The main three types of environmental remediation and reclamation

Remediation is the process of removing contaminants from sites that have been polluted from industrial, manufacturing, mining, and commercial activities. Remediation involves an all-encompassing step process of land restoration from detection, investigation, assessment, determination of remedial measure, actual clean-up, to site redevelopment. The following are different common types of remediation implemented in many polluted sites.

Soil remediation

There are many factors that affect the soil condition. Environmental remediation of soil covers all techniques and processes used for the removal of contaminants in soil. Soil contamination poses a lot of risks and hazards to human and ecological health through direct contact, ingestion, or introduction in the food supply chain. Soil remediation techniques treat many soil contaminants such as heavy metals, petroleum hydrocarbons, pesticides, and radioactive materials. These remedial processes can be physical, chemical, thermal or biological in nature depending on the contaminant that is being dealt with.

Soil rehabilitation is done in many sites, below are areas or environments where soil remediation are applied:

Urban environments
Brownfield redevelopment
Urban mining
Mining and raw material extraction areas
Opencast coal mines
Mining heaps
Mining terrains that have subsided
Quarries and open-pit mines
Peatlands

These sites undergo a systematic diagnostic assessment that is implemented in three phases:

Preliminary site assessment- the first phase in soil remediation provides a qualitative indication of the site based on inspection and interpretation of gathered data such as aerial photographs, geological and hydrological studies, and agency reports and witnesses
Comprehensive site assessment- this phase goes deeper with the investigation by collecting soil samples and analyze results
Implementation of remedial measures- the third phase expands into simulating solutions and the actual implementation of chosen soil remediation measures [1].

Groundwater and Surface water remediation

Water has been one of the most vital and essential natural resources that ensure the survival and sustainability of living systems. The quality of water sources must be managed and maintained to keep the safe levels for its desired application. Environmental remediation of industrial and potable grade water has recently had a forward thrust in enforcement with the rise of industrial effluent discharge.

Groundwater is waters that are underground found in large aquifers or water that is contained in the subsurface layer of rock and soil. It must be pumped out in order to tap into groundwater.

Arsenic, iron, chromium, selenium, and fluoride are some of the most common contaminant elements found in groundwater. Evaluating groundwater contamination starts with an assessment of feasible contamination sources. This may possibly originate from the land surface, above the water table or below the water table. Leachate sources must be examined and changes in water quality and cyclic fluctuations are some of the areas that must be monitored.

Groundwater deterioration that originates from the land surface could be related to the infiltration of contaminated surface water, wastes from land and water disposal, tailings and stockpiles, dumps, fertilizers and pesticides, accidental spills, and other airborne particulate matters.

Groundwater deterioration originating from above the water table are possibly brought by surface impoundments, septic tanks, landfills, excavated waste disposal systems, leakage from underground pipes and storage tanks, sumps and dry wells, or even graveyards.

Some groundwater problems that originate from below the water table are disposal on wet excavations, well disposal, agricultural drainage wells, mines, abandoned wells, and groundwater developments.

Surface water is water found in lakes, wetlands, rivers, streams, and other exposed cavity. Surface water is more vulnerable to contamination such as agricultural wastes, industrial wastes, animal wastes, and acid mine drainage.

There are many methods and techniques in groundwater restoration and protection, some of which are as follows:

Pumping systems
Interceptor systems
In situ treatments
Biodegradation
Groundwater barrier systems

Sediment remediation

Sediments are made up of clay, organic matter, hydrated oxides, other soil and water mixture that are brought into aquatic areas. Sediments are studied in their physical and chemical characteristics. Sediment remediation technologies utilize physical, chemical, biological processes to reduce contaminants or convert it into a less harmful state. In situ and ex situ remediation techniques are available for sediment remediation.

In situ technologies for sediment remediation:

Physical and chemical treatments
1. Capping
2. Barriers for containment
3. Stabilization
4. Solidification

Ex-situ remediation technologies

Biological treatments
1. Composting
2. Bioslurry
Physical and chemical treatments
1. Chelation
2. Oxidation
3. Solidification
4. Stabilization
5. Solvent extraction
6. Soil washing
7. Containment barriers
Thermal treatments
1. Thermal Destruction technologies
  1. Incineration
  2. Vitrification
  3. Pyrolysis
  4. High-pressure oxidation
2. Thermal Desorption technologies
  1. Anaerobic Thermal Processor
  2. Desorption and Vaporization Extraction
  3. High-Temperature Thermal System
  4. Low-Temperature Thermal System
  5. Low-Temperature Thermal Aeration [3]