ABSTRACT
Chemical treatment processes are used to remove inorganics, primarily by oxidation and precipitation. Occasionally chemical treatment will be used to remove organics, particularly those organics that are not, or are resistant, to biodegradation. Precipitation reactions are used to reduce suspended solids and for the removal of heavy metals from wastewaters. Ion exchange is used to remove heavy metals and can also be used to remove any inorganic cation or anion. It use a bed of a resin or gel bead material to hold ions, and exchange the ions in the wastewater for hydrogen or hydroxide ions. Electrodialysis membranes are stacked between electrodes. It will only work for salts that can ionize, and is ineffective for non-ionizing compounds, such as organics. Another consideration is the valence state of the metal. Several metals, such as Chromium and Copper, have several valence states. Oxidation to change the valence state may be necessary.
