Groundwater Remediation Solutions: An Overview
Groundwater is integral to the health of our ecosystems. However, since it lies below the surface, it is particularly vulnerable to contamination due to leaks and spills. Processing contaminated groundwater is often costly and lengthy, especially when the pollution is caused by harmful chemicals from industrial sites.
Various groundwater remediation solutions have emerged to address different types of contamination, preserve water supplies, and keep harmful substances from reaching end-users
What Is Groundwater Remediation?
Groundwater remediation refers to the process of removing contaminants from polluted groundwater or converting these contaminants into harmless products. The goal is to make the groundwater safe for human use and minimize the contamination’s negative environmental impact
Common Groundwater Contaminants
Before moving on to the different groundwater remediation solutions, it helps to understand why they are needed in the first place. Groundwater contamination can occur when pollutants from these common sources move beyond the soil and reach the aquifer.
Millions of storage tanks are estimated to be buried across the country. These contain different types of liquids, from oil and gasoline to chemicals.
As with all materials, these tanks can develop cracks or corrode over time. Severe contamination can occur if the liquids they contain eventually leak and reach the groundwater.
These systems used in homes, offices, and other commercial facilities are crucial for safely collecting and treating wastewater. However, improperly designed, constructed, or maintained septic systems can cause contaminants like fecal bacteria, household chemicals, and other sewage pathogens to leak into the groundwater.
Groundwater pollution can also result from the use of chemicals like pesticides and fertilizers in households and businesses. Improper containment of industrially-used chemicals is a major source of groundwater contamination, such as dry cleaning chemicals. These substances can eventually seep into groundwater.. Road salts used in winter can also get washed off the roads and end up in the water when the ice melts.
Ideally, landfills have a protective layer at the bottom to keep contaminants from leaking underneath. In reality, some sites have cracked or no protective layers at all. These landfills allow contaminants from garbage like household cleaners and car battery acid to reach the groundwater.
Groundwater is also part of the hydrologic cycle. Since it can undergo transformations and move from the subsurface regions to the atmosphere and back to the surface, contaminants in other parts of the process can also reach groundwater supplies.
The Importance of Groundwater Remediation
Different contaminants can infiltrate groundwater sources and present their own set of possible consequences. Once they enter drinking water supplies and ecosystems, they lead to various health hazards and long-lasting ecological damage.
Groundwater remediation is integral in preventing these potential issues and safeguarding both the environment and public health. Implementing the appropriate remediation solutions minimizes the impacts of the various contaminants on water resources and solves health problems for affected communities.
Two Primary Types of Groundwater Remediation
Groundwater remediation solutions are categorized into these two primary types:
- In Situ (On-site Remediation)
In situ or on-site remediation involves managing contaminants and treating the groundwater without physically moving it to a treatment site. Biological or chemical reagents are injected directly into the subsurface to neutralize the pollutants and ensure no harmful residues are left behind.
Since the water does not have to be removed, in-situ remediation is the faster, less expensive option between the two.
- Ex Situ (Off-site Remediation)
Ex situ or off-site remediation is generally a more expensive and time-consuming process of treating polluted groundwater. It involves excavating and moving the contaminated water off-site for treatment.
This remediation type is particularly helpful when on-site methods can no longer address the contaminant levels in the subsurface. It’s also beneficial in cases where the groundwater must be immediately protected from further pollution.
Groundwater Remediation Methods
On-site and off-site remediation can be performed with any or a combination of these remediation methods:
- Physical Remediation
Physical remediation methods typically involve the traditional “pump and treat.” In this process, the groundwater is pumped out of the aquifer using a vacuum pump and treated at the surface using substances and technologies that absorb the contaminants. Once the pollutants are removed, the groundwater is returned to its original site.
Air sparging or air stripping are other physical remediation techniques. This process entails injecting pressurized air into the contaminated groundwater to dissolve pollutants into a vapor state. The vapors containing the contaminants are then extracted using vacuum systems to leave behind the treated groundwater.
As its name suggests, bioremediation or biological remediation methods use organic matter and microorganisms to treat contaminated groundwater. Compared to physical techniques, biological techniques allow for easier and more cost-effective treatment, as the water does not need to be removed from its site.
There are three ways to use biological material to break down chemicals and compounds in groundwater:
- Bioventing involves aerating soils in the unsaturated zone to increase indigenous microbe activities and promote bioremediation.
- Like bioventing, biosparging stimulates microbial activities by injecting air into the soil subsurface. The difference is that the air is introduced into the saturated zone to speed up the breakdown of organic constituents in that zone.
- Bioaugmentation is a bioremediation technique wherein cultured microorganisms are added into the subsurface to degrade specific contaminants more quickly. This is commonly used in treating metal-contaminated locations.
- Chemical Remediation
Chemical remediation is considered the most effective for dealing with a wide range of contaminants, though it can sometimes take longer and be more costly. It is also necessary in cases where no biological options can remove the pollution from the groundwater.
Chemical remediation can be done in two main ways:
In Situ Chemical Oxidation (ISCO)
ISCO is an in situ remediation technology where chemical oxidants are injected into the contaminated area to stimulate rapid, destructive abiotic degradation activities. Strong oxidants used in this process include permanganate, persulfate, hydrogen peroxide, and calcium peroxide, among others.
In Situ Chemical Reduction (ISCR)
Also known as reductive dechlorination, ISCR involves injecting a reducing agent into the subsurface to change a contaminant’s toxicity, solubility, and mobility. The resulting strong reducing conditions support quick and effective remediation, especially when heavy metals like chromium are involved. Zero valent iron is often used in ISCR remediation, both alone and in combination with other remediation technologies, such as bioremediation and Fenton’s reagent.
When deciding which technique to use for a particular remediation project, factors like the type of contaminant, its concentration and location, and its physical and chemical properties must be considered.
Find the Products You Need for Your In Situ Remediation Project at CAP Remediation
While numerous factors can cause serious and problematic groundwater contamination, there are remediation solutions and techniques you can implement to prevent the destructive consequences of polluted groundwater.
CAP Remediation supplies a wide range of remediation-grade chemicals for in situ projects. Whether you need bioremediation products, oxidizers, or any additional products, we are here to provide you with what you need to remediate your site successfully. Browse our product list today or contact our team to request a quote.