composed by mineral particles, soot, organic debris and aerosols. There are different possibilities related to sampling such as the sampling directly in air, the collection of gas and physical/chemical trap Instead, the analytical methods depend on: physical state of the constituent of interest; sensitivity of the analytical procedure and Concentration of the constituent of interest. How does the presence of neutral condition/super adiabatic cases/inversions affect the dispersion of contaminants? The atmospheric stability is the tendency of the atmosphere to resist or enhance vertical motion. It plays an important role in the dispersion of air pollutants and hence of air quality. The possible scenarios are: NEUTRAL CONDITION: SUPER ADIABATIC CASES: INVERSION: A mass of air cools at the same Caused by Strong solar heating It happens when we have that by rate as the environment where relatively cold air is increasing heights, the air surrounding it and so a no transported over a much temperature actually increases. up/down movement. This warmer surface (sunlight heats These conditions lead to a very results in overcast skies and the ground much more stable atmosphere (strong moderate to strong winds, a efficiently than it does the air) tendency to resist vertical steadily expanding but slightly which causes an accelerated motion) where only little mixing tilted cone plume and a quick upward movement which is or dilution of pollutants Ground- rise of the pollutant ground- good for dispersing pollutants level inversions tend overnight level concentration to a BUT it is possible for a plume to (winds are light and skies clear). maximum at progressively develop ‘looping’ characteristic. greater distances, before slowly declining. There are different types of inversion: ADVECTIVE INVERSION 1) The horizontal movement of an air mass from over a warm surface to over a cool surface. This leads to warm air closest to the surface cooled by advection→GROUND LEVEL INVERSION 2) Cold air moves over a warm surface and so cold air displaces the warm air near the surface, pushing it upwards→ ELEVATED INVERSION FRONTAL INVERSION at the interface of two air masses of different temperatures. Warm air rises up and over the cold air and so it leads to cold air underneath a mass of warm air. Condensation and rain are the results. SUBSIDENCE INVERSION (associated with anticyclones) when a mass of air descends from aloft and becomes warmer adiabatically. The warmer layer is coming to rest above an original cool stagnant air mass. If clouds are present below the warm layer, radiation from their upper surfaces will accentuate the inversion. The stronger the inversion, the greater the barrier to intermixing. The ‘strength’ of an inversion depends on: The most negative value of the temperature lapse rate The effective depth of the inversion layer An elevated inversion formed above the stack means that the effluent will usually have insufficient buoyancy to penetrate the inversion and disperse upwards. This phenomenon leads to fumigation and the ground level concentration of pollutants increased dramatically. If the ground level inversion is formed below the point of discharge, it means that the effluent is unlikely to reach the ground in the vicinity of the chimney and a lofting plume will be formed and pollution at ground level reduced. How can atmospheric stability be identified? In order to identify atmospheric, we could exploit either a QUALITATIVE APPROACH (Pasquill approach) or a QUANTITATIVE ONE. What are the main air pollutants? SULFUR SO2 from human activity (SO2 is formed by the oxidation of sulfur impurities in fuels S +O2→SO2) Sulfuric acid produced when SO2 from air dissolves in water NITROGEN COMPOUNDS Photochemical smog, the ozone hole and acid rain:  Nitrogen (79 %atmosphere) Nitrous oxide (N2O), not harmful Nitric oxide (NO), not harmful at ambient atmosphere concentration N2 + O2 ⇌2NO Molecular nitrogen with hydrocarbon radicals from fuel→Oxidation of nitrogen compounds in fuel Nitrogen dioxide (NO2), secondary pollutant 2NO + O2 ⇌2NO2 Ammonia: weak alkaline solution with water. Reaction with acids produces ammonium compounds=airborne particles CARBON COMPOUNDS Primary air pollutant from combustion processes Carbon monoxide (CO), incomplete combustion of carbon-containing fuels; Carbon dioxide (CO2), responsible for over 60% of the ‘enhanced’ greenhouse effect– burning of coal, oil and natura gas; deforestation; Methane (CH4), powerful greenhouse gas– coal mines and gas reservoirs; biological breakdown (animal, landfill and composting) Livestock 35 % (fermentation of food by bacteria in the animals’ digestive tracts Rice cultivation 13 % (bacteria in the soil) Degradation of waste in landfill and sewage treatment Human activity = two thirds; Volatile organic compounds (VOCs): solvents, hydrocarbons from fuels, emission from sewers and wastewater plants, isoprene from trees ATMOSPHERIC AEROSOL The chemical composition varies with particle size and the shape is important for human health and light scattering. There are two different types of aerosol: Primary, directly emitted into the atmosphere, anthropogenic or natural Secondary, formed by chemical reactions or gas condensation PM10 Comprises a mixture of particles of varied size and composition and includes primary and secondary particles. The definition of PM10 is the mass fraction of particulate matter (PM) collected by a sampler with a 50% inlet cut- off at aerodynamic diameter 10 μm. It could be composed by sulfur dioxide and oxides of nitrogen, VOCs and ammonia. The sources of PM10 could be either primary, coming from combustion particles, secondary particles, formed in the atmosphere following release in the gas phase, or coarse or other particles, non-combustion sources. How can be produced the atmospheric aerosol? 1. Nucleation: Homogeneous nucleation: Gas molecules aggregate to form clusters Heterogeneous nucleation: gas forms a cluster on an existing surface 2. Coagulation: Chain aggregates: solid particles Coalescence: liquid particles 3. Cloud condensation nuclei (CCN) Activated to grow to fog and cloud droplets in the presence of supersaturation of water vapour What is acid deposition? Any precipitation made acidic by the dissolution of atmospheric acids in water (includes fog, dew, sleet and snow): Dry deposition Wet deposition Occult precipitation, low-lying clouds and fog containing acidic droplets make contact with trees There are many different causes of acidity. Rain is naturally acidic and from a natural pov lower levels of pH (say 4.7) may be produced exceptionally by sea- or volcanic-derived sulfate. If we are referring to an anthropogenic source, sulfur oxides and nitrogen oxides from fuel dissolve in water to produce acidic solutions. In any case, small changes in pH is equal to changes in H+ concentration, which have great biological impact. Nitric and sulfuric acids can be formed in the gas phase or after absorption in water droplets How can air quality be monitored? Air quality could be either controlled through MANUAL MONITORING (sampling bags, diffusion tubes (passive sampler), and sorbent tubes), CONTINUOUS MONITORING, a LONG PATH MONITORING or a biomonitoring. Long-path monitoring has significant advantages compared to conventional point sampling techniques: the result is more representative of the area; the technique is also useful for assessing fugitive emissions across a factory site; they do not interfere with the atmosphere, so no concentrations are altered by contact with sampling equipment; the spectroscopic techniques allow simultaneous determination of several pollutants How can particulate be controlled? Particulate is monitored through the MEASURING PARTICLE SIZE AND SHAPE. The first method possible is a MANUAL ONE where the sampling happens through filtration. The filter is moved to a sampling head which is linked to a connection tubing and the particles circulation is allowed through a pump. The detection is performed through gravimetry electron microscopy or atomic absorption/inductively coupled plasma spectroscopy. Another way possible is continuous monitoring where an APERED ELEMENT OSCILLATING MICROBALANCE (TEOM) is exploited. Heated air is drawn through a small filter, which sits on the end of a hollow, tapered tube that vibrates at its natural frequency of oscillation. However, the control is performed though SEPARATION TECHNIQUES, which are active processes and require a considerable amount of energy). The separation could happen through mechanical separator, washing or scrubbing, fabric filter and electrostatic precipitator. How can VOCs be controlled? The amount of VOCs could be controlled either through: COMBUSTION PROCESS Flares unusual process events where there is a vent to atmosphere at which flammable gases are burned Furnaces: Boiler or process heater (η=98%). We must assure the absence of an excessive airflow which leads to a non-efficient combustion. They are suitable for small scale Thermal incinerator: reaches 1000°C and are suitable for diluting mixtures. They can require supplementary fuel or catalytic incinerators: catalyst are used to enhance the rate of combustion but are sensitive to pollutants and exploit the platinum group RECOVERY PROCESS Adsorption: used when the organic compounds have a commercial value. Typical adsorbents include activated carbon and zeolites. This procedure is sensible to waste gas stream conditions. Absorption: a dissolution or a simple chemical reaction is exploited. A good gas-to-liquid contact is required and also a even distribution of scrubbing liquid in the absorber. Two factors determining the feasibility of this process are the availability of a suitable solvent and the disposal of the absorber effluent. Condensation: Condensers, refrigeration and cryogenic are used for the condensation of pollutants (the type of coolant used for the heat exchange is a critical factor). It is exploited as preliminary air pollution control devices What are the main water pollutants? The main water pollutants could be divided into: ORGANIC POLLUTANTS INORGANIC POLLUTANTS BIOLOGICAL POLLUTANTS Food processing waste n Cadmium, Copper, Lead, Zinc bacteria, molds, mildew, Petroleum hydrocarbons Nitrogen, nitrate, nitrite, cat saliva, viruses, animal Disinfection by-products (DBPs) ammonia dander, Volatile organic compounds Phosphorous, phosphate house dust, mites, (VOCs) cockroaches, and pollen Insecticides and herbicides Tree and bush debris Chlorinated solvents Perchlorate Polychlorinated biphenyl (PCB) Trichloroethylene POPs Endocrine disruptors What are typical water analyses? The typical water analyses can be divided into different group depending on the type of parameters we want to assess. As regard to the PHYSCAL one we can perform analysis of COLOR (through a spectrophotometer or a colorimeter), ODOUR/TASTE (which are identified and classified, and their intensity is measured), TURBIDITY (which is the reduction of the transparency of a sample due to suspended substances or colloidal material. Even though the latter doesn’t represent a health issue, it is an «alarm bell» and has influence on disinfection processes. The methods that can be used are either a Turbidimetric method (spectrophotometer) or a Nephelometric method). We can also measure the TRANSPARENCY (which is the evaluation of the density of suspended material of both biotic and abiotic origin through the measurement of the distance at which a white disk, immersed in water, disappears from the operator's view), the CONDUCTIVITY (which is an integral measurement of all mobile ionic species in solution which gives us back information about hardness and total dissolved solids), pH (it could be measured through colorimetric or potentiometric methods and too extreme values are related to it means that there is pollution, breakdowns of plants, problems in treatments) and HARDNESS AND CORROSIVENESS (determined by a complexometric titration and the recommended value are around 15-50 ° F). Instead, as regards to the CHEMICAL ones we have COD (oxidative treatment with bicromate and spectrophotometrically analysis) and BOD analysis (the sum of the two is TOD) as more integral analysis. As regard to more specific analysis, we could perform a METALS determination through ICP-OES (which consist in a measurement of the intensity of the electromagnetic radiation emitted by the excited ions of the species present in the sample, using spectrometric techniques with a plasma source.), IONIC CROMATOGRAPHY (i.e, the simultaneous determination of cationic species based on the separation of the analytes by means of a cation exchange column based on their affinity for the stationary phase.) or STRIPPING ELECTROCHEMICAL ANALYSIS. We could also do the determination of organic compounds, where GC-MSMS with triple quadrupole mass quantities for HIGH MW ORGANIC COMPOUNDS and GC-MS with single quadrupole mass are employed. Instead, when considering MICROBIOLOGICAL POLLUTION, monitoring is limited to indicator bodie and specific tests are used occasionally (high costs, detection complexity,...), such as crops (infection or growth is detected), microscopy, DNA determination (also with PCA amplification) and immunological assays. A very common type of indicator is the faecal one. This kind of bacteria is not pathogenic itself and is universally present in the feces of humans and animals in large numbers. It doesn’t multiply in natural waters but persist in water in a similar way to fecal pathogens. It is present in greater numbers than faecal pathogens and respond to treatment processes in a similar way to fecal pathogens. The detection is performed with simple and inexpensive culture methods Coliform bacteria and E. coli = absent in 100 ml This microbiological pollution has as its primary source human and animal waste. The biggest hazard is related to the presence of pathogens which are species that multiply in their host and in food, beverages, or hot water systems. Usually, they grow in the environment and can be found aggregated or adhered to solids suspended in water. The pathogens can be divided into: PATHOGENIC BACTERIA: these VIRUS: they are smaller PARASITES (protozoa and kinds of bacteria are more pathogens and therefore more helminths) and CYSTS: they are sensitive to inactivation by difficult to remove. less sensitive to chemical disinfection, some grow in water inactivation for disinfection, but and in general don't survive for a more effective uv radiation. long time. They are carried by Being in moderate size they are animals. For many of them there suitable for physical filtration are processes. They survive for a dose-response models). long time in the water. Usually, in order to ease up the classification, reference pathogens (i.e., representatives of groups of pathogenic agents) are established. In particular, these pathogens must fulfill these requirements: Water transmission established as a route of infection Sufficient data available to allow a quantitative assessment of microbial risk Presence in spring waters Persistence in the environment Sensitivity to removal or inactivation from treatment processes Infectivity, incidence, and severity of the disease When is disinfection generally applied along the chain of remediation process? The water treatment can be divided into three parts: Pre-treatment; Treatment; Final treatment; The PRE-TREATMENT consists of: RAW WATER STORAGE: It consists in settling of suspended solids and reduction of pathogenic organisms. Thes part is usually followed by some problems such as high in nutrients (algae), silt deposition and thermal stratification. Some possible solutions are draw-offs at different depths and destratification SCREENING: Normally it is the first stage of treatment, and it is performed through cup, drum, band, passive and disc. AERATION: It is especially done for groundwaters (surface water in equilibrium with air). The rate of absorption or release of gas by water is determined by concentrations in water and air, surface area across which the gas is transferred. It is usually performed through spray, cascade, tray, slatted tower, diffused air, packed tower. STRAINING: Done for the removal of algae. The process is similar to drum screens but with a fine mesh. PRELIMINARY SETTLING: It is performed for very large seasonal variations (monsoons). PRE OZONATION PRE-CHLORINATION The TREATMENT consists of: COAGULATION and FLOCCULATION: It is done to remove colloids through the formation of larger particles that can then be removed by physical treatment. Coagulation is a quick process which consists in the particle destabilization and formation of larger particles. Instead, flocculation, which is a longer process, consists in mixing which results in further collisions between the particles formed by coagulation, leading to the formation of relatively large particles, easily removed by settlement, flotation, or filtration. There are different types of destabilizations which leads to coagulation: Double layer compression through the addition of an electrolyte (trivalent cations). Charge neutralization through the addition of ion of opposite charge. Entrapment in a precipitate through the aluminium or iron salts addition. The addition of these salts leads to the formation of hydroxide flocs and so precipitation. Particle bridging through large organic molecules with multiple electrical charges (anionic and cation polymers). Whereas flocculation arises from three main processes: Brownian motion (smaller particles) Stirring (energy appropriate to size and strength) Differential settling CLARIFICATION: a particle with a density greater than water will settle with a velocity which is inversely related to kinematic viscosity (decreases with T). There are two basic types of settling basins for the removal of previously flocculated particles HORIZONTAL FLOW: for this kind of basin surface area is very important. Indeed, a shallower basin would be better than a deep one. VERTICAL FLOW: the area of the tank must be sufficiently big so that v 99.85%) and the color of the glass. However, lately some very fine color detectors have been implemented and colors can now be efficiently sorted. Glass recycling has great environmental benefits since it consumes a lot less energy than the production of virgin glass (1.89 GJ/ton vs. 2.67 GJ/ton) and it avoids glass being dispersed in nature since it takes several millions of years to biodegrade. Can you describe how Aluminum recycling works? Aluminum recycling presents some additional challenges when compared to glass. Indeed, urban waste Glass has, more or less, the same shape, appearance and composition, while Aluminum comes in an array of different shapes and thicknesses (cans, foil, pots, window frames) as well as different compositions since for different objects, different alloys (with Si, Mn, Mg, Cu, Cr etc.) are used. Nonetheless, Aluminum is anyway by far the element with the highest concentration, which makes recycling relatively easy. After collection, aluminum can either be sent to sorting plants where it is separated by other wastes using an induced currents method, or it can be conferred, together with other wastes, to incinerators for energy generation (If Al is < 50 µm thick it completely burns If Al is > 50 µm thick, after burning are recovered and brought to recycling plants). Then, from both sources, Aluminum is recovered and sent to foundries (500°C to remove organic parts, 800°C to completely melt) where it is melted and shaped. Recycling Aluminum is fundamental due to the high environmental impact cause by the process required to create it from Bauxite. Indeed, both the Bayer and Hall-Heroult process have very high environmental impacts due to the very high energetic demands and huge amounts of GHG emissions (2% of global human-cause emissions of CO2). On the other hand, recycling allows using only 5% of the energy used to produce virgin Al from bauxite and reduces the emissions up to 40 times.  Can you describe how Steel recycling works? Steel is disposed with aluminum. There are many kinds of steel packagings, having slightly different compositions, the most common kinds are: Tinplate: steel foil with Sn layer on both sides Chromeplate: steel foil with Cr or CrO3 layer on both sides Blackplate: steel foil with no layer Steel alloys can have a wide variety of compositions, but they are processed in the same way. Sorting is relatively easy and is made thanks to their magnetic properties. Once sorted, steel reaches foundries and is converted in semi-finished product (up to 3000°C). Steel recycling is fundamental since the production of virgin steel starting from iron oxide requires high temperatures and a lot of energy. More or less steel production accounts for 30% of CO2 emissions of the industrial sector (7-9% of all anthropogenic CO2 emissions). Steel production also accounts for 74% of the energy used in the industrial production of metals. During its processing a lot of wastes are produced such as metal dust and slags The solids obtained by fumes treatment are the most dangerous for human health. Along with recycling, metal replacement has been a huge trend in the past few years, which means that if it is possible to avoid using a metal, alternatives are employed. For this reason, plastics and Aluminum (that is not considered a metal) employment has been on the rise. Can you describe how Paper recycling works? Today, 40% of paper pulp is from wood (9-15% from trees, the rest from waste wood). About 35% of felled trees are for paper making (data: 2007) – 3 billion trees cut for paper making worldwide. It is common knowledge that there are many different kinds of paper, some of which should be put in generic waste. Paperboards are more “uniform”. Waste paper and paperboard is mechanically and manually «purified» and then grinded. Then a high quantity of water is added, and a diluted solution (about 99% water) is obtained. Sieves are used to collect plastic impurities. Water is heated (Heating partially depolymerizes cellulose, decreasing the mechanical properties of the material) and evaporated while extruding the new paper sheet. At the end of the process, virgin cellulose is always added, in different quantities according to the paper required. Energy saved by paper recycling is between 40 and 64%, according to different papers and estimates, while it also reduces the CO2 emissions of about 30%. Recycling one ton of newsprint (the low-quality paper used for newspaper) saves about 1 ton of wood, while recycling one ton of printing paper saves more than 2 tons of wood. The main issue of paper recycling is related to the possible contamination from many different chemicals, like Bisphenol A or PCBs. In 2020, in Italy 4.6 million tons of paper were put on the market 3.5 million tons were put in the paper waste in cities and towns 4 million tons were destined to recycling, which means that 58% of paper derives from recycling, with a recycling rate of 87%. Which are the peculiarities of plastics over more «traditional» materials? Generally, plastic waste is by far the most heterogeneous because plastic items are very different from one another, both for shape and composition. This derives from a simple consideration, which is that plastic is the first material completely invented by mankind (Bakelite was the first completely synthetic polymer). Moreover, plastics have an incredible array of advantageous properties (light, resistant to impacts, electrical and thermal insulator, flexible, resistant to ageing, easily moldable, very cheap) that gave them an edge over the more traditional materials and made them incredibly widespread in a great number of different sectors. Can you tell me which are the issues related to plastics durability and their use?  Due to great properties that various plastics present, they are employed in many different sectors, from packaging to construction. Most plastic are very durable and can take a very long time to biodegrade. When the material is used for construction, this is a good advantage since the average life of these kind objects is 35 years. On the other hand, when they are used for packaging (38% of total production), their average life is 6 months, after which they are thrown away. If this waste is not properly managed, it accumulates in the environment and pollutes. Which are the main problems related to recycling plastic objects? Thanks to their outstanding and easily modulable properties, plastics find use in many different sectors. This, however, also means that the families of polymers present on the market are almost infinite, depending on wanted properties one is chosen over the others. Despite the almost infinite number of different polymer families present on the market, plastics used for packaging are relatively few. The market is quantitatively dominated by PE and PP. 5 polymers share about 80% of all plastic production volume (I would add PET – another 8% of the global market). For each different application the base plastic is often additioned with various chemicals (i.e. plasticizers for LDPE, colorants) or used as a blend/multilayer material to modulate the properties of the material. During recycling operations materials with same base plastic but different additives are often mixed together, producing a material with downgraded properties when compared to virgin materials. Last (but not least) plastic processing temperatures play a key role. Processing temperatures are relatively low (commonly under 300°C) and depend on the type of plastic to be treated. These temperatures are not high enough to eliminate residual organic impurities, moreover some plastics start decomposing at temperatures used for processing other plastics (Typical case is PVC degrading at 290°C, processing temperature of PET. One PVC bottle is enough to completely pollute more than 1000 PET post-consumer bottles). The result is that recycled plastics very often present poor properties when compared to virgin materials. Can you make examples about the complexity of plastic items? A very clear example can be the great differences that can be observed between products made of polyethylene (PE). The first great distinction that can be made is relative to HDPE and LDPE, both are polyethylene but are obtained with different polymerizations (LDPE with high pressure radical polymerization and HDPE with an organometallic catalyst) and they present very different properties, which means that they can’t be recycled efficiently together. Moreover, even in between the LDPE (with LLDPE) and HDPE families there are many differences, depending on the branching of the polymer and their mean molecular weights. Finally, products made from polymers don’t only contain one compound, but very commonly present a number (5-6) of additives (plasticizers, flame retardants, colors, crosslinkers etc.) depending on the wanted characteristics, which again, further complicates the recycling procedures. What are microplastics and how are they generated? Microplastics are defined as plastics objects being smaller than 5 or 1 mm, according to different sources. The definition lacks precision since fibers are not considered: fibers microplastics must be shorter than 15 mm and have an aspect ratio (ratio between length and width) of at least 3. There are two kinds of microplastics, depending on how they are generated: Primary microplastics: they are produced in industry as such. They mostly come from cosmetics, abrasives or for biomedical applications. Secondary microplastics: Microplastic deriving from the physical degradation of bigger plastic objects (tires, textiles) due to weathering, physical action etc. Secondary microplastics represent by far the most common kind of microplastics present in the environment. How are microplastics spread in the environment and what is their interactions with living beings? Depending on how they are formed, they spread in the environment differently. The main sources of secondary microplastics are Tires and Textile products. The MP produced by tires (abrasion with  asphalt), can be carried around by the wind and reach water bodies (river, lakes. i.e. MP contamination has been observed in all sub-alpine lakes in Italy). MP produced by textile products are formed during washing (the more we wash our clothes, the more MPs we will release: after 7-8 washing cycle the release seems to reach a plateau) and enter directly the water system which will eventually carry them to bigger water bodies. In the end, the fate of microplastics is mostly in the ocean, but it may take a long time to reach it. MP’s have also been found in very remote areas (i.e. glaciers) probably due to wind or tourism (most technical clothing is made of some kind of polymer). MP’s are not intrinsically toxic. Tests were performed on medium sized and small organisms (i.e. giant snails and Daphinae), the former showed no effects on the survival, growth, ability of movement or any other biochemical factor, the latter showed effects on reproduction, growth and movement. This means that in “low doses” MP’s probably have no significant effects, while in larger doses they can be harmful. What are bioplastics and how is their market? European Bioplastics Association defines «Bioplastic» a plastic material that can be either biodegradable or be derived from renewable sources or both. In other words: It can derive from renewable sources (even only partially) and be not biodegradable (ex. bio-PE; -PP; - PET) It can derive from renewable sources (even only partially) and be biodegradable (ex. PLA; Mater-bi; PHA, PHB) It can derive from non-renewable sources and be biodegradable (ex. PBAT, PCL, PBS). Due to the confusing definition as well as continuously changing regulations, the market is far from being well established. The projections for the future made about 15 years ago were not met, specifically contrary to 2012 scenario, volumes of non-biodegradable plastics are lowering, and other «new» biodegradable plastics are gaining market. Make some examples on the most common bioplastics The most common bioplastics are: PolyButyleneAdipate Terephthalate (PBAT): this polymer is highly flexible and commonly used in blend with more rigid biodegradable polymers (Ecovio® - BASF – Blend between PBAT and PLA, Mater- Bi® - Novamont – Blend between PBAT and starch). To increase its mechanical properties it would be necessary to increase the share of Terephthalic Acid But in this way biodegradability would be jeopardized. It is prepared starting from two pre-polymers, which are then polymerized together using tetrabutoxy titanate as catalyst. Mater-Bi: the first generation was probably a blend of PE and starch, many different patents and patent extensions followed, and the contemporary composition is not disclosed. Polyhydroxyalkanoates (PHA) and Polyhydroxybutyrate (PHB): Born in the’80s, trademark Biopol of Monsanto (U.S.). They can be produced from different monomers (3-Hydroxybutyric Acid, γ- Hydroxybutyric acid, 3-Hydroxyvaleric Acid) which are compounds present in many metabolic pathways. This characteristic enables their synthesis through genetically modified microorganisms, however this synthetic path is too expensive in for the targeted applications. What are compostability and biodegradability? Differences and rules An object is defined “compostable” when it can degrade in a composting plant without being harmful, in other words, A material is compostable if, once put in the compost conditions (high T and RH), it disappears within 6 months. To be compostable, the object must be converted to CO2, H2O and biomass: at least 90% in 6 months in the compost (so no heavy metals or other species that could have negative effects on compost). It is important to note that the certification of compostable is given to objects, not materials, since A shopper made from biodegradable plastics is compostable a table made with the same biodegradable plastic is not compostable. Some rules related to compostability are given by TUV:  OK Biobased: If an object comes from renewable sources (the higher the number of stars, the higher the fraction from renewable sources) OK Compost: if an object can be composted in a home composter or ONLY in an industrial composter OK Biodegradable: if a material can biodegrade rapidly in soil, water or marine water Biodegradable refers to a substance or material that can be broken down into natural elements like water, carbon dioxide, and organic matter by microorganisms (such as bacteria or fungi) under natural environmental conditions. This process occurs over time and does not produce harmful residues.