Conditions: anaerobic(186 days) - aerobic(59 days) with leachate recirulation
Materials: MSW(70%), olive pits(30%) combined with sludge from anaerobic digestion of a waste water treatment plant.
Yes, it could be that it caught on fire. A well documented effect of aeration in landfills is the ignition. Dangerous and sometimes difficult to control.
Strange value, i suppose that there is some problem inside maybe the thermometer broken or some fire inside but more difficult.
That' s what I thought(broken thermometere) but in 2 of the 3 bioreactors I had similar results... And the high temperatures lasted for many days... So I wanted to give an alternative explaination. Is there any paper with high temperatures in landfill bioreactors?
Well it didn't product noisy explosion because of the low temperatures. The reason I don' t believe that it is is measurement error is that for 4 or 5 weeks, a bioreactor didn' t appear leachtes(that it means temperature over 100 Celsius degree).The temperature didn't exceed the 150 Celsius degree. I thing that the high tempereture was a result of chemical oxidation. The high temperature triggered other reactions that released heat. and reached that temperature. Sorry for my bad english I hope you understad what I mean.
One reason for the increase of temperature can be the irregularity in overturning which is necessary to introduce oxygen and to avoid anaerobic conditions.
Such increase in temperature for such a long time (2 - 3 weeks) also deteriorate the efficiency of the system.
Well, I concluded that the main reason of the high temperatures was the chemical oxidation, during the aerobic phase, compined with low recirculation rate. High temperatures can trigger other reactions that have the effect of other temperature increase. Also I found out that aluminium' s rust can react with water and lead to heat production.
sorry for the late input, but I can only think of one sound reason for this: slow burning triggered by methane ignition. It is impossible that the high T would be caused by biological processes (above 80 degrees most thermophyles stop functioning). You would definately have substantial production of methane, and if this catches fire under limited oxygen availability (high oxygen would lead to an explosio) you would see a slow combustion process that might go on for quite some time. Subsequently organic material might continue a low rate combustion under limited oxygen availability, but this will generate substantial heat.
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