Mercury Contamination in Brazil

1
Mercury Contamination in Brazil

• Ozan Kurtulus
• Louisa Meredith
• Jeremy Trewin

2
Introduction

• Hazardous environmental contaminant
• In Japan, 2252 people have been affected and 1043
  have died due to Minamata Disease caused by
  mercury pollution
• Compound that can be found naturally in the
  environment
• Mercury poisoning also occurs from exposure to a
  soluble forms of mercury known as methylmercury
• Inorganic mercury is transformed into soluble
  methylmercury (MeHg)
• dangerous concentration of methylmercury can be
  ascribed to human activity.

3
Implications

• Methylmercury works its way up the food chain
• through bioaccumulation in the environment
• Larger, predatory species of fish are a greater
  danger for consumption due to their high
  concentrations of methylmercury
• Fish is the main diet in Amazonial communities
• About 90 of the mercury in fish is methylated

4
Brazil Artisanal Gold Mining

• The modern gold rush in Latin America started in
  the 1980s
• 400 ton of gold produced per year
• 30 to 50 ton per year from Brazil 80 from
  Amazon region
• An estimated 200,000 to 400,000 miners in the
  Amazon region
• Mercury contaminants often caused by artisanal
  miners using poor mining practices, usually due
  to a lack of economic alternatives
• Mercury is used in order to separate gold from
  the extracted ores
• Often illegally dumped into nearby water streams

5
Brazil - Logging

• Mercury is released from cutting and burning of
  trees along river banks
• Relatively newly found contributor of mercury
  contamination
• through an investigation carried by Brazilian
  and Canadian researchers

100 to 200 tonnes of mercury released per year
6
Mercury Decontamination Methods

• Solidification

• Physically binds or encloses contaminants within
  a stabilized mass
• Chemically reduces the hazard potential of a
  waste
• Amalgamation is typically used to immobilize
  elemental mercury
• dissolving the mercury in another metal to form
  a semisolid alloy known as an amalgam
• Does not reduce the total mercury content of the
  waste
• it reduces the leachability of mercury
• product that still may require disposal in a
  landfill.

7
Mercury Decontamination Methods
Soil Washing

• Water-based process
• Physical particle size separation
• Aqueous-based chemical separation
• contaminants tend to bind to the finer soil
  particles rather than the larger particles
• Not cost-effective for small quantities
• Performed at the site of the contamination

Thermal Treatment

• Physical methods to remove mercury from the
  contaminated medium
• Heat is supplied under reduced pressure to the
  contaminated soil or waste, volatilizing mercury
• The off-gas is treated by condensation to
  generate liquid elemental mercury
• The treated medium may be used as fill material
  or disposed

8
Mercury Decontamination Methods
Precipitation

• Uses chemicals to transform dissolved
  contaminants into an insoluble solid
• Solid is then removed from the liquid phase by
  clarification or filtration
• Used to treat mercury-contaminated groundwater
  and wastewater
• Can reduce mercury concentrations to less than 2
  µg/L

Adsorption

• Contaminants concentrate at the surface of a
  sorbent reducing their concentration
• Adsorbent packed into a column
• Contaminants are adsorbed as contaminated water
  is passed through the column.

9
Mercury Decontamination Methods
Membrane Filtration

• Separates contaminants from water by passing it
  through a semi-permeable barrier or membrane

• Membrane allows some of the constituents to pass
  through while blocking others

10
Mercury Decontamination Methods
Capping

• Widely used to isolate contaminated sediment
• In Situ Capping (ISC) is placed on site
• Ex Situ Capping (ESC), contaminated sediment is
  dredged and relocated to another site
• One or more isolating layers are placed over the
  sediment
• Composed of sand or finer materials
• absorbs the mercury preventing it leaching into
  overlying water
• Advantages Low cost, low adverse environmental
  effects
• Disadvantages Not a treatable process, can be
  damaged

11
Mercury Decontamination Methods
Dredging

• Useful for heavily polluted areas
• Used in the process of gold mining
• Can cause damage to the environment through
  sediment re-suspension
• Tested to prove a significant reduction in
  mercury
• Must be well planned and implemented to avoid
  damage
• Only a temporary solution
• usually very costly and has issues with method of
  disposal

12
Mercury Decontamination Methods
Bioremediation

• Use of Mercury-resisting bacteria
• Enhances natural biological-chemical
  transformations that render pollutants harmless
• Reduces toxic mercury to volatile elemental
  mercury
• Existing passive adsorption and immobilization
  treatments
• produce a large volume of mercury-loaded biomass,
  disposal of which is problematic
• Microorganisms such as mer operon does not
  produce such results.
• Potentially low costs
• Promising new technology

13
Summary

• Current on-going problem
• No major remediation project planned
• Caused by local, illegal industry
• Large area therefore difficult to assess and
  control mercury pollution
• Large funds required
• Densely polluted areas combination of dredging
  and capping
• For permanent remediation, investment in
  bioremediation is required