Photosynthesis and Respiration

• Organisms require energy for life and growth, obtained from food.
• Respiration is the process where organisms break down complex chemicals in food into simpler ones, releasing energy.
• Wastes, a combination of organic matter, are produced during respiration as simpler chemicals that the organism can't use.
• The energy in food originates from the sun, trapped by green plants through photosynthesis.
• Photosynthesis is the process where green plants use the sun's energy to convert carbon dioxide and water into simple sugars (6CO2 + 6H2O + light energy → C6H12O6 + 6O2).
• Plants convert sugar into starch and also produce proteins and fats, requiring nitrogen, phosphorus, and other nutrients in addition to carbon, hydrogen, and oxygen.
• Oxygen is a byproduct of photosynthesis.
• Green plants, aerobic bacteria, and animals use oxygen to break down food during respiration, which is the reverse of photosynthesis (C6H12O6 + 6O2 → 6CO2 + 6H2O + energy).

The Food Chain

• A food chain is the path of food materials through the environment.
• Food chains begin with green plants, which directly use the sun's energy.
• Food Producers: Green plants are the initial source of food in an ecosystem; in aquatic environments, algae are primary food producers.
• Herbivores: Animals that consume green plants.
• Carnivores: Animals that consume other animals.
• Omnivores: Animals that eat both plants and animals.
• Parasites: Organisms that live on or in other living organisms (plants and animals).

Types of Living Things

• From a water/wastewater operator's view, organisms are grouped into bacteria, viruses, algae, protozoa, and higher organisms.

Bacteria

• Bacteria are one-celled organisms found everywhere.
• Bacteria can be rod-shaped (bacilli), spherical (cocci), or spiral (spirilla).
• Streptococcus is a twisted, spherical-shaped bacterium ("strepto" means twist).
• Bacteria reproduce through binary fission (dividing in half).
• A single bacterium can produce over a million bacteria in five hours under optimum environmental conditions.

Bacterial Growth

• Bacterial growth occurs under optimal conditions and follows a curve with distinct phases:
• Lag Phase: Little to no growth as bacteria adjust to the environment.
• Growth Phase: Rapid reproduction represented by a steep slope on a growth curve.
• Stationary Phase: Conditions become less favorable, with birth and death rates being approximately equal.
• Death Phase: Population rapidly declines due to depletion of food and accumulation of waste products.

Environmental Needs

• Most bacteria are heterotrophs, obtaining energy by consuming organic matter from other organisms; some act as decomposers.
• Some bacteria are autotrophs make food from inorganic compounds such as some iron bacteria oxidize iron compounds.

Environmental Classifications of Bacteria

• Bacteria are classified by optimum temperature range:
• Psychrophiles grow best between 10 and 20°C and cause milk souring in refrigerators.
• Mesophiles grow best between 20 and 40°C, and include human pathogens thriving at body temperature (38°C or 98.6°F).
• Thermophiles grow best between 45 and 75°C.
• Based on oxygen needs, bacteria are classified as:
• Aerobic: Require free oxygen to grow.
• Anaerobic: Thrive without free oxygen, using oxygen combined in chemical forms like starches or sugars.
• Facultative: Grow with or without free oxygen, but prefer aerobic conditions.
• Specialized bacteria inhabit specific environments due to their food, oxygen, and temperature requirements.

Specific Bacteria

• Iron bacteria oxidize iron, producing rust, which deposits a reddish or yellowish slime inside iron pipes. The decay of iron bacteria imparts a foul odor and taste to water.
• Sulfur bacteria, autotrophs in sewer pipes, thrive in acidic environments (pH as low as 1.0),utilize hydrogen sulfide, produce sulfuric acid, and deadly/explosive gases.

Bacteria in Treatment Plants

• Treatment plants use the prescence of coliform bacteria is used as a measure of the sanitary water quality.
• Mixtures of bacteria and protozoa are used in BOD tests to determine organic pollution.
• Bacteria are used to stabilize organic wastes are killed by chlorination or other methods.

Viruses

• Viruses are parasites that live in the cells of living organisms.
• Viruses cause cells to produce more viruses, leading to cell takeover.
• Viruses are transmitted through waste-contaminated water.
• Polio and infectious hepatitis are two water-borne viral diseases.
• Viruses resist dryness and heat.
• The best way to inactivate viruses is through chlorination, ozonization, coagulation, and filtration.

Algae

• Algae are green plants, typically one-celled in fresh water and can form colonies.
• Algae populations change seasonally, with some species growing at low temperatures in early spring and others at high temperatures in late summer.
• Algae are important oxygen producers.
• Excessive algae can cause taste/odor problems and clog filters.

Eutrophication

• Eutrophication is rapid algae growth caused by added organic matter (like sewage) to water.
• Excessive algae leads to a lake evolving into a marsh or dry state.
• Excessive algae block sunlight, causing algae in the lower layers to die and lead to oxygen depletion.
• Treatment plants eradicate unwanted algae by adding copper sulfate (CuSO4) to the water, between 0.10 and 1.00 mg/L.

Protozoa

• Protozoa are single-celled animals common in fresh water.
• Common types of protozoa are amoebas, flagellates, and ciliates.
• Protozoa eat algae, bacteria, or even other protozoa; some are parasites of larger animals, including humans.
• Protozoa can reproduce by dividing in half.
• Treatment plants use copper sulfate to control protozoa.

Protozoa Cysts

• Some protozoa create cysts.
• Cysts have a resistant membrane that that allows survival under bad environmental conditions
• Bacteria and algae can create spore structures.
• Protozoa survive in warm human bodies because they are transmitted by water

Problematic Protozoa

• Entamoeba histolytica causes amoebic dysentery.
• Giardia lamblia causes giardiasis
• Both exist in human intestinal tracts, forming cysts passed in feces, which can survive in water.
• Cysts resist chlorination but are removed by coagulation and filtration or destroyed by superchlorination with at least a 30-minute contact period.

Higher Organisms

• Treatment palnts can contain higher or multicellular organisms.
• Rotifers and daphnia can be found.
• Worms, snails and insect larvae can be found.
• Treatment plants kill higher organisms by Chlorination or removes them by coagulation and filtration.

worms

• Some can get into drinking water.
• Worms are fly larvae.
• Worms can be removed by draining and cleaning water storage basins.
• Covering basins after leaning stops infestation.