| 摘要 |
Provided are a sludge treatment method and a sludge treatment system that can be used as a useful improvement facility in an existing treatment facility in which sludge is dehydrated, then dried and discharged, and with which it is possible to minimize an increase in fuel cost. This invention has: a dehydration step for performing a dehydration process on raw sludge; a methane fermentation step for performing methane fermentation of a slurry-like sludge obtained by adding water to the dehydrated sludge, and obtaining digested sludge; a step for branching the digested sludge into a first digested sludge and a second digested sludge; a decompression and degassing step for performing a degassing process on the first digested sludge under decompression; a step for discharging high-temperature steam at a high speed, forming a vacuum state, and returning the concentrated digested sludge to the methane fermentation step with the high-temperature steam; and a dehydration separation process step for separating the second digested sludge into digested dehydrated sludge and a sludge separation liquid. Alternatively this invention has: a decompression and degassing step performed on the digested sludge produced by methane fermentation; a step for discharging high-temperature steam at a high speed, forming a vacuum state, and branching a mixed-phase fluid that is obtained; a step for returning the branched first mixed-phase fluid to the methane fermentation; and a step for returning a second mixed-phase fluid to the dehydration separation process. |
