Water Quality Lecture Notes Flashcards

The flashcards cover surface and groundwater differences, the reverse osmosis desalination process, categories of water pollution, chemical disinfection methods (Chlorination, Ozonation, Chlorine Dioxide), and the stages of sewage treatment.

Surface water?

Any body of water found on the Earth's surface, such as oceans, rivers, lakes, streams, and wetlands.

How is surface water primarily fed within the water cycle?

By precipitation like rain and snowmelt.

Where is groundwater specifically located?

Underground in the spaces and cracks between soil, sand, and rock.

What is an aquifer?

Underground layers of permeable rock that store vast amounts of water.

How does groundwater purify itself as it moves through the earth?

It is naturally filtered through layers of sediment.

Which source makes up the vast majority of Earth's liquid freshwater?

Groundwater.

What is the primary difference between surface water and groundwater regarding drought resistance?

Surface water dries up quickly, but groundwater is more drought-resistant.

What technology uses high pressure to force water through a semipermeable membrane?

Reverse osmosis (RO).

What percentage of total dissolved solids (TDS) can Reverse Osmosis eliminate?

$99\%$.

In Reverse Osmosis, what are the names of the two streams produced?

Purified water (permeate) and wastewater (brine).

In the 4-step desalination process, why is pre-treatment with sand and gravel necessary?

To remove larger debris like seaweed, algae, and sand that would otherwise clog and ruin expensive RO membranes.

What range of pressure is used by industrial pumps during the Extreme Pressurization step of desalination?

$55$ to $85\,bars$ ($800$ to $1,200\,psi$).

How many times greater is the pressure used in desalination compared to a car tire?

Roughly $20$ times the pressure.

During membrane separation in desalination, what specific ions are blocked while pure water molecules pass through?

Sodium and chloride ions (salt).

Why is freshwater too acidic and tasteless immediately after membrane separation?

Because it has been completely stripped of everything, including minerals.

What substances are injected back into the water during post-treatment remineralization?

Calcium, magnesium, and carbon dioxide.

What happens when aerobic bacteria consume oxygen-demanding waste in a water body?

They use up the dissolved oxygen, creating hypoxic zones (dead zones) where aquatic life suffocates.

List four waterborne diseases spread by disease-causing pathogens in contaminated water.

Cholera, dysentery, typhoid, and giardiasis.

What is turbidity and what is its negative effect on aquatic plants?

Turbidity is cloudiness caused by suspended solids; it blocks sunlight, halting photosynthesis.

What is the collective term for heavy metals like lead and mercury that do not break down easily?

Toxic pollutants.

What is the difference between bioaccumulation and biomagnification?

Bioaccumulation is the buildup of substances in an organism's tissues, while biomagnification is the process where concentrations increase as they move up the food chain.

How do dissolved salts like sodium chloride and calcium chloride enters freshwater?

Through road salt runoff used for winter de-icing, irrigation drainage, and industrial wastewater.

How does gasoline and oil contamination cause hypothermia in marine birds and mammals?

It coats feathers and fur, destroying their insulation and buoyancy.

What is thermal pollution, and what is its most common cause?

The unnatural heating or cooling of water, mostly caused by power plants and industrial factories using local water as a coolant.

What is the relationship between water temperature and dissolved oxygen?

Warm water holds less dissolved oxygen than cold water.

What is chlorination?

A chemical disinfection process involving the addition of chlorine or chlorine compounds to form oxidizing agents that destroy pathogens.

What is a 'chlorine residual' and why is it helpful?

It is a leftover dose of chlorine that prevents bacterial regrowth inside pipes as water travels to the tap.

How is ozone ($O_3$) generated on-site at treatment plants?

By passing oxygen through a high-voltage electrical field.

Which highly resilient parasite is specifically noted to be destroyed by Ozonation?

Cryptosporidium.

What is a drawback of Ozonation regarding the pipe network?

It leaves no chemical residue, so plants must still add a secondary disinfectant like chlorine to prevent regrowth in pipes.

What is chlorine dioxide ($ClO_2$) treatment?

An advanced disinfection process using a highly selective, dissolved gas that does not form harmful chlorinated byproducts.

Which two chlorine-resistant parasites are effectively destroyed by chlorine dioxide?

Cryptosporidium and Giardia.

What inorganic salt is found in fertilizers and can cause 'blue baby syndrome' in infants?

Ammonium Nitrate.

How does Ammonium Nitrate contribute to eutrophication?

It causes algal blooms that deplete oxygen in the water.

What is DDT (Dichlorodiphenyltrichloroethane)?

A synthetic pesticide categorized as a persistent organic pollutant (POP).

What is a specific impact of DDT on bird populations?

Thinning eggshells, leading to reproductive issues.

In sewage treatment, what occurs during the 'Screening' stage of Primary Treatment?

Removal of large solids such as sticks, plastics, and rags.

What is the result of the Sedimentation step in Primary sewage treatment?

Grit and solids settle to the bottom as sludge.

What happens in the Aeration Tank during Secondary Treatment?

Bacteria consume organic matter with the help of oxygen.

What is Biofiltration in the context of sewage treatment?

A process where sewage trickles over bacterial-covered media.

What is the function of the Final Settling (Clarifier) tank?

Remaining biological solids settle out of the water.

What are the three common methods for disinfection in Tertiary Treatment?

Chlorine, UV light, or ozone.

Where is the 'Clean Effluent' released after Tertiary Treatment?

Into rivers or oceans.