Volatile Organic Compounds (VOC's) and, in particular, solvents, constitute one of the primary elements of air pollution in the industry. They compounds are used for their capacity to evaporate after utilizing them for cleaning purposes, mixing purposes, pigment applications, ...
VOC's can be thermally oxidized, biologically oxidized and recuperatively oxidized.

Typical VOCs:
	alkanes: methane, decane; alkenes: ethylene, hexene
	aromatics & polyaromatics: benzene, toluene, xylenes; aldehydes & ketones: acetaldehyde, formol butanal alcohols & acetates: ethanol, propanol, ethylacetate
	organo-chlorinated HC chloroform, perchlor­- ethylene, dichloromethane
	sulfur containing components: H2S, CS2, COS, methanethiol, mercaptanes, dimethyldisulfide, dimethylsulfide
	nitro-organics & ammonia: diethylamine, trimethylamine, pyridine, acetonitrile, acrylonitrile

Applications

Painting booth (aeronautical, automotive, ...)

Paint, ink and adhesives

Printing and package graphics

Chemistry, pharmacy and petro-chemistry

Textile, dry-cleaning

Food industry

For these kinds of pollutants WATERLEAU France can bring, thanks to its competence in chemical engineering and its long experience, a package of solutions perfectly adapted to production and exploitation in accordance with the regulation.

These solutions are divided in 2 categories:

1. Recuperation processes

- condensation processes : ESOTHERM
- adsorption with regeneration processes : ESOSORB
- absorption processes : ESOLAV

2. Destruction processes

- thermal oxidation processes : ESOCOV
- biological treatment processes : BIOTON^® biofilter, BELAIR^® biotrickling + biofilter,
  BIOWAVE^® bioscrubber
- adsorption processes : ESOSORB

Categories of VOC destruction

1. Recuperation processes

Condensation processes

ESOTHERM

Adsorption on activated carbon with regeneration

ESOSORB is a solvent adsorption process on beds of activated carbon with recuperation by desorption through steam. The process is very well adapted to gases containing 1 or 2 solvents in a concentration lower than 30 g/Nm3 and gas flows between 200 and 200.000 Nm³/h.

These units are built out of several adsorbent beds containing activated carbon. The air to be treated is guided over the activated carbon where the VOC's ared adsorbed until the activated carbon is saturated. If one of the adsorbing beds is saturated, a regeneration process is set in motion. After passage of the steam for the desorption a fan dries and cools the activated carbon beds, which makes them ready for a new adsorption cycle.

Absorption process

ESOLAV is a range of absorption processes or washers which transfers the VOC's into a liquid phase in order to be solubilized, oxidized or separated. It is especially well suited for VOC's soluble in the washing solution with weak and low concentrations (< 1 g/Nm³) and for gasflows between 500 and 50.000 m³/h.

2. Destruction processes

Regenerative thermal oxidation (with and without catalyst)

ESOCOV is a regenerative thermal oxidation process on ceramic beds. The process is especially well adapted to a mixture of gases with concentrations between 1 and 10 g/Nm³ and flows from 1.000 to 100.000 Nm³/h.

The gas passes over a ceramic bed in which air is progressively heated and the VOC's are destroyed by oxidation above 800 C. The direction of the airflow is changed on a regularly basis in order to charge and discharge the calories in the bed(s). The thermal efficiency amounts to 90 - 98 %. In this way the regenerating systems are autothermal, so, without additional energy for concentrations higher than 1,5 g/Nm³. Addition of a catalyst to have the oxidation at a lower temperature (between 200 and 400 C).

Adsorption on activated carbon with catalytic destruction

ESOSORB is a VOC adsorption process on activated carbon beds with catalytic oxidative destruction. The process is well suited for mixtures of gases with concentrations lower than 1 g/Nm³ and big flows (5.000 to 100.000 Nm³/h).

The VOC-laden air is treated by adsorbents filled with activated carbon onto which the VOC's attach until they are saturated. At the end of the adsorption phase, a desorption phase begins. The oxidation process is initiated by an electrical resistance controlled by thyristors. The energy liberated during the VOC destruction is used for the oxidation and is recuperated by an exchanger who yields these calories to the new air of desorption. This use of energy ensures a saving in electricity at the level of the resistance.

Biological treatment

BIOTON^® biofilter is WATERLEAU's proprietary biofilter technology.

BELAIR^® biotrickling/biofilter : WATERLEAU has developed a two-stage biotrickling/biofiltration concept for the treatment of VOC's and odours in off gases released for example in WWTP systems.

BIOWAVE^® bioscrubber

Adsorption processes

ESOSORB