physical separation. Some "biosolids" sink, some floats: grease, oil. Skimmed off. Reducing total amount of organics remaining in water. Little microbial activity involve
treating "clarified" water. COntains microbe, possible pathogens, dissolved organics, suspended organics.
part of secondary treatment in which microorganisms are used to reduce organics.
secondary treatment. Manipulate the environment to promote growth of microogranism that degrades organics. Use ____ microbes to produce carbon dioxide and water.
peak efficiency of aerobic microbes in reducing organics. Secondary treatment.
activated sludge tank
clarified water aerated by injection of air. A way to add oxygen so that aerobic microbes will use up oxygen.
A way to add oxygen so that aerobic microbes will use up oxygen. Water sprayed from rotating booming water trickles through deep bed rocks. Pick up oxygen on rock-layers (biofilm) of decomposers. Remove organics as water passes
occurs throughout secondary treatment. Reduce pathogen by_________________
pathogens are trapped in floc. They get killed by _________: protozoans eat bacteria
pathogens are trapped in floc. They get killed by _________: intestinal microbes are not well adapted to this environment. Lose out by ____ for nutrients to "good bugs'
Disinfection after secondary treatment depends on next use. Most effective way to remove giardia and cryptosporidium
Disinfection after secondary treatment depends on next use. Causes fatal mutations
Injection of ozone
Disinfection after secondary treatment depends on next use. Very reactive, very damaging to living thing
Disinfection after secondary treatment depends on next use. Bleach, compressed gas. Very effective disinfectant that oxidizes everything such as proteins. Use at the end, inactivated by excess organics. Don't want to kill beneficial decomposers
anaerobic sludge digester
take care of solids leftover from secondary treatment. Rate of digestion is slower than secondary, metaoblism is less efficient, but faster if warmer. Heated to 95-100F. Does reduce final volume of solid, Some molecules can only be decomposed by this. End product: carbon dioxide and METHANE
end product of anaerobic sludge digester. Organics will be fermented or organic acids + carbon dioxide. It is then converted to _________ by methanogens.
End of water treatment process is left with __________. Very slow to decompose. Not likely to create big problems, can be buried in landfill. Could improve soils, but depend on what is in it.
(genus)-associated with poultry. Meant-contaminated during slaughtering and eggs that pass through cloaca.
(species) bacteria that grow in food, orginally from skin. Secrete toxin into food that induces vomiting and diarrhea. Self-limiting. Associated with SALTY foods.
(species) bacteria that will grow in food. Secrete toxin. Causes vomiting, diarrhea. Source: soil bacteria in dust.
(species) bacteria found in soil. Anaerobic in can food. Causes paralysis
(species) bacteria can grow at cooler temperature (psychrotrophic). Grow at fridge and body temp. Will cause infections and kill white blood cell. Eventually can reach the brain, can cause placenta. High mortality
(genus) bacteria associated with unpasteurized cheese and "pre-cooked meats"-hot dogs, deli meats
brief exposure to high temperature. Can't be too long or changes the quality of food. Used mostly in milk. Kills ALL pathogens, and reduce number of spoilage bacteria (extend shelf-life)
63C for 30mins
low temp, long time (LTLT)
72C for 15 sec
high temp, short time (HTST)
140C for 2 sec
ultra high temp. Usually sterilized milk, if sealed, don't need to refrigerate.
inverted by N.Appert, big prize from napoleon. Heating of food in bottles and seal it. Main concern now is growth from any surviving bacterial spores.
canning temperature needed for high acid foods (pH<4.5). Kills all vegetative cells. If spores survive, can't germinate at low pH
canning temperature needed for low acid food (pH>4.5). Spores will germinate at 100C, so need to use pressure and hotter water.
0-4C. Slows metabolism and growth. Extend shelf life but not forever. Does create good conditions for psychrophiles. Ex) lactobacillus, listeria, pseudomonas
(Genus) spoil meat, secrete green fluorescent slime.
below -20C. Solutes in food depress the freezing point of water. Must have all water in form of solid ice. Can preserve food indefinitely. Some are killed by ice-crystals. Some are simply preserved
high energy/ionizing radiation. Gamma rays. Knock electrons away from atoms. Creates very reactive free radicals that damage cell components. Kills cells
Range of radiation sensitivity: Pseudomonas
Range of radiation sensitivity: Lactobacillus
Range of radiation sensitivity: clostridium and bacillus (spores)
permitted for some foods. Will sterilize but can/will cause chemical changes in food. Creates peroxides that degrade proteins. End product: NH3 and amines. Degrade fats, short chain fatty acids. Was concern might create carcinogen.
prevent, slow spoilage. Dilemma, need to inhibit or kill microbes but agents can't be too toxic.
G.R.A.S. few resctrictions. Most will inhibit the uptake of key amino acids (key nutrients). All lower pH so enzymes won't work-inhibit growths.
Organic acids-often naturally produced in fermented foods. Foods naturally preserved. (cheese)
Organic acids. Vinegar. Often added to veggies, meats, mayo (pickles)
Organic acids. Added to juices, jams, tomatoes, soda (salt)
Organic acids. Added to fruits, margarine, meat
Organic acids. Produced by fermentation. Added to bread (Swiss cheese)
(species) Salt tolerant. Food poisoning in high salt food
nitrates and nitrites
common in preserved meats such as bacon, pepperoni. KILL microbes (Cidal agent) like salmonella by inhibiting enzymes used in ATP productions. Preserve red color of hemoglobin.
in body, we convert nitrites and nitrates to ______ which is CARCINOGENIC.
chemicals added primarily to stop chemical oxidation. Stop oxidation of fats that yields short chain fatty acids (odor, taste problems). May also have anti-microbial activity.