Air Pollution Modeling Services

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We evaluate the concentrations in air and the deposition at ground of the atmospheric pollutants using the right simulation software chosen among those considered as standard at international level, as CALMET/CALPUFF, AERMOD, CALINE3, OCD5, ISC3 and many others. Also, we develop new modeling tools for specific applications and needs. Our expertise is proven by hundreds of air dispersion studies in several countries regarding industrial stacks and fugitive emissions, traffic, construction sites, flares, cooling towers, offshore platforms, landfills, waste incinerators, ships and trains. We can support professionals and companies in preparing the technical documentation for compliance and permitting. We provide scientific support in litigation, on air dispersion modeling and atmospheric-related issues, together with our USA partner EnviroComp, Inc.

The typical steps of our air impact assessment studies include:

  • characterization of existing air quality conditions, based on the analysis of monitored data
  • climatological characterization of the area
  • collection of meteorological data to prepare the hourly input for the air quality model
  • preparation of the meteorological input files to run the meteorological preprocessor (for example CALMET) or for running the dipersion model
  • definition of the emission scenarios and preparation of the input files, including the calculation of the emission parameters, the georeferenced postioning of the sources and the surrounding buildings
  • definition of the statisics of interest to be evaluated, according to the existing legislation or guidelines
  • run of the models
  • post-processing of the results to obtain the statistics of intererest on regular grids and at specific receptors, for air concentrations and depositions
  • preparation of a technical report including georeferenced representations of the results
  • preparation of a Google Earth project summary file

Each study and each type of source has peculiar aspects that have to be addressed.

Industrial plants

Prevent or reduce air pollution from industrial plants is the main aim of the IPPC Directive. The Integrated Pollution Prevention and Control Directive (2008/1/EC) requires European Member States to ensure that specified categories of industrial plant obtain authorization before commencing operation and before undergoing substantial alteration.

Plants included in the IPPC Directive list must apply for renewal of the operating authorization. During the preparation of the Integrated Environmental Authorization for plants included in the IPPC Directive list, we can assist you in evaluating their atmospheric pollution levels.

The industrial activities covered by the IPPC Directive are:

  • Energy industries
  • Production and processing of metals
  • Mineral industry
  • Chemical industry
  • Waste management
  • Other activities

Industrial processes often cause the atmospheric release of pollutants, even if the best available technology (BAT) is adopted to cut down the emissions. Controlled emissions (for example from boilers, gas turbines, ovens) are generally released via stacks but area emissions can also be present. Emissions can be continuous and they may depend from the production process and thus show a seasonal, daily and hourly variation.

The air pollutants covered by the IPPC Directive are:

  • Sulphur dioxide and other sulphur compounds
  • Oxides of nitrogen and other nitrogen compounds
  • Carbon monoxide
  • Volatile organic compounds
  • Metals and their compounds
  • Dust
  • Asbestos (suspended particulates, fibres)
  • Chlorine and its compounds
  • Fluorine and its compounds
  • Arsenic and its compounds
  • Cyanides
  • Substances and preparations which have been proved to possess carcinogenic or mutagenic properties or properties which may affect reproduction via the air
  • Polychlorinated dibenzodioxins and polychlorinated dibenzofurans.

What we do:

  • Collection and analysis of European, national and local legislation
  • Climatological analysis of the site
  • Collection and analysis of the meteorological data for the simulation period
  • Collection and analysis of the air quality data
  • Geophysical characterisation (orography, landuse, coastline definition, etc.)
  • Analysis of sources and emissions
  • Evaluation of the atmospheric pollution levels by means of international recognised modelling software (e.g. the US-EPA recommended models AERMOD and CALMET/CALPUFF)
  • Comparison of the predicted air quality levels against the limit values established by the law
  • Preparation of a technical report describing the whole study in the details
Odors

Odor is an important environmental pollution issue because it can affect public amenity and the quality of life of the community. Attention to odor as an environmental nuisance has been growing as a result of increasing industrialization and the awareness of people need for a clean environment.

Efforts to abate odor levels are necessary in order to maintain the quality of the environment. Understanding the odor problem and the origin and dispersion of odors, abatement and detection methods are, therefore, very important aspects of odor pollution in the environment.

Many activities emit odors into the atmosphere, such as agricultural industries, bitumen pre-mix or hot-mix industries, breweries or distilleries, chemical industries or works, chemical storage facilities, composting and related reprocessing or treatment facilities, contaminated soil treatment works, drum or container reconditioning works, electricity generation works, livestock intensive industries, livestock processing industries, mineral processing or metallurgical works, paper pulp products industries, petroleum works, sewage treatment systems, waste facilities, wood or timber milling or processing works, wood preservation works.

Enviroware estimates the odor levels in terms od Odorimetric Units (OU/m3) by means of international recognized atmospheric dispersion software (e.g. CALMET/CALPUFF and AERMOD). The odor levels are then compared with the levels suggested by odor guidelines for specific environments (rural, urban, etc.). At the end of the study it is possible to set up all the actions capable to reduce the odour levels and, as a consequence, to reduce the population complaints.

Construction sites

The equipments used during the construction phase of an industrial plant or a building are responsible for the emission of many pollutants into the atmosphere.

Cranes, graders, compressors, dozers, scrapers, well drillers and other machinery emit atmospheric pollutants as carbon monoxide, nitrogen oxides, particulate matter and others. Moreover, the removal of inert material produces the emission of particulate. The evaluation of the emissions during the construction phase of a production plant is especially important for particulate, even if it is limited to a short period. This estimate is even more relevant in the construction phase of buildings and infrastructures.

Emitting activities include:

  • Engines of construction equipments (CO, NOX, VOC, PM)
  • Engines of personnel vehicles (CO, NOX, VOC, PM)
  • Loading and unloading os storage piles (PM)
  • Wind erosion of storage piles surface (PM)
  • Resuspension from equipment traffic in construction area (PM)
  • Resuspension from personnel traffic in construction area (PM)

We estimate the atmospheric emissions during the construction phase depending on the duration of the building phase, the yard extension, the type and number of machineries used, the number of workers. Besides the emissions from the machineries, the emissions from the vehicles of workers and the emissions from resuspension of particulate and the removal of inert materials are also estimated. All the emission estimations are made with reliable methodologies, such as the USA AP42 and the European COPERT.

What we do:

  • Collection and analysis of meteorological data
  • Estimation of dust emission due to loading and unloading of storage piles as function of wind speed, humidity of the material and amount of material worked daily
  • Estimation of dust resuspension as function of the surface silt content, the average vehicle speed, the average vehicle weight and the number of wheels
  • Evaluation of the emissions from the engines of construction equipments and personnel vehicles
  • Evaluation of the air quality levels induced by the emissions from the construction area
Industrial flares

Industrial flares are used for burning off undesired gases or mixture of gases and liquids which form as a consequence of unpredictable overpressures within the plant. The flares are used in many types of plants, for example oil wells, refineries, chemical industries, and landfills. The main function of a flare within a landfill is to burn methane, while in the other plants it has a protective function against unpredictable overpressures: in case of anomalous event, the safety valves convoy gases and liquids in excess toward the flare, where they are burned. The ignition of the flare as a consequence of an anomalous event generates a very long flame and the release of a huge quantity of heat. If the flare is not properly sized, its activation can generate serious damages to the human beings and the materials within and outside the plant.

The most important guidelines for desiging a flare system are:

  • American Petroleum Institute. API Recommended Practice 521, Fourth Edition, March 1997. Guide for Pressure-Relieving and Depressuring Systems.
  • American Petroleum Institute. API Standard 537, First Edition, September 2003. Flare Details for General Refinery and Petrochemical Service.

We have developed a methodology based on the American Petroleum Institute documents for the correct sizing of the flare and of the evaluation of its thermic and acoustic impact. The methodology, applied to many plants of natural gas, is based on a careful meteorological analysis of the site and the evaluation of the impact for a minimum period of one year with hourly resolution. The result of the study is a document which contains the correct size parameters of the flare, the maps of the impacts and the more risky area in case of the flare activation. In collaboration with GandZ sas, we can chemically and physically characterise the burning mixture using the Hysys software.

Cooling towers

Cooling towers are heat exchangers used for dissipating large quantities of heat into the atmosphere. They are important components in many industrial and commercial processes.

The evaporative cooling towers use the latent heat of evaporation of water to exchange heat from the process and the air which flows within the tower. This kind of tower emits into the atmosphere large quantities of vapour and water drops of different sizes (drift). The water drops contain, with varying concentrations, the same impurities contained in the cooling water, hence they are potentially dangerous when they deposit on a surface.

For example, if sea water is used for cooling, the drift water will contain salt. Therefore the greater drops, which will fall close to the tower, will be dangerous for the industrial plant, since they can generate corrosion of the equipments or short-circuit in the electric plants. On the other hand, the smallest drops, which will fall far from the tower, can be dangerous for the coltures.

Other environmental impacts of the cooling towers are due to the huge vapour quantity emitted into the atmosphere. The production of a large visible plume induces a decrease of the solar radiation below the plume itself, with possible damages for the coltures. The fog episodes can also increase, so as the episodes of ice formation on the roads.

We study the atmospheric impact of cooling towers considering all the above mentioned problems. We use simulation models capable to predict the deposition field of the impurities contained in the drift (WetPlume, SACTI). The modelling results allow, for example, during the construction of a plant, to determine the safe distances for the installation of equipments (e.g. pumps, electric generators) which could be damaged from the impurities contained in the water. The models also allow to determine the impact of the cooling tower emissions outside the plant perimeter, as for example the damages to the coltures and the probability of formation of fog and ice.

Traffic

Traffic is one of the major sources of pollution in urban environments. The construction of new residential and commercial buildings, for example for the requalification of urban dismissed areas, produces a relevant impact on the environment. This is not only due to the construction activities and the heating of the new buildings, but also to the variation of the traffic induced by the new installments.

Starting from traffic counts, fleet composition and average speed we can evaluate the emissions from the road network of interest. We can apply the European COPERT methodology and the US AP42 methodology.

We have experience on such calculations from microscale (i.e. single link) to regional scale. We have in fact created the regional emission inventory for the whole Sardinia region.

The simplified COPERT4 methodology for calculating the emissions from the road transport sector at national level is available on line.

Industrial accidents

The main objective of the European Directive 96/82/CE (SEVESO II) is to prevent the major accidents caused by the presence of dangerous substances and the limitation of the consequences for man and environment.

The simulation models are useful tools for evaluating the accident scenarios and they are a valid support to setup the industrial emergency plans. By means of the simulation of the possible accidents for a specific industrial plants and the successive consequence analysis, it is possible to individuate all the measures to avoid the accidents or to reduce their adverse effects.

We use simulation models and other software tools which allow to simulate the effects of releases of toxic or flammable liquids and vapours, fires (pool fire, jet fire, fireball) and explosions (UVCE, BLEVE), and to estimate the effects produced on human beings and materials.

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