US 2026/0097975 A1 · Combined Electrodialysis and Reverse Osmosis CERO

Abstract

Previous patent applications described, by way of examples, a Combined Electrodialysis and Reverse Osmosis (CERO) system capable of extracting 100% of the water in the saline feedwater as desalinated water and all its dissolved salt as solid salt. These examples only cover one special case of the reverse osmosis system operating with a 50% water-recovery factor of its input water. The present invention extends this principle, illustrated by narrow in scope examples, to accommodate any permissible RO water-recovery factor. In addition, whereas earlier descriptions of the CERO process required a cyclic sequence of serial operations, the invention further provides an implementation in which those cyclic operations are performed concurrently while achieving the same overall functional result.

Claims3

Dependent claims

The Combined Electrodialysis and Reverse Osmosis (CERO) system operates by combining a fixed amount of saline feedwater with ion-reduced dilute water produced by the Electrodialysis (ED) system on the previous CERO cycle of operations. This combined saline water is then fed to the Reverse Osmosis (RO) system. The RO system generates two outputs:

(1) desalinated product water and (2) ion-enriched saline water. The ion-enriched saline water is routed to the dilute water of the ED system, where a fixed quantity of ions is transferred into a circulating concentrate water stream of the ED system. This concentrate water stream, which is slightly supersaturated, circulates through a concentrate water tank that contains salt crystals. As it passes through the crystals, the excess ions precipitate as solid salt. After ion removal, the dilute water stream of the ED system is left at a lower-salinity state and becomes ready for the next CERO cycle of operations. These operations can repeat either sequentially as stated or simultaneously with a modified system. When the masses of the water and dissolved salts are appropriately controlled throughout the CERO system, the CERO system can provide 100% recovery of the water in the input saline feedwater and all the dissolved salt in the input saline feedwater as solid salt.

When the CERO system is operated cyclically using a series of repeated sequential operations within each cycle and meets specified water requirements for each operation, it can achieve 100% recovery of the water in the input saline feedwater and complete recovery of all dissolved salts as solid salt. Each cycle processes a fixed quantity of saline feedwater consisting of:

water mass mo and
dissolved salt mass So mo
where So is the Total Dissolved Solids TDS in ppm (Example 20,000 ppm=0.02). By definition, So equals the mass of dissolved salt divided by the mass of the water. Within each cycle, the RO system recovers any permissible fraction r of the water entering the RO unit as desalinated product water. The CERO cycle consists of the following serial operations, each with corresponding water and salt mass requirements:
The saline feedwater containing a
mass mo of water and
mass So mo of dissolved salt
is combined with the ion-reduced dilute water carried over from the previous cycle of the ED system. This ion-reduced dilute water of the ED system is composed of
mass
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
of
⁢
water
⁢
and
mass
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
⁢
of
⁢
salt
⁢
ions
giving it the same TDS So as the feedwater,
The resulting combined saline water therefore contains a
mass
⁢
{
1
/
r
}
⁢
m
o
⁢
of
⁢
water
⁢
and
mass
⁢
{
1
/
r
}
⁢
S
o
⁢
m
o
⁢
of
⁢
dissolved
⁢
salt
,
maintaining a TDS of So,
The combined saline water enters the RO system, which then produces two output water streams:
(1) a desalinated product water steam containing a fraction r of its input water's mass and (2) ion-enriched water stream containing the remaining
fraction
⁢
(
1
-
r
)
of RO input water's mass together with essentially all the dissolved salt originally present in the RO feed. The desalinated water has a mass mo, which has the same mass mo as the mass of the water in the input saline feedwater, and contains essentially no dissolved salt (ions). The ion-enriched water stream passes to the dilute water of the ED system dilute water of the ED system. This ion-enriched dilute water consists of a
mass
⁢
of
⁢
water
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
plus
mass
⁢
of
⁢
dissolved
⁢
salt
⁢
of
⁢
{
1
/
r
}
⁢
S
o
⁢
m
o
,
which makes the
TDS
⁢
of
⁢
ion
-
enriched
⁢
dilute
⁢
water
⁢
S
o
/
(
1
-
r
)
,
The ED system transfers a
mass So mo
of dissolved salt ions into its circulating concentrate water stream, that is circulating through the ED system and the Concentrate Water Tank. The concentrate water stream becomes slightly supersaturated, but still below the threshold where spontaneous precipitation would occur,
The slightly supersaturated concentrate water of the ED system flows through a bed of salt crystals that are in the concentrate water tank, causing the
mass So mo
of excess dissolved salt to precipitate onto these crystals and form additional solid salt,
The ion-reduced dilute water produced by the ED system, containing
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
is then made ready for use in the next cycle of CERO operations, and . . . .
The previously described serial sequence of CERO operations is carried out repeatedly in a continuous cycle.

214 more elements

When the CERO system operates using a set of repeated, concurrent operations, each having the specified water requirements described herein, it can achieve 100% recovery of the water that is in the input saline feedwater, as well as completely recover all the dissolved salt that is in the input saline feedwater as solid salt. Each cycle processes a fixed quantity of saline feedwater consisting of a

water mass mo and
dissolved-salt mass So mo
where So is the Total Dissolved Solids (TDS) concentration in parts per million (ppm). The TDS value So is defined as the ratio of the dissolved salt mass to the water mass, and typically ranges from values between zero to one. The RO system recovers a fraction r of the water mass that is in the feedwater entering the RO unit as desalinated product water. The CERO system, using concurrent operations in each state X or Y, operates continuously by alternating between the two states, X and Y, in sequence:
X, Y, X, Y, X, Y, . . . . The operations performed concurrently in each state, along with their respective water and salt mass requirements, are as follows:
X State
Initially, Tank A contains ion-reduced dilute water with a
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
⁢
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
,
all carried over from the previous State Y, while Tank B is empty,
The valves are set so that the RO system draws water from Tank A and directs its RO ion-enriched water (wastewater) into Tank B,
The valves are set so that Tank B is connected to both the dilute-water inlet and outlet ports of the ED system,
Simultaneously, the RO and ED systems begin operating. Saline feedwater enters Tank A where it combines with the ion-reduced dilute water of the ED system produced on the previous cycle of operation and sends this combined saline water with
mass
⁢
{
1
/
r
}
⁢
m
o
⁢
of
⁢
water
⁢
and
mass
⁢
{
1
/
r
}
⁢
S
o
⁢
m
o
⁢
of
⁢
dissolved
⁢
salt
,
through the RO system,
The RO system produces nearly salt-free product desalinated water, and the RO ion-enriched water (wastewater) is directed into Tank B,
the ED system transfers ions from the ion-enriched dilute water from Tank B to the concentrate water of the ED system,
The slightly supersaturated concentrate water from the ED system circulates through the concentrate water tank, where a mass of
mass of So mo
of excess dissolved salt eventually precipitates onto the existing salt crystals and forms additional salt mass,
State X concludes when all the following conditions have been met:
When a
water mass mo and
dissolved salt mass So mo
in the input saline feedwater with TDS So has entered Tank A, Tank A is now empty, and the RO system has produced a mass mo of desalinated product water, then the RO system operation stops,
Tank B, which is connected to the ED system, has received the full RO ion-enriched water (wastewater) stream consisting of a
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
⁢
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
,
The ED system has removed a
dissolved salt mass So mo
from Tank B and transferred it to its concentrate water stream of the ED system, leaving Tank B with a remaining
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
⁢
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
,
at a TDS of So. This ion-reduced dilute water in Tank B is made available for the next State Y operation and the ED system stops.
The RO system must stop before the ED system stops, but for the most part they are both operating at the same time.
Y State
Initially, Tank B contains ion-reduced dilute water with a
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
⁢
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
,
all carried over from the previous State X, while Tank A is empty,
The valves are set so that the RO system draws water from Tank B and directs its RO ion-enriched water (wastewater) into Tank A,
The valves are set so that Tank A is connected to both the dilute-water inlet and outlet ports of the ED system,
Simultaneously, the RO and ED systems begin operating. Saline feedwater enters Tank B where it combines with the ion-reduced dilute water of the ED system produced on the previous cycle of operation and sends this combined water with
mass
⁢
{
1
/
r
}
⁢
m
o
⁢
of
⁢
water
⁢
and
mass
⁢
{
1
/
r
}
⁢
S
o
⁢
m
o
⁢
of
⁢
dissolved
⁢
salt
,
through the RO system,
The RO system produces nearly salt-free product desalinated water, and the RO ion-enriched water (wastewater) is directed into Tank A,
the ED system transfers ions from the ion-enriched dilute water from Tank A to the concentrate water of the ED system,
The slightly supersaturated concentrate water from the ED system circulates through the concentrate water tank, where a
mass of So mo
of excess dissolved salt eventually precipitates onto the existing salt crystals and forms additional salt mass,
State Y concludes when all the following conditions have been met:
When
water mass mo and
dissolved salt mass So mo
in the input saline feedwater with TDS So has entered Tank B, Tank B is now empty, and the RO system has produced a mass mo of desalinated product water, then the RO system operation stops,
Tank A, which is connected to the ED system, has received the full RO ion-enriched water (wastewater) stream consisting of a
water
⁢
mass
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
-
salt
⁢
mass
⁢
of
⁢
{
1
/
r
}
⁢
S
o
⁢
m
o
,
The ED system has removed a dissolved salt
mass So mo
from Tank A and transferred it to its concentrate water stream of the ED system, leaving Tank A with a remaining
water
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
m
o
⁢
and
dissolved
-
salt
⁢
mass
⁢
of
⁢
{
(
1
-
r
)
/
r
}
⁢
S
o
⁢
m
o
at a TDS of So. This ion-reduced dilute water in Tank A is made available for the next State X operation and the ED system stops.
The RO system must stop before the ED system stops, but for the most part they are both operating at the same time.

380 more elements

Dependencies are inferred from the claim text.

Combined Electrodialysis and Reverse Osmosis CERO

Life of this patent

Combined Electrodialysis and Reverse Osmosis CERO

Life of this patent

Abstract

Claims3