Evaporation ponds are used for non-brine wastewater too, so in some cases they do not need such stringent engineering and security as the brine pond. Drying up storm water or irrigation runoff doesn’t usually bring up quite as many considerations as with brine. If you’re preparing to build a brine pond for salt harvesting or wastewater processing, consider the extra features that these projects need to succeed. You can also use this as a guide to repurposing an existing evaporation pond into a brine pond.
High Levels of Salt and Dissolved Minerals
Brine is naturally corrosive, and higher concentrations of salt and other dissolved minerals increase the intensity of this reaction. Other types of evaporation ponds tend to experience far less corrosion, reducing wear and tear on any lining materials used to seal the bottom and sides. Concrete and clay linings can break down faster than expected when exposed to highly concentrated brine. Metal storage tanks also react to dissolved mineral content, even when they’re coated with protective sprays. Corrosion-resistant RPE liners, such as the liners fabricated from industry leading BTL Liners is the best material for protecting existing or desired pond materials from the reactions triggered by the ingredients in brine waste water.
Greater Risk of Damage from Spills
Basic evaporation ponds are only used for holding relatively clean irrigation or storm runoff water. While these waters may include small amounts of fertilizer, pesticides, or roadway residues that need to stay out of the local waterways, they’re relatively easy to handle with remediation if there’s a spill. Since the salt from brine can remain in the soil surrounding the spill site for years to even decades depending on the concentration, it’s essential to build brine ponds so there’s as little chance of spills or flooding as possible. Undersized brine ponds are particularly risky when high rainfall levels push water over the banks. Some industrial brines also include high levels of secondary contaminants that also affect drinking water and soil health when spilled.
Extensive UV Exposure
The bottoms and sides of brine ponds often receive far more exposure to direct sunlight than other evaporation ponds. While some storm water and irrigation ponds are designed to hold some minimal amount of water year-round, most brine evaporation ponds specifically remove as much moisture as possible to create dry solids to reuse or send to the landfill. Combine this with the light reflecting properties of crystalline salt or mineral deposits and you’re multiplying the UV rays reaching the liner material. RPE offers the best UV resistance from a flexible liner material, and BTL Liners ArmorPro is an ideal choice for salt and mineral harvesting ponds with a lot of direct sun exposure.
Reclamation of Valuable Products
Most other evaporation systems for reducing or eliminating wastewater don’t aim to gather any specific materials in the process. On the flip side, most brine ponds built for evaporation instead of long-term storage, specifically include a mineral harvesting component. Many brine evaporation ponds are built just for the harvesting of lithium, salt, chloride, and other valuable components from natural and created brine. This affects the entire design of the brine pond, from liner selection to the evaporation rate.
Increasing the Evaporation Rate with Wind Assistance
For most storage and containment ponds, high winds are a problem to avoid rather than something to encourage. When evaporation is the goal, wind may be encouraged or even created to speed up the evaporation rate. This is especially likely with brine ponds since there are valuable minerals to harvest. These byproducts can be used more quickly by accelerating the evaporation process. Wind-aided intensification of evaporation, commonly shortened to WAIV, involves installing a set of sail-like membranes that are regularly wetted with the brine from the pond. Since the liquid is spread across a saturated solid surface rather than the surface of the water, evaporation is rapid and it’s easy to harvest the minerals left behind. Storage ponds built to work with WAIV systems will need extra pumps and the equipment that goes with them, and the best results will come from lined storage areas since unlined ponds will contribute dissolved soil that fouls the evaporation sails.
Mechanical Damage Risks
When you add in the need for heavy equipment to scoop up the salt and other solids from the surface of the evaporation brine pond, you dramatically increase the chances of mechanical damage. Salt and other crystalline minerals begin contributing to the wear and tear on the lining of the pond as they form and gather along the bottom and edges. Other evaporation ponds for wastewater may develop algae and other plant growth that can slowly damage low quality liners. If a weak, flexible liner is used, there is a risk of tears from machinery use during even the first mineral harvest. Cleaning equipment also increases wear on concrete and flexible liners for all types of evaporation ponds.
Lack of Ballast for a Smooth Harvesting Surface
Ballast materials like gravel, crushed stone, boulders, concrete blocks, sand, and soil are commonly layered over flexible pond liners in evaporation ponds. This doesn’t create the smooth surface desired for the brine pond where minerals will be harvested, so ballast is rarely used. The flexible liner may be covered by smooth concrete or used as the uppermost surface. Floating ballasts that slow down evaporation and keep wildlife out of the area are commonly used on all types of storage ponds, including brine ponds. However, these floating ballasts are rarely used on evaporation ponds of any kind since the surface covering effect works against the intended goal of reducing water volume.
Evaporation ponds don’t work in every area. Brine ponds, in particular, perform best in dry, relatively warm climates since they aim to evaporate as much water as possible to maximize mineral harvests. Brine mining is concentrated in dry and warm climates with rapid evaporation rates. Areas with weather features, like steady seasonal winds, are some of best locations. Other ponds, that combine the purposes of storage and evaporation processing, can be used in a wider range of climates. This is specifically the case if standing water during cold winter months or seasons of high rainfall are not problematic. Brine storage ponds are also more adaptable to a wide range of climates since they’re usually designed to minimize the evaporation rate rather than increase it.
Later Reuse Options
Most evaporation ponds are used for years or decades at a time, but the land is eventually needed for reuse in many communities. Farmers in California looking for more arable land are turning to reuse projects that turn dried out irrigation runoff ponds with high salt accumulation into useful farmland. Traditional crops won’t grow where the soil salinity is too high, but coastal grasses often thrive after a few years. These grasses will feed livestock like cows, sheep, and goats that deposit valuable manure resulting in significant soil enrichment. Years of grass growth can help reduce the soil salinity and potentially prepare former brine ponds for agricultural reuse. For even faster rehabilitation of former pond land, install flexible liners over every square inch of the soil from the beginning. This keeps salt and other minerals from soaking into the soil below, making it much easier to reuse once the liner is peeled back again.
By taking all of these various factors into consideration as you design a brine evaporation pond, you’ll build a processing facility that requires relatively little maintenance while providing years of reliable use. Brine ponds are rarely used just for a few batches of water since they’re labor-intensive to build and do require a hefty investment, but they offer a better return on that investment over time thanks to greater adaptability than other processing options. Using a reliable liner from BTL Liners is the key to building a brine pond for evaporation that lasts for decades of use.