Biology In Human Welfare

Microbes In Human Welfare

Primary treatment of waste water

• Waste water is the water that is drained out of various sources like industries, households, etc.
• Primary treatment is the initial step in treating waste water before it is released into the environment.
• Microbes play a crucial role in the primary treatment of waste water.
• The primary treatment process involves physical and biological methods.

Physical Methods:

• Screening: Waste water is passed through screens to remove large debris and objects.
• Grit Chamber: The waste water is then channelized into a grit chamber where heavy particles like sand and pebbles settle down.
• Sedimentation: In this step, suspended solids settle down due to gravity, forming sludge.

Biological Methods:

• Activated Sludge Process: Waste water is mixed with a culture of microorganisms called activated sludge.
• Organic matter present in the waste water gets decomposed by aerobic bacteria present in the activated sludge.
• The organic matter is converted into carbon dioxide, water, and microbial biomass.
• The microbial biomass forms flocs which settle down forming sludge.
• The treated water is sent for further treatment to remove excess nutrients and pollutants.

Advantages of Primary Treatment:

• Removal of physical impurities and suspended solids.
• Reduction in organic load.
• Decreased turbidity and foul odor of waste water.
• Faster breakdown of complex organic compounds by microorganisms.

Disadvantages of Primary Treatment:

• Limited removal of nutrients and pollutants.
• Treatment of waste water is not complete.
• Further treatment processes are required to make the water fit for reuse or safe disposal.

Examples of Primary Treatment:

• Primary treatment is commonly used in sewage treatment plants.
• It is also used in industries to treat their waste water before final disposal.

Equations:

1. Organic matter + Oxygen → Carbon dioxide + Water + Energy
2. Microbial biomass + Organic matter → Carbon dioxide + Water + Energy

In conclusion, primary treatment of waste water is an important step in the overall treatment process. It involves physical and biological methods, with microbes playing a significant role. While primary treatment removes physical impurities and reduces organic load, additional treatment processes are necessary for complete purification. 11. Types of Microorganisms in Primary Treatment

• Bacteria: Aerobic and anaerobic bacteria play a key role in decomposing organic matter in waste water.
• Protozoa: These single-celled organisms feed on bacteria and help in reducing the bacterial population.
• Fungi: Certain species of fungi can decompose complex organic compounds present in waste water.
• Algae: Algae can help in reducing the concentration of nutrients like nitrates and phosphates through their growth and photosynthesis.
• Viruses: Although not actively involved in the treatment process, viruses may be present in waste water and can pose a risk to human health.

12. Microbial Transformations in Primary Treatment

• Aerobic Decomposition: Aerobic bacteria utilize oxygen to break down organic matter into simpler compounds like carbon dioxide and water.
• Anaerobic Decomposition: Anaerobic bacteria decompose organic matter in the absence of oxygen, producing methane gas as a byproduct.
• Nitrification: Some bacteria convert ammonia into nitrate ions, which can be taken up by plants or further transformed into nitrogen gas.
• Denitrification: Certain bacteria convert nitrate ions back into nitrogen gas, which is released into the atmosphere, completing the nitrogen cycle.
• Phosphorus Removal: Certain microbes facilitate the precipitation of phosphorus as insoluble compounds, reducing its concentration in the waste water.

13. Factors Influencing Microbial Activity

• Temperature: Microbial activity is affected by temperature, with optimal activity occurring within a specific range.
• pH: Different microbes thrive under different pH conditions, affecting their activity in waste water treatment.
• Nutrient Availability: Adequate amounts of nutrients like carbon, nitrogen, and phosphorus are essential for microbial growth and activity.
• Oxygen Availability: Aerobic bacteria require oxygen for their metabolic activities, while anaerobic bacteria thrive in oxygen-deficient conditions.
• Toxic Substances: Presence of toxic substances in waste water can inhibit microbial activity and slow down the treatment process.

14. Advantages of Microbes in Primary Treatment

• Cost-effective: Using microbes in waste water treatment can be a more economical option compared to chemical treatments.
• Environmentally Friendly: Microbial decomposition is a natural process that has a minimal impact on the environment.
• Improved Treatment Efficiency: Microbes can break down complex organic compounds effectively, resulting in better treatment outcomes.
• Reduction in Odor: Microbial activity helps in reducing the foul odor associated with waste water.
• Potential for Resource Recovery: Some microbes can help in recovering valuable resources like methane gas or biofertilizers from waste water.

15. Limitations of Microbes in Primary Treatment

• Sludge Production: Microbial activity can lead to sludge production, which needs to be managed properly.
• Variability in Performance: The efficiency of microbial treatment can vary depending on the characteristics of the waste water and microbial population.
• Long Treatment Time: Microbial decomposition may take longer compared to chemical treatments, increasing the overall treatment time.
• Sensitivity to Environmental Conditions: Microbes can be sensitive to environmental changes, which may affect their activity and treatment efficiency.
• Risk of Pathogen Contamination: Although rare, there is a potential risk of pathogen contamination if the treatment process is not properly managed.

16. Examples of Microbes used in Primary Treatment

• Bacillus subtilis: This bacterium is commonly used for its ability to degrade organic compounds and reduce sludge production.
• Pseudomonas aeruginosa: Known for its versatility in degrading various pollutants, this bacterium is often utilized in waste water treatment.
• Aspergillus niger: This fungus is used for its ability to degrade cellulose and complex organic compounds in waste water.
• Paramecium caudatum: This protozoan feeds on bacteria and helps maintain microbial populations in balance during treatment.
• Chlorella vulgaris: This green alga can help in reducing nutrient levels through uptake and photosynthesis.

17. Equations in Microbial Transformations

• Aerobic Decomposition: Organic matter + Oxygen → Carbon dioxide + Water + Energy
• Anaerobic Decomposition: Organic matter → Methane + Carbon dioxide + Energy
• Nitrification: Ammonia → Nitrite → Nitrate
• Denitrification: Nitrate → Nitrogen gas
• Phosphorus Precipitation: Phosphorus ions + Calcium ions → Insoluble Calcium phosphate

18. Case Study: Primary Treatment Plant

• Location: ABC City
• Capacity: 100 million liters per day (MLD)
• Process: Screening, Grit Chamber, Sedimentation, and Activated Sludge Process
• Microorganisms: Bacteria, protozoa, and fungi
• Effluent Quality: After primary treatment, organic load reduced by 50%, suspended solids removed, and sludge generated for further treatment.

19. Application in Industries

• Primary treatment methods involving microbes are not limited to sewage treatment plants.
• Industries like food processing, pharmaceuticals, and petrochemicals utilize similar microbial processes for treating their wastewater.
• By implementing primary treatment, industries can reduce their impact on the environment and ensure compliance with regulations.
• These methods also present opportunities for resource recovery, such as methane gas or biofertilizers.

20. Future Developments and Challenges

• Advances in microbial genetics and biotechnology can lead to the development of more efficient and specific microbial strains for waste water treatment.
• Integration of renewable energy sources like solar or wind power can reduce the energy requirements of the treatment process.
• Managing emerging contaminants like pharmaceuticals and microplastics poses a challenge for microbial treatment methods.
• Increasing global water scarcity calls for the development of innovative and sustainable waste water treatment technologies using microbes.
• Collaboration between researchers, engineers, and policymakers is essential to addressing these challenges and promoting the use of microbes in waste water treatment.

21. Role of Microbes in Secondary Treatment

• Secondary treatment is the next step in waste water treatment following primary treatment.
• Microbes play a crucial role in breaking down organic matter and removing nutrients in secondary treatment.
• The most commonly used method for secondary treatment is the activated sludge process.
• In this process, waste water is mixed with a culture of microorganisms and allowed to undergo aeration and settling.
• The microorganisms decompose the organic matter further, reducing its concentration in the waste water.

22. Microbes Involved in Secondary Treatment

• Aerobic Bacteria: These bacteria require oxygen to carry out the decomposition of organic matter.
• Facultative Bacteria: These bacteria can function in both the presence and absence of oxygen, allowing for treatment in various conditions.
• Nitrosomonas and Nitrobacter: These bacteria are responsible for the conversion of ammonia to nitrate ions during nitrification.
• Denitrifying Bacteria: These bacteria convert nitrate ions back into nitrogen gas during denitrification.
• Phosphate Accumulating Organisms (PAOs): These microbes take up phosphate ions from the waste water and store them within their cells.

23. Steps in the Activated Sludge Process

• Aeration: The waste water is mixed with a culture of microorganisms in an aerated tank.
• Organic Matter Breakdown: The aerobic bacteria decompose the organic matter present in the waste water, converting it into carbon dioxide, water, and microbial biomass.
• Flocculation: The microbial biomass forms flocs, which are clusters of microorganisms.
• Settling: The flocs settle down due to gravity, forming a sludge at the bottom of the tank.
• Effluent Discharge: The treated water is separated from the sludge and discharged for further treatment or safe disposal.

24. Advantages of Secondary Treatment

• Enhanced Organic Matter Removal: Secondary treatment further reduces the concentration of organic matter in waste water compared to primary treatment.
• Nutrient Removal: Secondary treatment removes excess nutrients like nitrogen and phosphorus, which can cause eutrophication in receiving bodies of water.
• Improved Odor Control: The decomposition of organic matter by microbes helps in reducing the foul odor associated with waste water.
• Reduction of Pathogens: The secondary treatment process contributes to the removal of pathogens, making the water safer for reuse or disposal.

25. Disadvantages of Secondary Treatment

• Energy Consumption: The aeration and mixing processes in secondary treatment require energy, contributing to the overall operational cost.
• Sludge Management: Secondary treatment generates a significant amount of sludge, which needs to be properly managed and treated.
• Time-Consuming: The secondary treatment process usually takes longer compared to primary treatment, increasing the total treatment time.
• Complexity: The control and maintenance of the microbial population in secondary treatment can be challenging, requiring skilled personnel and advanced monitoring techniques.

26. Examples of Secondary Treatment Methods

• Trickling Filter: In this method, waste water is distributed over a bed of rocks or plastic media, allowing for the growth of a biofilm composed of microorganisms. The biofilm breaks down organic matter as the waste water trickles through.
• Rotating Biological Contactor (RBC): RBCs consist of rotating discs or drums with attached microorganisms. As the discs rotate, the microorganisms come into contact with the waste water and decompose organic matter.
• Sequencing Batch Reactor (SBR): SBRs operate in cycles, where waste water is filled into a single tank, treated with microorganisms, undergoes settling, and then the treated water is discharged. The process is repeated in subsequent cycles.
• Oxidation Ditch: This method utilizes a doughnut-shaped channel where waste water is mixed with microorganisms. The microorganisms undergo aeration and settling, similar to the activated sludge process.

27. Equations in Secondary Treatment

• Aerobic Decomposition: Organic matter + Oxygen → Carbon dioxide + Water + Energy
• Nitrification: Ammonia → Nitrite → Nitrate
• Denitrification: Nitrate → Nitrogen gas
• Phosphorus Uptake: Phosphate ions + Microbes → Phosphate-rich microbial biomass

28. Application in Industries

• Secondary treatment methods involving microbes are also applicable in industrial wastewater treatment.
• Industries like pulp and paper, textile, and chemical manufacturing utilize secondary treatment processes to reduce the impact of their wastewater on the environment.
• By implementing secondary treatment methods, industries can comply with regulatory standards and minimize their ecological footprint.
• The treated water can also be potentially reused within the industry, leading to additional resource conservation.

29. Emerging Technologies in Secondary Treatment

• Membrane Bioreactors (MBR): MBR combines the activated sludge process with a membrane filtration system, resulting in improved effluent quality and reduced sludge production.
• Advanced Oxidation Processes (AOPs): AOPs utilize powerful oxidants like ozone or ultraviolet radiation to enhance the elimination of recalcitrant compounds in waste water.
• Biofilm Reactors: These reactors promote the growth of biofilms, which significantly increase the surface area for microorganisms to attach and treat waste water efficiently.
• Anaerobic Digestion: In certain cases, anaerobic digestion can be employed as a secondary treatment method, particularly for high-strength organic waste waters.

30. Conclusion

• Secondary treatment is an essential step in waste water treatment, further reducing organic matter and removing excess nutrients.
• Microbes play a crucial role in the decomposition of organic matter and the transformation of nutrients.
• Different methods, such as the activated sludge process, trickling filters, and sequencing batch reactors, are used for secondary treatment.
• Advancements in technology offer opportunities for improved treatment efficiency and resource recovery.
• Collaboration and continued research in waste water treatment can lead to more sustainable and effective methods using microbes.