With Activated Carbon Increasingly wide range of applications, activated carbon recovery begun to be people’s attention. If not recycling of used activated carbon, in addition to the cost per ton of wastewater treatment will increase from 0.83 to 0.90 yuan, are also on the Environment Secondary pollution. Therefore, the regeneration of activated carbon has extra significance.
1 traditional method of active carbon regeneration
1.1 Thermal regeneration Thermal regeneration is the most widely used, industry is the most sophisticated methods of activated carbon regeneration. After treatment of organic wastewater by activated carbon in the regeneration process, heated to different temperatures according to changes in organic matter, generally divided into dry, high temperature carbonization and activation stages. In the drying stage, and activated carbon to remove volatile components. High-temperature carbonization stage is to make part of organic carbon on the adsorption of boiling, vaporization desorption, part of the organic matter decompose to produce hydrocarbon desorption of small molecules out of the residual elements remain in the activated carbon pores to become “fixed carbon.” At this stage, the temperature will reach 800 ~ 900 C, in order to avoid the oxidation of carbon, generally in vacuum or inert atmosphere. Next, the activation phase, the reactor access to CO2, CO, H2, or water vapor and other gases, to clean up the porous activated carbon, adsorption properties to restore the activation stage is key to the regeneration process. Although renewable heat regeneration efficiency, wide range of application features, but in the regeneration process to be applied Energy Heating, higher investment and operating costs.
1.2 Biological regeneration Biological regeneration is the use of bacteria by the domesticated, analytical activated carbon adsorption of organic matter, and further digested down into H2O and CO2 in the process. Biological regeneration and Sewage Processing biologic method similar, but also aerobic and anaerobic methods divided. As the activated carbon pore size itself is small, some only a few nano-, micro-pores can not enter it, usually that will happen in the regeneration process cell autolysis, and cell to extracellular enzyme flow, while the activated carbon adsorption of the enzyme, Therefore, enzymatic centers of carbon formed on the surface, so as to promote decomposition of pollutants, to achieve the aim of regeneration. Biological method is simple, low investment and operating costs, but the longer time required by water quality and temperature greatly.
1.3 wet oxidation regeneration At high temperature and pressure conditions, the use of oxygen or air as an oxidant, will be in a liquid state, carbon oxidation and decomposition of organic matter on adsorption of small molecules into one method, called wet oxidation regeneration. Regeneration of activated carbon experiments the best conditions are: regeneration temperature of 230 C, regeneration time of 1h, oxygenation pO20.6MPa, increase the amount of carbon 15g, the amount of water 300mL. Regeneration efficiency (45 5)%, after 5 cycles regeneration, the regeneration efficiency decreased by only 3%. The surface of microporous activated carbon is recycled to the oxidation efficiency decline.
Conventional activated carbon regeneration technology in addition to their own shortcomings, the usually have three common defects: (1) loss of activated carbon regeneration process is often relatively large; (2) activated carbon adsorption capacity after regeneration there will be decreased; (3) regeneration exhaust gas generated when the air can cause secondary pollution. Therefore, people, or the traditional renewable technologies to improve or explore new renewable technologies.