Environmental Science, week 8

lecture 13, water management

point pollution

discharges pollutants at specific locations

• sources: factories, animal feed lots, underground mines, oil wells, and oil tankers

• easy to identify because you can go back to the specific source, so it is also easy to monitor and regulate

nonpoint pollution

• broad, diffuse areas due to rainfall or snowmelt washing pollutants from land into surface water

• sources: runoff, fertilizers and pesticides, logged forests, lawns, and golf courses

• can be more challenging to identify, monitor, and regulate because you cannot identify a specific source, since its so broad

sewage in Philly

fewer streams in modern Philly compared to before

→ can be due to urban development

→ more evaporation

→ sewage

• Philly built sewage system where historic streams are located

types of sewers: combined sewer and separate sewer 

combined sewer:

• used in older cities

• storm drain and sewage drain are combined in the same infrastructure

• to prevent solid waste to enter rivers, a dam structure is made into the pipes

• MORE EFFICIENT

separate sewer:

• sewage goes to a sewer to water treatment plan, not into the creek

• stormwater goes to the creek

history of water management in the US

• Cuyahoga river in Cleveland caught fire 10 times between 1868 and 1969 because it was covered in oil

• caused by high amounts of flammable materials dumped by industry into the river

• after the 1969 fire, the mayor worked to push for environmental regulation

clean water act of 1972

environmental protection agency (EPA) implements pollution control programs such as:

•Set wastewater standards for industry

•Developed national water quality criteria

•Funded construction of sewage treatment plants

safe drinking water act of 1996

• regulations to reduce harmful products in drinking water

• EPA can establish regulations for new contaminants

• EPA can review and revise existing national drinking water regulations

• new contaminants can continually be discovered

50-year perspective in 2022

• only half of US waters have been assessed as of 2013

• EPA lacks reliable information needed to ensure polluters are complying with their permits

• nonpoint sources are difficult to trace and manage 

drinking water treatment

water from a dam gets treated and tested → goes through a water supply system → after use, municipal sewer lines collect wastewater → quality of wastewater is restored by sewage treatment before the treated effluent is dispersed into a nearby body of water 

wastewater treatment

primary treatment

• physical properties can be modified to treat things

• debris and grit are removed & go to a landfill

• then, it enters a primary clarifier to REMOVE PARTICULATE ORGANIC MATERIAL (oil/sludge)

Secondary treatment

• after water enters the primary clarifier

• chemical treatment is applied

• ex= chlorine is applied to remove bacteria

• undergoes another secondary clarifier to further remove sludge from killed bacteria

• can then be released back into the environment

phosphorous and nitrogen

• nutrients that cause eutrophication

• MUST BE FILTERED OUT 

case study: flint water crisis

• 2014 - modern day

• national emergency

• lead poisoning, present in children’s blood

• water is heavily polluted

• switched from detroit to flint water (flint water was cheaper), and flint water was heavily polluted:

→ lead leaching from pipes, legionnaires disease, fecal coliform bacteria, elevated levels of cancer-causing chemicals due to over-chlorination of water

1. capture runoff- sustainability solution

rainwater harvesting with barrels and cisterns

• preventing runoff from going on impermeable surfaces

1. improve infrastructure

1. green stormwater infrastructure- ways to divert water from impermeable surfaces to vegetative surfaces that retain water during storm events and slow runoff into existing stormwater drains

2. permeable pavement- uses materials that allow water to seep through and helps reduce runoff into waterways and increase groundwater recharge

blue-green roofs- apart of improving infrastructure

• new design

• captures rainwater

• concept of a sponge city (takes in freshwater supply and can be diverted for more useful practices)

• ex= water is held in a tank that sits on a roof, and water is released (in a timed manner) to allow for more storage of freshwater

→ outflow is controlled and can be captured for other purposes

through evapotranspiration, roots of plants can take some of this water for their own purposes

3. desalinization

removal of salt from ocean or brackish water

2 methods:

1. distillation- evaporation of salt water and water vapor is condensed into freshwater

2. reverse osmosis- forcing salt water through a membrane permeable to water, but not salt

4. conserve water use

decrease demand for water

• grey water use: can be used to flush toilets, wash cars, or water a lawn

• water saving household fixtures

• Xeriscaping- replacing your lawn with gravel and plants that thrive in dry environments, so watering your lawn is not needed

summary for water week

• readily accessible freshwater is relatively scarce and not evenly distributed

• human activity is impacting the hydrologic cycle and polluting our existing source of freshwater

• sustainable solutions are ones that reduce the use and contamination of our water resources