iron and manganese Flashcards by marissa halil | Brainscape

Q

where can you find Mn and Fe?

A

as high concentrations in groundwater and as high concentrations in surface water during specific times of the year

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Q

why does the concentration of Fe and Mn in surface water changes in some specific times of the year?

A

local and temporal changes are the reason, they happen due to biochemical reactions

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Q

what are some dissolving iron compounds in water?

A

-its mostly found as ferric iron (Fe+3) and pyrite (FeS2) in soil
-FCO3, siderite->its solubility in water is low but CO2 that gets carried by grounwater converts siderite into easily soluble HCO3
-

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Q

explain the solubility of Mn compounds in water

A

Mn in water is found as MnO₂ and it does not dissolve
-under anaerobic conditions in soil, if MnO is converted to +2 valuable manganese compounds by reduction, then CO2 containing water can easily dissolve Mn + 2

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Q

what are the 4 points of dissolution of Fe and Mn ions into water?

A

1) Fe+2 and Mn+2 are found in water w/less oxygen and higher CO2 like groundwater
2)the original organic wastes that are piled around wells are valuable and give good quality water however when Fe and Mn contamination occurs, poor quality water occurs as well
3)Fe and Mn will concentrate on the lower layers of a stratisfied lake and keep that environment anoxic -in autumn especially
4)Fe+3 and Mn+4 can be found in oxygenated water

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

why are Mn and Fe important in env. eng.?

A

Mn is more readily absorbed from drinking water than food filled with Mn
-acidic groundwater and industrial discharges have higher levels of Fe and Mn
-Mn is found more in groundwater
-excess amount of Fe and Mn is not that harmful to humans
-when Fe+2 and Mn+2 are oxidized, Fe+3 and Mn+4 occur and they cause cloudy and colorful look in water
-they cause growth of iron bacteria colonies in distribution piipes
-Fe gives taste to water
-Fe should be less than 0.3 mg/L
-Mn should be 0.05 mg/L

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Q

explain oxidation in Fe and Mn treatment

A

-the oxidant chemically oxides Fe or Mn and it kills any iron bacteria or pathogenic microorganisms
-a filter removes the Fe/Mn particles
-after oxidation, filtration happens
-Fe+2 is oxidized to Fe+3 which helps forming insoluble iron hydroxide complex Fe(OH)3
-Mn+2 is oxidized to Mn+4 which forms insoluble MnO
-most common chemical oxidants: chlorine, chlorine dioxide, potassium permanganate and ozone.

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Q

what are the types of treatment for Fe and Mn in water?

A

-oxidation/filtration
-aeration/filtration
-filtration
-sequestration
-ion exchange

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Q

explain aeration/filtration as a Fe/Mn treatment process

A

-backwashing the filter periodically is important
-its not recommended for water with Fe/Mn bacteria or colloidal Fe/Mn cause they clog aspirators and filters
-air is pulled and mixed with the water stream
-the air+water enters a precipitator/aerator vessel where water-air.
-then water flows through a filter with various filter media screen out oxidized particles of Fe/Mn/HCO3/SO4

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Q

explain filtration in Fe/Mn treatment

A

-types of filtration for Mn/Fe: Mn greensand, anthra/sand or ironman sand, electro media and ceramic
-the most common one: Mn green sand (through pressure filtration)

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Q

explain sequestration

A

-its the addition of chemicals to groundwater in order to control Mn and Fe problems
-they’re added at the well head or at the pump intake before water gets in contact with chlorine or air
-Mn and Fe stays in a soluble form
-polyphosphates+chlorination: use when Fe is less than 1 mg/L and Mn is less than 0.3 mg/L (no sludge)

Q

explain ion exchange

A

-only for removing small amounts of Fe/Mn
-it can cause clogging
-it uses synthetic resins

Q

how can we minimize problems due to Mn/Fe in distribution mains?

A

-prior removal by appropriate treatment
-protecting iron/steel mains with bitminous linings or using non corrosive materials
-avoiding dead end mains
-avoiding disturbances in the water flow
-flushing oftenly

Q

what are the negative effects of excess Mn/Fe in water?

A

-corrosion in pipes
-bad smell and taste
-color
-scales in boilers
-excessive amounts(over 3000 mg/L) causes disturbences in livestock