BIOLOGY & WATER INDUSTRY

Objectives

The readers will be able to:

Name some contaminants of water.
Identify polluted water by using the Biological Oxygen Demand (BOD).
Describe biological processes of purifying sewage.
Explain why fish is an efficient converter of plankton into flesh.
Describe ways of conserving fish stocks in water bodies.
Explain the need for fish farming.
List at least three each of advantages and disadvantages of fish farming.

BIOLOGY &WATER INDUSTRY

Water Contamination

Water pollution is any chemical, physical or biological change in the quality of water that has a harmful effect on any living thing that drinks or uses or lives in it.

Sources of surface water pollution are generally grouped into two categories:

v Point source pollution refers to contaminants that enter water bodies from a single, identifiable source, such as a pipe or ditch. E.g., discharges from a sewage treatment plant, or industry.

v Nonpoint source pollution refers to diffuse contamination that does not originate from a single discrete source. E.g., the runoff nitrogen compounds from fertilized agricultural lands.

Common Water Contaminants

Water contamination is a significant concern globally, affecting the quality and safety of drinking water. Here are some common water contaminants, along with their sources and potential health effects:

1. Microbial Contaminants

Bacteria: Escherichia coli (E. coli), Salmonella, Legionella

Sources: Human and animal waste, septic systems, agricultural runoff
Health Effects: Gastrointestinal illnesses, including diarrhea, vomiting, and cramps

Viruses: Norovirus, Hepatitis A, Rotavirus

Sources: Sewage contamination, runoff from livestock areas
Health Effects: Gastrointestinal and respiratory illnesses

Protozoa: Giardia lamblia, Cryptosporidium

Sources: Contaminated water, animal waste
Health Effects: Diarrhea, nausea, abdominal cramps

2. Chemical Contaminants

Pesticides and Herbicides
- Sources: Agricultural runoff, residential areas
- Health Effects: Hormonal disruption, cancer, neurological issues
Heavy Metals: Lead, Mercury, Arsenic, Cadmium
- Sources: Industrial discharge, mining, plumbing systems
- Health Effects: Neurological damage, kidney failure, cancer
Nitrates and Nitrites
- Sources: Agricultural runoff, sewage
- Health Effects: Methemoglobinemia (blue baby syndrome), cancer
Volatile Organic Compounds (VOCs): Benzene, Trichloroethylene (TCE), Perchloroethylene (PCE)
- Sources: Industrial processes, fuel storage tanks, solvents
- Health Effects: Liver and kidney damage, cancer
Pharmaceuticals and Personal Care Products (PPCPs)
- Sources: Improper disposal, wastewater treatment plants
- Health Effects: Hormonal disruption, antibiotic resistance

3. Physical Contaminants

Sediments and Suspended Solids

Sources: Soil erosion, construction activities, urban runoff
Health Effects: Clogging of water systems, habitat disruption for aquatic life

Microplastics

Sources: Breakdown of plastic products, industrial processes
Health Effects: Potential for chemical leaching, ingestion by marine organisms

4. Radiological Contaminants

Radon

Sources: Natural radioactive decay of uranium in soil, water, and rock
Health Effects: Increased risk of lung cancer

Uranium

Sources: Natural deposits, mining activities
Health Effects: Kidney toxicity, increased cancer risk

5. Biological Contaminants

Algal Toxins

Sources: Harmful algal blooms, nutrient pollution
Health Effects: Liver damage, neurological effects, respiratory issues

6. Disinfection Byproducts (DBPs)

Chloramines, Trihalomethanes (THMs), Haloacetic Acids (HAAs)

Sources: Reaction of disinfectants (like chlorine) with organic matter in water
Health Effects: Increased risk of cancer, liver and kidney damage, reproductive issues

For more detailed information, resources such as the Environmental Protection Agency (EPA) and the World Health Organization (WHO) offer comprehensive guidelines and standards for water quality.

Bacterial Contamination of Water

Bacterial contamination of water is a major concern for public health. Contaminated water can harbor various harmful bacteria that can cause a range of illnesses, from mild gastroenteritis to severe infections. Here's an in-depth look at bacterial contamination of water:

Common Bacterial Contaminants

Escherichia coli (E. coli)
- Source: Human and animal feces
- Health Effects: Diarrhea, urinary tract infections, respiratory illness, and pneumonia. Some strains, such as E. coli O157
  , can cause severe abdominal cramps, bloody diarrhea, and vomiting.
Salmonella
- Source: Contaminated water, food, and contact with infected animals
- Health Effects: Gastroenteritis, typhoid fever, severe diarrhea, abdominal cramps, and fever.
Legionella
- Source: Warm water systems like hot tubs, cooling towers, and large plumbing systems
- Health Effects: Legionnaires' disease (a severe form of pneumonia) and Pontiac fever (a milder illness).
Vibrio cholerae
- Source: Contaminated water, raw or undercooked seafood
- Health Effects: Cholera, which causes severe watery diarrhea, dehydration, and can be fatal if untreated.
Shigella
- Source: Contaminated water and food, person-to-person contact
- Health Effects: Shigellosis, characterized by diarrhea (often bloody), fever, and stomach cramps.
Campylobacter
- Source: Contaminated water, undercooked poultry, unpasteurized milk
- Health Effects: Campylobacteriosis, causing diarrhea (often bloody), fever, and abdominal cramps.
Enterococcus
- Source: Human and animal feces
- Health Effects: Urinary tract infections, bacteremia, endocarditis, and wound infections.

Sources of Bacterial Contamination

Human and Animal Waste
- Improper disposal of sewage and animal waste can lead to the contamination of water sources with fecal bacteria.
Agricultural Runoff
- Runoff from farms carrying animal waste and fertilizers can introduce bacteria into water bodies.
Stormwater Runoff
- Heavy rains can wash bacteria from streets, lawns, and farms into water supplies.
Inadequate Water Treatment
- Insufficient treatment of drinking water and wastewater can result in bacterial contamination.
Leaking Septic Systems
- Faulty or poorly maintained septic systems can leak bacteria into groundwater and surface water.

Health Impacts

Bacterial contamination of water can lead to various illnesses, ranging from mild to severe. Common symptoms include:

Diarrhea
Nausea and vomiting
Abdominal cramps
Fever
Dehydration
In severe cases, infections can lead to long-term health issues or be fatal, especially in vulnerable populations such as young children, the elderly, and individuals with weakened immune systems.

Detection and Prevention

Water Testing
- Regular testing of water sources for bacterial contamination is essential. Methods include membrane filtration, multiple-tube fermentation, and enzyme substrate tests to detect coliforms and specific pathogens.
Water Treatment
- Effective water treatment methods, including filtration, chlorination, UV irradiation, and boiling, can eliminate bacterial contaminants.
Sanitation and Hygiene
- Proper sanitation and hygiene practices, such as handwashing, safe disposal of human waste, and preventing cross-contamination during food preparation, can reduce the risk of bacterial contamination.
Infrastructure Maintenance
- Regular inspection and maintenance of water supply systems, sewage treatment plants, and septic systems help prevent leaks and contamination.

For more information on water safety and bacterial contamination, resources like the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) provide comprehensive guidelines and recommendations.

Measurement Water Pollution

Measuring water pollution is essential for assessing water quality and ensuring the safety of drinking water, aquatic ecosystems, and public health. It involves the analysis of various physical, chemical, and biological parameters to detect and quantify pollutants. Here are some key methods and parameters used to measure water pollution:

Physical Parameters

Temperature
- Importance: Affects chemical reactions, dissolved oxygen levels, and aquatic life.
- Measurement: Thermometers or digital temperature probes.
Turbidity
- Importance: Indicates the presence of suspended particles, which can harbor pollutants and reduce water clarity.
- Measurement: Turbidity meters or Secchi disks.
Conductivity
- Importance: Measures the water’s ability to conduct electricity, indicating the presence of dissolved salts and other inorganic materials.
- Measurement: Conductivity meters.
Total Dissolved Solids (TDS)
- Importance: Represents the total concentration of dissolved substances in water, affecting water quality and taste.
- Measurement: TDS meters or gravimetric methods.

Chemical Parameters

pH
- Importance: Indicates the acidity or alkalinity of water, which can affect aquatic life and the solubility of chemicals.
- Measurement: pH meters or pH indicator strips.
Dissolved Oxygen (DO)
- Importance: Essential for the survival of aquatic organisms; low levels can indicate pollution.
- Measurement: DO meters or Winkler titration method.
Biochemical Oxygen Demand (BOD)
- Importance: Measures the amount of oxygen required by microorganisms to decompose organic matter in water, indicating the level of organic pollution.
- Measurement: BOD test (incubation of water samples followed by oxygen measurement).
Chemical Oxygen Demand (COD)
- Importance: Measures the total quantity of oxygen required to oxidize both organic and inorganic matter in water, indicating overall pollution levels.
- Measurement: COD test using strong chemical oxidants.
Nutrients: Nitrogen (Nitrate, Nitrite, Ammonia) and Phosphorus (Phosphate)
- Importance: Excess nutrients can lead to eutrophication, harming aquatic ecosystems.
- Measurement: Spectrophotometric methods, ion-selective electrodes, or colorimetric tests.
Heavy Metals: Lead, Mercury, Arsenic, Cadmium, etc.
- Importance: Toxic to humans and wildlife even at low concentrations.
- Measurement: Atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), or X-ray fluorescence (XRF).
Pesticides and Organic Pollutants
- Importance: Harmful to health and ecosystems; persistent organic pollutants (POPs) can bioaccumulate.
- Measurement: Gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS).
Microplastics
- Importance: Persistent contaminants that can cause physical and chemical harm to aquatic life and potentially humans.
- Measurement: Filtration, visual identification, and spectroscopic techniques.

Biological Parameters

Microbial Contaminants: Bacteria (e.g., E. coli, Salmonella), Viruses, Protozoa
- Importance: Indicate contamination by fecal matter and the presence of pathogens.
- Measurement: Culture-based methods, polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA).
Bioindicators
- Importance: Certain species (e.g., algae, macroinvertebrates, fish) can indicate water quality based on their presence or absence and population health.
- Measurement: Biological surveys and biotic indices.

For comprehensive guidelines and standards, resources like the Environmental Protection Agency (EPA) and the World Health Organization (WHO) provide valuable information on water quality monitoring and pollution control.

Biochemical Oxygen Demand

Biochemical oxygen demand (B.O.D) is the amount of oxygen required for the microorganisms (bacteria) present in the waste water to convert the organic substance to stable compounds such as CO₂ and H₂O OR is the amount of oxygen that bacteria in waste water will consume in breaking down waste.

This is a standard water-treatment test for the presence of organic pollutants.

B.O.D is considered to be the measure of organic content of the waste. The B.O.D determination has been done by measuring the amount of oxygen utilized by the microorganism in the stabilization of waste water for 5 days at 20^oC or 25^oC.

Experiment to Determine the B.O. D of a Given Sample of Wastewater

Procedure:

Take two B.O.D tubes and half fill it with distilled water.
Add 3ml of waste water (polluted water) to the B.O.D tubes with the help of pipette.
Now filled the tubes with distilled water and fix stopper on it.
Put one of the tubes in incubator at 20 C for 5 days.
Add 2ml of alkali iodide oxide and shake well if oxygen is present the color will be brown)
Add 2ml of concentrated H₂SO₄ and shake well which will give intense yellow color.
Take 200ml from this solution in a graduated cylinder and add 1ml of starch indicator to it which will give a yellowish color.
Put the graduated cylinder below the burette containing standard solution of sodium thiosulphate and note the initial reading.
Fill dissolved oxygen of the first tube the dissolved oxygen is found in similar way.
Find the B.O.D by using the formula

B.O.D (mg/lit) = (zero-day Dissolved Oxygen (D.O) - 5 days D.O) x 300/ml of sample

The BRCES (British Royal Commission Effluent Standard) allows a B.O.D of 20 mg/lit in a treated sewage to be discharged to body of water.

Wastewater Treatment Processes

Wastewater treatment processes are essential for removing contaminants from wastewater, making it safe for discharge into the environment or for reuse. These processes involve a combination of physical, chemical, and biological methods to treat the water to acceptable standards. Here's an overview of the main stages and methods used in wastewater treatment:

1. Preliminary Treatment

The primary goal of preliminary treatment is to remove large solids and materials that could damage equipment or interfere with subsequent treatment processes.

Screening: Physical barriers like screens or sieves are used to remove large objects such as sticks, rags, and plastics.

Grit Removal: Grit chambers are used to settle and remove sand, gravel, and other heavy particles that could cause abrasion and wear in treatment equipment.

Flow Equalization: This process evens out variations in flow rate and contaminant load, improving the efficiency of downstream processes.

2. Primary Treatment

Primary treatment focuses on the removal of suspended solids and organic matter.

Sedimentation: In primary clarifiers, wastewater is held in large tanks where heavy solids settle to the bottom as sludge, and lighter materials like grease and oils rise to the surface for removal.

Flotation: Air is introduced into the wastewater to form bubbles that attach to particles and float them to the surface, where they can be skimmed off.

3. Secondary Treatment

Secondary treatment aims to remove dissolved and colloidal organic matter using biological processes.

Activated Sludge Process: Microorganisms are introduced into aeration tanks, where they consume organic pollutants. The mixed liquor (microorganisms and wastewater) then flows to secondary clarifiers, where the biomass settles as sludge.

Trickling Filters: Wastewater is distributed over a bed of coarse material covered with biofilm. As the water trickles down, microorganisms in the biofilm degrade the organic matter.

Rotating Biological Contactors (RBCs): Discs coated with biofilm rotate through the wastewater, facilitating the growth of microorganisms that degrade organic matter.

Oxidation Ponds/Lagoons: Large, shallow ponds where natural processes, including microbial action and sunlight, reduce organic content and pathogens.

4. Tertiary Treatment

Tertiary treatment provides additional polishing of the wastewater to remove residual contaminants and improve quality.

Filtration: Sand filters, multimedia filters, or membrane filtration are used to remove remaining suspended solids and particulate matter.
Disinfection: Methods such as chlorination, ultraviolet (UV) irradiation, or ozonation are used to kill pathogenic organisms.
Nutrient Removal: Processes like nitrification-denitrification, chemical precipitation, and biological phosphorus removal are used to eliminate nutrients like nitrogen and phosphorus, which can cause eutrophication in water bodies.
Adsorption: Activated carbon can be used to remove residual organic compounds, including micropollutants.

5. Sludge Treatment and Disposal

Sludge generated during treatment must be processed and disposed of safely.

Thickening: Concentrates sludge by removing a portion of the liquid content.
Stabilization: Processes like anaerobic digestion or aerobic digestion reduce the volume of sludge and stabilize organic matter, reducing odors and pathogens.
Dewatering: Removes more water from sludge, using centrifuges, belt filter presses, or drying beds.
Disposal: Treated sludge, now termed biosolids, can be landfilled, incinerated, or applied as fertilizer if it meets regulatory standards.

6. Advanced Treatment and Reuse

For applications requiring very high water quality, such as potable reuse or industrial processes, advanced treatment may be necessary.

Reverse Osmosis (RO): Uses a semi-permeable membrane to remove dissolved salts, organics, and other impurities.
Advanced Oxidation Processes (AOPs): Combine oxidants like hydrogen peroxide, ozone, or UV light to break down complex organic pollutants.
Ion Exchange: Removes specific ions from the water, often used for demineralization or softening.

For more detailed information and standards, resources like the U.S. Environmental Protection Agency (EPA) and the World Health Organization (WHO) offer comprehensive guidelines on wastewater treatment.

BIOLOGY & FISHING INDUSTRY

Fish farming refers to the rearing of water dwelling organisms in controlled or semi controlled environments to enhance productivity. It is also used to refer to Aquaculture, Pond Culture and Mariculture (fish farming in sea water). The organisms are farmed or grown because they have value to man. These organisms include fishes, mollusks, crustaceans, etc.

Fish as Efficient Converter of Plankton into Flesh

Fish grow fast and stay healthy if they have enough nutritious food to eat. Living organisms are natural fish foods and are produced in the water where the fish live. Phytoplankton (microscopic plants), zooplankton (microscopic animals), insects and certain other plants are all examples of natural foods. Fish feed directly or indirectly on the expense of plankton. They are relatively efficient converters of plankton into flesh because, as ectothermic animals, they do not use a share of the energy intake to maintain a high and constant body temperature. Their body temperature changes with that of the environment. Fish are therefore able to use more of their food intake for growth. Fertilization increases their abundance.

Fish Stock management and Conservation

Good fishing in farm ponds depends on understanding of and ability to follow some fundamental rules. The essentials of fish pond management include:

¨ Removal of unwanted and overpopulated species of fish.

¨ Regular application fertilization, provide phytoplankton with adequate nutrients for growth, which intend increases food availability for fish in the pond.

¨ Weed control or removal of pond weeds allows dissolution of oxygen and penetration of sunlight to the bottom which promote the growth of phytoplankton (fish food).

¨ Monitor and maintain seafloor habitats to make sure fish have food and shelter.

¨ Supplementary feed should be given in sufficient quantity at regular interval to ensure rapid growth and fast maturity.

¨ Ponds should be separated from row-crop land by a turf barrier to prevent pesticides, herbicides and soils contamination.

¨ Ponds with soft, acidic water require the addition of lime to improve fishing.

The Need for Fish Farming

¨ Productive use of poor agriculture lands

Hilly land, eroded, Swampy areas or soils with high salt which are difficult to farm can be utilized for fish ponds.

¨ High Economic Value

Aquaculture provides thousands of jobs in operations and serves as source of income.

¨ High nutritional Value

Fish is high quality protein source that ranks superior in many respects to red meats. Fish farming provides means of increasing the availability of protein at a reduced cost.

¨ Foreign Exchange

Fish farming serves as a means of foreign exchange when large volume of fish and fish products are exported to other country.

¨ Scientific Research

Fish farming provides opportunities for scientific studies and research works on aquatic systems.

¨ Natural Resource Conservation

Aquaculture and water harvesting can contribute to substantially to the conservation of natural resources, especially water and soil. Ponds can reduce the dangers of downstream flooding by holding water high in watersheds and checking the erosional force of sudden runoff. Surface water is often allowed to drain away instead of being harvested and stored for beneficial use. Ponds can build to harvest and store large quantity of water, which makes water available for supplemental irrigation, stock watering and domestic needs.

Advantage of Fish Farming

v Source of good quality protein rich food

v Source of income to farmers and revenue to government

v Creates employment opportunities

v Contributes to National food security

v Fish farming can be combined with irrigation practices which reduces costs for providing water and fish as a food source.

v Reduction in the number of harmful insects, such as mosquito, whose larvae are eaten by fish.

Disadvantage of Fish Farming

¨ Fish packed tightly in a confined are more susceptible to infection and disease.

¨ High cost in operating fish farm. Fish farming is highly dependent upon technology and farms must invest in expensive equipment. Additional costs are involved in fertilizing and feeding the fish.

¨ Improper and indiscriminate use of chemicals in fish farming may lead to residual effect on the consumers.

¨ Ponds may serve as breeding places for mosquitoes.

¨ Construction of fish pond destroys the habitats of certain aquatic and terrestrial organisms.