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Demonstration Testing Results: Oxidation, Coagulant and

Flocculant Demand in Reuse Applications

Buddy Boysen – Water Standard

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Water Use is Increasing: Reuse is Attractive

Photo Source: Fortune Magazine

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Overview

• Intro: Demonstration testing program

• Chemical pretreatment process development

• Key drivers

• Performance and critical variables

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Pilot Test Program OverviewKey Objectives:

Cost effective reuse of

flowback and produced

water

Reuse scenarios included:

Frac/drilling reuse

Industrial reuse

Surface water discharge

Evaluation of process

unit operations

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Water Variability: Unconventionals

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Produced Water Treatment

Testing needs varied by reuse applications

Core treatment requirements

Oil and grease

Suspended solids

Dissolved metals

Hydrogen sulfide

Bacterial inactivation

Advanced treatment

Electrochemical treatment

Biological nitrogen removal

DesalinationAdvanced

Treatment

Sedimentaiton/

Solids Separation

Chemical

Pretreatment

Desanding

Feed Tanks

If Required By

Reuse Application

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Chemical Pretreatment Process

Core treatment needs:

Oxidation of dissolved metals and H2S

Coagulation of fine suspended solids

and oils

Advanced treatment needs:

Conversion of dissolved organics

Process Focus

Performance

Overall treatment costs

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Typical Treatment Approach

Oxidation

Purpose is to precipitate metals and hydrogen

sulfide. TOC treatment may be beneficial.

Coagulation

Purpose is destabilization of colloidal material

to build larger particles (floc).

Flocculation

Purpose is to agglomerate coagulated solids.

Improve particle characteristics for separation.

Flocculation Separation

Oxidant

Coagulant

Flocculant

Produced Water and

Flowback

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Visual Process Overview

Raw PW Oxidized PW Coagulated PW Flocculated PW

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Chemical Oxidation

Chemical oxidants accept electrons to

prepare ions and molecules for separation.

Typically Targets

Dissolved metals

Hydrogen sulfide

Organics

Common Oxidants

Sodium hypochlorite

Chlorine dioxide

Hydrogen peroxide/caustic

Sodium/potassium permanganate

Ozone

Photo Source: Georgia State University

Hydrogen Peroxide2Fe+2 + H2O2 + 4OH- → 2Fe(OH)3 (precip.)

H2S + H2O2 → S0 + 2H2O

Chlorine Dioxide

Mn+2 + 2ClO2 + 4OH- → MnO2 + 2ClO2- + 2H2O

ClO2 + 5Fe(HCO3)2 + 3H2O → 5Fe(OH)3 + 10CO2 + H+ + Cl-

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Oxidant Comparison

Oxidant Relative Cost ($/lb) Performance

Sodium Hypochlorite $ +

Sodium Permanganate $$ ++

Chlorine Dioxide $$ ++

Hydrogen Peroxide $$ ++

Ozone $$$ ++++

Each product has benefits and

challenges.

Hypochlorite, chlorine dioxide and

ozone can be generated onsite with

varying complexity.

Bulk storage considerations also enters

into the discussion.

Ability to produce/maintain a

disinfectant residual and value to

project need to be considered.

Ozone performance was not evaluated as part of the

2018 study program.

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CoagulationCoagulants affect colloidal stability, increasing particle

collisions to promote the formation of larger particles

through absorption.

Target particles

Clays

Precipitated metals

Organic colloids

Typical coagulants

Alum

Ferric sulfate

Ferric chloride

Prehydrolyzed aluminum (PACl, ACH)

Photo Source: Koutsos et. Al, 2011

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Coagulants

Testing focus has been on polyaluminum

chloride and ACH products.

Range of polyaluminum chlorides provides an

ability to tailor product performance for

downstream processes.

Low Basicity PAC: Larger floc particles. Better settling.

More residual aluminum.

Medium Basicity PAC: Medium sized particles,

potentially better flotation. Slight residual aluminum.

ACH: Improved TOC removal and lowest residual

aluminum. Much finer particles. Potential issues with

separation process.

Source: Behn Mayer

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Flocculation

During flocculation, a bridging agent is added

to agglomerate destabilized colloids, small

particles and oil droplets.

Mechanisms

Bridging and Patch Flocculation

(Anionic-, Non-Ionic, Cationic+)

Some flocculating agents:

Polymers: HPAM/CPAM/APAM

Guar

Alginate-

Chitosan+

Photo Source: SSWM

Photo Source: M. Hubbe

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Flocculation

Most organic flocculants are a blend of polymers.

Each flocculant component alters the final solids

product.

Our focus has been on biopolymers that can

create bridging with minimal impact on

downstream processes.

This is very important when considering

membrane applications.

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Basic Treatment Goals

Typical Water Quality Targets

Free oil: <1.5 ppm (EPA 1664 MDL)

Turbidity: <5 NTU

Total iron: <5 NTU

Hydrogen sulfide: non-detect

Treatment beyond these levels requires

more advanced post treatment.

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Advanced Treatment Goals

Range of Water Qualities

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Advanced Treatment Goals

Floating vs. Settling Solids

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Additional Treatment Questions

How does the treatment process respond to upsets?Feed water quality changes

Chemical dosing upsets

What is the downstream impact of chemical treatment process upsets?

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Test Program Findings

All treatment objectives were achievable.

Secondary objectives, related to downstream

process performance, should be considered

when developing the chemical treatment

process.

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Questions/Contact Info

Buddy BoysenDirector of Engineering and Technology

Water Standard

bboysen@waterstandard.com

Phone: 713-400-4777