Algae, Viruses, and Water Quality

Questions and Answers

What is one reason algae are important for water quality?

They support aquatic life only.

They enhance the clarity of water.

They can produce toxic substances. (correct)

They reduce the organic matter content.

What component makes up the structure of a virus?

A lipid bilayer only.

Only a cell membrane.

Ribosomes and proteins.

A protein coat and nucleic acid. (correct)

Why are viruses considered host-specific?

They only reproduce in specific organisms. (correct)

They can survive in extreme conditions.

They can infect any type of cell.

They have a broad range of hosts.

In what way do viruses differ from other microorganisms?

Viruses cannot reproduce outside living cells. Signup and view all the answers

What role does algae play in the oxygen balance of water?

They contribute to oxygen supersaturation. Signup and view all the answers

What occurs when a virus reproduces within a host cell?

The host cell typically dies. Signup and view all the answers

What can happen when pathogens are present in the water supply?

Health risks can be posed to consumers. Signup and view all the answers

What is a common characteristic of viruses that use bacteria as hosts?

They are referred to as phages. Signup and view all the answers

What are the two types of hardness in water?

Carbonate and Non-carbonate hardness Signup and view all the answers

Which ions are primarily responsible for water hardness?

Ca2+ and Mg2+ Signup and view all the answers

What is carbonate hardness associated with?

Carbonates and bicarbonates Signup and view all the answers

What is the impact of hardness on soap usage?

It wastes soap Signup and view all the answers

At what pH does HCO3 begin to convert to less soluble carbonates?

Above 9 Signup and view all the answers

What unit of measurement is commonly used for water hardness?

mg/L as CaCO3 Signup and view all the answers

Which category indicates very hard water based on hardness measurement?

<blockquote> 300 mg/L as CaCO3 </blockquote> Signup and view all the answers

What defines alkalinity in water?

The capacity to neutralize acids Signup and view all the answers

What is the primary component of organic matter in wastewater by weight?

Carbohydrates (30 – 50%) Signup and view all the answers

Which parameter is NOT typically used to quantify organic matter in wastewater?

Nitrogenous oxygen demand (NOD) Signup and view all the answers

When can the theoretical oxygen demand (ThOD) be used?

When the organic compound's chemical equation is known Signup and view all the answers

What does the chemical oxygen demand (COD) measure?

The oxygen needed to chemically oxidise organic matter Signup and view all the answers

Which of the following compounds are typically neglected in ThOD calculations?

Phosphorus and sulphur compounds Signup and view all the answers

What percentage of organic matter in wastewater do fats typically represent?

10% Signup and view all the answers

What is one adverse effect of algae on water supply?

Bacterial aftergrowth in distribution system Signup and view all the answers

How do aquatic weeds adversely affect water supply systems?

Clogging of intake screens Signup and view all the answers

What happens to sulphate under anaerobic conditions?

It is reduced to sulphide Signup and view all the answers

What is a key hazard associated with oil and grease in water bodies?

Creation of fire hazards Signup and view all the answers

How does oil and grease affect the natural re-aeration of water bodies?

Interferes with natural re-aeration Signup and view all the answers

What recent controversy surrounds fluoride?

Its benefits regarding dental health are debated Signup and view all the answers

What is a consequence of the presence of oil and grease in the water?

Imparting taste and odour to water Signup and view all the answers

What is a consequence of having aquatic weeds in waterways?

Clogging of intake screens for water supply Signup and view all the answers

What is the abbreviation for Total Kjeldahl nitrogen?

TKN Signup and view all the answers

Which of the following forms of nitrogen is an ion?

Nitrite Signup and view all the answers

At which pH level is ammonia favored over ammonium ions?

pH 9 Signup and view all the answers

What is the consequence of high nitrate levels in drinking water?

Methemoglobinemia Signup and view all the answers

Which bacteria are involved in nitrification?

Nitrosomonas and Nitrobacter Signup and view all the answers

What does the Total inorganic nitrogen (TIN) measure?

Ammonia, nitrite, and nitrate Signup and view all the answers

Which test quantifies total nitrogen in raw municipal sewage?

TKN test Signup and view all the answers

What is the chemical formula for ammonia gas?

NH3 Signup and view all the answers

Which form of nitrogen is created from bacterial decomposition?

Organic nitrogen Signup and view all the answers

What causes blue baby syndrome?

Nitrate poisoning Signup and view all the answers

Study Notes

Algae and Water Quality

Algae contribute significantly to water quality, influencing taste, odor, and toxicity.
Affect the oxygen balance in aquatic environments, potentially causing supersaturation or anaerobic conditions.
Play a role in organic matter content and turbidity, impacting water filtration.

Viruses

A virus consists of nucleic acid (DNA or RNA) and a protein coat (capsid), forming a nucleocapsid.
Viruses can be naked or enveloped; examples include influenza and herpes viruses.
Highly host-specific and may target specific tissues or cells within the host.
Viruses do not reproduce outside living cells and typically lead to host cell death after replication.
Bacteriophages utilize bacteria as hosts and are about 100 nm in size.

Pathogens in Water

Waterborne pathogens can compromise human health, posing direct risks or being associated with aquatic insects.
Microorganisms can survive in water for extended periods, impacting overall water quality.

Water Hardness

Two types of hardness in water: carbonate (temporary) and non-carbonate (permanent).
Primary contributors to hardness are calcium (Ca) and magnesium (Mg), with minor contributions from iron (Fe), manganese (Mn), strontium (Sr), and aluminum (Al).
Carbonate hardness (easily removed by heating) relates to carbonates and bicarbonates, while non-carbonate hardness comes from other anions like sulfates and chlorides.
Hardness affects soap efficiency and creates precipitates that can stain surfaces.

pH and Hardness Impact

pH changes can lead to precipitate formation using bicarbonates, especially above pH 9.
Hardness is measured in mg/L as CaCO3, categorized as soft (<50 mg/L), moderately hard (50-150 mg/L), hard (150-300 mg/L), and very hard (>300 mg/L).

Alkalinity

Alkalinity measures water's capacity to neutralize acids, critical for maintaining pH stability.

Organic Matter in Wastewater

Wastewater contains substantial organic matter, categorized into carbohydrates (30-50%), fats (10%), and proteins (40-60%).
Various oxygen demand parameters measure organic matter, including ThOD, COD, BOD, and TOC.

Oxygen Demand Types

ThOD: Theoretical oxygen demand based on known chemical equations; phosphorus and sulfur often overlooked in calculations.
COD: Amount of oxygen needed to chemically oxidize organic matter in wastewater using potassium dichromate.

Nitrogen Compounds

Common forms: organic nitrogen, ammonia (NH4+/NH3), nitrite (NO2-), nitrate (NO3-), and gaseous nitrogen.
Ammoniacal nitrogen distribution varies with pH; NH4+ is favored at lower pH, while NH3 is favored at higher pH.

Nitrogen Measurements

Total forms include total ammonia nitrogen (TAN), total inorganic nitrogen (TIN), total Kjeldahl nitrogen (TKN), and total nitrogen (TN).
High nitrate levels in drinking water can lead to serious health issues like blue baby syndrome (methemoglobinemia).

Algal Effects on Water Supply

Algae increase the demand for coagulants, clog filters, and promote bacteria aftergrowth.
Aquatic weeds obstruct water supply screens, increase evapo-transpiration, and affect fish populations.

Sulfate in Water

Present naturally in water and wastewater, essential for protein synthesis.
Under anaerobic conditions, sulfate reduces to sulfide and can react with hydrogen to form hydrogen sulfide (H2S).

Oil and Grease in Water

Interfere with natural re-aeration, are toxic to aquatic species, and pose fire hazards.
Deteriorate water reuse potential, impart undesirable tastes and odors, and diminish recreational water quality.

Fluoride

An inorganic anion associated with dental health benefits, though recent studies question its efficacy.
WHO reports conflicting outcomes regarding cavity rates in children with and without fluoride exposure, raising skepticism over its supposed benefits.

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Description

This quiz explores the critical roles of algae, viruses, and pathogens in influencing water quality. It covers the effects of these microorganisms on oxygen balance, turbidity, and human health. Test your understanding of their characteristics and impacts in aquatic environments.