Water and Wastewater Treatment Analysis of Water Quality Water Purification Wastewater Treatment

Analysis of Water Qualtity Microbial Indicators Indicators of the presence of fecal contamination of water supplies Coliforms: Total Coliforms: Gram-negative, facultatively anaerobic, nonsporing, rod-shaped bacteria that ferment lactose with gas formation at 35°C Fecal Coliforms: Coliforms that can grow at 44.5°C

Analysis of Water Quality Methods for Detecting Coliforms Most Probable Number (MPN) test Multiple dilution tubes of lactose or lauryl tryptose broth are inoculated with 10, 1, and 0.1 ml of a water sample, then incubated at 35°C for 24 hr Tubes that are positive for gas are used to inoculate brilliant green lactose bile broth tubes, which are incubated at 35°C for 48 hr Tubes that are positive for gas are further confirmed by streaking onto EMB or Endo agar Estimated value of Most Probable Number is determined from MPN tables

Analysis of Water Quality Methods for Detecting Coliforms Membrane Filtration Technique Samples are filtered on 0.45 um filters and plated onto selective media at appropriate temp Total Coliforms: Endo medium at 35°C for 24 hr Fecal Coliforms: mFC medium at 44.5°C for 24 hr Fecal streptococci (enterococci): KFS medium at 35°C for 48 hr

Analysis of Water Quality Methods for Detecting Coliforms Presence-absence (PA) test 100 ml of a water sample is cultured in a single bottle of lactose broth, lauryl tryptose broth, and bromocresol purple indicator Yellow color indicates a positive presumptive test & requires further confirmation

Analysis of Water Quality Methods for Detecting Coliforms Colilert MUG test 100 ml of sample added to MUG medium, containg ONPG and MUG Incubated for 24 hr at 35°C Yellow color indicates coliforms Examined under a long-wave UV lamp for fluorescence; this indicates presence of E. coli

Analysis of Water Quality Measurements of carbon in water Total Organic Carbon (TOC) Organic carbon in the sample is oxidized at high temperature with an oxygen stream The resulting CO 2 is quantified by infrared or potentiometric methods

Analysis of Water Quality Measurements of carbon in water Chemical Oxygen Demand (COD) Instead of using oxygen, the organic carbon in the sample is oxidized with a strong chemical oxidizer under acidic conditions Potassium permanganate has often been used; however, permanganate will not react with lignin, potentially resulting in an underestimate of the carbon content

Analysis of Water Quality Measurements of carbon in water Chemical Oxygen Demand (COD) Potassium dichromate has been shown to be more effective in oxidizing almost all the organic carbon in a sample After oxidation is complete, the amount of Cr 3+ is determined as an indirect measure of organic carbon

Analysis of Water Quality Measurements of carbon in water Biological Oxygen Demand (BOD) Estimates the organic carbon in a sample by measuring the amount of oxygen required by microorganisms in the sample to degrade the organic matter under a set of standardized conditions (usually 5 days at 20°C)

Analysis of Water Quality Measurements of carbon in water Biological Oxygen Demand (BOD) The water sample is often seeded with a small amount of microbes (for example, an activated sludge sample) The sample is diluted with water saturated with oxygen (saturation can be achieved by shaking up the bottle), the initial oxygen concentration is determined with an oxygen electrode, and the bottle is sealed and placed in the dark After 5 days at 20°C, the final oxygen concentration is determined. The final value is subtracted from the initial value and divided by the dilution factor to give the BOD

Water Treatment Initial Filtration Coagulation (Flocculation) & Sedimentation Disinfection Other treatments Softening Aeration Fluoride treatment

Wastewater (Sewage) Treatment Primary sedimentation Solids are allowed to settle to form sludge and primary effluent Secondary treatment The primary effluent is pumped into a secondary treatment system, where microbes are allowed to digest the bulk of the organic matter in the effluent Aeration Tanks/Activated Sludge Systems Trickling Filter Systems

Wastewater (Sewage) Treatment Secondary treatment (cont.) The sludge from the primary treatment is processed either in an anaerobic sludge digester or an aerobic sludge digester, where microbes in the sludge reduce the amount of organic matter The secondary sludge may be used as fertilizer or disposed of in landfills

Wastewater (Sewage) Treatment Tertiary Treatment The secondary effluent is clarified by removing finely divided, suspended solids in a clarification tank; flocculating agents such as alum may be used in this step The clarified water is disinfected by chlorination, ozonation, and/or UV treatment The treated water is released into the environment, such as a lake or river

Wastewater (Sewage) Treatment Septic tank system Used for homes in areas where there is no sewer system Wastewater flows into a septic tank that is buried near the home Solids in the waste settle to the bottom of the septic tank and are digested by anaerobic microbes Liquid effluent from the waste flows into the ground through “field lines,” which are perforated pipes connected to the septic tank