Methods and systems for treating wastewater from induced hydraulic fracturing

Patent metadata

Field	Value
Publication number	US-2016176741-A1
Application number	US-201414911061-A
Country	US
Kind code	A1
Filing date	Aug 8, 2014
Priority date	Aug 9, 2013
Publication date	Jun 23, 2016
Grant date	—

Abstract

A system for treating waste water includes a waste water inlet, a pretreatment system in fluid communication with the waste water inlet, which is adapted to reduce the concentration of at least one of suspended solids, oil and grease, and a crystallization system downstream of the pretreatment system. A method for treating waste water include introducing the waste water into a pretreatment system being adapted to reduce the concentration of at least one of suspended solids, oil and grease, and introducing liquid effluent from the pretreatment system to a crystallization system.

First claim

1 . A system for treating waste water comprising:
a waste water inlet; a pretreatment system in fluid connection with the waste water inlet, the pretreatment system being adapted to reduce the concentration of at least one of suspended solids, oil and grease; and a crystallization system downstream of the pretreatment system.

2 . The system of claim 1 wherein water separated front sludge generated in the pretreatment system is recycled to the system and wherein water separated from a concentrate generated in the crystallization system is recycled to the system.

3 . The system of claim 2 wherein the pretreatment system comprises at least one of an electrocoagulation system, a system for adding precipitating agents and flocculating agents followed by clarification, or a membrane filtration system.

4 . The system of claim 2 wherein the crystallization system comprises a supersaturation generation system.

5 . (canceled)

6 . The system of claim 2 wherein the crystallization system comprises a magma recirculation system to control supersaturation generation.

7 . The system of claim 2 wherein the crystallization system is configured such that a mixed suspension is provided as an active volume for relieving the supersaturation.

8 . The system of claim 2 wherein the crystallization system is configured to be operated in a metastable zone of a solute-solvent system.

9 . The system of claim 2 wherein the concentrate from the crystallization system is directed to a dewatering unit selected from the group consisting of a filter press system, a centrifuge system, and an electro-dewatering system.

10 . The system of claim 2 further comprising a system adapted to adjust the pH of waste water entering the pretreatment system.

11 . The system of claim 3 wherein the pretreatment system comprises the electrocoagulation system and wherein removed contaminants from the electrocoagulation system are fed into a sludge concentrator selected from the group consisting of a filter press system, a centrifuge system, and an electro-dewatering system.

12 . The system of claim 3 further comprising a gravity separation unit for use in separating floating oil, floating grease or heavy suspended solids from the waste water before the waste water enters the at least one of the electrocoagulation system, the system for adding precipitating agents and flocculating agents followed by clarification, or the membrane filtration system.

13 . The system of claim 12 wherein the gravity separation unit includes a baffled bank system, an oil-decanting port and a solid removal port.

14 . The system of claim 3 further comprising a centrifugal separation unit located upstream of the at least one of the electrocoagulation system, the system for adding precipitating agents and flocculating agents followed by clarification, or the membrane filtration system.

15 . The system of claim 3 further comprising a filtration unit located downstream of the at least one of the electrocoagulation system, the system for adding precipitating agents and flocculating agents followed by clarification, or the membrane filtration system but before the crystallization system.

16 . The system of claim 3 wherein the system for adding precipitating agents and flocculating agents comprises a mixing tank connected to a precipitating tank from which precipitating agents are injected, and is connected to a flocculating agent tank from which a flocculating agent is injected.

17 . (canceled)

18 . A method for treating waste water comprising:
introducing the waste water into a pretreatment system being adapted to reduce the concentration of at least one of suspended solids, oil and grease; and introducing liquid effluent from the pretreatment system to a crystallization system.

19 . The method of claim 18 further comprising:
recycling water separated from sludge generated in the pretreatment system to the waste water introduced into the pretreatment system, or to another inlet; and
recycling water separated from a concentrate generated in the crystallization system to the crystallization system, or to another inlet.

20 . The method of claim 19 wherein pretreatment in the pretreatment system comprises at least one of electrocoagulation, adding precipitating agents and flocculating agents followed by clarification, or a membrane filtration.

21 . The method of claim 20 further comprising crystallizing a solute by providing a heating source to remove solvent from the liquid in the crystallization system.

22 . The method of claim 21 further comprising controlling supersaturation generation using a magma recirculation system.

23 . The method of claim 21 further comprising providing a mixed suspension as an active volume for relieving supersaturation.

24 . The method of claim 21 wherein operating conditions during heating are within a metastable zone of a solute-solvent system in the crystallization system for a period of time.

25 . The method of claim 21 wherein the concentrate from the crystallization system is directed to a dewatering system selected from the group consisting of a filter press system, a centrifuge system, and an electro-dewatering system.

26 . The method of claim 20 further comprising adjusting the pH of waste water before it enters the pretreatment system.

30 .- 37 . (canceled)

38 . The method of claim 20 further comprising directing removed contaminants from the electrocoagulation system into a sludge concentrator selected from the group consisting of a filter press system, a centrifuge system, and an electro-dewatering system.

39 . The method claim 20 further comprising separating at least one of floating oil, floating grease and or suspended solids from the waste water using a gravity separation system before the waste water enters the at least one of the electrocoagulation system, the system for adding precipitating agents and flocculating agents followed by clarification, or the membrane filtration system.

Assignees

• Univ Pittsburgh Of The Commomwealth System Of Higher Education
• Univ Pittsburgh

Inventors

• Gao Di

Classifications

• C02F2001/5218

  Crystallization · CPC title

• C02F1/463

  by electrocoagulation · CPC title

• C02F2001/007

  Processes including a sedimentation step · CPC title

• C02F1/66

  by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) · CPC title

• C02F1/02

  by heating (methods of steam generation F22B; preheating boiler feed-water or accumulating preheated boiler feed-water F22D) · CPC title