Cyclic process for selective coagulant recovery from clarifier sludge
US5304309A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 1992 |
| Grant date | Apr 19, 1994 |
| Priority date | — |
| Expiry date | Jun 24, 2012 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J47/018
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
An improved, continuous, cyclic process for selective coagulant recovery from clarifier sludge in water treatment plants. The improvement comprises several steps. First, the pH of the clarifier sludge is adjusted to about 3.5. Next, a composite membrane is provided having a chelating exchanger enmeshed in porous polymeric thin sheets. That composite membrane is placed in contact with the acidified sludge for selectively sorbing metal ion from the acidified sludge onto the composite membrane. The composite membrane, now carrying the metal ion, is withdrawn from contact with the acidified sludge and introduced into a stirred regeneration tank containing acid. In that tank, the chelating exchanger of the composite membrane is regenerated by desorbing the metal ion, thereby recovering the coagulant substantially devoid of organic material and undesirable metals. Finally, the regenerated composite membrane is recycled into contact with more acidified sludge while, at the same time, the acid is recirculated through the regeneration tank. In short, the improved cyclic process recovers alum selectively from clarifier sludge with insignificant carry-over of undesirable substances like organ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.