Page 22 - Opportunities in the Treatment of Water and Other Wast Streams

Application:
Why: Reduce produced water volumes.
Where: On-site or off-site at a centralized location. Generally, near the well head, but
in some areas, centralized ponds are used for many wells.
Target Contaminants:
Contaminants that can be addressed in concentrated volumes. If evaporation ponds can be reduced to dry solids suitable for landfills, then solids may be transported or ponds may be covered and converted to disposal pits.
Benefits:
• Relatively low cost • Low energy and chemical requirements • Minimal maintenance Limitations:
• No beneficial products • Large footprint • Lack of mobility • Long retention time to complete evaporation • Permitting and protection issues
Evaporation ponds can use the latent heat of evaporation to reduce produced water volumes for disposal. Evaporation, without a condensation system to recapture treated water, is a concentrate minimization technique, and thus evaporation alone will not recover water for beneficial use. Evaporation ponds leave all ions as residuals. Evaporation is most effective in areas with high solar radiation.
Environmental concerns to wildlife, particularly migratory birds, require permitting and protection of certain open water ponds. Furthermore, protection for wildlife, such as cattle, may also be required to prevent livestock from consuming produced water.
Similar to settling ponds, evaporation ponds are open to the atmosphere and also allow some limited oxygen diffusion and photolysis to occur.
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