Method and system for treating wastewater

1. A method for preparing de-wasted water from oil and/or natural gas production wastewater comprising the steps of:

receiving wastewater from oil and/or natural gas production;

pretreating the wastewater to produce a pretreated water, said pretreating comprising passing the wastewater through a pretreatment train that comprises a pH adjustment/chemical addition tank, a clarifier, and an equalization tank;

distilling the pretreated wastewater to produce a distilled water comprising contaminates including nitrogen compounds, said distilling comprising:

introducing the pretreated water to a crystallization unit to produce distilled water and a brine therefrom;

purifying the distilled water to produce a purified water, said purifying comprising:

passing the distilled water produced by the crystallization unit through a temperature control unit to adjust the temperature of the distilled water to between 20° C. to 35° C;

adding the distilled water to a pre-anoxic tank comprising micro-organisms;

denitrifying the nitrogen compounds in the added distilled water in the pre-anoxic tank,

wherein the denitrification is performed by the micro-organisms under anoxic conditions;

transferring the distilled water from the pre-anoxic tank to an aeration tank,

wherein additional nitrogen compounds in the distilled water are nitrified under aerobic conditions by the micro-organisms; and

transferring the distilled water from the aeration tank to a membrane bioreactor comprising a membrane to remove a portion of the contaminants and micro-organisms from the distilled water to arrive at a purified water from the membrane bioreactor; and

converting the purified water into a de-wasted water that meets or exceeds each de-wasted water criterion of General Permit WMGR123 (Pennsylvania Department of Environmental Protection, 2012), said converting comprising:

passing the purified water through a reverse osmosis pre-filter; and

introducing the purified water to a reverse osmosis system comprising a plurality of semipermeable, thin-film composite reverse osmosis membranes.

2. The method of claim 1 , further comprising introducing the purified water from the membrane bioreactor to an ion exchange system.

3. The method of claim 1 , further comprising the step of pre-filtering the distilled water prior to adding the distilled water to the pre-anoxic tank to remove a portion of contaminants comprising suspended solids from the distilled water.

4. The method of claim 1 wherein phosphorus is added to the pre-anoxic tank to facilitate the denitrification of the nitrogen compounds in the distilled water added to the pre-anoxic tank.

5. The method of claim 1 further comprising the step of recycling nitrates from the aeration tank to the pre-anoxic tank, wherein the nitrates are formed during the denitrification of the additional nitrogen compounds.

6. The method of claim 1 wherein contaminants and micro-organisms are trapped in the membrane and further wherein the trapped contaminants and micro-organisms are collected and added to the pre-anoxic tank.

7. The method of claim 1 , wherein the purified water comprises a Nitrite level at or below 2 mg/L.

8. A system for preparing de-wasted water from oil and/or natural gas production wastewater comprising:

a pretreatment train for producing a pretreated water from received wastewater, the pretreatment train comprising a pH adjustment/chemical addition tank, a clarifier, and an equalization tank;

a distillation train for producing a distilled water from the pretreated water, the distillation train comprising:

a crystallization unit in fluid communication with the pretreatment train, the crystallization unit adapted to receive the pretreated water and to produce distilled water and a brine therefrom;

a distilled water tank in fluid communication with the crystallization unit, the distilled water tank adapted to store the distilled water from the crystallization unit;

a purifying train for producing a purified water from the distilled water, the purifying train comprising:

a pre-anoxic tank in fluid communication with the distilled water tank and operable to receive distilled water from the distilled water tank, wherein the pre-anoxic tank comprises activated sludge comprising micro-organisms;

an aeration tank in fluid communication with the pre-anoxic tank and operable to receive distilled water treated in the pre-anoxic tank; and

a membrane bioreactor comprising a membrane, in fluid communication with the aeration tank and operable to receive distilled water treated in the aeration tank,

wherein the distilled water comprises contaminants including nitrogen compounds and the nitrogen compounds are denitrified in the pre-anoxic tank and nitrified in the aeration tank; and

wherein the membrane removes a portion of the contaminants and micro-organisms from the distilled water to arrive at a purified water from the membrane bioreactor; and

a post-treatment system in fluid communication with the membrane bioreactor and adapted to receive the purified water therefrom, the post-treatment system adapted to convert the purified water to a de-wasted water that meets or exceeds each de-wasted water criterion of General Permit WMGR123 (Pennsylvania Department of Environmental Protection, 2012), the post-treatment system comprising:

a reverse osmosis pre-filter; and

a reverse osmosis system comprising a plurality of semipermeable, thin-film composite reverse osmosis membranes.

9. The system of claim 8 , wherein the post-treatment system further comprises an ion exchange system.

10. The system of claim 8 further comprising a temperature controller operable to adjust the temperature of the distilled water received by the pre-anoxic tank to the range of between 20° C. to 35° C. prior to adding the distilled water to the pre-anoxic tank.

11. The system of claim 8 further comprising a pre-filtering module operable to filter the distilled water received by the pre-anoxic tank prior to adding the distilled water to the pre-anoxic tank to remove a portion of contaminants comprising suspended solids from the distilled water.

12. The system of claim 8 further comprising a phosphorus source operable to add phosphorus to the pre-anoxic tank to facilitate the denitrification of the nitrogen compounds in the distilled water added to the pre-anoxic tank.

13. The system of claim 8 further comprising nitrate recycle pump operable to transfer nitrates from the aeration tank to the pre-anoxic tank, wherein the nitrates are formed during the denitrification of the additional nitrogen compounds.

14. The system of claim 8 wherein the membrane bioreactor further comprises a membrane scouring system to remove contaminants and micro-organisms trapped in the membrane.

15. The system of claim 14 further comprising a pump for returning the removed contaminants and micro-organisms to the pre-anoxic tank.

16. The system of claim 8 further comprising an antifoam agent source configured to introduce an antifoaming agent into the aeration tank.

17. The system of claim 8 further comprising an alkalinity source configured to introduce alkalinity agents to adjust the pH in the pre-anoxic tank.