Let’s begin with the fundamentals. What does the term “groundwater” refer to? Humanity relies on groundwater for its water source. About 30% of the freshwater on the planet is in the form of ice and snow, with only 0.2% found in lakes, streams, or rivers. The remaining 70% is located on mountains and in the poles. Most of the water we use for agriculture, industry and drinking water is either groundwater or was groundwater at some time in the water cycle.
Groundwater is frequently polluted and unsafe to use as a result of different contaminants that reach it, such as petroleum, fuel, road salts, and harsh chemicals. So, what can be done about it? When this occurs, the groundwater must be remediated in order to safeguard public health, vegetation, and animals. It even extends beyond that, affecting the industry and the economy. Let’s take a look at what groundwater remediation is and how it’s done.
Groundwater remediation refers to the procedures for treating contaminated groundwater by either eliminating the contaminants or converting them to safe products. There are a variety of groundwater remediation techniques, but they all aim to clean up polluted water.
On-site and Off-site groundwater remediation
Groundwater remediation can be done on-site or off-site. On-site remediation entails cleansing the water where it is actually stationed rather than removing and relocating it elsewhere. This is a less costly method than removing it and treating it elsewhere on the property. Off-site cleanup involves excavating the polluted water and disposing of it elsewhere. The benefit of this strategy is that no more harm can be done at the existing place, but it prolongs the procedure and is pricier. When subsurface pollution levels surpass those that can be handled by on-site cleanup, off-site remediation may be more useful. Most essential, both types complete the mission.
Number of remediation techniques
Groundwater remediation techniques cover physical, chemical, and biological treatment approaches, with the majority of them combining one another.
When it comes to purifying water, you need to remove the biggest particles and obstacles from the source water. The Pump-and-treat method, Air sparging, Dual-phase vacuum extraction, and Monitoring-well oil skimming are all examples of physical remediation approaches.
- Pump-and-treat is one of the most often utilized groundwater remediation methods. Impurities are removed by pumping groundwater to the surface and treating it chemically or biologically.
- Air sparging involves directly blowing air into the groundwater. As the bubbles rise, toxins are physically stripped from the groundwater and transferred up into the unsaturated zone (i.e., soil). A soil vapor extraction system typically removes vapors when pollutants migrate into the soil.
- Dual-phase vacuum extraction (DPVE) employs a high-vacuum system to remove both polluted groundwater and soil vapor. In DPVE systems, a screened high-vacuum extraction well is placed in the contaminated soil and groundwater zone. Fluid and vapor removal systems lower the water table, allowing quicker extraction.
- Monitoring wells are frequently dug to collect groundwater samples for testing. Using a belt-style oil skimmer, these wells may also remove hydrocarbons from a contaminated flow inside a groundwater aquifer. Simple belt oil skimmers are used to collect oil and other floating hydrocarbon impurities from industrial water systems.
Carbon adsorption, ion exchange, oxidation, and chemical precipitation are all ways of chemical cleanup. In order to get the greatest outcomes, chemical remediation methods are frequently utilized in combination with physical water treatment.
- The activated carbon adsorbs reactive organic compounds from groundwater, and the chemicals adhere to the graphite-like surface of the activated carbon, thereby removing the contaminants from the groundwater.
- For groundwater remediation with ion exchange, the water is forced downhill via a fixed bed of granular medium or spherical beads. Certain cations and anions in solutions displace cations and ions respectively. These include zeolites and synthetic resins.
- Chemical oxidation delivers oxidants far below to degrade organic molecules. The oxidants might be liquids or gases. A few examples of oxidants are air or oxygen, ozone, and specific liquid compounds like hydrogen peroxide. An on-site ozone and oxygen generator can be used to clean up polluted soil and groundwater.
- Chemical precipitation is used to reduce hardness and heavy metals from wastewater. In general, an agent is added to an aquatic waste stream in a stirring reaction vessel, either batch-wise or continuously. Most metals may be made insoluble by combining an agent with dissolved metal ions. Insoluble chemicals (precipitates) are filtered or relocated.
Biological remediation uses microorganisms to break down and remove pollutants from water. Chemicals that are difficult to remove from water, such as industrial waste, are broken down by these biological organisms. One benefit is that biological treatment does not necessitate physically removing groundwater. Methods include bioventing, biosparging, and bioaugmentation.
- Bioventing employs microorganisms to biodegrade organic components in groundwater. Through the introduction of air or oxygen into the unsaturated zone and if necessary, nutrients, Bioventing increases the activity of native bacteria, promoting natural in-situ biodegradation of hydrocarbons. During bioventing, oxygen may be injected directly into soil pollution. Bioventing aids in the decomposition of adsorbed fuel residuals and volatile organic compounds as vapors flow slowly through biologically active soil.
- Biosparging is a type of on-site remediation that employs organic microorganisms to breakdown organic substances in the saturated zone. Biosparging involves injecting air and nutrients into the saturated zone to boost the bioactivity of the microorganisms. Petroleum compounds that are dissolved in groundwater, adsorbed to the soil below the water table, and inside the capillary fringe can be reduced through biosparging.
- Bioaugmentation is yet another method of adding cultured microorganisms into the subsurface for the purpose of biodegrading specific soil and groundwater contaminants.
To completely restore groundwater, remediation sometimes necessitates a variety of testing and cleaning processes. Following each phase, the groundwater must be sampled and evaluated to check if it fits the state, federal, and municipal governments’ standards.
Groundwater treatment is an essential part of environmental protection in general. These are the most often utilized groundwater restoration techniques, and there are advantages and disadvantages to each. The objective is the same for all of them: to eliminate impurities and leave behind clean, drinkable water.