Environmental Technology ChimH409 (2-0-1) Michel Verbanck 2012 Universite Libre de Bruxelles 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 Prevention Quantity Quality – environmental impact Re-use Recycle 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 < m/s landfills for non-hazardous waste (Class II); intermediate landfills for inert waste (Class III). k > 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) 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.

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Controlled landfill

Structural elements of a class II landfilling facility

MSW

Pulverising, shredding equipment

Air classification

Magnet separators

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 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