| 摘要 |
<p>1401566 Converting sewage sludge into compost F KNEER 24 Oct 1973 [28 Oct 1972 14 April 1973] 49455/73 Headings C1B and C1C [Also in Division B1] In a continuous process for production of compost from sewage sludge by contacting a downward flowing stream of the latter with an upward flowing countercurrent of air and additional oxygen (preferably 5-20 vol. per cent), the sludge is fed to the top of the reactor together with (a) an organic additive to raise its C/N ratio, e.g. peat, sawdust, straw, processed sludge, and optionally (b) bentonite flour to reduce its content of sodium and heavy metal ions. Zones of different temperatures and oxygen concentrations form at different levels in the reactor, the highest oxygen concentration being near the bottom and the highest temperature being near the top where there is preferably a sanitizing "heat-trap zone" of 70-80‹ C. The location and biological activity of the zones may be monitored by temperature and gas probes (to measure O 2 and CO 2 concentrations), and controlled by adjusting the sludge or air/O 2 feed rates. The sludge feed may be sprayed with water and seeded with bacteria at the top of the reactor, and takes 14-20 days to reach the bottom. The air may be fed to the reactor through small-diameter nozzles.</p> |
