Asd of Engineering

Only available on StudyMode
  • Download(s) : 68
  • Published : May 16, 2013
Open Document
Text Preview
Contaminant Hydrogeology ENEN90030 CONTAMINATION REMIDIATION LECTURE - 7 Dr. Meenakshi Arora

Groundwater contamination
• Groundwater Contaminants - Organic contaminants - Inorganic contaminants - Radio nuclides • Contaminant Transport - Conservative - Non-conservative (Retardation and Decay) • Site Remediation - Source Control - Pump and Treat - Sorption - Membrane Treatment - In situ Bioremediation, NAPL Recovery - Permeable Reactive Barrier - Contaminated Land Cleanup

Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Remediation Techniques: Recap so far
 Source control
◦ Removal and disposal ◦ Physical Containment ◦ Hydrodynamic isolation ◦ Target the plume ◦ Usually in combination with source control  Sorption
◦ Adsorption, Absorption, Ion exchange ◦ Isotherms ◦ Breakthrough curves

 Pump and Treat

 Membranes
◦ Types of Membranes ◦ Membrane selection ◦ Fouling and Cleaning

 In Situ Treatment
Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

In-situ Treatment
• Very low concentrations of contaminants over wide area (Bioremediation). • Post treatment (to safeguard against retarded solutes). • If soil is contaminated too and removal and disposal is not feasible (minimal disruption and/or disturbance to on-going site activities). • Cost • Bioremediation • Permeable Reactive barriers Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Bioremediation
• organic wastes are biologically degraded by the microorganisms into relatively harmless byproducts, such as carbon dioxide and water. • Contaminants destroyed or transformed in harmless substances. • Low technological requirements, Low maintenance. • No additional disposal costs • Does not create an eyesore • Can be performed on-site

Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Bioremediation
 Useful where physical removal not practical  Can be enhanced through Aeration by sparging and supply of nutrients via injection wells  Lab investigation is generally required to determine optimum air and nutrient requirements  If treating oil spill, remove the floating NAPL mass, if possible  If both soil and groundwater are polluted, inject nutrients in soil  Otherwise in ground water. Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Enhanced Bioremediation

Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Three types of Bioremediation
• Natural Attenuation • Enhanced Bioremediation (optimizing the nutrients, air, temperature, pH etc.) • Bioaugmentation (addition of microbes)

Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Bioremediation
• Natural Attenuation is Not fast enough, Not complete enough, Not frequently occurring enough to be broadly used for some compounds, especially chlorinated solvents • The most commonly used approach is to stimulate/enhance a site’s indigenous subsurface microorganisms by the addition of nutrients and air.

• In some cases, bio augmentation is necessary when metabolic capabilities are not naturally present. Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Common Contaminants biodegraded
• Petroleum hydrocarbons - Major contaminants: 1.BTEX compounds 2.Heterocyclic aromatics • Halogenated aliphatic compounds - Major contaminants: 1.Trichloroethylene 2.1,1,1-Trichloroethane 3.Tetrachloroethylene 4.1,1-Dichloroethane • Industrial waste - Major contaminants: 1.Polynuclear aromatics (or PAHs) 2.Pentachlorophenol 3.Nitrogen heterocyclic aromatics 4.Aromatics Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Remediation Processes
• Bioremediation is the conversion of contaminants to mineralized (e.g. CO2, H2O, and salts) end-products via biological mechanisms. eg. Glucose to CO2 and H2O. • Biotransformation refers to a biological process where the end-products are not minerals e.g., transforming TCE to DCE

Dr. Meenakshi Arora ENEN90030 Contaminant Hydrogeology

Aerobic v. Anaerobic
• If oxygen : aerobic biodegradation •...
tracking img