Global NEST Journal

Adsorption and removal of commercial dyes were studied in aqueous suspensions of fly ash mixtures
with a sandy clay loam soil of low organic matter content. The commercial dyes, acid orange 7, acid yellow
23, disperse blue 79, basic yellow 28 and direct yellow 28 represent the widely used nitroazo structures.
Batch and column experiments were carried out at equilibrium conditions for concentrations of
dyes between 5 and 60 mg l-1. The logarithmic form of Freundlich equation gave a high linearity and
the k constants are increasing with the increase of fly ash content in adsorbent mixtures and the affinity
between the adsorbent surface and adsorbed solute. The mean removed amounts of dyes by adsorption
batch experiments in soil mixture with 20% fly ash content were up to 53.0% for acid yellow 7,
44.9% for acid yellow 23, 99.2% for direct yellow 28, 96.8% for basic yellow 28 and 88.5% for disperse
blue 79. The removal of dyes from column experiments decrease with the increase of the solution concentration
form 10 to 50 mg l-1 at 20 °C, showing the process to be highly dependent on the concentration
of the solution. The mean removed amounts of dyes by adsorption on columns of soil mixture
with 20% fly ash content and for initial concentration of dye solutions 50 mg l-1 were up to 33.8% for
acid yellow 7, 59.4% for acid yellow 23, 84.2% for direct yellow 28, 98.2% for basic yellow 28 and 60.3%
for disperse blue 79.

An attempt is made for a first general study of the relation between high/very high concentrations of
nitrogen dioxide and ozone with the discomfort index (DI) values. The nitrogen dioxide data of
«Patision» station and ozone data of «Liosia» and «Marousi» station have been analysed. The relation
between air pollution episodes and the corresponding values of DI during the period 1993-1995 have
been examined for the Greater Athens Area (GAA). For the warm period of the year, the frequency of
the DI values for different levels of air pollution in the GAA is also examined.

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.

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.