The work deals with coal combustion in a pilot-plant fluidised bed (7 cm i.d.) under atmospheric conditions.
The aims are to capture and analyse qualitatively as well as quantitatively the volatile polycyclic
hydrocarbons emitted by using coal as energy source under various combustion conditions. After establishing
the sampling procedure, the emissions are caught in five different traps (two cyclones, nylon and
teflon filters, and XAD-2). The contribution of each of the sixteen polycyclic aromatic hydrocarbons
(PAH) listed by the US Environmental Protection Agency (EPA) as priority pollutants is analysed, and
their emissions as a function of the combustion variables (combustion temperature, percentage of
excess oxygen, air flow and fluidising agent) are reported. Synchronous Fluorescence Spectroscopy is
the analytical tool used for identification and quantification of the PAH emissions.
The activity and selectivity of Pd catalysts supported on YSZ and dosed with different amounts of Na promoter
has been investigated for the reduction of NO by alkenes (C3H6) or alkanes (CH4). It is found that
Na strongly promotes the reduction of NO by C3H6. Rate increases by an order of magnitude are achievable,
while the N2-selectivity is improved from ~75% over the unpromoted Pd catalyst to >95% over the
optimally Na-promoted catalyst. With CH4 as the reductant, a very different behaviour is observed: for all
loadings, Na induces only poisoning. The experimental data indicate that Na increases the strength of NO
chemisorption relative to the hydrocarbons. This is accompanied by weakening of the N-O bond, thus
facilitating NO dissociation, which is proposed as the critical reaction-initiating step. According to this
model the promoting or poisoning effect of Na depends on the interaction strength of the catalyst surface
with the hydrocarbon. The different behaviour of propene and methane reflects the weaker interaction of
alkanes with metal surfaces compared to that of alkenes. XPS and Auger data demonstrate that Na coverage
increases monotonically with promoter loading and that there is no significant tendency for the promoter
to agglomerate with increasing promoter loading. However, a very small but constant tendency to
accumulate subsurface or dissolved Na was observed as the promoter loading is increased.
A mathematical model is presented, consisting of a two-layer, finite difference hydrodynamic submodel
and a compartmental water quality sub-model. The model is calibrated with field data. Then, it
is applied to Southern Evoikos Gulf, an open coastal water body of particular ecological significance in
the region of Attiki, in Greece. The application of the model aims at assessing the effect of three alternative
treatment scenarios (i.e. biological treatment, biological treatment with N removal and biological
treatment with N and P removal) performed in four sewage treatment plants (of a total capacity of
1,000,000 equivalent population) on the water quality of the Gulf. The calculations show that N is the
limiting nutrient and its removal results in an improvement of the quality of the recipient, whereas the
additional implementation of P removal has a rather limited impact.
Chlorination of drinking water leads to the formation of a variety of Disinfection By-Products (DBPs)
that may have adverse health effects on humans. Research on this subject has been continued and new
epidemiological and toxicological studies have been conducted. This review summarizes factors affecting
DBP formation and predictive equations proposed for it, physical and chemical properties, environmental
fate, actual measurements of these compounds and technologies for controlling them, as
well as regulation and currently proposed changes of their Maximum Contaminant Levels (MCLs)
after evaluation by EPA of new data available.
A climatological analysis of atmospheric concentrations of primary air pollutants in Athens, Greece, is
presented for the 11-year period 1987-1997, since the automated local air pollution network operating
by the Ministry of Environment started to record all conventional pollutants. The concentration levels
of the atmospheric pollutants carbon monoxide, nitrogen oxides, sulfur dioxide and black smoke for the
most polluted stations (Patission, Athinas and Piraeus) of the air pollution network were examined. For
all primary pollutants a seasonal variation with minimum in summer and maximum in winter is
observed. Sulfur dioxide has the strongest seasonal cycle and black smoke the weakest. There is a significant
downward trend for almost all pollutants in all stations. The highest reductions are observed in
Patission where a comparison between the 3-year periods 1988-1990 and 1995-1997 gives 52%, 34%,
26% and 20% decreases for sulfur dioxide, carbon monoxide, nitrogen oxides and black smoke, respectively.
The pollution abatement measures taken by the state authorities during the period 1990-1994,
mainly consisting in the replacement of the old technology gasoline-powered private cars and the
reduction of the sulfur content in diesel oil, seem to be the primary cause of the improvement in air quality in Athens during the recent years.
This paper deals with the analysis of atmospheric concentrations of secondary photochemical air pollutants
in Athens for the 11-year period 1987-1997. Photochemical pollution, which seems to be the
most serious air pollution problem in Athens, is originating mainly from the transformation of car
emissions, and its control is a quite complicated task since various non-linear phenomena are implicated.
The main subject of this work is to examine whether the substantial decrease observed in the
concentrations of the primary air pollutants, especially for CO, in Athens in recent years is followed by
a corresponding decrease in the photochemical air pollutant levels in the Athens basin, while the characteristics
of the seasonal and diurnal profiles of photochemical pollution are investigated. In this context,
the interannual variability of O3 and OX (O3 + NO2) is examined for the peripheral stations of
Liossia (10 km northwest from city center) and Smyrni (5 km southeast), which have continuous
records of O3 and NO2 data since 1987. In general, the concentrations of the photochemical pollutants
(especially OX) in both examined stations are comparable, while they seem to have remained essentially
at the same levels since 1990. Further pollution abatement measures should be taken in order to
comply with the EU ozone air pollution standards in the Athens basin.
Accumulation of airborne pollutants in vegetation is an important initial step in the uptake process of
the terrestrial food web, providing direct and indirect routes by which biota and, eventually, humans
are exposed to chemicals. A set of algorithms for estimating atmospheric pollutant interactions in soilvegetation-
air systems is developed and tested. The model incorporates significant transport pathways
with appropriate parameterization and requires a relatively limited number of meteorological input
data and pollutant characteristics and vegetation parameters. Testing applications include model comparison
to field data in the cases of cadmium in grass and six polycyclic aromatic hydrocarbons (PAH)
in maple leaves. Results indicate that the model provides a reasonable compromise between model
complexity and the ability to obtain realistic data characterizing model parameters. It is well suited for
screening-level assessments; and it can also be used as a component of a management-oriented and
multimedia-based environmental assessment of atmospheric pollutants. On-going work is incorporating
the model algorithms into a multimedia simulation framework to provide better capabilities.
In recent years, a considerable research effort has been devoted to Life-Cycle Assessment (LCA).
However, most of the work has been focusing on improving the methodology as such and providing
guidelines for carrying out LCA studies. Much less effort has been dedicated to the exploration and
analysis of the applications of LCA within the actual context of business. Which are the drivers for
starting LCA activities in a company? Which are the main applications? Which business departments
are involved? This is the kind of questions addressed by the present paper.
The paper reports the results of a survey about the use of LCA in business in four selected European
Countries, namely Germany, Italy, Sweden and Switzerland. 1600 questionnaires have been sent out to
selected companies in the four countries. As expected, there are considerable differences between
countries because of a different level of environmental awareness. However, there are some main common
results. The first one is that the cultural approach of Life-Cycle-Thinking is spreading out, but not
yet the tool. LCA is not yet used as a routine tool for assessing environmental aspects of product innovation
and it is still rather employed in a retrospective way than in a prospective one. Benefits of LCA
are considered to be rather long-term ones. On the other hand, the large majority of firms is optimistic
about the future use of LCA, most likely linked together with other instruments.
A model and spreadsheet-based numeric approximation for computing risk-based soil cleanup level to
be protective of petroleum-contaminated soil to an indoor air exposure pathway is presented. The algorithm
incorporates traditional equilibrium partitioning equations (3 or 4-phase) for the conservation of
mass and volume, as well as Raoult's law convention, and subsequent diffusive and convective transport
A risk-based decision analysis methodology is presented, that can be used as a water policy tool in the
design of economic incentive instruments, under conditions of uncertainty. A contaminated groundwater
resource system with unknown hydrogeological parameters is used as a case study. The polluter
has to select the policy to be followed among a series of alternatives, ranging from the extreme and
environmentally risky scenario of paying pollution charges as long as the aquifer will remain polluted,
up to the conservative option in terms of reduced environmental risks policy of safely rehabilitating the
groundwater system. The full-cost price of water, including direct, opportunity, and environmental
costs, both actual and probabilistic, as well as the risks of failure of the alternative scenarios due to the
uncertainty, as they result from stochastic simulation, are embedded in a risk-cost-benefit decision
model, developed for the evaluation of the alternatives. The pollution charges to be imposed by the
local water authority are determined through the appropriate development of this model and the use
of a proposed algorithm, in a way that these charges can act as incentives to the polluters, forcing them,
or the authorities, to select the most environmentally sustainable water policy, namely that of safely
restoring the aquifer.