Environmental Technology 1 - ULB

monkeyresultMechanics

Feb 22, 2014 (3 years and 5 months ago)

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Environmental Technology
ChimH409

(2
-
0
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1)

Michel Verbanck

mikeverb@ulb.ac.be

2012

Universite Libre de Bruxelles


Welcome @ Bruface

Dept Water Pollution Control

Course structure



Part 1. Introduction (
incl.

generic methods)



Part 2. Air pollution control engineering




Part 3. Water & wastewater treatment


Part 4. Solid and hazardous wastes



Hierarchy


P
revention


Quantity


Quality


environmental impact


Re
-
use


R
ecycle


Material recovery


Composting


Organical treatment


Incineration with energy recovery


Incineration without energy recovery


Landfilling

pore water flow governed by Darcy’s Law:




Q =
k

A

S



Q =
flow rate (m
3
/s)



k

=
hydraulic conductivity (m/s)



A =

cross
-
sectional area (m
2
)



S

= slope of hydraulic gradeline (
-
)







Based on this, landfills will usually be divided into three classes


(Eur Directive 99/31/EC)



landfills for hazardous waste (Class I);
k < 10
-
9

m/s



landfills for non
-
hazardous waste (Class II);
intermediate



landfills for inert waste (Class III).
k > 10
-
6

m/s



In this chapter we only address classes III and II. Environmental technology favors
treatment & decontamination of hazardous waste, rather than storing them.


Recent evolution of the PCI (lower heat value) of municipal solid wastes accepted

at Brussels
-
Energy combustion plant (kcal / kg)




1996
-

2011

Reminder
: 9.0 MJ / kg on this diagram would read 2150 kcal / kg


In terms of energy recovery, in the Brussels agglomeration, more and more heat value is
presently lost to blue and yellow bags (selective collection of sorted municipal solid wastes)
which are not reaching the combustion unit any longer.

12

Controlled landfill


Structural elements of a class II landfilling facility

MSW

Pulverising, shredding equipment

Air classification

Magnet separators

furnaces with Martin® reverse
-
reciprocating grates

furnaces with Martin® reverse
-
reciprocating grates

The heat generated from the burning waste is used in
the boiler to superheat the water pipes into steam.
The steam is super
-
heated and can be then utilized to
generate electricity.

An alternative to grate firing systems is the fluidized bed incinerator. On this type of waste
incinerators the waste has to be processed prior to burning into a refuse
-
derived fuel (RDF), free of
noncombustible materials. Once the waste is homogenized, it is fed into the fluid
-
bed chamber
which burns wastes in a turbulent bed of heated inert materials, such as sand or other
noncombustible substances.

Fluidized bed systems operate in a temperature range between 750 and 850
°
C. As they can
operate with only 30
-
40 percent excess air, they are more energy recovery efficient than grate
furnaces.

Fluidized Bed Incinerator

Cement rotary kilns are convenient tools to ensure that the
triple T rule (Temperature


Time
-

Turbulence) is respected
for the destruction of specific organics.


They were, for instance, used at the time of the Belgium
‘dioxinated chicken’ crisis in 1999.

Management of fine
-
grained
contaminated sediments
deposited in harbours