BIOL108 Lecture Notes - Lecture 24: Activated Sludge, Settling, Laundry Detergent
3 Aug 2018
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15th of May 2018: Lecture 28 – Microbes and Humans
▪ Fermentation in Food Processing:
− Fermentation: the microbial activity converts carbs into lactic acids or alcohol
under anaerobic conditions. The low pH or the alcohol produced then prevents
the growth of spoilage organisms
− There are numerous of food products that are fermented; cheese, yoghurt,
salami, fish sauces, olives, pickles, bread, soy sauce, chocolate, coffee
▪ Harvesting microbial enzymes:
− Enzymes are a valuable part of many industrial and medical processes
− Almost all commercial enzymes are obtained from microorganisms
− For example; enzymes such as proteases, lipases and amylases are purified from
microorganisms that live in cold temperatures. These enzymes are active in the
cold and work so well in the cold water laundry detergent
▪ Biochemical from Micro-organisms:
− Amino acids:
− Animals cannot synthesis some amino acid, and these must be obtained in diet.
− Worldwide production of amino acids from microorganisms is some 400,00
tons/yr
− Steroids:
− Difficult to chemically synthesis or purify
− Valuable steroids such as cortisone (anti-inflammatory), estrogens and
progesterone (in oral contraceptives) can be more easily synthesized from plant
sterols using microbial species
− Vitamins:
− Microbially synthesized where chemical methods are too expensive
For example: B12 is purified from Propionibacterium shermanii or Pseudomonas
denitrificans
▪ Sewage Treatment:
− In the past, disposal of untreated waste was commonly achieved by direct
disposal into rivers and streams
− Free flowing, aerated streams can self purify, but the quantity of water and solid
matter discharged cities overwhelms such natural regeneration
1. Primary Treatment:
− Large floating materials are screened out, skimmers are used to remove floating
oil and grease and sediment and grit are allowed to settle out. In a second
settling tank, more solids settle out as “primary sludge”. This removes up to 60%
of the suspended solids
2. Secondary Treatment:
− Effluents from the primary sedimentation tanks undergo aeration in an activated
sludge system or a trickle filter system. Microbial activity oxidizes the organic
matter. The remaining secondary sludge is sent to a sludge digestion tank where
anaerobic microorganisms decompose the organic waste to genetic methane.
3. Tertiary Treatment:
− Removes all remaining nitrogen, phosphorus and organic matter. It is mainly
dependent on physical and chemical treatments
Document Summary
15th of may 2018: lecture 28 microbes and humans: fermentation in food processing: Fermentation: the microbial activity converts carbs into lactic acids or alcohol under anaerobic conditions. The low ph or the alcohol produced then prevents the growth of spoilage organisms. There are numerous of food products that are fermented; cheese, yoghurt, salami, fish sauces, olives, pickles, bread, soy sauce, chocolate, coffee: harvesting microbial enzymes: Enzymes are a valuable part of many industrial and medical processes. Almost all commercial enzymes are obtained from microorganisms. For example; enzymes such as proteases, lipases and amylases are purified from microorganisms that live in cold temperatures. These enzymes are active in the cold and work so well in the cold water laundry detergent: biochemical from micro-organisms: Animals cannot synthesis some amino acid, and these must be obtained in diet. Worldwide production of amino acids from microorganisms is some 400,00 tons/yr.
