Environmental Science – Water Pollution

Any harmful substance towards water quality and aquatic life is considered a pollutant. They can be diseases, carriers, inorganic chemicals, sediments, radioactive chemicals, heat, or feces.

There are multiple ways to measure water quality, especially the water quality index (WQI) that compiles several different measurements. Biological oxygen demand (BOD) is the amount of dissolved oxygen (DO) needed by the aerobic organisms in an aquatic environment. Fecal coliform are bacteria that are from feces that suspend in the water, and high levels of this take in a lot of DO that should be used by the natural aquatic organisms, and this enters usually through livestock waste runoff. Indicator species that are intolerant to extremes in the aquatic environment are good hints at when an environment’s quality is getting better or worse.

DO and BOD Sag Curve

Point sources are specific locations where pollutants came from like factories and sewage while non-point locations are not specified like runoff from crops or parking lots.

Pollution in groundwater comes from oil spills, pipeline bursts, and dumping tanks and landfills.

The cleanup process is split up into several steps:

Primary treatment is physical, containing filters to remove particulate matter such as fecal matter, debris, and floats producing a raw sludge byproduct.

Secondary treatment involves using bacteria to biologically remove hazardous and organic material by letting it get ingested by the detritus feeders. Oxygen is added to this part to help the biological cleaners to live as well. This leaves behind a nutrient-rich byproduct so secondary BNR systems are added to remove the feeders and the substances like Phosphorous and Nitrogen that could cause eutrophication.

The last step is to disinfect the water full of bacteria that ate organic waste. Chlorine gas can be used as well as ozone and UV radiation.

The byproduct sludge could be used as fertilizer once pathogens are killed but most of it is wasted.

Thank you and stay tuned!

-Neil 

Editor of StemTalksNC

Credit:

https://www.ecosia.org/images?q=bod+and+do+sag+curve#id=9AAC5EDD62C7FC2B3B56294501BADE6AA76BE6A0

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