2/3/99

Public Health

 

Food Safety

-Nutrition book, ch 18, table 18.1

 

Sewage treatment

-need to make water non-offensive

-3 steps:  primary, secondary, tertiary

-required by all states to have at least secondary treatment facilities

-in secondary treatment add soda-lime, a chlorine rich material

-tertiary treatment is extreme purification process--only done where water has to be recycled esp. in areas of dry weather

 

Primary Treatment

-screens remove wastes, use skimmers, sedimentation tanks w/ flocculating agents to get solids to settle,--removes large solids

-water is drained and sludge is removed

 

Secondary Treatment

-water from tanks now flows into filtering tanks and filtrates are subjected to biological breakdown or oxidation

-this produces CH4 gas--advantage

-organisms used are anaerobic gram (+) (peptococcus, methanococcus

 

Septic Tank System

-must be 15m from water wells

-must be 15ft from house

-drains fields and cistern tanks

 

Clivus Multrum

-collecting unit w/exhaust fan to remove odor

-solid waste is allowed to settle and microorganisms act on solid waste to turn it into fertilizer

-kept in basement

-composing toilet in Europe

-gray water--water from kitchen

-eventually waste used as fertilizer