In the present work, Fourier Analysis is applied to the mean monthly NOx concentrations of the period
1989-1999, for a network of 7 stations. Treating NO and NO2 as a single primary pollutant, we succeeded
the assessment of NOx concentrations. The main causes of NOx emissions in urban areas are
the road traffic and the industrial activity.
The annual variation of NOx concentration is well described with only two harmonic components,
which explain over 90% of the total variance. The spatial distribution of the time of maximum, for every
one of the two harmonic components in Athens basin, is also presented.
Air pollution forecasts in major urban areas are becoming a problem concerning the day to day environmental
management for city authorities. This paper describes the development of an application to
forecast the peak ozone levels with the aid of meteorological and air quality variables, in the Greater
Athens Area. For this purpose, a number of regression models were considered, while the selection of
the final model was based on extensive analysis and on literature. The model adapted includes variables
that are available on a daily basis, so as daily operational maximum ozone concentration level forecast
can be achieved.
The sustainable management of water resources often requires the identification of wastewater as a valued
source of water. Although the benefits of wastewater reuse and reclamation have increased significantly
in Europe because of the advances in effectiveness of wastewater treatment and disinfection technologies
there is currently no legislation nor guidelines regarding reuse. It is well known that there is a
great variation of wastewater reuse quality criteria applied, mainly related to significant differences in
socioeconomic conditions, environmental policies, available water resources. In this work the parameters
that affect the wastewater reuse criteria in Greece are evaluated, concerning among others reuse
priorities, available treatment plants and effluent characteristics and recommendations are made for
developing future guidelines or regulations for Greece in relation to reuse practices (agricultural, urban,
etc). The intention is not to propose an unquestionable and rigid set of standards, but to present them
on the basis of the rationale developed, in order to form a basis for further consultation, involving all the
interested parties. The recommendations are presented in relation to the different types of reuse, with
appropriate specific standards and recommended treatment systems wherever applicable.
The paper discusses a methodology for integrated municipal wastewater management. In compliance
to the EU Directive 91/271, there is a legal binding to ensure that all agglomerations with populations
over 2000 are provided with wastewater collecting system and adequate treatment. The conditions for
optimum application of the Directive in Greece, especially in the light of the recent administrative reorganization,
and the management of small rural communities not covered by the Directive are
addressed, with reference to a case study application in the Achaia County. In compliance to the EU
Directive 91/271, it is estimated that collecting systems and treatment should expand to at least 70% of
the total population. However, due to the expanding touristic activity, the limited availability of land,
environmental considerations, and favorable population characteristics (high density, relatively large
communities) and morphological and socioeconomical conditions, it is proposed that coverage can
reach to 85% of the total population. As for the rest of the County population (15%), decentralized on
site wastewater treatment and disposal schemes were proved to be the most technically effective and
economically efficient alternative.
This study was conducted to assess the removal efficiency of Di-n-butyl phthalate (DnBP) from aqueous
medium using the photo-Fenton process. The Fenton's reagent that consists of a mixture of hydrogen peroxide
(H2O) and ferrous ions (Fe2+) was used to generate the hydroxyl radical (OH0) that attacks the target
contaminant and degrade it. An ultraviolet (UV) source was used to provide the radiation needed in
the photo-Fenton method (i.e. UV/H2O2/Fe2+). The results demonstrated that photo-Fenton process was
more effective and faster than Fenton's reagent in removing DnBP and that photolysis by UV irradiation
was the dominant mechanism in degrading the compound. The results also showed that enhancing the
removal via UV irradiation was achieved by increasing either the temperature or the H2O2 concentration.
A procedure that should be implemented for the evaluation of materials suitability, in terms of their
use as metal retention agents, is presented. It derives from a review of materials and waste treatment
mechanisms, which has been studied and is also presented. Lignite fly ash, agricultural ashes, lime and
sawdust were chosen for the experimental study of their metal uptake capacity, according to the proposed
stages, during the treatment of an acidic liquid waste loaded with metals (Cu, Zn, Fe, Ni, Cd,
Cr). Fly ash, agricultural ashes and lime exhibited increased metal retention percentages through
adsorption and precipitation, as it was expected due to their structure, while sawdust acted as sorbent.
The effects of effluent from Thessaloniki, the second most populated Greek city, reclaimed either by
activated sludge or by stabilization ponds, were studied on field-grown corn. The experimental layout
was that of a split- plot design with six replications, three water qualities and two irrigation methods.
Potable water was used as the control. No significant differences in corn yield have been observed
among the three water-quality treatments. However, significant differences have been observed in corn
yield between the irrigation methods. Furrow irrigation has produced about 10% more corn yield than
trickle irrigation. There is a potential risk of facing problems related to soil salinity and alkalinity if no
consideration for soil reclamation is taken into account. The trace element concentration in the soil and
plant was low. The chlorinated effluent was free of pathogens, while the presence of pathogens was
detected in the non-chlorinated effluent reclaimed by the stabilization ponds.
The scope of this paper is the evaluation of wastewater reuse quality criteria and treatment specifications,
appropriate to Greek conditions. The parameters that affect wastewater reuse criteria were taken
into consideration, concerning among others reuse priorities, available treatment plants and effluent
characteristics. The proposed wastewater reclamation criteria were verified by a series of lab-scale
experiments, designed to study the feasibility and effectiveness of the following treatment schemes to
produce treated wastewater suitable for reuse: a) disinfection of secondary effluent with UV radiation
and chlorination and b) tertiary treatment and disinfection of wastewater with UV radiation and chlorination.
The experimental data were analyzed using a stochastic statistical model that employs Monte
Carlo simulation. The main scope of the stochastic approach was the regeneration of a greater set of
data, based on the defined by the experimental information mathematical distribution of each parameter
involved and the determination of relative probability distributions. Following this approach the
standards proposed are realistic and feasible and in the case of restricted reuse can be readily achieved
by the existing wastewater treatment plants in Greece. Even in the case of unrestricted reuse the additional
treatment required can be achieved at a moderate cost, through upgrading of the existing plants
with tertiary treatment.
In this study, ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) stereo
imagery was analysed in combination with Global Positioning System (GPS) data and field observations,
using Geographical Information Systems (GIS) techniques to examine the potential of satellite
remote sensing to support watershed management. Terrain elevation data were derived for the region
of Heraklion, Crete. The accuracy of the ASTER derived DEM (Digital Elevation Model), was better
than 20 meters (planimetric) and better than 15 meters (elevation). Supervised classification techniques
were applied for land cover production using ASTER multi-spectral imagery and filed observations
at predefined application sites. The determination of training areas required in the supervised
classification scheme was based on these observations. Finally, GIS methods were applied to estimate
watershed characterization parameters for the study area offering the advantages of spatial data handling
capabilities and automatic extraction of thematic information. The drainage pattern, which was
derived, provided a generally representative depiction of the watershed. The output pixel spacing of 15
m of the produced DEM as well as the high spatial resolution of ASTER imagery found to be quite satisfactory
for the watershed characterization of the study area, indicating the high potential of ASTER
imagery to support watershed management.
The current study presents the development of a Forecasting Information System for geographic data
(cross-sectional time-series for different geographic regions). GFIS, Geographic Forecasting
Information System, was developed with MS Visual Basic (User Interface), ArcView (GIS) and MS
Access (DBMS) during the MSc thesis of one of the authors in 2000.
GFIS is suitable for the management and forecasting for all time-series that present a geographic
dimension and can be illustrated in a Geographical Information System (GIS). The forecasting capabilities
of the system extend from classical time-series extrapolation methods (exponential smoothing,
regression) (Assimakopoulos, 1994) to more complex methods (Theta model).
The applicability of the system was tested with a case study in Water Resources Management. GFIS
was used in order to create rainfall forecasts for the watersheds in Lakonia, a region in southern
Greece. The estimation, forecasting, planning and management of hydrological resources are of great
importance and prerequisite for sustainable development.