| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a compost rich in fertilizing ingredients including nitrogen, phosphorus, potassium and magnesium by subjecting effluent to intermittent aeration type activated sludge treatment and by subjecting the surplus sludge thus produced to composting treatment. SOLUTION: This compost is produced by the following process: contaminant- contg. effluent 3 is biologically cleaned using pref. a two-tank type intermittent aeration type activated sludge treating equipment 1 and discharged as treated water 6; part of sludge produced is extracted as surplus sludge 4, which is then charged into a composting equipment 2 to obtain the aimed compost 5 rich in nitrogen, phosphorus, potassium and magnesium; wherein the contents of nitrogen, phosphorus, potassium and magnesium in the effluent are pref. >=1.25 wt.%, >=0.25 wt.%, >=0.05 wt.%, and >=0.05 wt.%, respectively, based on BOD and also >=2.5 wt.%, >=0.5 wt.%, >=0.1 wt.%, and >=0.1 wt.%, respectively, based on readily soluble BOD; the surplus sludge is flocculated with a flocculant within one hour and then dehydrated using a dehydrator into the objective compost. The process described above enables both the labor saving and cost reduction in fertilizer application.</p> |
