A complex wastewater treatment system to avoid a prohibition of discharge by the local authorities

Introduction In many industrial operations, the products produced in campaigns vary greatly in their composition. This is common in waste management companies, chemical and pharmaceutical production sites, as examples. These campaigns often change because of different input streams, smaller but different production lots, as well as frequent contract manufacturing. This may also lead to fluctuating…

Pourbaix Diagram

What is a Pourbaix diagram This section will explain the Pourbaix diagram and the parameters that influence the speciation of chemical elements in a solution such as pH Redox Ions in water can have different oxidation numbers depending on the potential of the water. Each different ion will dissociate into different species depending on pH.…

Chromium removal from water

Where does chromium come from? Chromium, which is evenly distributed in the earth’s crust, is obtained from chromite ores, an iron chromium oxide mineral (FeCr₂O₄). The hexavalent chromium (Cr˅ˡ⁺) is very toxic and has both mutagenic and carcinogenic effects, in contrast to the trivalent elementary chromium (Crˡˡˡ⁺), which is an essential nutrient. Figure 1: Chromite ore.…

Perchlorate (ClO₄¯) ion removal from water

Perchlorate is poorly abundant on earth, except combined with sodium nitrate mineral in some specific arid areas. Natural perchlorate is extracted to produce fertilisers. Perchlorate is intensively used in the formulation of explosive propellant for various explosives and weapons. To cover this strategic need, perchlorate is produced industrially. Perchlorate Molecular structure of perchlorate. Perchlorate is…

Nickel (Ni²⁺) removal from water using chelating resins

Where does nickel come from? Pure nickel (Ni) is a silvery-white metal that is rarely found as a pure metal in the earth’s crust because it will oxidise when it comes into contact with oxygen. Pure nickel can be found in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside the earth’s atmosphere or in ultramafic rocks.   Nickel is…

Mercury (Hg⁰ and Hg²⁺) removal from water

Introduction Mercury species exists in various forms: elemental (or metallic); inorganic (e.g. mercuric chloride); and organic mercury (e.g., methyl- and ethylmercury), which all have different toxic effects. Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapour, or by ingesting any form of mercury.…