MEMORANDUM

TO: Record

FROM: Debra Falatko, ERG

DATE: 09 February 2015

SUBJECT: 2014 International Water Conference (DCN SGE01067)

On November 17th and 18th, ERG attended the 2014 International Water Conference. The 

conference materials were not made available at the time of publishing. Notes on the 

presentations are provided in this document.
Memorandum

09 February 2014

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International Water Conference, Monday AM, November 17, 2014

Boron Removal from Produced Water (IWC 14-07)

Boron causes gelling of additives. Snot Balls – guar solutions plus boron.

Flowback – high volume, short term. Contains valuable chemicals for recovery.

Water sources – brackish formation water

Fresh water – need to add salt to create correct isotonic salt background.

Treatment options for boron:

- Precipitation/coagulations and filtration. Problem because boron is only semi-soluble.

- RO can remove boron to the desired limits. OK, but poor yields and brine disposal issue.

- Best option is boron selective Ion Exchange Resins

Ion exchange pretreatment is important:

- Particulates, sand, dirt, oily solids

- Oil

- Water soluble oil, BTEX, GRO, DRO, TPH

- Hardness

Light hydros are valuable – BTEX, GRO, DRO, TPH (maybe 200 ppm). Sale can pay part to all 

of the operating, costs.

Boron Selective Ion Exchange Resin. Experience with “worse water” FGD waste water. Boron 

selective resin is regenerated with acid (Hydrochloric acid), producing a concentrated boron 

waste for disposal. Small, concentrated waste.

Boron causes gel frac additives to gel/crossline – must be removed.

Feed water – 55.9 ppm Boron. Treated water is XXX (get paper). <5ppm, really <1ppm.

1 Bed volume of waste is <1% of feed water.

3 year old resin looks like new resin. So, long life. Confident 5 or more years.

Economic data in paper:

25 ppm B reduced to <5ppm B

10,000 bpd – 292 gpm – 3.5MM bpy
Memorandum

09 February 2014

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Pretreatment to remove particulate and suspended oil.

$500,000 capital, $303,000 resin cost, $115,000 annual chemical cost. Total cost is 6 cents/brl 

(15 yr cap amortization, 5 yr resin amortization).

Discussion of Paper:

Other cost data:

$5/lb of boron removed at a power plant (most cost is boron disposal)

$2.08/1000 gallons water treated with 50 ppm boron in influent

Cost rises to $12.50/1000 gallons with high boron concentration is 300ppm

With backwash and rinses, 20-25% waste.

What do you do with the waste? Have you solved the problem or only concentrated?

Another concern is cost of transportation. For example, getting drums of acid to the middle of 

nowhere. But agrees that ion exchange is the only way to get to 5ppm boron.

Curious whether can add guar to the wastewater, then remove the snot balls containing the 

boron?

Operational issues:

- Very complex system with acid and caustic, rinse recycle, backwash recovery, etc. Can’t 

rely on 3rd party operator like Haliburton as they don’t know how to run. Need to provide 

an experienced operator.

- Pretreatment must be perfect or the resin will foul

- HCL will corrode everything. Better than sulfuric.

Author Response:

-High cost to dispose of the boron at thousands of ppm at power plant

-Can reduce waste volume by reusing acid (doesn’t matter is boron is in the acid) Requires 2 

extra tanks.

-Agrees that complex. But not dissimilar to high TDS Weak Acid Cation regeneration.

-Agree that good pretreatment is necessary.

-Partners offer service agreement to run system.
Memorandum

09 February 2014

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-HCL is corrosive, need correct metallurgy.

-E&Ps are large companies with good buying power. Can get chemicals for not as much money.

Other discussion:

-Many costs are missing – operating, waste disposal

-Can recycle acid, but can’t recycle acid rinsewater. Must use softened water for final rinse of 

resin in the regeneration process. Disagree that bed volumes will ever be less than 3 to 4.

-If TDS is reasonable, don’t need to go to ion exchange. Mixed bed would be better. (Author 

says TDS is too high)

Other Discussion:

-What strength acid?

-Disagrees that can’t get to <3-4 bed volumes. Has done it with coal bed methane. Requires 

careful design and operation, acid recycling.

Author Response:

-4% HCL

-Haven’t yet had a first installation. Need a first to learn and answer questions.

-There is a race to be second.

-Can’t chlorinate the water as would harm the resin.
Memorandum

09 February 2014

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Automated Self-Cleaning Filter for Ultra-High and Variable Suspended Solids Loading 

(IWC 14-08)

Spiral Water Technologies, Inc

High TSS = High CapEx + High OpEx

-Automatic filters don’t work. Plug up instantly with oil/grease and solids

-Bag, cartridge and media filters used to help. Armies of people needed to change bags. Plus bag 

cost, plus disposal costs

Automatic self-cleaning filter. Heritage as prefiltration of sea water. Up to 25,000+ mg/L

10-100 micron filtration (macro filtration)

No backwash

No cross flow.

Continuous filtrate (no shutdown for cleaning)

99%+ water recovery due to continuous cleaning

Low pressure drop (<1 psi) because continuous clean

Simple to maintain (only one rotating mechanism)

Scalable

Components:

-filter housing

-SS filter element

-Spiral cleaning brush. Fits inside the filter element.

Water moves from inside of the filter to the outside. Spiral brush constantly spinning and 

pushing dirt to bottom of filter.

Energy required to drive mechanism is very small. Also low pumping costs as not operated under 

pressure.

Solids stored at bottom of element. (1) constant drain of solids, (2) timed purge, (3) solids 

content trigger. Output is 30% solids by volume.
Memorandum

09 February 2014

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Offer filter units, filter skids, and pump skids.

Salt Water Disposal Well Process:

Spiral water replaces bag filters at WW injection disposal. (Trucks to gun barrel separators to 

spiral water to load tanks/well tanks to well pump to disposal well)

Spiral Water Increases Capacity (truck to offload tanks (add from paper)

Technology used at haz waste disposal site in ND. Evaluated for produced water, flowback, tank 

bottom cleanouts, drilling muds, etc. So, worst case scenario. Filtered water to salt water 

disposal site (SWD)

For test – trailer mounted.

Analysis methods:

-particle size analysis – 2 part sieve ASTM D422 (above and below pore size)

-TSS Std Methods 2540D

-O&G, 1664A

-Salinity

-Prefers sieve particle testing to newer laser particle counters. Lasers not very accurate. Laser 

particle counters needs to be very dilute to work

Analysis challenges:

-high TDS affects TSS measurement during rinsing and drying. Solve with fixed amount of DI 

rinse water and low drying temp (60-70C)

-O&G matrix affects TSS and PSA measurements. Rinses important

-Non-homogeneous tanks.

O&G – no fouling with this technology. 

Tests with 25 and 50 micron filtration. No correlation between salinity and TSS removal 

efficiency. No issues with scaling over 6 -12 months of operation.

Might the filter be breaking up the particles and sending particles through? Tested the solids 

before and after to verify removal.

Inlet TSS as high as 194,350 mg/L solids
Memorandum

09 February 2014

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63% removal above micro rating and 33% removal blow micron rating.

TSS removal 35% for 50 micro fiter and 50% for micron rating.

Discussion:

How does “the most challenging WW” apply to Shale Gas?

How is the concentrated sludge disposed?

What is the average concentration of the sludge stream?

Mention made of reduced cost, but no data or comparison shown. 

Any routine maintenance anticipated? An corrosion and abrasion.

Author response:

-Disposal of solids only, not bag plus solids, so less expensive. Cost is 0.1 to 0.5 cents per barrel 

to operate.

-Sludge disposal – to dewatering and drop box

-Routine maintenance of pump seals. Filter replacements every 6 mo to year.

Other discussion:

-Why not 100% removal through wedgewater screen versus 67%.

-Often 10 micron limit for disposal. How manage that?

-Info on costs

-max pressure?

Response:

-This testing was a relative removal rather than actual removal. The % were relative to each 

other rather than total removal. Looking at ratio of removals below versus above.

-Now offer 15 micron filter, but not yet at 10 micron. Will not replace a 10 micron cartridge.

-Produced is generally 100 to 1000 TSS.

-If provide a particle distribution, they can predict removal by their filter.

-Competing with omniotic filters. When compare costs by flow, significantly cheaper.
Memorandum

09 February 2014

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-Pressure up to 150 psi. New filters with SS versus plastic housing can handle higher pressures 

and temperatures.

-Nylon brushes. Brushes are not the wear feature, but rather abrasion on the filter.

-Difficult to have constant purge with variable TSS influent.

-Holes in the brush evenly distribute the flow across the filter.
Memorandum

09 February 2014

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How to Access, Select, and Develop Your Optimal Water Management System (IWC 14-09)

Critical factors of water mgmt system:

-Identify and assess- feasibility report, project execution strategy, schedule, CAPEX, OPEX

-Select and define-basic design engineering package, project execution plan, updated CAPEX, 

updated OPEX, updated schedule

-Execute and operate- detailed design, construction, startup and commission, operate

Feasibility Report:

-background, opportunities, short/mid/long term, transportation, regulatory

Project Execution Strategy:

-background, scope, risks, stakeholders, contracts&procurement, reg, HSSE

Opportunities:

-ID water sources – aquifer (wells), surface water (rivers), produced water, municipal

-ID water users – frac water, water flow, water disposal, process water, beneficial re-use

Planning short/mid/long:

-unconventional well –frac flowback and decreasing water production with time? few wells that 

expand to multiple well facilities (increasing water production with time)? Conventional?

Options:

-water treatment (treat produced water, purchase treated water, purchase raw water)

- trmt facilities (mobile, multiple facilities, central)

-Transportation

Schedule:

-milestones (level 1 schedule (high level for mgmt), ID/assess milestones, select/define 

milestones, execute/operate milestones

Cost Estimates:

-CAPEX and OPEX. Get within +- 15% (Class 4)

-Keep to accepted industry standards
Memorandum

09 February 2014

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Contracts and Procurement:

-Contacts: understand the contracts associated with the project – defined scope, defined 

milestones/durations, defined consequences

-Procurement: what procurement work will be done in house? What assistance will be required 

of contractor?

-Make sure you understand your capabilities before decide what portions to do inhouse.

Construction:

-if self perform, assess in-house abilities for design, procurement, construction, operations

-contract the work

-self-perform and contract the work – assess in-house capabilities, scope definition (batter limits, 

coordination plan, schedule)

ID Stakeholders:

-Internal : technical, maintenance, operations, facilities, management

-External: shareholders, regulators, public

Basic Design Engineering Package:

-background, meteorological data, design criteria, design standards...

-based on feasibility report

-confirm operations

-process flow diagrams (freeze – no changes as move along)

Present budgets, schedules, opportunities and risks to stakeholders at the start of the project. Be 

prepared to manage change.

Reference: Colorado School of Mines, Advanced Water Technology Center –AQWATEC 

(http:/aqwatec.mines.edu/)

Which tech works best? Presented a checklist of technologies, but no true recommendations.

Discussion:

-Paper covers planning and org and not on selecting technologies
Memorandum

09 February 2014

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-How are technical restrictions addressed?

-Project schedule must be owned by the project manager.

-EPCs often request OEMs to provide budgetary pricing +/-5%. This is beyond AACE Class 1. 

Why do EPCs request this?

-What class of estimate at end of detailed design?

-Basic Design Engineering Package (BDEP) should also contain civil engineering information.

Should be complete such that can hand to any firm to request a detailed design.

Author Response:

-Technical restrictions assessed during feasibility study.

-EPCs +/-5%? Vendors should be able to provide a hard bid.

-Guidelines for FEED study duration and cost? Ballpark – spend 30-50% of design cost on these

steps, and will end up with a 30% design.

Other Discussion:

-If decide to recycle/reuse produced water, then need maybe 3-5 years to design and implement. 

But customers want it yesterday, and then the design phase is cut back from documents to 

checklists, etc. Often need to complete within 6 months.
Memorandum

09 February 2014

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International Water Conference, Monday PM, November 17, 2014

Evaluating ZLD Strategies (IWC 14-13)

Conventional ZLD – pretreatment (remove foulants) to concentration to solidification. Distillate 

or permeate to post treatment of recovered water, depending on reuse.

Pretreatment – clar/filt, de-oiling, biocide dosing, acid dosing (prevent scaling) anti-scale, 

Concentration – RO and/or evaporation are most common to date

Solidification – crystallization with dewatering of salts, evaporation pond, spray dryer (solids 

collected in a baghouse).

Post-Treatment: air or steam stripping, absorption, OX, electrodialysis, electrodionization, RO. 

Range of trmts depending on resuse.

RO/Evap/Cryst Challenges:

-Scale, fouling – sulfate, carbonate, silica, organics

-Permeate/Distillate quality – VOC, alkalinity, boric acid, ammonia

-Osmotic pressure/boiling point rise – highly soluble salts (CaCl2, MgCl2, NH4Cl, NaNO3, salts 

of organic acids)

-Foaming Agents – dissolved organics, suspended fines. Hard to predict foaming behavior

-Solids separation – organics, high viscosity, suspended solids

RO:

-Spiral wound RO does not allow for backpulsing with water or air to scour the membrane 

surface and remove solids, so the membranes are highly susceptible to scaling and fouling.

-The more concentrated the solution, the more difficult to further separate when osmotic pressure 

of system approached.

Evaporator (Brine Concentrator):

-Used to evap water (not crystallize salts)

-Pretreat with scaling chemicals and adjust pH (acid, caustic, anti-scalant).
Memorandum

09 February 2014

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-Feed Preheater, de-aerator to prevent scale, thermal unit (falling film evap typical), heat source 

(typically compression device) – mechanical vapor recompression, recirculation pump, seed 

recycle, concentrated brine

-Vertical tube bundles (hundreds or thousands of tubes). Vapor condenses on outside or tube and 

falls down.

-Seeded slurry process – low solubility scaling salts precipitate on seed crystals instead of tubes. 

Supersaturation is relieved.

MVR Brine Crystallizer – crystallizer heater, crystallizer vapor body (only sensible heat 

transferred), compression device. Side stream brine slurry to dewatering device (typically 

centrifuge) to remove crystals from brine.

Upper limit of RO is approx 80,000 ppm (8%). Upper limit evap is 20%. Beyond that is 

crystallizer to nearly 100% solids.

Membranes least CapEx and OpEx. Falling film need metallic construction is 2x price of 

membranes. Crystallizer is by far most expensive. Ideally maximize membrane and minimize 

crystallizer. MF/RO =1, evap = 2.5, crys 4 (relative fraction of cost)

ZLD drivers:

-environmental regs

-Water stress/scarcity

ZLD trends:

-forward osmosis, membrane distillation, electrolysis

Discussion:

-Would like more info on forward osmosis and other future technologies.

-Vendors claim 90% or more recovery. Not realistic – don’t deliver more than 85%.

-Add microfilter before RO to reducing plugging. But microfilter can cost more than RO.

-Alternatives to centrifuge dewater crystallizer are belt filter (Oberline Filer)

-RO in SAGD application – osmotic pressure is not main concern, but rather that the process 

water is hot and laden with membrane fouling organics. This will be discussed in Wednesday 

SAGD sessions. Pilot work is currently under way in Alberta using hot RO and special RO pretreatment technologies.
Memorandum

09 February 2014

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-Brine solidification – possible to solidify with fly ash. This is being done at one power plant, is 

in the startup phase of another and is being considered for several others. Work in this area has 

been ongoing for several years with COSIA for SAGD applications. See paper from last yer (13-

70).

Author response:

-Do due diligence when considering ZLD.

-Don’t take the sales pitch at face value.

-Meet the tech experts, get their explanation and justification for: pre-treatment, concentration 

solidification...

Other papers:

-Forward Osmosis Paper 11-13

-Membrane Distillation 14-37

-Cold crystallization 09-52, 10-39, 

-Brine mix with fly ash. Only one plant so far, so not yet proven.

Other discussion:

-Organics – biotreat upstream or downstream? If concern or question on technology, look to 

vendors to do bench/pilot scale treatment.
Memorandum

09 February 2014

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Design Issues for a Zero Liquid Effluent Discharge Wastewater Treatment System for a 

6X800MW WFGD Retrofit Project (IWC 14-14)

South Africa plant

Plant currently under construction

Planned FGD for each unit with 85% to 96% purity limestone

ZLD to treat:

-FGD blowdown stream

-Organic scavenger regeneration wastewater

-Cooling tower blowdown

Conceptual design challenges:

-ZLED facility

-No total site outages

-Limited storage capacity (caused need for more train redundancy versus just store in ponds)

-FGD limestone quality

-Staged startup of FGD units

-Organics considerations – organics scavenger wastewater. 

-Limitations on working with OEMs. Normally partner with OEMs, but this procurement doesn’t 

allow that.

System:

-holding and mixing ww sources to reaction tank (lime slurry/soda ash) for precipitation to 

clarifier, clearwell. From clearwell to brine concentrator and crystallization. Sludge to 

dewatering (4X33% plate&frame filter presses).

-two physical/chemical pretreatment trains

-brine concentrator crystallizer – falling film vapor compressor driven brine concentrators

-Steam driven crystallizers
Memorandum

09 February 2014

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-Considered variety of trains for brine concentrators/crystallizers: 2X100%, 4X50%, 4X33%, 

5X25%. Lowest cost is 2X100 and highest was 5X25%.

-4X50% was selected (not typically, as this is generally overkill). Aligns well with site 

limitations of 1 train in cleaning, 1 train in outage (unplanned), 2X50% trains available, no total 

site planned outage, limite upfront storage

-Salt conversion: partial softening pretreatment for the crystallizer. Reduce Mg to 320 ppm, Ca 

to 1,500 ppm

-Lime/soda ash usage. Large amounts required.

-Heavy metals partitioning. Pretreatment versus crystallizer solids. 

-Organics consideration – may need a slip stream off the brine concentrator? Organics in 

distillate stream, which is recycled back to FGD

Path forward:

-Risk Analysis Report

-Detailed Design

Discussion Comments:

-Design hampered by limited availability of OEM information to support design considerations.

-Ongoing design changes will inevitably be required. Project (and plant operation) will need 

slack time and the capital required to implement these changes.

-Maintaining 100% availability on an unproven system will be a challenge until experience is 

gained (every ZLED plant is unique).

-Flexibility is key to successful design and operation of WWTP. One way is to cross-connect 

trains.

-Have ready spares on hand for any long lead time equipment.
Memorandum

09 February 2014

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Case Study for Cost Effective Mine Water Treatment to Meet Stringent Selenium 

Regulatory Limits (IWC 14-19)

+6 Selenate (mining)

+4 Selenite

0 Elemental selenium

-2 Selenide

Bioreactor takes from oxidized state to particulate 0

How to achieve 5 ug/L end-of-pipe?

Challenges: variable water quality, competing electron acceptors, high flow, low concentration

Few treatments provide to 5 ppm

Bio selenium reduction – selenate to elemental Se, which is retained in the bioreactor.

Anaerobic reaction

HRT – minutes to hours to days

Biofilter technology selected: Frontier Water Systems biofilter

Modular technology (50-500 gpm modules). Use proprietary organic source.

Pilot test in 2013. Pre-filtration with 200 micron filter

-2.7 gpm, <40 min HRT

Pilot test selenium results:

-Inf at approx 60 mg/L (spiked selenium to get to 60). All in dissolved form.

-Eff consistently <5ppm (avg 1.7 ppm)

Full Scale:

-design flow of 500 gpm, 2 biofilter modules at 250 gpm each

-ponds to media/bag filters to another pond to the bioreactors. Nutrient feed source tank. H2S 

scrubbers for venting from anaerobic treatment. Final aeration tank to raise DO.

-Solids periodically removed and disposed of on site.
Memorandum

09 February 2014

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-Each module (250 gpm) has three parallel train )3 gpm) each)

-Each train has two stages – upflow fixed bed and biologically active filter

-Design: January-May 2014

-Construction over the summer

-Commissioning in Oct/Nov

-Cost $5 million total installed cost (engineering, equipment, construction, commissioning)

-Published cost estimates for 500 gpm:

-$10-62million (Sandy and Disante 2013)

-$6.5-11million (Soller and Harwood 2013)

Why the cost difference?

-Biofilter equipment cost (modular design)

-Mild climate (water heating not required, building not required, freeze protection not required)

Long term operating data is critical.

Discussion:

-what kind of mine?

-Perform selenium speciation of inf and eff samples

-Lack balance data for selenium, nitrate, sulfate

-Alkalinity, nitrate, sulfate, metals, and TDS are not included in paper

-Why type of media used in biologically active filter to retain the elemental selenium?

-Published data suggest low particle size (50 to 60 nM). What is pore size of biologically active 

filter?

-Impacts of re-oxygenation on elemental selenium in the aerobic polishing tank?

Author Response:

-Mine type confidential

-Inf was spiked with selenate, eff too low to speciate
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09 February 2014

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-TDS is 980 to 1200. Alkalinity 250 ppm. 

-Also concerns about nickel. Frontier removed 80%.

-Pilot used bag filter. Full scale will use media filter.

-Pore size not really applicable to biofilter. Particulate selenium is not really physical filtration, 

but absorbed onto the biofilter.

-Not concerned about re-oxygenation because selenium eff levels so low.

Other Comments:

-What about operational costs? This is a small system and not much electron demand, so not a 

significant cost.
Memorandum

09 February 2014

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Meeting Nevada DEP-BMRR Profile II Parameters with Electrocoagulation-Based 

Treatment Solutions (IWC 14-20)

Mine water treatment 

Original electrocoagulation patent for bilgewater treatment

Reemerged over the last 10-15 years

Used for stormwater treatment, environmental remediation, marine pollution prevention, 

automotive cleaning (car wash), food and beverage, mining, oil and gas

Use sacrificial anode to form active coagulants which as used to remove pollutants by 

precipitation and flotation in-situ.

The smallest charged particles have a greater potential to be removed.

Electrical current across a set of plates. Small particulates agglomerate into larger particles 

through precipitation and adsorption.

Does not remove TDS. Does precipitate some dissolved metals.

Advantage is that coagulation achieved with electricity rather than chemical addition.

Chem trmt can have large volumes of sludge that is difficult to dewater. 

Nevada Profile II: Limits for aluminum, antimony (0.006 ppm), arsenic is also issue need paper 

to complete.

Need to oxidize antimony and arsenic, which will then be reactive with iron.

Using electrocoag, anode releases iron

Trmt Methods:

-untreated influent

-aerate and raise ORP with EOX,

-then to EC cell, settling, filtration

Three case studies with mine waters with elevated antimony and arsenic. Three log reductions.

EC advantages:

-Full compliance demonstrated
Memorandum

09 February 2014

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-Breadth of pollutants targeted

-Lack of trade-offs with other contaminants

Discussion:

-A significant portion of pollutants not measurably effected due to low concentration and 

detection limits and methods used. Removals limited to 4-6 pollutants.

-Removal of contaminants without increase in TDS and other anions above effluent standards is 

encouraging.

-Process includes both electro-oxidation (EOX) and electro-coagulation (EC), but the relative 

contribution of each is not clear.

-Claims EC is cost effective, but not cost data or cost comparison provided.

-What are the key advantages over traditional alternative from a cost and energy consumption 

perspective?

-Filterability and dewatering of sludges/solids not mentioned.

Author Response:

-EOX is bleach generated electrically – not considered very important

-Not appropriate to discuss cost since only lab scale to date

-Information provided about filterability and dewatering is based on published literature. Full 

scale application is underway, after which they can provide data.

-Chart on EC power usage versus conductivity. As conductivity increases to ~2,200, will spend 

less power than pumping waters.

Other Discussion:

-Add acid to drop pH to precipitate pollutants.

-EC fell out of favor, not only for cost of electricity, but also anode consumption.

-Replace anodes ~1million gallons treated. Hope to improve.
Memorandum

09 February 2014

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International Water Conference, Tuesday AM, November 18, 2014

Modeling and Experimental Results of Vapor Compressor-Driven Membrane Distillation 

(IWC 14-37)

Testing at deep well disposal project. Transitioning this technology concept one step closer to 

demonstration.

Treat water that is normally too high TDS for traditional membranes.

Objective is lower cost concentration of brine wastewater.

Lower costs achieved by:

-lower cost materials of construction

-lower energy requirements

GE partnered with memsys (German company) for UOG applications.

Standard membrane distillation (MD) process uses waste heat and cooling water to drive multieffect distillation through the use of hydrophobic PTFR membranes. GE revised to add vapor 

recompression to allow operation without waste heat source.

Establish vacuum to lower boiling point. Apply heat to produce water vapor, which passes 

through the membrane. The number of effects determined based on differential temperature 

between heat source and cooling water source (membrane blocks).

Pilot Unit (prototype unit with relatively low recovery versus eventual commercial unit):

-2 effect MD system

-20 m3/day (4gpm)

-5m3/day distillate

-mechanical vapor compressor

-containerized for ease of install

MD Shale Application: source water to well field. Generates flowback and produce water, which 

is transported to deep well disposal. Primary opportunity for reuse is following primary treatment 

at the well field, but doesn’t remove TDS. This technology can be used following primary 

treatment at the well field to produce clean water for reuse and to concentration contaminants in 

the brine for lower volume disposal at disposal well.
Memorandum

09 February 2014

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Stable operations concentrating the brine from 100,000 to 280,000 mg/L

Flux as a metric for CAPEX savings.

Isentropic compressor energy as a metric of OPEX savings

Pretreatment:

-raise pH to remove Fe and Mn

-clarification for TSS reduction

-activated carbon for TOC reduction

-neutralize pH

Field Test:

-200 hours continuous operations

-100% uptime

-stable performance with brine concentrations near saturation (280,000 mg/L)

-40% energy savings compared to conventional evaporation systems

-distillate quality less than 300 ppm TDS

-feed was 160,000 to 200,000 mg/L TDS

Average flux is total mass flow of distillate divided by total membrane area (41 m2)

Need high alloy materials for compressor. Didn’t use one during the test, and iron came off the 

compressor and condensed onto the membrane foils.

Testing criteria was met, validating the hypothesis that MD has the potential to lower the cost for 

brine concentration in shale applications.

Isentropic Energy (kwh/m3) = 14

Discussion:

As industry continues to mature, brine treatment will become more important.

It’s all about the money. What technologies or methods did you compare against?

What is the specific gravity of water for deep well disposal?
Memorandum

09 February 2014

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Why select the Barnett shale region as opposed to other regions? The boiling point elevations are 

higher for Marcellus than for Queensland CSG.

Author Response:

Compared against traditional evaporation.

For applications to WW with low TDS, recommend first use RO as a preconcentrator.

Consideration of changing materials of construction from polypropylene to something more 

robust would allow increasing temperature which will increase efficiency.

Specific gravity is 1.8 or 10# brine.

Producer is concerned about future reduction in production and so will need solutions regarding 

how to manage all the water.

Temperature of the preheated feed stock to the modules is 74C. Saturation temperature is 78C.

Timeframe for one cycle: From cold system to preheat, need about 30 minutes to preheat. 

Other Discussion:

Don’t understand how can save 40% energy? Can operate on a smaller delta T because using 

polypropylene, which allows a lot of area in a smaller footprint, which results in energy savings.

Capital cost savings: 30% savings depending on mtl of construction. 

Operating cost savings: difficult to predict. For larger sizes, greater savings as energy becomes 

more important. For smaller system, labor more significant, so lower operating cost savings.
Memorandum

09 February 2014

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The Impact of Ionic Strength Upon Inhibitor Speciation and Efficacy (IWC 14-38)

What happens to scale inhibitors in flowback systems, water reuse, and other high TDS 

applications?

Previously documented that the dissociated form of scale inhibitors tends to be the active form. 

This paper extends the concept into the high TDS environment of RO.

Scale inhibitors are weak acids that dissociate...

Why pH and TDS affect active inhibitor concentration... equations.

When pH>pKa, the protonated inhibitor > the non-protonated inhibitor.

When pH=pKa, the protonated inhibitor = the non-protonated inhibitor.

When pH<pKa, the protonated inhibitor < the non-protonated inhibitor.

Experimental work:

-Inhibitor solutions prepared (HEDP, AA-AMPS, and PMA inhibitors)

-pH adjusted to 2

-Titrated to pH 12

-pH and volume data entered into CurTiPot and a custom spreadsheet.

-Phosphonate and polymer corrosion inhibitors tested.

-Calculated correlations

Results:

-Look at inhibitor pKa’ versus TDS. At high solids, great effect on pKa for HEDP inhibitor. 

Similar for polymer inhibitor. For maleic inhibitor, much less effect.

-Graphs of active fraction versus TDS at various pH for the different inhibitors.

Conclusion:

-TDS has a dramatic impact upon pKa for inhibitors and inhibitor efficacy

-Need to run inhibitor optimization studies at approx TDS of the application modeled.

Discussion:

Previous papers IWC 11-77 and IWC 13-62
Memorandum

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New experimental data

Relevant to handling, treatment, reuse hydraulic fracturing fluids

Some points/questions on accuracy of certain statements and rigor of experimental approach.

Wants more details to better assess. Surprised that similar pKa’ values for inhibitors when the 

chemistry of the inhibitors is so different – would expect pKa’s to differ.

Performance of scale inhibitors improved in high TDS brines suggest can lead to lower product 

dosages. May not be correct as assumes that “dissociated state” is active species and other points.

But tantalizing new experimental data for speciation of scale inhibitors with high TDS brines.

Author response:

-Acknowledges some confusion in terminology that will fix in the final paper. Also fix typos.

Other Discussion:

Need some real world data on actual effect on scale inhibition. Use wastewater samples and heat 

exchangers.
Memorandum

09 February 2014

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Rash Statements and Equivocation – Lessons Learned in ZLD Design, Produrement, 

Commissioning, and Operation (IWC 14-35)

Rash Statements: GCEs (gross conceptual errors), designers/developers, purchasers, suppliers, 

operators

Equivocation required: absolutes seldom exist, some equivocation and explanation necessary

ZLD is not a WWTP. Really a targeted salt and water recovery system. A chemical process with 

stringent chemistry and flow limits. Designed to recover specific salts.

There is no such thing as no liquid discharge. Can’t treat sanitary or cleaning wastes. Can’t treat 

oily waste. 

Chemistry and/or contaminants may limit concentration. Usually nitrates or total organic carbon. 

Bleed often required.

Not the best technology if goal is to reduce fresh water usage. Will reduce by only 14%. Better to 

reuse water.

Designer/Developer – conceptual design focuses on theoretical rather than practical capabilities 

(operating cost impact omitted or underestimated, little or no risk analysis, design system based 

on nameplate capacity at minimum capital cost)

Designers/developers may have little operational experience.

We can’t afford redundancy – big problem

-Capacity impacts: feed chemistry often uncertain, but any deviation from design results in loss 

of capacity, mechanical reliability often 75-95%, degradation 20% between cleanings, expect 60-

70% nameplate capacity, effective capacity decreases as complexity increases

-Redundancy: 2x60-70% of required peak flow. For complex systems use 2x100%

Improve needed redundancy with:

-Shelf or installed spares improve reliability/capacity

-lower redundancy OK other discharge operation exist, or system reliability isn’t critical

-Cognizant designers allow for uncertainty

There are always other options. ZLD is the last resort. Only if mandated by regulations. Broadly, 

500-gpm ZLD costs about $50 milliion over 20 years.

Other options: deepwell injection, long pipelines, off-site projects (mitigate easier wastewaters)
Memorandum

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Vendors: present technologies as favorably as possible, understandable but may create wrong 

impression during bids/development, operation issues

Rash statement: you don’t need (higher alloy, hydrocyclones, chem feed, etc.)

-Vendors assume design feedwater chemistry won’t change in 20 years.

-Design feedwater chemistry often uncertain and purely theoretical, theoretical system doesn’t 

require expensive extras

-Claim this is proven technology. But if experience is for different process, then it’s not proven. 

Only proven if used on the same process with the same process chemistry under the same 

operating conditions (seldom happens, so no ZLD technology is really proven)

-Check ALL the vendor’s references, independently operated references best, one-on-one 

discussion with system operator with the vendor absent, confirm that system still operating 

(vendors may provide installations only), confirm operability, no references=no sale, “emerging” 

or “new” technology is beyond extreme process risk (pilot test)

Common mistake to assume that ZLD can be operated with same staff as a typical water plant. 

Not accurate to state that system uses PLC so basically runs itself. Need 7 to 9 extra people for 

“simple” system. 12 to 14 people for complex design.

Need at least one experience person at all times.

While system problems are typically because not operating correctly, the problems begin during 

commissioning with vendor involvement: commissioned with off-spec water, no real 

performance test, temporary logic/setpoints to facilitate startup, operators learn to operated 

during this time, carry these habits into “normal operation”

Commission properly

Operator Rash Statements: system will never work-discover system is not easy to operate; 

vendor’s procedures lack detail – true but not the vendor’s fault as vendors provide operating 

philosophy.

Competitive bidding is stupid for ZLD. Best approach is to select the supplier and system first 

and then negotiate price.

True that complex systems cost more for the same amount of water. This is because the 

equipment and the people cost more.

Avoid the use of intermediate concentration. Minimize process that require chemical feed

Minimize complexity
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Move concentration as far back in the system as possible

Discussion:

Agrees that claim of zero liquid discharge is questionable. “Zero” terminology is questionable 

and leads to misinterpretation.

Would like the author to talk more about solutions to these issues.

Author response:

Lexicon is important. Brine recovery system is probably better than ZLD.

Solutions: operating costs are real. Also understand that always other options.

Other discussion:

$50 million figure includes CAPEX and OPEX. Net present value.

Bench testing versus in the field pilot systems. Vendors seem to push for bench testing and then 

full-scale.

Assuming feedwater exists, pilot will be $1 million, so large investment. But the full scale install 

is not much more.

Bench problem is that won’t capture variation.

Need to operate pilot for a least a year.

Solution is to have the supplier to operate for 2 years and provide guarantees.

While $50 million for 20 years is high, a power plant spent $20 million for only selenium 

removal.

Complex processes – need to look at storage. Storage in days, not hours. 

Agrees about storage. Suggests one week of storage for a dual system design. If can’t fix in a 

week, will need 6 months to fix and will need to shut down anyway.

Commenter says too pessimistic. Has a ZLD and 9 days of storage. Looked at all alternatives, 

and ZLD was best choice. Located in remote area.

Vendor from Aquatec. Can’t disagree with much that was said. ZLD can’t be purchased as a 

commodity. Needs to be more technically driven, working with the vendor. But purchasing 

wants to cut these costs out. Presenter agrees – determine vendor and system and then determine 

the cost.
Memorandum

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Wants info on FGD purge water. Is this a no go or money well spent? Author – FGD is too 

variable with fuel changes, FGD operational ranges, etc. Too tough a nut to crack.
Memorandum

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31

Innovative Treatment of Shale Fracturing Water Using Magnetic Ballast Clarification 

(MBC) and Advanced Membrane Systems (FMX-RO) (IWC 14-40)

Objective to develop an innovated technology for treatment primarily of produced water, but also 

flowback. Initial focus was to produce water with quality suitable for direct discharge and less 

for reuse, but industry is now moving to reuse.

Performing bench-scale efficacy studies to demonstrate and pilot scale (economic and 

operational data).

Note that these waters are complex and unique to each location. So, one test can’t answer all the 

questions.

Water many be sufficient quality for reuse following MBC. Need FMX-RO in addition to MBC 

to allow for direct discharge.

MBC really targeting TSS to protect the membranes. Also failsafe for oil and grease, but oil and 

grease will foul the magnetite. The membranes are two steps: nano filtration (FMX-NF) and 

reverse osmosis (RO).

MBC:

-clarification using magnetite and polymer. Magnetite is a fully oxidized form of iron. Polymer 

attaches suspended solids to magnetite. Solids are removed from the top. I believe magnetite is 

captured and reused.

FMX:

-patented fouling resistance membrane filtration system. Treatment of high solids, density, and 

viscosity wastewaters. Reduces chemical cleaning requirements. Uses a vortex generator system 

to create strong turbulence and minimum energy (Karman Vortex). Foulants on the boundary 

layers are disrupted and carried away by the feed stream.

Concept studies performed for Bakken Produced Water (Williston), Eagle Ford Flowback Water 

(Galvan) and Eagle Ford Flowback water (Gonzalez). Bakken by far the most concentrated.

MBC efficacy:

-80% TSS removal and most greater than 90% TSS removal.

-wide range of polymer and coagulant aides. Feed <1,800 mg/L oil and grease and overflow <70 

mg/L

FMX-NF:
Memorandum

09 February 2014

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-removes remainder of the TSS. Removes some TDS. Generate a water suitable for reuse in 

additional fracturing operations. Protect downstream RO filter from TSS (if used).

-Removal of 80-99% of the remaining TSS that escaped the clarifier in the preferred operating 

region.

- Expect FMX filter to remove 30-60% of the TDS from the influent, depending on weave, ion 

selectivity, as well was flowback

RO Filter:

-to generate highly purified water that can meet NPDES requirements.

-RO results for TDS. Influent 367 to 769 mg/L TDS; effluent is “non-detect”. Very efficient at 

these low concentrations as a polishing step.

Future work will better consider waste management, as this is a significant cost component.

1,000L feed generates 615L clean water and rest brine.

Discussion:

-Not all paper objectives were met. 

-Claims up to 80% water recovery. But NF water recovery is 80% and RO water recovery is 70% 

for combined 56% recovery.

-Would have liked to see observations of resistance to fouling in FMX membranes, as that’s the 

reason they were selected. Would also like to see the NPDES limits comparison.

Presenter Response:

-Original abstract submitted was ambitious.

Other Discussion:

-Clarified that NF, not UF.

-TSS concentration was too low to warrant and to demonstrate MBC treatment. Future tests may 

require spiking with TSS. Need to better understand these economic and operational thresholds 

(to warrant selection of the appropriate treatment train).

-Discharge limits would be very site specific. Analyzed for everything to get a good mass 

balance. In this particular case NORM was a driver. Also some metals.
Memorandum

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Memorandum

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International Water Conference, Tuesday PM, November 18, 2014

Alternative Disinfection for Reverse Osmosis Systems (IWC 14-45)

Autopsies of membranes – fouling mostly due to biofouling.

Biofouling is irreversible adhesion on a membrane.

Greatest adhesion – surface roughness, membrane surface charge, hydrophic

Biofouling: increase in differential pressure, decrease in membrane flux, higher operating 

pressure needed to maintain flow rate, higher potential for scaling and salt passage.

Objectives: kill microbes, remove microbes and dead bodies, prevent adhesion, remove nutrient 

in feed.

Techniques: membrane surface modification, modification of bacterium or nutrient, disinfection 

(chem., phys – UV/pretreatment, operational-change cleaning cycle)

Chlorine:

-chemical technique

-oxidizing biocide

-forms (gas, sodium hypochlorite). Both forms form HOCl.

-efficacy: exposure time 20-30 min at head or pretreatment train

-pH is important. Lower pH is my hypochlorous acid, which is most effective form.

-advantages: inexpensive, easy to apply, effective

-limitation: ineffective with some pathogens, oxidizes larger organics into smaller compounds 

that microbes can assimilate, forms THM HAA, oxidizes RO membranes so complete removal is 

required

Chloramine:

-Oxidizing biocide (much lower biocidal capacity than chlorine, slower kinetics than chlorine)

-Forms (monochloramine, dichloramine, trichloramine, depending on pH). Want to run at higher 

pH for greatest efficiency.

-advantages: little or no formation of THM and HAA
Memorandum

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-limitations: forms organic chloramines with no disinfection capability, slow RXN rate with 

micros, not as effective as CL, free chlorine may be present, ammonia

Chlorine Dioxide:

-Oxidizing biocide: very effective, low contact time

-Generation: chlorine-based not recommended as not compatible with membranes

-Generation: acid-based is recommended

-Decreasing production over time depending on dosage and time.

-Advantages: more effective than chlorine, does not form THMs and HSSs

-Limitations: highly volatile and explosive when compressed, must generate onsite, forms 

chlorite and chlorate DBPs, difficulty in dosing when other oxidants

Ozone:

-Strong oxidizing biocide: 50% stronger than chlorine, 3000 times faster than Cl, works by direct 

action or by radical generation

-Efficacy: hard to predict, based on conc over time, in practice dosage controlled by residual

-Generation: Corona discharge is most common, electrolysis of acid, ultraviolet

-Advantages: effective, onsite generation

-Disadvantages: more costly than Cl, very corrosive (mtl of construction), dosage can be hard to 

predict, potential for organic breakdown into smaller organics favoring growth, potential for 

bromated formation, ozone must be removed before membranes or will damage membranes. 

Removal using UV

UV:

-Mechanical technique by electromagnetic radiation: primary disinfection is 200-300nm

-Efficacy: dosage, wavelength, exposure time, distribution; impacted by high turbidity; excellent 

on protozoa; less effective on bacteria, virus and endospores, works best in conjunction with an 

oxidizer

-Advantages: no residual effects, easy to install and maintain, no harmful byproducts
Memorandum

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-Disadvantages: More costly than Cl, no residual kill effect, not as effective as other techniques 

as a stand alone, filtration required, potential for organic breakdown, initial investment is

substantial, units prone to scale and fouling

Other Chemical: non-oxidizers (DBNPA, Isothiazolones), pH adjustment (caustic), 

bromine/iodine/BCDMH (weak oxidizers), other oxidizers (KMnO4/H2O2/Peracetic Acid), 

dichloroisocyanurate (not fully studied), copper sulfate (algaecide only), biochemical (enzymes, 

bacteriophages), sodium bisulfate (shock trmt more effective on aerobic bacteria)

Operational methods: preventative cleaning (single bacteria easier to remove than full biofilm)

Mechanical methods: UF, MF, multi-media filtration; electrical or electrochemical or pulsed 

electric fields; ultrasound and thermosonication, membrane surface modification

Discussion:

Modified membranes: new fouling resistant elements have been introduced since the reference 

given in the paper. New FR elements utilize a combination of membrane and feed screen 

modifications. Further study of these new products are needed. Won’t eliminate biofouling or 

need to clean, but can extend time between cleanings. Fewer cleanings also extend membrane 

life.

Heat sanitizable elements use special construction and membrane developed for the purpose of 

high temperature exposure. Today there are no high temperature elements commercially 

available.

Need to always refer to membrane manufacturer specifications.

Good, comprehensive paper with an excellent reference list.

Other Discussion:

Generally off-line batch treatment. Continuous online not typical due to regulatory discharge 

limitations. Recommend dosing 2-3 times per week for perhaps 60 minutes.

Often the best solution could be combinations of techniques.
Memorandum

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Reactive Iron Media – An Enhanced Zero Valent Iron Process for Metals and Metalloid 

removal from Water and Wastewater (IWC 14-58)

Zero Valent Iron (ZVI) technology has been around a long time. Shown to remove metals.

Solving historical problems of passivation.

Development of a method for promoting and maintaining reactive oxide coating (FeOx) at 

TAMU. Start with ZVI, Fe oxide coating forms on ZVI. 

Evoqua and TAMU licensing agreement.

Contaminants: different mechanisms lead to many possibilities: redox reaction, immobilization 

through surface adsorption on FeOx

Static Test: small sample treatability study to provide indication of time to treat.

Dynamic Test: benchtop flow-through test gives more complete process information than static 

test.

Pilot Test: 25gpm demonstration plant.

Application and Results:

-Plant A, 25gpm FGD pilot plant. 2 media sizes: coarse media and fine media. Fine media 

significantly increased reaction rate. Selenium from 1,700 down to 1.69.

-Plant C – 1 gpm FGD pilot plant. Good removals across a range of conditions in challenging 

wastewater environment. See sister IWC paper for selenium removal

-Plant E – ash pond water, static test. Thallium primary contaminant of concern.

-Plant F – mine runoff, static test.

Conclusion: Pironox TM Advanced Reactive Media System treatment is appropriate in a number 

of applications for removal of selenium, mercury, arsenic, and other contaminant metals across a 

range of wastewater types.

Discussion:

Good to find alternatives to thermal and biological treatment options.

WRT FGD, what influent conditions are needed or pretreatment require? How would nitrate be 

addressed in a total solution? This is a partial solution as doesn’t address nitrate.
Memorandum

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Operational Considerations: how does the process handle FGD variability? Are there inhibitory 

constituents or conditions (e.g. , ORP, scaling) and what is mitigation?

As the media has a finite life, is there breakthrough in the effluent? How is this 

predicted/managed?

How much attrition of the media can be expected? How much sludge would be generated?

Pilot system seems complicated. 

Is the metals data total or dissolved? Is the FGD testing data representative to the bulk of FGD 

system in the US? What is the speciation of Se, Hg, and As? Are there differences observed with 

differing species?

Why did Tl removal drop so much (%) in Plant A?

Author Response:

Sludge is really just the iron sludge. Not a huge sludge issue.

Pilot data is total metals. Only exceptions are Plant A fine study.

Speciation is selenate.

Tl concentrations are quite low to begin with, so don’t want to overemphasize removals.

Other Discussion:

Considering need to nitrate pretreatment? Yes – best pretreatment would be a biological step.
Memorandum

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Pilot Studies for the Treatment of a Highly Oxidized Flue Gas Desulphurization 

Wastewater (IWC 14-59)

SC power plant power studies (SCANA). Project funded by SCANA and EPRI.

Began pilots in June 2013 and ended April 2014. All pilots feed from pond wastewater.

Contaminants of concern: As, Hg, Se, NO3/NO2 to meet ELGs (lower than drinking water). 

Emphasized the limits are very low, especially NO3/NO2 (lower than rainwater).

At start of test, pH was 3-4 and ORP at 500. Distinct chlorine smell and WW would bleach 

jeans. After scrubber changes in Dec 2013, pH 7 and ORP 200. So, vastly changing FGD feed 

stream during the test.

Throughout pilot test, selenium conc correlated to OPR. So, when ORP came down, selenium 

did as well. 1,900 to 200 mg/L. Influent predominantly selenate form.

Similar relationship between HG and ORP. 100 to <1 mg/L

Nitrate also comes down with ORP. 60 to 20-25 mg/L

Manganese was completely opposite to Se. Theory is that manganese dioxide acts as a catalyst.

Arsenic is absorbed to iron, so very little arsenic coming into or out of pilot.

Observations:

-higher ORP increases concentration of Se, Hg, and maybe NO3, higher ORP results in lower 

pH, higher ORP results in more oxidants in FGD, highly oxidized FGD is transient, oxicized 

MnO2 catalyzes the Se oxidation, FGD WQ variations will impact all treatment technologies 

evaluated.

Significant variation in performance of technologies in removing Se: AnMBR X-Flow, 

Envirogen, ABMet, Pironox, LHI. Majority of the technologies did not come close to meeting 

the proposed ELGs for Se.

Tried for months to figure out why the wastewater was so highly oxidized. 

AnMBR Se Removal: Adjusted pH and ORP, but quickly returned back to where it was. 

Wastewater was very transient. Reduced Se from about 1,500 to few hundreds. After change in 

scrubber, effluent performance improved.

Fluidized Bed Reactor/MBR. For first several weeks no removal, but then biological suddenly 

kicked in. Reduced Se to about 150 mg/L.
Memorandum

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Zero valent iron (Pironox). At start the technology struggled quite a bit –highly variable. Revised 

operating conditions and much better treatment, down to 4-5 Se. Believe change could be due to 

nitrates.

Zero valent iron Blue. Similar performance as Pironox, but end performance not as good.

Mercury: the Pironox technology did the best. Believe that the iron is complexing with mercury.

Arsenic: Pironox also performed the best, but hard to tell as arsenic levels were so low. ABMet 

levels spiked a few times. Suspect Arsenic sorbed to the biomass.

Nitrate: Pironox not effective. AnMBR X-Flow and ABMet and Envirogen performed the best. 

Biotreatments performed similarly and did not meet limits. Chemical systems had difficultly 

removing Se. Se removal improved with lower NO3 concentrations. Lesson learned that 

probably should remove nitrates before other treatment.

How did oxidants affect treatment? Did not affect nitrates, but definitely Se.

Discussion:

Would like more info on treatment mechanisms.

What changes was made during scrubber changes that made the wastewater more amenable to 

treatment? This could be a paper in itself.

Was influent wastewater to pilot systems within usual vendor guidelines? Was any pretreatment 

provided to prevent scaling or to reduce ORP? Would a full-scale treatment plant require 

phys/chem. Pretreatment (i.e., traditional FGD ELGs)?

Any data on media fouling and changes in hydraulic capacity?

ZVI converted nitrate to ammonia – bad! Need denitrification pretreatment.

ZVI and bio systems operate via different mechanisms, with different results. Are they 

competitors or complementary? Feasibility of two-stage system using both technologies?

Author response:

All the technologies has some issues. Perhaps that’s not fair to say – they just couldn’t get to 10.

Biggest issue with wastewater was the changing water quality of the FGD. Would like to know 

what happened with the scrubber. Scrubber guys claimed that nothing changed. All they did was 

replace the mixer. Was it a change in coal? WOW! Quite a lack of understanding of chemistry in 

the scrubber.
Memorandum

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Pretreatment was only adding sodium bisulfate (reducing agent). Worked fairly well, but 

problems with transients of FGD. Really need to change immediately before entering the reactor 

because changes back.

Ponds also serve as pretreatment.

Wonderful opportunity to run all the pilots side by side.

Other Discussion:

-Bill Kennedy, Duke: Monitor temperature in the ponds? Polar vortex occurred during the 

testing. Water temperature did go down to 40, which is close to the threshold for bio treatment. 

But other treatments generate their own heat. Could temperature affect chemistry? Didn’t look at 

that. Want to have a better understanding of absorber/scrubber chemistry.

-Author: don’t want to make too much of ORP, which is a terrible measurement. Hard to get true 

readings. So many reactions, the ORP is really just instantaneous. Need ORP probes everywhere 

to understand ORP.
Memorandum

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Removal of Selenium and Mercury from Refining Wastewater (IWC 14-52)

Mercury: Present as soluble Hg+2, also insoluble particulate.

Selenium: multiple oxidation states result in complex water chemistry. Focus on selenocyanate, 

selenite, and selenate.

Many methods to remove Hg and Se. Separate treatment steps needed when Se present in 

different oxidation states:

-Biological - remove by anaerobic bacteria, seleocyanate removed only after preoxidation.

-Iron co-precipitation: Selenate removed poorly if at all. Selenocyanate removal only after 

preoxidation to selenite.

ZVI: historic versus innovative treatment.

ZVI Historic:

-Use elemental iron

-Generates electrons as iron corrodes (oxidizers). Treatment metals and other contaminants by 

(1) galvanic displacement/cemention) and (2) co-precipitation/absorption.

-Historic problem: passivating iron oxides form Fe2O3, which prevents/slows electron transfer 

and halts beneficial reaction.

Overcoming ZVI Passivation:

-TAMU prevents red rust formation by allowing formation and maintenance of reactive FeOx 

coatings on ZVI. Commercialized the technology as PironoxTM. Broadly treats metalloids and 

metals. See Duke IWC 14-58.

Testing: Take iron and fluidize it in 4 reactors.

Test Methods:

-Static testing (jar tests): Inexpensive, small sample volume

-Dynamic testing: Benchtop continuously stirred tank reactors (CSTRs), larger sample volume, 

treatment process details are more complex.

Bench Test Results for Mercury:

-Vary HRT and amount of media for treatment of sour water stripper from multiple refineries. 

Influent 762 ppt total mercury (dissolved 206 ppt). Most conditions reduced to <1ppt.
Memorandum

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-Some test runs spiked with amine with and without H2S. Good removals in all cases (<1ppt). 

Sulfide precipitation likely happening.

-Summary: Mercury removal rather independent of HRT and media amount. H2S may be 

helpful.

Batch Test Results for Selenium:

-First refinery (didn’t catch WW type): Treatment goal of 4.6 ug/L. Influent of 330 ug/L. Amine 

spike without H2S had good results while amine spike with H2S did not have as good results.

Improved treatment with more media.

-Second refinery (didn’t catch WW type): Treatment goal of 20 ug/L. Influent of 440 ug/L. Filter 

and/or chemical pretreatment reduced to 5.3-40 ppm. 

-Sour water stripper treatment reduced Selenium from 1,200 to 1.9 ug/L.

-Data from two addition bench scale tests. 

-Summary: Rate of Se removal by reactive iron treatment is a function of media mass and HRT.

Pilot Test Results: Didn’t achieve 4.6 ppm with 2 reactors. Went back to bench tests on site with 

4 reactors. Pilot tests now with 4 reactors. Presenter ran out of time to present. Need to wait for 

paper.