Wastewater sludge is known to have excellent clustering and stable properties. By using carbide manufactured from the sludge in coal-based thermal power plants for mixed combustion, it is possible to help prevent global warming, while recycling wastewater sludge in a stable manner for the long term. This technology belongs to a wastewater sludge fuel system realized by joint R&D between Electric Power Development Co., TSK Co., J-Pec Co., Japan Sewage Works Agency and METAWATER.
By carbonizing wastewater sludge at a low temperature ranging from 250℃to 500℃, it can be recovered as a fuel substance with sufficient calorific value to be used as a coal substitute.
By giving consideration to the granular formation of dehydrated sludge or addition of steam in carbonization equipment, a number of advantages can be achieved including fuel safety (control of self-heating), improved handling convenience, control of odor specific to sludge and so forth.
By adopting a lower temperature in carbonization versus the conventional high-temperature carbonization, generation of N2O can be suppressed. Besides, the fuel obtained from wastewater sludge is a carbon-neutral product. Therefore, by using it in a power generation plant as an alternative to coal, it is possible to drastically decrease CO2 emissions derived from fossil fuels.
Others Low-temperature carbonization technology
Besides regeneration as a fuel, some other technologies for regenerating resources have been developed including an alternative to phosphate fertilizer material. Through low-temperature carbonization of the water-soluble phosphate included in the wastewater sludge, efficient enrichment of phosphate can be achieved.