SLAMFÖRBRÄNNING OCH - ÅTERVINNING I JAPAN / Sludge Incineration and Reuse in Japan
Sludge incineration has been used in Japan for the last 30 years, as a method to reduce the sludge volume and to destroy organic pollutants. Today, incineration is conducted mainly in conventional fluid bed incinerators, however there is a shift towards the use of circulating fluid bed incinerators instead. The occurrence of dioxins is very small when burning wastewater sludge, since the original content of chlorine is low. Another reason is that a higher and more even temperature can be maintained in the reactor due to more homogenous content in the sludge compared to solid waste. A problem with incineration is the disposal or reuse of the ash. Several projects have been conducted where the ash is used in the production of different ceramic materials. Although, the produced ceramic product had the same quality and property as ordinary products it was still difficult to market the ash as an alternative raw material. Instead, the use of ash as a raw material in cement production or as a phosphorus fertilizer might have a better chance. To implement advanced incineration technologies large sludge treatment plants have been constructed, where raw sludge from surrounding wastewater treatment plants is collected and treated.