Inevitable product of wastewater treatment processes, this is the annual production of sewage sludge assuming that the sewage water from the world urban population in 2016 were to be collected and treated.
In major EU countries, most of the sewage sludge still goes to landfill or is used in agriculture. Because of these ways of disposal, land and water bodies can be contaminated by the pollutants contained in sewage sludge.
Lead, mercury and cadmium can be found in sewage sludge and are the most harmful heavy metals for human health causing well-known troubles such as troubles of vital functions but also anxiety and depression.
The Clean WOx® technology is implemented for the treatment of urban and industrial liquid effluents with a high content of non-biodegradable organic matter. It is based on the principle of wet oxidation, a process where non bio-degradable organics are degraded by oxidation in liquid phase in a high pressure reactor. This technology is offered via Granit Technologies and Engineering (GRT) SA, in which GRT GROUP participates with 47%.
A Clean WOx® unit degrades the non-biodegradable organic matter into smaller molecules by oxidation. It also transforms the inorganic matter into its oxidized form, for recovering these compounds or to neutralize them from a chemical point of view. This reaction is performed at high temperature and pressure in a bubble column reactor, using oxygen or air as oxidation gas. It generates heat, which can be used for electricity production by cogeneration or steam/hot water production depending on local needs. The outputs of the process are carbon dioxide (CO2), water and in some cases, a mineral residue (depending on the treated inlet). The system does not generate any toxic emission of gas.
In the case of sludge treatment, for which an important content of mineral in the effluent entering the Clean WOx® unit, the mineral fraction is separated from the liquid phase and dewatered in a filter press or a centrifuge.
The Clean WOx® process is unique and fully protected by patents.