Carbonate precipitation is known to occur in landfilled ashes and is often reported as a problem because of the precipitates tendency to clog drains and other leachate transport facilities. The Up-take of carbon dioxide by alkaline wastes and leachates will influence their properties e.g.; The hydraulic and gas conductivity of solid wastes will decrease as carbonates precipitate in the pores of the waste. The pH will change towards neutral values as carbonates form changing the mobility of metals and other elements A neutral pH will also allow biological reactions to act on the waste, especially if the waste contain organic material as e.g. ashes often do. Adding carbon dioxide to wastes can thus be a cheap and powerful treatment, yielding a less hazardous waste.