Split treatment phosphorus removal from waste
US4017388A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 26, 1973 |
| Grant date | Apr 12, 1977 |
| Priority date | — |
| Expiry date | Jan 26, 1993 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/906
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A process and apparatus for economically removing algae producing phosphorus, from sewage by separating sludge from the sewage, recirculating the sludge, mixing into this the lime needed to bring the pH up to 11.0 or more and then mixing the limed sludge with the raw feed to a pH of 10.5 or under to precipitate more phosphorus from the total flow than would result from an equal amount of lime fed directly into the total flow. This result is also obtained by splitting the feed and heavily dosing one part with lime before returning it to the remainder of the feed. The high pH reached in the heavily dosed part also produces a water softening effect, which makes the sludge easier to dewater and the effluent more acceptable for discharge or reuse. Additional precipitation is economically secured by mixing polyvalent metal salts or polyelectrolytes with the lime treated waste material before separation of the lime sludge from the waste material effluent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.