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Metallrening av lakvatten med SRB

Torén, Dante LU (2020) KMBM05 20192
Applied Microbiology
Abstract
Hässleholm Miljö who own the landfill site in Vankiva in southern Sweden are having difficulties in keeping their heavy metal emissions within the limits of their very strict permit. Today reduction is reached by chemical precipitation, but a more effective and environmentally friendly process is wanted.
Biological heavy metal removal in leachate water, using sulfate reducing bacteria (SRB) and metal sulfide precipitation, was tested in a pilot study situated in Vankiva, just outside of Hässleholm city. Two 1 m3 reactors of up-flow fixed bed configuration were used in parallel. The two reactors were filled with different growth mediums, plastic AnoxKaldnes k5 carriers and wood chips. The analyzed metals were Copper, Lead, Zink, Iron,... (More)
Hässleholm Miljö who own the landfill site in Vankiva in southern Sweden are having difficulties in keeping their heavy metal emissions within the limits of their very strict permit. Today reduction is reached by chemical precipitation, but a more effective and environmentally friendly process is wanted.
Biological heavy metal removal in leachate water, using sulfate reducing bacteria (SRB) and metal sulfide precipitation, was tested in a pilot study situated in Vankiva, just outside of Hässleholm city. Two 1 m3 reactors of up-flow fixed bed configuration were used in parallel. The two reactors were filled with different growth mediums, plastic AnoxKaldnes k5 carriers and wood chips. The analyzed metals were Copper, Lead, Zink, Iron, Aluminum, Nickel, Arsenic, Manganese and Chromium. Results from the reactor with plastic carriers showed an average reduction of total metal concentration of Cu, Pb, Fe, Zn, Al, Ni and As to be 65, 66, 71, 74, 52, 32 and 16 % respectively. The reduction of dissolved metals in the same reactor was observed to be 86, 97, 87, 87, 25 34 and 15 % respectively. The reactor with wooden chips as substrate showed similar results except for Aluminum for which it was more effective, and for Arsenic for which it was considerably less effective. No reduction of Manganese or Chromium was observed in either of the reactors.
The SRB showed high resistance to changes in waterflow and water quality. Temporary disturbances caused temporary loss in sulfate reduction, but the capacity was rapidly restored when conditions were returned to “normal”. The reactors showed a sensitivity to suddenly increased flow resulting in a flush out of metals.
A high production of sulfide was reached (about 85-99 % of all sulfate) and to take advantage of the abundance of sulfate a new reactor step was introduced. In the new step sulfide containing leachate water from the SRB reactor was mixed with untreated water resulting in an additional reduction of dissolved metals in a larger volume of water. Results showed that 2-3 times the amount of dissolved metals could be reduced by adding this step.
If this process would have been added at a full scale, it would have been enough to pass the emission limits for all metals that exceeded them in 2018, except for chromium. (Less)
Popular Abstract (Swedish)
3,5 miljarder år gamla bakterier kan rädda våra vatten från metallutsläpp

Långt innan det fanns syre i atmosfären så fanns bakterier som ”andades” svavel. I stället för att andas ut koldioxid andas dessa bakterier ut sulfid, en negativt laddad svaveljon som binder till metaller. På en avfallsanläggning utanför Hässleholm står en testanläggning där man forskar på att minska utsläppen av metaller till naturen med hjälp av svavelreducerande bakterier.

Varje år läggs omkring 55 miljoner ton avfall utspritt på över 250 olika deponier i Sverige. Detta är 55 miljoner ton skräp årligen som varken återvinns eller förbränns, utan bara läggs på en hög. En deponi kan sammanfattas som en lite bättre planerad soptipp, de designas så att de inte... (More)
3,5 miljarder år gamla bakterier kan rädda våra vatten från metallutsläpp

Långt innan det fanns syre i atmosfären så fanns bakterier som ”andades” svavel. I stället för att andas ut koldioxid andas dessa bakterier ut sulfid, en negativt laddad svaveljon som binder till metaller. På en avfallsanläggning utanför Hässleholm står en testanläggning där man forskar på att minska utsläppen av metaller till naturen med hjälp av svavelreducerande bakterier.

Varje år läggs omkring 55 miljoner ton avfall utspritt på över 250 olika deponier i Sverige. Detta är 55 miljoner ton skräp årligen som varken återvinns eller förbränns, utan bara läggs på en hög. En deponi kan sammanfattas som en lite bättre planerad soptipp, de designas så att de inte ska avge föroreningar till grundvattnet och när en deponi tas ur användning täcks den över med plast eller annat material för att minska intrånget av nederbörd, men trots detta läcker de en viss mängd föroreningar till bäckar och sjöar, och slutligen våra hav.
Vatten som varit i kontakt med en deponi och blivit förorenat kallas för lakvatten, lakvatten från en deponi behandlas, och när det släpps ut innehåller det låga mängder metaller, men eftersom metaller lagras i fettvävnad hos levande organismer som musslor och fisk kan detta ha stora konsekvenser för ekosystemen.
Metaller i vatten förekommer i olika former, antingen löst som enskilda joner eller bundet till organiska partiklar. Metaller i form av fria joner är de som är svårast att bli av med i reningsverken och stora delar rinner rakt igenom. Fria joner är också den mest giftiga formen av metallutsläppen.
För att bli av med metaller behandlas idag vattenmassor genom tillsats av kemikalier som gör att jonerna binder och klumpar ihop sig till större partiklar (flockar), dessa kan man sedan filtrera bort eller bli av med genom sedimentation. För att ha ett miljömässigt och ekonomiskt hållbart reningssystem så är det önskvärt att hitta en lösning som inte innebär tillsats av kemikalier.
På testanläggningen har man lyckats odla svavelreducerande bakterier som reducerar sulfat till sulfid. Sulfiden binder till de flesta metalljoner och skapar flockar som kan renas från vattenmassan, detta utan att något som helst tillskott av externa kemikalier behövs. Sulfatet tillsammans med organiskt material är naturligt förekommande i lakvattnet vilket gör processen potentiellt både miljömässigt och ekonomiskt överlägsen konventionella reningsmetoder. (Less)
Please use this url to cite or link to this publication:
author
Torén, Dante LU
supervisor
organization
alternative title
En studie på Vankiva deponi i Hässleholm
course
KMBM05 20192
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Metallrening, Metaller, Lakvatten, SRB, Fällning, Sulfid, Deponi, applied microbiology, teknisk mikrobiologi
language
Swedish
id
9005467
date added to LUP
2020-02-25 13:14:48
date last changed
2020-02-25 13:14:48
@misc{9005467,
  abstract     = {Hässleholm Miljö who own the landfill site in Vankiva in southern Sweden are having difficulties in keeping their heavy metal emissions within the limits of their very strict permit. Today reduction is reached by chemical precipitation, but a more effective and environmentally friendly process is wanted.
Biological heavy metal removal in leachate water, using sulfate reducing bacteria (SRB) and metal sulfide precipitation, was tested in a pilot study situated in Vankiva, just outside of Hässleholm city. Two 1 m3 reactors of up-flow fixed bed configuration were used in parallel. The two reactors were filled with different growth mediums, plastic AnoxKaldnes k5 carriers and wood chips. The analyzed metals were Copper, Lead, Zink, Iron, Aluminum, Nickel, Arsenic, Manganese and Chromium. Results from the reactor with plastic carriers showed an average reduction of total metal concentration of Cu, Pb, Fe, Zn, Al, Ni and As to be 65, 66, 71, 74, 52, 32 and 16 % respectively. The reduction of dissolved metals in the same reactor was observed to be 86, 97, 87, 87, 25 34 and 15 % respectively. The reactor with wooden chips as substrate showed similar results except for Aluminum for which it was more effective, and for Arsenic for which it was considerably less effective. No reduction of Manganese or Chromium was observed in either of the reactors. 
The SRB showed high resistance to changes in waterflow and water quality. Temporary disturbances caused temporary loss in sulfate reduction, but the capacity was rapidly restored when conditions were returned to “normal”. The reactors showed a sensitivity to suddenly increased flow resulting in a flush out of metals.
A high production of sulfide was reached (about 85-99 % of all sulfate) and to take advantage of the abundance of sulfate a new reactor step was introduced. In the new step sulfide containing leachate water from the SRB reactor was mixed with untreated water resulting in an additional reduction of dissolved metals in a larger volume of water. Results showed that 2-3 times the amount of dissolved metals could be reduced by adding this step. 
If this process would have been added at a full scale, it would have been enough to pass the emission limits for all metals that exceeded them in 2018, except for chromium.},
  author       = {Torén, Dante},
  keyword      = {Metallrening,Metaller,Lakvatten,SRB,Fällning,Sulfid,Deponi,applied microbiology,teknisk mikrobiologi},
  language     = {swe},
  note         = {Student Paper},
  title        = {Metallrening av lakvatten med SRB},
  year         = {2020},
}