Method of treating sludge containing fibrous material
US5557873A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1995 |
| Grant date | Sep 24, 1996 |
| Priority date | — |
| Expiry date | Feb 10, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A40/20
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A method of converting industrial, domestic or other sludge, into a pelletized or granular fertilizer, as well as a sludge converter for practicing the method. The sludge is dewatered to form sludge cake solids which are dried in a dryer, and then sorted with a sorter into a sorted product comprising oversized, undersized, and standard sized product. Oversized product containing fibrous material is reduced in size by grinding in a hammermill. A portion of the sorted product is recycled for mixing and sizing in a mixer with the dewatered sludge cake solids. To control dust and odors, cyclones and a condenser remove a substantial portion of the gaseous particulate matter and condensable gases from the converter, and any remaining noncondensates are burned in the heat source flame. A waste oil burning heat source supplies heat energy to the dryer. The heat source exhaust gas by-products are filtered in a bag house using a conditioner additive, such as lime or sodium bicarbonate, which may be reclaimed and supplied to the standard sized product to serve as a pelletizing binder, to enhance the fertilizer nutrient value, or to enhance the fertilizer shelf life.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.