Your SlideShare is downloading. ×
Compostagem
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Compostagem

2,752
views

Published on

Técnicas de compostagem. …

Técnicas de compostagem.
Todos os processos envolvidos e situações a ter em conta.

Published in: Technology, Business

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
2,752
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Composting for Soil Remediation João Ricardo Sousa, UTAD
  • 2. Overall Process Schematic Composting Rocks Excavated contaminated soil Rotary screen Amendment soil mix Treated soil to landfill Washed rocks to landfill Windrows Wash tank
  • 3. Composting Amendment mix Windrows Screen Monitoring Rotavator
  • 4. Process Description Composting
    • Wet organic solids are oxidized to biologically stable forms such as humus
    • Low moisture result in accumulation of heat
    • Can be engineered to be aerobic or anaerobic process
    • Since concentration of hazardous chemicals is often low, organic chemicals should be added to the contaminated soil to initiate process
    • Hazardous chemicals can be broken down or biotransformed to innocuous end products
  • 5. Process Application Composting
    • Originally composting has been applied to agricultural, yard and kitchen wastes and biosolids
    • Initial application to hazardous wastes in 1960s for treating biodegradable insecticides (e.g.. diazinon, parathion)
    • Current applications cover petroleum hydrocarbons, explosives, and chlorinated compounds (e.g.. DDT, PCB, TNT) in soils and sediments
  • 6. Design Considerations Composting
    • High temperatures are desirable to enhance solubility and mass transfer rates
    • Pile dimensions should be chosen to ensure microbial heat generation is greater than heat dissipated through the surface
    • Since concentrations of contaminant is very small, the amendment materials must provide the necessary carbon, nitrogen and act as heat source as well
  • 7. Design Considerations Composting
    • Amendment materials should also include bulking agents to improve porosity
    • Absorbent bulking materials are preferred to retain moisture (e.g.. straw, wood chips, rice hulls)
    • Inert absorbent bulking materials are ideal (e.g.. inert synthetic chemicals)
    • Bulking agents should be resistant to compaction and biodegradation
  • 8. Design Considerations Composting
    • Adequate acclimated microbial inoculum may be present in the contaminated soil
    • Sewage sludge is often added to augment the microbial population
    • Specially developed in the laboratory may be required for specific chemical groups
    • Recycling composted soil can also provide additional viable microbial population
  • 9. Design Considerations Composting
    • Moisture is essential for microbial growth in transporting contaminants, nutrients, and oxygen across the cell membrane
    • High moisture levels reduce porosity and therefore result in decrease microbial activity
    • Optimum moisture level is ~ 50 to 80% of water- holding capacity
  • 10. Types of Composting Systems Composting - Soil placed in closed reactor with mechanical mixing and forced aeration - Aeration by turning the pile manually or mechanically - Aeration by forced air injection Windrows Systems Static Mix Systems In-vessel System Open Systems Closed Systems
  • 11. Windrows System Composting Pile Width = 3 to 4 m (10 to 12 ft) Pile Height = 1.2 to 1.5 m (4 to 5 ft) Overhead sprinkler system
  • 12. Details of Windrow House Composting Overhead sprinkler system Aeration system Leachate collection system
  • 13. Static Pile System Composting Pile height = 3 to 6 m (10 to 20 ft) Aeration system Leachate collection system
  • 14. Static Pile System Composting
    • Mechanical aeration by forced aeration or vacuum extraction
    • Airflow controls temperature and provides oxygen
    • Vacuum extraction minimizes emission of VOCs and off gases; but cools down the pile
    • Forced aeration improves pile temperature by bringing in the heat of compression
  • 15. In-vessel System Composting
    • Better control of temperature and oxygen
    • Emissions of VOCs and OH gases can be captured and treated if necessary
    • Better treatment efficiency due to improved mixing and mass transfer
    • Less affected by environmental and weather conditions
    • Capital intensive

×