Method for treating produced water
AssigneeVeolia Water Solutions & Technologies Support
InventorsJohn A. Korpiel, LNSP Nagghappan, Brad Biagini
Life of this patent
Estimating the term…
Abstract
A method for treating produced water in a system for treating wastewater is disclosed. The system includes a reverse osmosis unit for removing dissolved solids. The reverse osmosis unit produces a permeate and concentrate. To reduce the fouling potential of the membranes associated with the reverse osmosis unit and/or to increase membrane lifetime and/or to increase system recovery, at least a portion of the concentrate is recycled and mixed with the wastewater stream at a point upstream of the reverse osmosis unit.
Claims8
A method of treating produced water with a reverse osmosis (RO) unit that includes membranes and in the process of treating the produced water, reducing RO membrane fouling, the method comprising:
- pretreating the produced water and wherein pretreating the produced water comprises:
- chemically softening the produced water in a chemical softening unit to remove hardness and producing precipitants;
- removing the suspended solids and precipitants from the produced water through one or more solid-liquid separation processes;
- after removing the suspended solids and precipitants from the produced water, removing residual hardness from the produced water in an ion exchange unit;
- directing the produced water from the ion exchange unit directly or indirectly to an RO unit and removing dissolved solids from the produced water in the RO unit and producing a permeate stream and a concentrate stream;
- splitting the concentrate stream into first, second and third streams;
- wasting the third stream;
- recycling the first stream to the RO unit or to a point between the ion exchange unit and the RO unit and mixing the first stream with the produced water;
- and
- recycling the second stream to the chemical softening unit and processing the second stream in the chemical softening unit.
A method of treating produced water with a reverse osmosis (RO) unit that includes membranes and in the process of treating the produced water, reducing RO membrane fouling, the method comprising:
- pretreating the produced water and wherein pretreating the produced water comprises:
- chemically softening the produced water in a chemical softening unit to remove hardness and producing precipitants;
- removing the suspended solids and precipitants from the produced water through one or more solid-liquid separation processes;
- after removing the suspended solids and precipitants from the produced water, removing residual hardness from the produced water in an ion exchange unit;
- directing the produced water from the ion exchange unit directly or indirectly to an RO unit and removing dissolved solids from the produced water in the RO unit and producing a permeate stream and a concentrate stream;
- splitting the concentrate stream into first, second and third streams;
- wasting the third stream;
- recycling the first stream to the RO unit or to a point between the ion exchange unit and the RO unit and mixing the first stream with the produced water;
- recycling the second stream to the chemical softening unit and processing the second stream in the chemical softening unit;
- wherein the ion exchange includes a resin for removing residual hardness from the produced water;
- from time-to-time, regenerating the resin in the ion exchange by the following steps in sequence:
- backwashing the resin in the ion exchange by fluidizing the resin and removing accumulated particulate matter from the resin, resulting in a backwashing waste stream;
- injecting an acid into the ion exchange unit and contacting the resin with the acid and removing hardness and metals from the resin and returning the resin to a hydrogen form;
- rinsing the acid from the resin by directing water into the ion exchange and through the resin;
- injecting a caustic into the ion exchange and contacting the resin and converting the resin from the hydrogen form to a sodium form;
- and
- rinsing the caustic from the resin by flowing water through the resin;
- recycling the backwash waste stream to the chemical softening unit.
Dependencies are inferred from the claim text.