Sewage/Water Treatment and Products that Use Microbes – Exam 4

Water

• potable water is what that is fit for human consumption

• human pathogens in water usually come from human feces

  • E. coli is an indicator organism

  • boiling gets rid of most microbes that come from fecal matter

Water purification

• Water from deep wells does not usually require extensive purification

• purification of non-potable water

  • Flocculation – precipitation of insoluble particles by the addition of alum (aluminum potassium sulfate)

  • Filtration – through sand or charcoal removes most microorganisms

  • Chlorination – kills bacteria

Sewage

• used water and the waste it contains (household, industrial, rain runoff)

• until fairly recently, sewage was flushed directly into rivers (1956 for South Bend)

Sewage treatment

• primary

  • physical removal

  • screens, skimmers, sedimentation

• secondary

  • biological removal

  • treating with microbes

  • uses bacteria to decompose organic waste

• tertiary

  • chemical and physical

  • sand/charcoal filters then chlorine or UV light

• the water is not potable at the end but it is able to be put out again

Septic tanks

• microbes decompose sludge that accumulates

• still must be pumped

• gravel and soil do the final filtration into ground water

• no chlorine

Bioremediation

• use of natural or genetically engineered microbes to transform harmful substances into less or non-toxic ones

• has been used for cleaning up tanks of oil tankers, Exxon Valdez clean-up, decomposing waste in landfill, pig poop

Microorganisms as food

• yeast (health food stores)

• algae (sushi)

• bacteria

• all have been used, all have very high levels of protein per kg

Microorganisms in food production: bread

• yeast produces gas which allows bread to rise – a leavening agent

• Saccharomyces cerevisiae (baker’s yeast) mixed with water, flour, salt, sugar, and shortening at 25ºC will ferment and produce carbon dioxide

Microorganisms in food production: milk products

• cultured buttermilk = bacteria + skim milk

• sour cream = bacteria + cream

• yogurt = bacteria + milk

  • some yogurt manufacturers destroy bacteria, some advertise “live and active cultures”

    • probiotics

• fermented milk beverages – alcohol is produced

  • kefir

Microorganisms in food production: cheese

• bacteria plus bacterial enzymes (rennet) added to milk

  • enzymes cause coagulation

• curd – solid

• whey – liquid (waste) – allowed to drain (soft cheeses) or heat and pressure added for hard cheeses

• ripening – action of microorganisms on curd – from weeks to years (bacteria or fungi)

Microorganisms in food production: others

• vinegar – bacteria

• sauerkraut – anaerobic bacteria and brine

• pickles – anaerobic bacteria and brine

• green olives – bacteria

• poi – bacteria and yeast (natural) – from the taro plant

• soy sauce – fungi and bacteria

Beer, wine, and spirits (potent potables)

• strains of Saccaromyces cerevisiae (brewer’s yeast) are fermenters for all alcoholic beverages

• starting material and strain of yeast determine flavor

• distillation separates alcohol from solids and non-volatile substances

• yeast turn sugar to carbon dioxide and alcohol

Beer

• cereal grains (barley, wheat) are malted (germinated)

• malted grain is crushed and mixed with hot water to make mash

• liquid is removed (wort)

• hops (flower from hop plant) added for flavor

• yeast is added

• typical alcohol content = 6%

Wine

• juice from grapes (or other fruit)

  • (normal flora killed)

• sugar and yeast added

• liquid is siphoned off – may be filtered

• aged in barrels then bottled

• typical alcohol content = 12%

  • about twice as high as beer

Spirits

• barley – scotch whiskey

• rye – rye whiskey

• corn – bourbon

• wine or fruit juice – brandy

• potatoes – vodka

• molasses – rum

• distillation separates volatile substances

• typical alcohol content = 40-50% (30-50%)

• 100 proof = 50% alcohol

  • proof is about the fire that is made when the liquid is burned

Other uses for microbes

• explosives – Clostridium to make acetone

• antibiotics

• genetic engineering

• vitamin production

• simple organic compound production

• synthetic enzymes, amino acids, vitamins, hormones

• biofuel