[article]
| Titre : |
Chemical treatment |
| Type de document : |
texte imprimé |
| Auteurs : |
Karl Flowers, Auteur |
| Année de publication : |
2020 |
| Article en page(s) : |
p. 40-44 |
| Langues : |
Anglais (eng) |
| Catégories : |
Coagulation
Déchets industriels -- Elimination
Eaux usées -- Epuration
Eaux usées -- Recyclage
Floculation
pH
Précipitation (chimie)
|
| Index. décimale : |
675 Technologie du cuir et de la fourrure |
| Résumé : |
The removal of pollutants from a tannery wastewater is an elementary requirement. Whether it is in the tanner's owen effluent treatment plant (ETP), a communal/common effluent treatment plant (CETP), or a municipal effluent plant will use a combination of methods in the treatment process to achieve this. The three broad categories of these treatments are physical, biological and chemical. These could also be hybridised into treatment systems that use more than one type of treatment. Physical removal methods like one type of tratment. Physical removal methods like screens, brushes, flow velocity fluctuations, pipe pressures or membrane filtration, can force pollutants out of a strem. Physico-chemical methods like electrolysis or reverse osmosis add a physico-chemical attribute to the separation.
Biological systems that are plentiful in tanneries where the weather permits rapid growth of bacteria, algae and other micro-organisms, play a role in removal of pollutants through the action of their enzymes or through bioaccumulation of the effluent chemistry into their biomass. A chemical method that is not going to be detailed in this article is the chemical inclusion of oxygen into the effluent ; a method known as aeration. Other chemical methods are detailed below. |
| Note de contenu : |
- pH modification
- Coagulation
- Flocculation
- Precipitation (clarification) or flotation
- Fig. 1 : A soluble chemical is often a charged molecule that can electrostatically interact with the polar solvent
- Fig. 2 : By changing the pH or by adding a counterion, the solubility is decreased, and the solute will precipitate or float
- Fig. 3 : When a solute has one charge, it generally repels similar molecules and remains in solution and with a low particle size
- Fig. 4 : If a polymer is added to a solution of a specific charge, the polymer could cause the solute to precipitate and floc together to form very large particle sized aggregates (easili removed)
- Fig. 5 : In a flotation system instead of precipitating and allowing thesludge to sink, dissolved air flotation precipitates the floc and the air bubbles carry the aggregate upwards - to be skimmed off |
| En ligne : |
https://drive.google.com/file/d/1e4N2UD9XyhXfrFAOjW4rtqoZB65Ot6zy/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33708 |
in INTERNATIONAL LEATHER MAKER (ILM) > N° 40 (03-04/2020) . - p. 40-44
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