Concentrate Management and Disposal By Dr. M. Karl Wood Director New Mexico Water Resources Research Institute located at New Mexico State University Presented at Water Shortages and Desalination In New Mexico Seminar March 29, 2007 Albuquerque, NM Lorman Educational Services

Settings Near Oceans – Many challenges Inland – Severe limitations May need to remove toxics before disposal

Concentrate Disposal I. Traditional Disposal Techniques II. New Beneficial, Innovative, and Non-Traditional Uses III. Other Beneficial and Non-Traditional Uses

Concentrate Disposal I. Traditional Disposal Techniques 1. Surface Water Discharge 2. Sewer Discharge 3. Deep Well Injection 4. Evaporation Ponds 5. Rapid Infiltration

Concentrate Disposal I.Traditional Disposal Techniques 1. Surface Water Discharge – Into rivers, lagoons, and ocean Direct ocean outfall Shore discharge in wave and current mixing zone Powerplant mixing with cooling water Beach well disposal Rivers or canals – Simple – Low cost – Most common – Limited mostly to areas near oceans – Ecological risks

Concentrate Disposal I. Traditional Disposal Techniques 2. Sewer Discharge –For small membrane plants –Low cost –Easy to permit –Good for low TDS and low-flow membrane concentrates –Does not need a National Pollutant Discharge Elimination System (NPDES) permit –Largest cost is the fee at the waste water treatment plant

Concentrate Disposal I. Traditional Disposal Techniques 3. Deep Well Injection – Favorable sites: Porous subsurface geologic formations for injection Impermeable layer to prevent upward migration Low seismic activity potential Isolated from mineral resources recovery zones such as ores, coal, oil, or gas – Well depth typically 1000 to 8000 ft – Most suitable for inland areas – An alternative disposal method is needed when well down for maintenance – Suspended solids (>2 ppm) may cause plugging – Organic carbon may feed bacteria causing fouling

Concentrate Disposal I. Traditional Disposal Techniques 3. Deep Well Injection continued… – Limited to larger plants due to costs including: Permitting Site selection Flow rate of membrane concentrate Permeability of geology Depth of injection zone Concentrate pre-treatment Well type Conveyance

Description of Deep Well Classes for Permitting Deep Well Description Class IInjectate > 10,000 mg/L of TDS Geologic confining layer present to prevent contamination of upper-level Underground Sourced of Drinking Water IIWells used in the recovery of natural gas or oil e.g. produced water injection IIIWells used to mine sulfur and other minerals by the Frasch process IVWells used to dispose of radioactive waste VInjectate is of greater quality than the water into which it is being injected Injectate < 10,000 mg/L of TDS

Concentrate Disposal I. Traditional Disposal Techniques 4. Evaporation Ponds – Rely on solar energy to evaporate water – May be suitable for low volumes in arid areas where land is cheap – Multiple ponds are needed for flexibility of maintenance – Salts are usually disposed in a landfill – Misters can be used in areas with low winds – Vertical cloths used in Israel

Concentrate Disposal I. Traditional Disposal Techniques 4. Evaporation Ponds continued… – Advantages: Easy to build Low maintenance Mechanical components limited to pumps for conveyance Can be low cost – Disadvantages: Large land area may be required Expensive liners may be required Seepage can pose risk to groundwater Minimum economy of scale High costs for large plants May develop odors May be a hazard to wildlife

Annual Evaporation (inches)

Concentrate Disposal I. Traditional Disposal Techniques 5. Rapid Infiltration – Concentrate percolates through soil at high rates (4-80 inches/week) – Soils are typically sands or loamy sands – Typically used to dispose of low-TDS concentrate – Heavy metals tied up in soils during passage – Salts not tied up in soils during passage – Water can be taken up for reuse – Limited to areas with very low quality underlying water table – Costs include: Land acquisition Construction of basins Conveyance of concentrate to the disposal site Recovery pumping, Maintenance of basins – Some risk to wildlife – Probably not a viable method for most facilities

Concentrate Disposal II. New Beneficial, Innovative, and Non-Traditional Uses 1. Oil Field Injection 2. Solar Ponds 3. Land Application and Irrigation 4. Zero Liquid Discharge 5. Aquaculture 6. Wetland Creation and Restoration 7. Constructed Wetlands

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 1. Oil Well Field Injection – A variation of deep well injection – Could be injected into abandoned oil wells – Could be used for oil well pressure maintenance and/or in a secondary recovery process – Injected concentrate may constitute an improvement in water quality in the receiving formation – Conveyance costs could be high if wells located far from concentrate source

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 2. Solar Ponds – Collect and store solar energy that can be productively used – Salt gradients used to inhibit convection – Has potential energy use with rising fossil fuel costs – Energy best used for medium- or low-temperature thermal applications – Concentrate could be used as source water – Only operating solar pond in U.S. was decommissioned in 2003 in El Paso – Salts need to be replaced about every 10 years – Solar pond-powered desalination is a promising technology

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 3. Land Application and Irrigation – Used as supplement or sole water source – Can discharge to canal or other conveyance for blending – Used to dispose of low-TDS concentrate – Periodic flushing with fresh water is needed – Always concerns of groundwater contamination – Landscape irrigation Turf, trees, shrubs primarily for aesthetics, erosion control, and/or recreation – Agriculture irrigation Limited as most cash crops have low salt tolerance Some potential for growing trees for wood products

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 4. Zero Liquid Discharge – Processes that extract essentially all water from concentrate – Resulting salts are landfilled – Potential for separating and recovering specific salts – High capital and operating costs, especially for energy – Near Zero Liquid Discharge (90% volume reduction) may have acceptable costs – Limited permitting needed – No geographic limitations – High community acceptance

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 5. Aquaculture – Rapidly growing industry due to declining ocean fish supplies – Most potential is saltwater (marine) aquaculture – Presently not used in U.S. and no known research is ongoing – To date, aquaculture has used water < 7000 mg/L – Unknown effects of using inland salts (other than sodium chloride)

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 5. Aquaculture continued… - Major potential species include Tilapia which needs 82-86° F for optimal growth, shrimp for human consumption, and brine shrimp - Brine shrimp are worth over $30 million from the Great Salt Lake

Major implementation issues include: Overall salt and water balance II. New Beneficial, Innovative, and Non- Traditional Uses 5. Aquaculture continued… Concentrate Disposal Influent toxicity issues Environmental and human health risks Costs Species selection Effluent regulations

Concentrate Disposal II. New Beneficial, Innovative, and Non- Traditional Uses 6. Wetland Creation, Restoration, and Enhancement – Creation of new brackish or salt marshes using concentrate as the primary water source – Augmentation of existing brackish or salt marshes with concentrate – probably most difficult to obtain permits – Used for many decades for conventional wastewater pollutants – Only used on an experimental scale for concentrate disposal – May reduce selenium, nitrate, and salt loads – Potential to function as pretreatment technology

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 1.Stormwater blending 2.Recreation 3.Transport of mineral resources 4.Subsurface storage 5.Feedstock for sodium hypochlorite generation 6.Cooling water 7.Dust control and de-icing 8.Biodiesel from algae

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 1.Stormwater or wastewater blending – Requires huge storage facility

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 2.Recreation – Offshoot of irrigation and wetland reuse

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 3.Transport of mineral resources –Logistic challenges and final disposal

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 4.Subsurface storage –Allows later recovery –Best for <10,000 mg/L

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 5.Feedstock for sodium hypochlorite generation –Household bleach –Used to control bio-fouling

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 6. Cooling water

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 7.Dust control and de-icing Most promising for concentrate with CaCl 2 and MgCl 2 30 acre pond in Texas for magnesium chloride removal from concentrate

Concentrate Disposal III. Other Beneficial and Non-Traditional Uses 7.Biodiesel from Algae  Research conducted by DOE from  Utilized waste CO 2 from coal-fired power plants  Cost is about 2X cost of diesel from petroleum  Many R&D hurdles before it can be practicable Crop US gal/acre Corn18 Oats23 Kenaf29 Cotton35 Hemp39 Soybean48 Coffee49 Mustard seed61 Rice88 Sunflowers 102 Peanuts 113 Olives 129 Pecans 191 Jojoba 194 Avocado 282 Oil palm 635 Algae 10,000 Yields of common crops

Conclusions 1.Several current and emerging potential treatments and uses have been presented 2.There is no panacea for concentrate disposal 3.It may be possible to develop creative local options 4.A combination of methods of conventional and non-traditional uses may be most cost-effective 5.Options tend to have critical site-specific issues that include: Climate Markets Regulatory issues Ecological risks 6. Additional research appears especially needed for: Volume reduction technologies Oil field well injection Halophyte, crop, and turf irrigation Treatment wetlands Recovery of separated salts.

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