final Flashcards
Define point of entry household water treatment. What issues does it address?
Whole home filtration system installed where the water enters the house
Addresses issues of hard water from calcium and magnesium and taste and odor due to chlorine
Define point of use filters.
Treats a portion of water in the home that would not be used for bathing or cleaning
Most systems are used for drinking water and cooking use through a separate tap rather than the faucet
Installed under sink or at the beginning of the fridge water
Most common are carbon filtration systems that improve taste and odor
Define reverse osmosis
The processes of osmosis and reverse
A reverse osmosis membrane is a semi permanent membrane that allows the passage of water molecules but not the majority of dissolved salts, organics, and microorganisms
water is pushed through the reverse osmosis membrane by applying pressue that is greater than the naturally occuring osmotic pressure in order to desalinate water in the process
This allows pure water through while holding back a majority of the contaminants
Reverse osmosis membrance rejects contaminants based on their size and charge
Define the clean water act
The clean water act addresses water pollution and discharges
Enacted in 1948 and amended in 1972
Established a structure for regulating pollutant discharges into the waters of the US
Gave EPA authority to establish pollution control programs
Define the Safe Drinking Water Act
Protects public drinking water supplies throughout the US
EPA set standards for drinking water quality and implements various programs to ensure drinking water safety
Define the drinking water contaminant candidate list (CCL)
A list of contaminants that are currently not subject to any proposed or promulgated national primary drinking water regulations but are known or anticipated to occur in public water systems
Define watewater-based epidemiology
a method to understand the distribution and determinants of health-related states and events using wastewater samples from the sewershed
non-invasice, unbiased, population-level, near real time status
How did the Greeks have a history in wastewater?
Beginning of plumbing and drainage in Greece began in 1500 BC
Prior to the 19th century, Greece had the most developed waste managment of any division
Describe the steps of wastewater treatment
- Transportation to WWTP through WW system
- Preliminary treatment: SEDIMENTATION - removes grit, rags, and solids that float and may harm other operations at the WWTP(bar racks, mechanical screens, grit chamber)
- Primary treatment: sewage flows slowly to frit tanks where particles of sand and grit settle out - fine particles remain suspended in sewage so it is passed to large primary sedimentation tanks where most of the remaining particles settle out to form sludge
- Secondary treatment: biological process that involves the oxidization of dissolved organis material by microogranisms to decompose the organic compounds (filter beds and activated sludge), increases oxygen availibility
- Tertiary treatment: only used if necessary to reduce plant nutrients or toxic compounds beyond acceptable levels (nutrient stripping, UV disinfection, filter membrance)
How is advanced purified watre treatment proposing to be used?
A portion of treated WW will go directly to an advanced water purification facility where the purified water becomes a new source of drinking water to increase drinking supply
What are the two methods used in secondary ww treatment?
- Filter beds: liquid is sprayed slowly over beds of broken stone or gravel which provide a large surface area for oxidization microbes living eithin filter beds to break down organic matter - liquid that collected at the base of the filter bed contains some waste products that are then separated from effulent and sent to sedimentation tanks producing more sludge
- Activated sludge: a sludge containing bacteria and other organisms is mixed with the liquid and the whole mixture is agitated by paddles or has compressed are bubbles through it to keep it well oxygenated - process lasts ten hours then mixture flows to sedimentation tanks where sludge settles out from effluent
What gas can be produced by the digestion of sewage sludge?
Methane
Why implement drinking water treatment?
- Remove the things that can cause disease
- Remove the things that can create nucances
Overall goal of protecting public health
Name some health-related contamiants
Pathogens
Inorganic agents (arsenic, lead, nitrate, nitrite)
Disinfection byproducts formed during cholrination
Name some aesthetic contaminants (affect appearance, odor, and taste)
Iron, magnesium, and calcium (taste and hardness)
Chlorine and Chloromine (taste and hardness)
Organic Colloidal particales (color)
hydrogen sulfide has (bacterial anaerobic decay causing odor)
turbidity (suspended solids)
Name the steps of water treatment
- Assessing intake water: cornerstone of water treatment, when groundwater is involved first concern is to design an intake that draws in the least possible amount of soil and sand; surface water intake must be adapted to various elements that water sources may contain
- Chemical action: Prechlorination is when chlorine is applied to water immediately after entering treatment facility - eliminated algea and other forms of aquatic life so they won’t cause issues later; aluminum sulfate added as a coagulant to bind fine particles; CaOH added to adjust pH
- Sedimentation Basins: water moves slowly causing heavy particles to settle to the bottom; flock/sludge sinks to bottom of basin
- Filtration: water flows through filter designed to remove particles; filters made of layers of sand and gravel or crushed anthricite; filtration collects the suspended impurities which enhances the effectiveness of disinfection
- Disinfection: ensures that any pathograns are destoyed, usually using chlorine; provides residual disinfectant
What system is used for treatment of water with a surface water intake?
Filtration system to control microorganisms, turbidity, color, taste, and odor
What system is used to treat water from a groundwater intake?
Removal of manganese, arsenic, iron, CO2, and HSO common in groundwater
Define hardness
Results from presence of magnesium and calcium ions in water; associated with groundwater
Define flouridation
Fluoride added to drinking water supply
How do you mitigate taste and odor control
oxidation using chlorine, ozone, potassium permanganate or granular activated carbon
How do you mitigate corrosion control in pipes
Lyme and soda ash increases pH to reduce corrosion
Sinz orthophosphate lines the inside of pipes as protection
Where is the best location for WW sampling for analyzing infection trends of a community?
Primary tanks
Where is the best location for WW sampling for analyzing the infection status of a university campus?
Building level sampling