| 摘要 |
<p>In the treatment of waste water sludge, the fouling process requires a period of 20 to 24 days. In order to be able to substantially reduce this period, the fermentation of the waste water sludge is carried out in two steps, the first step being a thermophilic fermentation and the second step being a mesophilic fermentation, and the waste water sludge in each case being thoroughly mixed. The residence time of the waste water sludge in the first step is approximately 12 to 24 hours, and in the second step 8 to 10 days, so that the previously required period for the fouling process can be reduced to half and less. Both the first and the second step of the fermentation take place in a so-called loop container (9, 18), these containers being arranged vertically or horizontally, and each having, in the centre of the inlet area, an axial wheel (13, 19), which mixes the sludge entering the container and imposes to it an axial speed component. The sludge is then conveyed through the loop container (19, 18) in question with this speed component in a positively controlled fashion.</p> |
