Università di Padova
SECOND CYCLE DEGREE PROGRAMME (MSC
LEVEL) IN ENVIRONMENTAL ENGINEERING
MODELLING AND CONTROL OF
ENVIRONMENTAL SYSTEMS
A.A. 2014-2015
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
The equilibrium between spheres
Sky
Land
Acquifer
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
The spheres of the
geo-chemical-physical model
of the earth
The area near the surface of the
planet can be divided into 4
interconnected geospheres
University of Padua
LASA – Environmental Systems Analysis Lab
Atmosphere
Hydrosphere
Litosphere
Biosphere
Modelling and control of environmental systems
a.a. 2014/2015
Atmosphere
The atmosphere is the body of air which
surrounds our planet. Most of our
atmosphere is located close to the earth's
surface where it is most dense.
The air of our planet is 79% nitrogen and
just under 21% oxygen; the small amount
remaining is composed of carbon dioxide
and other gasses.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Hydrosphere
The hydrosphere is composed of all of the
water on or near the earth. This includes
the oceans, rivers, lakes, and even the
moisture in the air.
97% of the earth's water is in the oceans.
3% is fresh water; three-quarters of the
fresh water is solid and exists in ice sheets
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Lithosphere
The lithosphere is the solid, rocky crust
covering entire planet.
Inorganic and composed of minerals.
It covers the entire surface of the earth from
the top of Mount Everest to the bottom of the
Mariana Trench.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Biosphere
All living organisms: plants, animals, and
one-celled organisms are all part of the
biosphere.
Most of the planet's life is found from
three meters below the ground to thirty
meters above it and in the top 200 meters
of the oceans and seas.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Hydrogen oxide
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Hydrogen oxide
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Hydrogen oxide
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
The anomalies of H20
High melting and boiling temperature
High specific heat
is the substance that exists in more stable
(and metastable) states crystalline and
amorphous
is an excellent solvent
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
The anomalies of H20
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
H20 in the BIOSPHERE
Water is of major importance to all living things; in some
organisms, up to 90 % of their body weight comes from
water.
Up to 60 % of the human body is water, the brain is
composed of 70 % water, and the lungs are nearly 90 %
water. About 83 % of our blood is water, which helps
digest our food, transport waste, and control body
temperature. Each day humans must replace 2.4 litres of
water, some through drinking and the rest taken by the
body from the foods eaten.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Heavy metals
Are chemical elements that have the following
characteristics:
• 
densities exceeding 5.0 g/cm3;
• 
behave as cations
• 
remarkable ability to form complexes;
• 
low solubility of their hydrates;
• 
different oxidation states depending on pH and
Eh conditions;
• 
great affinity for sulfides, in which they tend to
concentrate.
Belong mainly to transition elements in groups VIB,
VIIB, VIIIB, IB, II B, but also in groups IIIA, IVA.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Heavy metals
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Soil as a filter
The basic parameters that govern the ability of soil to
store heavy metals are:
–  pH,
–  redox potential,
–  content of organic matter,
–  cation exchange capacity.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
DM 25 October 1999, No. 471 “Regulations establishing
criteria, procedures and arrangements for the securing and
restoration of polluted sites (...)”
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Reclamation
A very important point of the decree is that concerning the
choice of remediation techniques.
Art.4 .4 “Obligation of reclamation and environmental
restoration” it is stated:
«The interventions for remediation and environmental
restoration of a polluted site should give priority to the use of
techniques that promote the reduction of the handling, in situ
treatment, and reuse of the soil, subsoil and landfills
materials subject to remediation..»
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Equilibrium between spheres
Toxic substances are present in various forms in the
different spheres:
» lithosphere
» hydrosphere
» atmosphere
» biosphere
The various spheres can be in equilibrium or there
may be dynamic exchange phenomena
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Equilibrium between spheres
Exchanges between the spheres are usually described by
relations between the equilibrium concentrations. The
transfer of a compound takes place until the equilibrium
concentrations are reached
The rate is generally proportional to the distance from
equilibrium, depends on the diffusion coefficient of the
compound and the resistance at the interface between the
spheres
The resistance at the interface and the diffusion coefficient
depend on the temperature, the area exposed to the
atmosphere or to the liquid volume, the rate of flow.
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Hydrosphere-Atmosphere
•  Henry’s law
Ch =
Pg
He
Ca He
=
Ch RT
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Interphase transport
GAS BULK
δg
δl
GAS FILM
LIQUID
FILM
J l = kl (Ci − Cl ) J g =
pg
pi
kg
RT
(p
g
− pi )
INTERFACE
Ci
Pi
Ci =
He
Cl
LIQUID
BULK
CONCENTRATION AND PARTIAL
PRESSURE
Fig. 3.11: Mass transfer at the interface
between a liquid and a gas phase
(layer model).
University of Padua
LASA – Environmental Systems Analysis Lab
J g = Jl = J
pg
− Cl
J = He
RT
1
+
k g He kl
Modelling and control of environmental systems
a.a. 2014/2015
% Resistance to gas transfer in liquid phase
as a function of He
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Volatilization
& pg
#
dCl
V
= νAs $$
− Cl !!
dt
% He
"
For toxic substances (pg~0):
dCl
V
= −νAs Cl
dt
K l He
ν=
& Kl
He + RT $
$K
% g
1/ 4
K l = K l ,O2 (32 / M )
University of Padua
LASA – Environmental Systems Analysis Lab
Kl =
#
!
!
"
Kg =
Dl
δl
Dg
δg
1/ 4
K g = 168u w (18 / M )
3B.7
Modelling and control of environmental systems
a.a. 2014/2015
Volatilization rate
uw = 5 m / s
3B.7
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015
Litosphere-Hydrosphere
Freundlich Isotherm
Langmuir Isotherm
Partition coefficient
University of Padua
LASA – Environmental Systems Analysis Lab
Modelling and control of environmental systems
a.a. 2014/2015