Water Treatment and Safety

Water Treatment Process

• Water treatment removes contaminants, such as feces, industrial waste, naturally occurring metals, solids, chemicals, bacteria, and viruses, from water.
• Water treatment also removes undesirable odor or taste.
• Water can be treated at the point of collection, at a large municipal site, or at the point of use.

Water Treatment Chemicals

• Flocculants are used to remove suspended bacteria and fungus.
• Neutralizing agents are used to balance pH.
• Corrosion inhibitors are used to prevent oxidation with metal surfaces.
• Coagulants are used to remove suspended solids.
• Antifoam is used to reduce the amount of foam present.
• Algaecides are used to kill algae.
• Disinfectants are used to kill microorganisms.

Physical Processes in Water Treatment

• Sedimentation allows water to become still so suspended particles will settle to the bottom using gravity.
• Water can be filtered by passing it through a semipermeable barrier of various pore sizes.
• Common types of water filters include:
  • Screens: used at the source to remove debris and large objects.
  • Sand filters: move water through beds of sand and gravel to remove suspended solids.
  • Membrane filters: water runs through a porous cloth or organic material.
  • Reverse osmosis: forces water under pressure through a semipermeable membrane.

Biological Process in Water Treatment

• Biological filters rely on plants, bacteria, or microorganisms to purify water and remove organic compounds.
• Biological treatment can be aerobic, anaerobic, or anoxic.
• A slow sand filter is a type of biological filter that requires a large area of layered rock, gravel, and sand.

Water Treatment Systems

• Water treatment systems are used to clean drinking water and process wastewater to prevent the spread of disease.
• Water can be treated at the source, at the distribution point, or at a central processing plant.
• Developing countries often use a single treatment method, such as chlorination, due to its low cost.

Wastewater Treatment

• Wastewater treatment is vital to the control of diseases.
• In the U.S., wastewater is handled in two ways: central wastewater treatment plants or individual septic systems.
• Septic systems are used in rural areas and process wastewater through a series of steps.

How Do Water Treatment Plants Work?

• The five main steps to treating water are:
  • Coagulation and flocculation: adding chemicals to remove suspended solids.
  • Sedimentation: allowing water to settle so flocs can settle at the bottom.
  • Filtration: passing water through filters of various sizes to strain out particles.
  • Degasification: mixing air and water to reduce dissolved gases.
  • Disinfectant: adding a disinfectant to kill remaining parasites, bacteria, or viruses.

Wastewater Treatment

• The three steps in the treatment process are:
  • Primary or physical treatment: removing 60% of suspended solids.
  • Secondary or biological treatment: removing biological components using aerobic and anaerobic bacteria.
  • Tertiary treatment: removing remaining fine grain suspended solids, salts, nitrates, or phosphates.

Water Treatment Process

• Water treatment removes contaminants, such as feces, industrial waste, naturally occurring metals, solids, chemicals, bacteria, and viruses, from water.
• Water treatment also removes undesirable odor or taste.
• Water can be treated at the point of collection, at a large municipal site, or at the point of use.

Water Treatment Chemicals

• Flocculants are used to remove suspended bacteria and fungus.
• Neutralizing agents are used to balance pH.
• Corrosion inhibitors are used to prevent oxidation with metal surfaces.
• Coagulants are used to remove suspended solids.
• Antifoam is used to reduce the amount of foam present.
• Algaecides are used to kill algae.
• Disinfectants are used to kill microorganisms.

Physical Processes in Water Treatment

• Sedimentation allows water to become still so suspended particles will settle to the bottom using gravity.
• Water can be filtered by passing it through a semipermeable barrier of various pore sizes.
• Common types of water filters include:
  • Screens: used at the source to remove debris and large objects.
  • Sand filters: move water through beds of sand and gravel to remove suspended solids.
  • Membrane filters: water runs through a porous cloth or organic material.
  • Reverse osmosis: forces water under pressure through a semipermeable membrane.

Biological Process in Water Treatment

• Biological filters rely on plants, bacteria, or microorganisms to purify water and remove organic compounds.
• Biological treatment can be aerobic, anaerobic, or anoxic.
• A slow sand filter is a type of biological filter that requires a large area of layered rock, gravel, and sand.

Water Treatment Systems

• Water treatment systems are used to clean drinking water and process wastewater to prevent the spread of disease.
• Water can be treated at the source, at the distribution point, or at a central processing plant.
• Developing countries often use a single treatment method, such as chlorination, due to its low cost.

Wastewater Treatment

• Wastewater treatment is vital to the control of diseases.
• In the U.S., wastewater is handled in two ways: central wastewater treatment plants or individual septic systems.
• Septic systems are used in rural areas and process wastewater through a series of steps.

How Do Water Treatment Plants Work?

• The five main steps to treating water are:
  • Coagulation and flocculation: adding chemicals to remove suspended solids.
  • Sedimentation: allowing water to settle so flocs can settle at the bottom.
  • Filtration: passing water through filters of various sizes to strain out particles.
  • Degasification: mixing air and water to reduce dissolved gases.
  • Disinfectant: adding a disinfectant to kill remaining parasites, bacteria, or viruses.

Wastewater Treatment

• The three steps in the treatment process are:
  • Primary or physical treatment: removing 60% of suspended solids.
  • Secondary or biological treatment: removing biological components using aerobic and anaerobic bacteria.
  • Tertiary treatment: removing remaining fine grain suspended solids, salts, nitrates, or phosphates.