These mercury species should be understood because some pretreatment technologies can effectively remove only certain species. In addition, the various species of mercury may bind to particulate matter in the wastewater to form physical agglomerates containing mercury. Metallic mercury is typically found in thermometers, manometers, sphygmometers, fluorescent lamps and switching devices. Metallic mercury slowly vaporizes at room temperature and can cause dangerous vapor concentrations in enclosed rooms. The vapor form of metallic mercury is readily absorbed through the lungs and is very toxic.
Ionic mercury can exist in two forms.
Often called organomercuric compounds, these forms of mercury are quite soluble in water and wastewater and are extremely toxic to aquatic life. If fish having bioaccumulated organic mercury are consumed, there can be major human health concerns. In addition, inorganic mercury in the environment can be converted by microbiological activity into methyl mercury compounds that can be absorbed by fish. The various species of mercury can bind to the particulate matter that may exist in ambient water or wastewater. In analytical testing of wastewater samples, total mercury concentrations are usually determined by analytical laboratories using EPA Method 245.1.