What are the equipment specifications?

Biological treatment systems require a lot of space. Size may be a problem for offshore.

Perhaps use biotower on platform or Deep Shaft (suspended growth) system attached to platform support. Clarifier will significantly increase total size.

Need blower for air supply, influent feed pump and piping.

Pretreatment may include filtration for particulate removal, and other steps for removal of oil and iron.

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Possible tanks and feed pumps for nutrient and polymer addition.

5. What is technology's current operational state (¡.e. , pilot, laboratory-scale or full-scale)?

Well known technology for on-shore applications. Small-scale package systems are being used, but would need t o be adapted for use on platforms.

Best applications may be biotower or Deep Shaft processes.

GRI is conducting pilot studies with fluidized bed biological/GAC process(?).

6. What is the potential for technology improvements (¡.e., many versus few, rapid versus slow).

High potential for technology improvements through ongoing research.

Need t o develop smaller, efficient systems for offshore applications.

Perhaps obtain/develop bacteria that are specifically designed t o treat produced water components.

7. Are there any toxicity reduction performance data?

Data available for refineries.

None for produced water.

8. List the advantages and disadvantages with regard t o weight, size, energy requirements, produced water residence time, throughput capacity,

inputhoading rates, operating temperatures, waste stream types, fouling potential and scaling potential.

Weight: Major disadvantage - Long produced water residence times will require large tanks.

Size: Major disadvantage - Long produced water residence times will require large tanks.

Energy: Fairly l o w - power for blower and pumps.

produced water Residence Time: Could be many hours. Depends on A- 3

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the degradation rate of the toxicants. The longer the residence time the larger the system.

Input/Loading: Will handle variable loadings, if acclimated. Long-term slugs may upset system.

Operating Temperatures: Uncertain. Review literature for tolerance t o high temperatures.

Waste Stream Types: Waste sludge. May also need t o bypass slug loadings.

Fouling Potential: Buildup of oil and iron can hinder biological activity.

Scaling Potential: Aeration may cause precipitation.

9. Describe any side effects from use of the technology (e.g., side stream wastes or alteration of ionic composition).

Off-gas emissions may require treatment t o meet future air regulations.

Waste sludge must be disposed of.

Discharge is oxygenated.

1 O. Consider appropriateness, or necessity, of sequential use of treatment technologies. Note which technologies are compatible/incompatible.

M a y need pretreatment for removal of particulates, oil and iron.

Compatible with most technologies.

11. Evaluate cost as best as possible. Summarize overall costs here.

Not possible t o estimate. Must review literature for appropriate small- scale systems.

12. List any recommendations for research needed to make the technology more practical for offshore use.

Need t o evaluate methods for decreasing the residence time, such as using high biomass concentrations, genetically engineered bugs, and improved engineering.

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Need more information about tolerance to high temperatures and salinity. Evaluate system kinetics for these conditions.

Determine the degree t o which fouling and scaling may be a problem and h o w t o handle.

Evaluate operation and maintenance requirements.

Adsomtion Technoloav WorkarouD Parti ciD ants :

Lawrence Reitsema, Moderator Billy Kornegay, Expert

Brian Shannon Gary Rausina Fernando Vidaurri Bac karound.

The workgroup reviewed the following questions posed b y the expert:

a. What are the major data requirements for the evaluation and design of GAC systems?

Need flow rate and concentrations of the toxicants.

Isotherms.

Rate of adsorption for empty bed contact time in pilot studies.

Confirmation that GAC filtration will remove toxicants.

b. What are the typical superficial and empty bed contact times for wastewater treatment?

Superficial velocity = 2 t o 5 gal/min f t 2, but may go higher with higher mesh size (8 by 30 instead of 1 2 b y 30).

Empty bed contact time = 1 0 t o 30 min. If toxicity due t o high molecular weight, 6 t o 1 0 min.

Phenolic compounds, 1 O t o 1 5 min.

L o w molecular weight compounds (Butyric acid) = 15 t o 30 min.

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The workgroup developed the following treatment scenario:

May require large system. 6,000 bbl/d would require 10 ft diameter for 30 min empty bed contact time.

10 ft. diameter columns can be transported by road, but may want lesser diameter for platforms.

Can buy modular unit, 6 or 8 ft diameter unit.

For industrial waste, can exhaust 400 to 1,000 Ib of carbon per 1

million gal. For 6,000 bbl/day (250,000 gal), 100 Ib. exhausted per day or 20,000 Ib (in 10 ft column) in 200 days.

Carbon would be effective if only some components needed removal.

Depends on what is toxicant. Acetic acid is poorly adsorbed (low molecular weight). High molecular weight toxicants would be more readily adsorbed.

Assume free oil is acceptable a t 2 mg/l.

Assume total suspended solids (TSS) is acceptable a t 10 mg/l.

Iron, calcium and alkalinity will foul carbon. Either pretreat to remove these or adjust pH to keep in solution. Use computer program for Langmiur index (Difference between existing pH and pH a t saturation).

High index ( + 2) = deposition, negative index = solution

If iron, calcium and alkalinity are a problem for carbon, they will also be a problem for the other technologies.

Carbon is not an explosion hazard. Not DOT regulated.

GAC not a hazardous waste unless shown by TLCP. Only GAC used for veterinary medicine and munitions is classified as hazardous waste.

Channeling in GAC not a problem, if good underdrain system. Taller, narrower systems will reduce chance of channeling.

Produced water will be saturated with methane and some CO2.

Equilibrium with air (loss of CO,) will cause precipitation of calcium.

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Answers to Technolow Checklist Questions.

1. How well do technologies treat (reduce the concentrations of) specific chemical groups (e.g., volatiles, metals, H,S, ammonia and organics)? (Note: salinity is incorporated as a matrix effect).

Effective a t removing hydrocarbons and acid, base and neutral organic compounds provided free oil and TSS levels are sufficiently l o w enough not t o plug GAC.

Although H,S can be removed by GAC, other technologies provide greater removal efficiencies.

Should not be adversely affected by high TDS, but uncertain about the effect of H,S.

Metals should not be a problem a t high H,S because insoluble metal sulfides will be formed.

2. Is additional chemical usage necessary t o reduce toxicity?

If high iron, or calcium/alkalinity, then pretreatment will be required t o reduce fouling potential.

May require additional chemical usage t o reduce fouling.

High temperature will reduce capacity, but increase adsorption rate;

therefore, no net effect.

3. What range of oil and grease and salinity can the technology tolerate?

Free oil and grease will plug GAC; therefore, need t o pretreat, especially to prevent slugs.

Desirable design limit is 2 mg/l free oil, although may be able t o go to 4 mg/l.

Salinity should n o t be a factor, but efficiency ranges must be established.

Need t o evaluate effects of completion brines on treatment efficiency.

What does brine do t o the bed?

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4. What are the equipment specifications?

GAC is corrosive; therefore, columns need t o be pre-lined, stainless steel or fiberglass.

If fiberglass, the system should be operated in the upflow mode instead of downflow mode so tank will not rupture.

Need underdrain with nozzles.

Pressure rated tanks. Vents can be included to prevent volatile build-up, such as methane.

Require 6 to 7 f t diameter by 10 ft tall (not necessarily in one place, could be distributed in series of canisters) for empty bed contact time (volume of carbon divided by flow) of 15 min.

Total weight including wet carbon would be 6,500 Ibs for 10 ft. column (carbon alone is 30 Ib per cu.ft., but with water it is 1.5 times specific gravity of water or a total of 93-94 Ib per cu.ft.1.

Could pre-backwash columns onshore, but more weight to transport.

Columns will require backwashing because of sand (looks like black vaseline).

If backwash on platform, need holding tank for waste. If series of columns, replace first column and move other columns up the line.

Monitor break-through and need for carbon replacement using infrared (IR), fluorescence or UV at 254 nm.

5. What is technology's current operational state (¡.e.' pilot, laboratory-scale or full-scale)?

GAC used in many on-shore applications for oily wastes There are pilot stage systems offshore, but not much, if any, information on applicability.

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6. What is the potential for technology improvements (Le., many versus few, rapid versus slow).

Improve packaging (¡.e., modular) for use and change-out.

7. Are there any toxicity reduction performance data?

Yes, but don't have enough data showing toxicant removals for produced water.

8. List the advantages and disadvantages with regard t o weight, size, energy requirements, produced water residence time, throughput capacity,

inputlloading rates, operating temperatures, waste stream types, fouling potential and scaling potential.

Weight and size: same as fixed film biological, but smaller than ozone system.

Energy requirements: less than other technologies.

Residence time: same as fixed film biological, higher than other technologies, especially air-stripping.

Throughput capacity.

Input/loading rates: Can accept higher rates than other technologies, except fixed film biological.

Temperature: no major effect.

Waste stream types: Non-specific, can handle broad range.

Fouling/scaling potential: High potential, but also high for other technologies, especially membranes and UV.

Best technology for removal of high molecular weight organic toxicants.

9. Describe any side effects from use of the technology (e.g., side stream wastes or alteration of ionic composition).

Generates waste stream (Carbon waste and backwash).

Potential pretreatment wastes.

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1 O. Consider appropriateness, or necessity, of sequential use of treatment technologies. Note which technologies are compatiblelincompatible.

Pretreatment required to prevent scaling by calcium/alkalinity and fouling by iron.

If BTX is high, use air-stripping to remove volatiles and GAC for non- volatiles.

Use cartridge filters for particulates.

Don’t want GAC following biological treatment due t o plugging problems.

11. Evaluate cost as best as possible. Summarize overall costs here.

$65,000 & $1 0,000 for 1 O f t unit. $60,000 to $70,000 including equipment, such as pumps and piping.

$0.06 per bbl capital costs

$1 per Ib of carbon; therefore, $20,000 for 20,000 Ib.

Regeneration will cost $2-3/lb, including disposal of adsorbed carbon, but not including transportation.

Transportation is $1 O t o 1 5 per bbl.

Regeneration of 1 barrel of carbon (2,000 Ibs) would be about $4,000 t o $6,000 (assuming it is non-hazardous).

Operating costs: If 400 Ib of carbon exhausted per million gal., operating costs would be about $0.04 t o $0.05 per bbl.

12. List any recommendations for research needed t o make the technology more practical for offshore use.

Lab tests needed to determine efficiencies, especially where iron, calcium/alkalinity and TDS are present.

Look at NORM disposal.

Evaluate ways t o improve packaging.

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Chemical Reactions Technoloav Workaroup Particbants:

Stan Curtice, Moderator Alan Bowers, Expert Chip Bettle

Dan Caudle Ted Sauer Backsround.

Chip Bettle (Ecozone) gave a presentation describing a typical otonation system.

System consists o f direct oxidation with ozone in first module and catalytic oxidation with oxygen in the following modules. Oxygen is recycled.

Achieves 99% reduction of BTEX.

Can treat waste streams with up t o 100 mg/l oil.

Only pretreatment is 75 um cartridge filter o n well head.

A pilot study in Baton Rouge achieved effluent oil concentrations f r o m ND t o I O mg/l.

Organic compound destruction is accomplished by direct oxidation and ring opening (e.g. benzene).

Byproducts include carboxylic acid and ketones.

Trihalomethane (THM) formation (¡.e., chlorination of bromines) is

controlled b y limiting the ozone dosage t o each module. This limits BTX removal t o 70% per module, but the aggregate removal is 99%.

Ozone is an initiator and creates a chain reaction with oxygen.

Ozone forms one hydroxyl - reacts with oxygen t o form peroxy free radical.

Oxygen reaction keeps ozone production costs down.

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Results for a t w o module system were shown - plot of natural log of decontamination ratio vs. gas flow (oxygen). This plot shows a 1st order reaction with oxygen not ozone.

When the oxygen recirculation rate is fixed, the reaction is 1st order with ozone dose.

A 10,000 bbl/d system would consist of 2 containers (8 ft x 30 ft x 9 ft height each): 1st container is feed tank and direct ozonation in one catalytic module, second container is 2 catalytic modules.

System requires 1 6 0 kW.

Land-based systems use pure oxygen.

Ozonator is n o t large.

Includes 200 pm prefilter.

System operates as a fluidized bed system - handles slug loads of oil.

Can recycle when feed tank is low.

Alan Bowers had the following comments about Chip Bettle's presentation.

100s o f other consultants are marketing similar types o f systems.

Workgroup should n o t focus o n single system.

Also, reaction with oxygen has not been proven or published.

System n o t been tested long-term; it will be difficult t o control the ozone dosage (not necessarily regulated based on flow).

Answers t o T e c h n o l o w Checklist Questions.

1. How well do technologies treat (reduce the concentrations of) specific chemical groups (e.g., volatiles, metals, H,S, ammonia and organics)? (Note: salinity is incorporated as a matrix effect).

Treats a broad range of organic materials: hydrocarbons; acid, base- neutral organics; volatiles and non-volatiles; and high molecular weight organics.

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Also H,S.

Low-molecular weight organic acids may n o t be removed because they are already partially oxidized.

Ammonia probably n o t well removed.

Incidental removal of particulates.