Water treatment systems and methods
Separation processes using osmotically driven membrane systems are disclosed generally involving the extraction of solvent from a first solution to concentrate a solute by using a second concentrated solution to draw the solvent from the first solution across a semi-permeable membrane. Pre-treatment and post-treatment may also enhance the osmotically driven membrane processes.
1. A water treatment system comprising:
at least one softening system configured for receiving a raw feed of the water; and
a two-stage clarifier proximate to and in fluid communication with the at least one softening system, the two-stage clarifier comprising:
a generally rectangular enclosure comprising two longitudinal side walls, two end walls, and a floor extending therebetween and defining an open space therein;
a first baffle extending between the side walls and upwardly from the floor for a substantial portion of a height of the side walls, the first baffle sealingly engaged with the side walls and floor and with one end wall defining a first settling zone;
a second baffle extending between the side walls and downwardly from top edges thereof for a substantial portion of the height of the side walls, the second baffle disposed proximate to and spaced from the first baffle and defining a transition zone between the first baffle and the second baffle, a second settling zone between the second baffle and one of the end walls, and a passageway between the transition zone and the second settling zone proximate the floor; and
a lamella plate assembly disposed within the second settling zone,
wherein the water treatment system further comprises at least one osmotically driven membrane system in fluid communication with and disposed downstream of the two stage clarifier,
wherein the at least one osmotically driven membrane system comprises at least one forward osmosis system in fluid communication with and disposed downstream of at least one reverse osmosis system and configured for receiving a retentate stream from the at least one reverse osmosis system, and
wherein the at least one forward osmosis system comprises a combined forward osmosis membrane and electrodeionization membrane.
2. The water treatment system of claim 1 , wherein the floor comprises at least one trough for collecting sludge.
3. The water treatment system of claim 1 , wherein the enclosure further comprises a cover extending between the side walls and over at least a portion of the open space.
4. The water treatment system of claim 1 , wherein the at least one softening system comprises at least one of a lime softening system or a soda ash softening system.
5. The water treatment system of claim 1 further comprising a flocculation system disposed between the at least one softening system and the two stage clarifier.
6. The water treatment system of claim 1 further comprising means for introducing at least one of a chemical additive or an energy source to at least one of the first settling zone, the second settling zone, or the transition zone.
7. The water treatment system of claim 3 , wherein introduction means are disposed in the cover.
8. The water treatment system of claim 1 , wherein the at least one osmotically driven membrane system further comprises at least one reverse osmosis unit.
9. The water treatment system of claim 1 , wherein a permeate flow from the at least one forward osmosis system is directed to a separation system to obtain a product solvent and a concentrated draw solution.
10. The water treatment system of claim 9 , wherein the product solvent is directed to the at least one reverse osmosis system.
11. The water treatment system of claim 1 , wherein the two stage clarifier further comprises an electrocoagulation unit disposed in at least one of the first settling zone, the second settling zone, or the transition zone.
12. The water treatment system of claim 1 further comprising a filtration system in fluid communication with and disposed downstream of the two stage clarifier.
13. The water treatment system of claim 1 further comprising an ion exchange system in fluid communication with and disposed downstream of the two stage clarifier.
14. The water treatment system of claim 1 , wherein the at least one softening system comprises a bacterial softening system.
15. The water treatment system of claim 14 , wherein the bacterial softening system comprises sulfate-reducing bacteria.
16. The water treatment system of claim 15 , wherein the bacterial softening system comprises a reservoir comprising means for removing hydrogen sulfide gas.