There are, of course, many ways that brine is, or has been, handled in different times and in different parts of the world. Today, there are seven alternative methods to brine ponds in common use. However, each of them has serious disadvantages that need to be considered.
Surface Discharge
Companies that produce brine as a waste product, especially when it’s a small amount and not extremely concentrated, are occasionally tempted to simply dump the brine onto the ground, perhaps in an undeveloped part of the lot that’s covered with weeds anyway. However, even a single discharge can create a situation of high salinity which affects the soil and the quality of groundwater in the vicinity. In fact, the risk of damage is high enough that this kind of brine disposal requires approval from both the EPA and the appropriate state agencies. Since this approval process may take some time and is likely to be approved only for small amounts of brine with a low salt concentration, it’s generally far easier to get approval to install some lined ponds. If brine will be produced regularly, even in relatively small amounts, a pond is most certainly a better strategy.
Deep Well Injections
Deep well injection is a strategy used to dispose of several kinds of liquid waste. The concept is to place wastewater, in this case hazardous or untreated brine, deep underground into geologic formations that have no potential to permit migration into nearby aquifers. Early feasibility studies of this method indicated the risk of wastewater coming into contact with topsoil, aquifers, potable water supplies, or living creatures was negligible. However, practical experience has demonstrated links between underground waste injection and water contamination, damaged or destroyed ecosystems, toxic leaks and even earthquakes.
Of course, waste that is pumped into tight geologic formations and properly sealed will never drain. While that is indeed the goal of this disposal method, it means that each well has a strictly limited capacity and there is a finite number of wells that can be safely drilled. These wells require permanent, constant monitoring to detect seepage or leaks, which makes them expensive to maintain, especially when compared to lined brine ponds.
Sewage System Discharge
Many types of wastewaters are effectively treated using municipal sewage treatment systems, so it may seem reasonable to simply dump brine down the drain where it mixes together with all the rest of a city’s wastewater. But salt solutions cannot be digested or simply filtered out in a water treatment plant. Instead, multiple stages of reverse osmosis must be employed to completely remove dissolved salts before treated water can be released. Without those steps, the municipal water that has been contaminated with brine is unusable.
Even if a producer can locate a treatment plant relatively close by who has the capability to process salt water, the processing fees can be significant. You’ll also need to pay for the installation of drain lines to connect to the sewage system in many areas since this is a non-traditional wastewater arrangement.
Direct Return to the Seawater
Producers close to oceans, particularly desalination plants, simply dump leftover brine concentrates back into the ocean. On the surface, that seems to make sense, but delicate coastal ecosystems like reefs and kelp beds cannot tolerate exposure to such high concentrations of brine as it dissipates, and the chain of environmental damage can be devastating. In some areas, ocean dumping is restricted by establishing extremely high prices for required permits. On the other hand, some countries don’t regulate ocean release at all.
Irrigating Without Further Treatment
Depending on the soil, it is sometimes possible to use very weak brines to irrigate crops. However, stronger salt concentrations applied to fertile fields can leave salt accumulations that significantly suppress crop yields for years or even decades to come. If brine is used in situations where the soil is sandy or loose, the salt is shed much more quickly, but this leads to the chance of salty runoff which damages local waterways.
Reverse Osmosis
The most advanced method of treating brine and other waste waters is reverse osmosis, commonly abbreviated as RO. This method is used for desalination and offers up to 20% more clean water than traditional vapor distilling methods. In RO, water is forced through multiple layers of filter membranes until it’s clean enough to reuse or even drink. This is one of the most expensive wastewater treatment options and has high ongoing maintenance costs, yet all RO processes leave behind some amount of super-concentrated brine that still needs evaporation to render it dry enough for ultimate disposal.
Above Ground and Buried Storage Tanks
For brine that must be stored for long term, some operators choose metal or plastic tanks that can be buried underground or placed above ground. These tanks are typically coated inside to protect the seal from corrosion, but protection provided by coatings is not permanent. While this is initially an effective and secure method to contain brine and prevent unauthorized access, the corrosive effect on even moderately resistant materials quickly increases the risk of a failure and leaks. Even the possibility of leaks means that expensive monitoring equipment is required, especially for underground tanks.
Another built-in disadvantage of tanks for any type of storage is their limited capacity. If the volume of stored brine is ever increased, additional tanks must be placed, along with leak detection and secondary containment systems. Ponds are similar in many ways to storage tanks, but they’re much larger and offer far greater storage capacity at a lower price point.
After comparing a multitude of brine treatment options, you’ve likely decided that a brine pond is the best solution for at least part of the processing. Flexible, reinforced polyethylene (RPE) liners from BTL Liners will help you create affordable, secure, and long-lasting brine ponds that offer all the benefits and none of the disadvantages of these alternatives.
