Issue 3

Undoubtedly, sun is the cleanest energy source. Specific systems are needed however for the
collection and transformation of solar energy and the manufacturing processes of such systems, as
well as the production of the raw materials required, are associated with impacts to the environment.
As a result, the life cycle environmental impact of solar systems depends on the type and the size of
the systems. System characteristics and also the climate of the installation area, affect the substituted
conventional energy (solar coverage). In this paper, the net environmental gain of flat plate
thermosyphonic solar systems for domestic use is determined, accounting for the household size
(different collector sizes) and the installation area (different solar coverage and transportation
distance) for the major cities of Greece. Calculations are based on the “Eco-Indicator ‘99”
methodology and database and it is proved that substituting electricity with solar energy is always
environmentally beneficial for systems installed in all major cities of Greece.

In hydrology, as in a number of diverse fields, there has been an increasing use of Artificial Neural
Networks (ANN) as black-box simplified models. This is mainly justified by their ability to model
complex non-linear patterns; in addition they can self-adjust and produce a consistent response when
‘trained’ using observed outputs.
This paper utilises various types of ANNs in an attempt to assess the relative performance of existing
models. Ali Efenti, a subcatchment of the river Pinios (Greece), is examined and the results support
the hypothesis that ANNs can produce qualitative forecasts. A 7-hour ahead forecast in particular
proves to be of fairly high precision, especially when an error prediction technique is introduced to the
ANN models.

The use of conventional textile wastewater treatment processes becomes drastically challenged to
environmental engineers with increasing more and more restrictive effluent quality by water
authorities. Conventional treatment such as biological treatment discharges will no longer be tolerated
as 53% of 87 colours are identified as non-biodegradable. Advanced oxidation processes hold great
promise to provide alternative for better treatment and protection of environment, thus are reviewed in
this paper. An overview of basis and treatment efficiency for different AOPs are considered and
presented according to their specific features.