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The conventional landfilling does not promote sustainable waste management due to
uncontrolled emissions which potentially degrade the environment. In this regard,
pre-treatment of municipal solid waste prior to landfilling significantly enhance waste
stabilization and provides various advantages. So in this regard pre-treatment methods of
municipal solid waste were investigated. The major objectives of biological pretreatment are to
degrade most easily degradable organic matters of MSW in a short duration under controlled
conditions so as to produce desired quality for landfill; and to enhance methanogenic condition
in the landfill. Factors affecting the choice of pretreatment processes include the composition
of MSW, retention times, odor emissions, fate of toxic chemicals and costs. To investigate the
economical pretreatment method prior to landfilling for developing countries four pretreatment
simulators were developed at bench scale in the laboratory at different operating conditions
forced aeration and leachate recirculation (APSFALR), aerobic pretreatment simulator by
natural convection of air with leachate recirculation (APSNCLR), aerobic pretreatment
simulator by natural convection of air (APSNC) and anaerobic simulator (AS).The organic
matter, pH, temperature, settlement, leachate quantity and quality were monitored regularly. In
the leachate quality BOD5, COD, NH4-N, pH and trace metals were analyzed. The molecular
size distribution of dissolved organic matters (DOM) in leachate was determined after the
pretreatment of 45 days. The results of these methods are compared. The APSNCLR method
is economically effective method to reduce the organic matters, leachate COD and BOD5. With
the biological pretreatment significant amount of easily biodegradable matters and volume of
solids are reduced due to the decomposition of the waste.
Landfilling of pretreated waste improves landfill behavior, characteristics, and operation.
Leachate quantity, quality and landfill gas emissions also would be reduced. It is predicted by
the comparison of carbon content in the fresh and pretreated MSW that resultantly increases
the landfill age and decreases in aftercare monitoring period. The volumes of the solids were
reduced and density increased significantly in eight weeks pretreatment of MSW due to
biodegradation of organic matters. The BOD, COD5 and NH4-N content also reduced
significantly as compared to the anaerobic simulator. Pretreatment simulators results are
compared and concluded that pretreatment with passive aeration and leachate recirculation is
better as compared to the other pretreatment simulators.

During recent years special attention has been paid to various environmental impacts from
aircraft emissions. The effects become more important considering the present situation in the
air traffic sector and future expectations for higher air travel demands.
In this paper the evolution of aircraft air pollutant emissions in Greek airports from 1980 to
2005 is analysed. The estimation of emissions, based on the EMEP/CORINAIR methodology,
takes into account all flight categories (domestic, international, scheduled, charters) and all
aircraft types used in civil aviation in Greece. Emissions are estimated for Landing and Take
Off (LTO) cycles. Estimations cover 38 airports used by civil aviation and show a high
increase of emissions, which followed the high increase of air traffic in all Greek airports. Total
flights increased by 2.4 times from 1980 to 2006. Athens airport has the higher contribution to
total air traffic, as well in total emissions, but with decreasing trend (59.0% in 1980 - 42.2% in
2005). Thessaloniki and Iraklion airports follow with increasing share (6.3 - 11.7% and 6.8 -
9.8% respectively).
Changes in aircraft fleet composition together with changes of each airport contribution in total
civil aviation traffic influenced the increase rates of each air pollutant. NOx emissions showed
higher increase rates than air traffic, while VOC and CO emissions showed lower increase
rates. Average per flight emissions from 1980 to 2005 have shown increased trend for NOx,
decreased trend for VOC and CO and almost stable per flight emissions for SO2 and PM2.5.

Treatability by the electro-coagulation (EC) and electro-Fenton (EF) methods have been
applied to the tannery wastewater from an organized industrial region consisting mostly of
tannery plants and compared with each other in this study. Iron plates were used as the
anode and cathode. Electrical current was applied at a value of 33.3 mA m-2 for all processes
in order to determine the electricity consumptions for chemical oxygen demand (COD) and
sulfide removal. The optimal contact duration for each process was discovered at the end of
the first five minutes. During the EC process, the removal efficiencies of COD and sulfide
were 46% and 90%, respectively. Electricity consumptions were also obtained as 1.8 kWh kg-
1 COD removed and 27.7 kWh kg-1 sulfide removed. During the EF process, on the other
hand, the removal efficiencies of COD and sulfide parameters were 54% and 85%,
respectively, and electricity consumptions were also obtained as 1.5 kWh kg-1 COD removed
and 8.3 kWh kg-1 sulfide removed. Furthermore, the removal efficiencies of total Chrome and
suspended solids were determined to be 97% and 70%, respectively.

Furrow irrigation is used for row crops. S.C.S., based on a great number of field experiments,
under different circumstances and soil families, has developed design equations for furrow
irrigation. These equations have been used for steady flow rate or for flow rate with one
reduction when the water reaches the end of the furrow. They can also be used for a small
period of time (time step) when the flow rate can assumed to be steady.
Many scientists, who dealt with furrow irrigation, try to improve the application efficiency by
investigation the importance of the parameters that influence the furrow irrigation. Slope,
furrow length, intake family have extensively been studied. Flow rate has been studied as
steady or with a cutback of flow when water has advanced to furrow end. This article studies
the influence of altering flow rate at furrow irrigation to application efficiency.
The steepest descent method is implemented for the optimisation at each time step flow rate.
Steepest descent method evaluates the derivative of the function, which has to be optimized
(application efficiency), to the parameter that is changing (flow rate). The derivative of the
application efficiency to flow rate is calculated analytically. The optimized application
efficiency is achieved when the derivative is zero, thus the value of flow rate is raised if the
derivative is positive or is decreased if the derivative is negative.
When the flow rate at each time step is optimised, the process begins again because the
optimisation for the flow rate of the initial steps didn’t take into account the optimized flow
rates of the later time steps. This process converges and estimates the optimised flow rate at
each time step.
The results of the optimisation for two samples are alike. The maximum application efficiency
is achieved by increasing the flow rate at the beginning of irrigation and before the water
reaches furrow end the flow rate must be decreased to the minimum value of flow rate that
fulfils instant infiltration.