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Water Pollution control using microorganisms
- 1. Microbial Approaches to PollutionControl WATER POLLUTION
- 2. Water Pollution • Waterpollution occurs when harmful substances, such as chemicals, pathogens, and waste products, contaminate water bodies like rivers, lakes, oceans, and groundwater. • It refers to the contamination of water bodies (e.g., rivers, lakes, oceans, and groundwater) by harmful substances, making the water unsafe for human use and aquatic life.
- 3. • According toSharma et al. (2022) in the Environmental Chemistry Letters, water pollution arises from industrial discharges, agricultural runoff, untreated sewage, and plastic waste, which introduce toxins like heavy metals, pesticides, and pathogens into water systems.
- 4. Continued... • Both pointsources (e.g., factory effluents) and non-point sources (e.g., agricultural chemicals) contribute to pollution, with developing nations facing severe challenges due to inadequate waste management.
- 5. Continued... • The Frontiersin Environmental Science article by Khan et al. (2022) adds that emerging contaminants, such as pharmaceuticals and microplastics, further exacerbate pollution, as they are not fully removed by conventional treatment methods (Khan et al., 2022). • The IJCBS paper emphasizes that natural processes like erosion can also contribute, but human activities remain the primary cause of water pollution (IJCBS, 2023).
- 6. Water Pollution: Sources ChemicalPollution • Harmful chemicals like heavy metals (lead, mercury), pesticides (DDT, glyphosate), and oil enter water systems through industrial discharge or runoff from farmland. • These chemicals may remain in the water for long periods, accumulating in sediments, and can poison aquatic life and humans.
- 7. Continued... Nutrient Pollution (Eutrophication) •Excessive nutrients like nitrogen and phosphorus (from fertilizers or untreated sewage) enter water bodies, leading to eutrophication. • This process encourages the rapid growth of algae (algal blooms), which deplete oxygen levels in the water when they decay. • Oxygen depletion creates dead zones, where aquatic life cannot survive. These areas disrupt ecosystems and can cause fish kills.
- 8. Continued... Pathogen Pollution • Pathogenicmicrobes (bacteria, viruses, protozoa) enter water from human or animal waste • . When water is consumed or used in recreational activities, these pathogens can cause diseases like cholera, dysentery, and typhoid fever.
- 9. Continued... Plastic Pollution • Plasticwaste enters waterways through litter, improper disposal, and waste mismanagement. Over time, plastics break into smaller particles called microplastics, which contaminate rivers, lakes, and oceans. • Plastics physically harm aquatic animals (through ingestion or entanglement) and break down into microplastics, which can enter the food chain.
- 10. Continued... Oil Spills • Petroleumhydrocarbons from oil spills coat marine animals, plants, and shorelines, poisoning organisms and disrupting ecosystems. • Oil spills lead to long-term environmental damage, including the death of marine life, destruction of coral reefs, and economic losses in fisheries and tourism.
- 11. Microbes in WaterPollution Pseudomonas putida • Hydrocarbon Degradation: Pseudomonas putida is a gram-negative, rod- shaped bacterium known for its metabolic versatility, it can degrade a wide variety of toxic organic compounds, especially hydrocarbons, which are major components of oil and fuel. • P. putida produces oxygenase enzymes (e.g., toluene dioxygenase) that break down complex hydrocarbons into simpler, less toxic compounds.
- 12. Continued... • These enzymesinsert oxygen into the hydrocarbon molecules, enabling them to be used as carbon and energy sources by the bacteria. • The hydrocarbons are ultimately converted into carbon dioxide and water, especially under aerobic conditions. • Environmental Application: Used in oil spill bioremediation, industrial waste treatment, and soil decontamination.
- 13. Continued... • Engineered strainsof P. putida have been developed to target even more toxic or recalcitrant pollutants.
- 14. Heavy Metal Remediation MicroorganismsInvolved in Heavy Metal Remediation • Microbial species are effective in heavy metal removal. These include bacteria (Pseudomonas, Bacillus), fungi (Aspergillus, Penicillium), and algae (Chlorella, Spirulina). • Kumar et al. (2022) found Pseudomonas aeruginosa is particularly effective in cadmium and lead removal through biosorption.
- 15. Biosorption • Biosorption isa physicochemical process by which biological materials, particularly non-living biomass,passively adsorb and bind contaminants, especially heavy metals, from aqueous solutions. • Fungal species like Aspergillus niger show remarkable chromium(VI) reduction capabilities due to their high surface area and functional groups.
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- 17. Case Study • Ina study conducted in Singapore, Utomo et al. (2016) investigated the use of non-living algal biomass for the biosorption of heavy metals from surface water. The biomass, composed of common freshwater algal species such as Chlorella and Scenedesmus, which were dried and applied to contaminated water samples containing lead (Pb²⁺), cadmium (Cd²⁺), zinc (Zn²⁺), and copper (Cu²⁺).
- 18. Continued... • Metal removaloccurred through passive mechanisms, including adsorption, ion exchange, and surface complexation, primarily involving functional groups such as carboxyl, hydroxyl, phosphate, and amino groups on the algal cell wall. The study demonstrated that algal biosorption is a sustainable and low-cost method for treating metal- contaminated surface waters in tropical urban environments.
- 19. Bioaccumulation • Bioaccumulation isthe process by which living organisms absorb and retain substances, such as toxic chemicals or heavy metals, from their environment at a rate faster than they can eliminate them. • Bioaccumulation involves two major pathways, direct uptake and trophic transfer.
- 20. Continued... • Direct Uptakefrom the environment: • Organisms absorb pollutants directly from water, soil, or air through their skin, gills, or membranes. For example, fish can absorb mercury or cadmium through their gills from contaminated water.
- 21. Continued... • Trophic Transfer(Dietary Uptake): • Contaminants enter the organism through food ingestion when it consumes other contaminated organisms. This is especially significant in higher trophic levels (e.g., predatory fish, birds).
- 22. Biochemical Transformation • Microorganismsfacilitate metal transformation through redox reactions. • Gupta et al. (2022) studied on how Chromobacterium violaceum reduces toxic Cr(VI) to less mobile Cr(III). • The bacterium expresses chromate reductase enzymes, which catalyze the reduction of Cr(VI) to Cr(III). These enzymes use NADH or NADPH as electron donors.
- 23. Continued... • Cr(VI)+NAD(P)H→Cr(III)+NAD(P) + +H2O • This reduces the highly toxic and mobile Cr(VI) (which is soluble and penetrates cells easily) to Cr(III), which is poorly soluble and precipitates out of solution. • Similarly, sulfate-reducing bacteria convert soluble metal ions into insoluble sulfides.
- 24. Organic Pollutant Degradation •Pseudomonas species are aerobic, gram-negative bacteria with exceptional metabolic flexibility. • They can utilize hydrocarbons (e.g., alkanes, toluene, benzene, xylene) from petroleum as carbon and energy sources. • This makes them essential players in bioremediation of oil- contaminated environments.
- 25. Continued... • Pseudomonas speciesare the first-line enzymes in hydrocarbon degradation. • They incorporate oxygen atoms into hydrocarbon molecules, increasing solubility and making them more reactive for further breakdown.
- 26. Monooxygenases Add one oxygenatom to the substrate, for example Pseudomonas putida (Toluene monooxygenases-Degrades Toluene, benzene, xylene) • Example equation: Toluene monooxygenase adds oxygen to toluene → benzyl alcohol.
- 27. Dioxygenases • Add twooxygen atoms across a double bond. • Example: Naphthalene dioxygenase breaks aromatic rings (e.g., benzene, naphthalene).
- 28. Dehydrogenases • These enzymesoxidize the intermediates formed by oxygenases. • Dehydrogenases are a class of oxidoreductase enzymes that catalyze oxidation-reduction (redox) reactions by removing hydrogen atoms (protons and electrons) from a substrate and transferring them to an electron acceptor, usually NAD⁺, NADP⁺, FAD, or quinones.
- 29. Continued... • Example ofmicroorganisms involved include: Escherichia coli, which uses lactate dehydrogenase in TCA cycle. Pseudomonas putida uses dehydrogenase in biodegradation of hydrocarbons, Rhodococcus erythropolis uses aromatic compound dehydrogenases in biotransformation, and bioremediation of xenobiotics.
- 30. Bioaugmentation in Water •Bioaugmentation in Water refers to the process of introducing specific microorganisms into a polluted water system to enhance the breakdown of contaminants and improve water quality. How It Works: • Selection of Microbes: Specialized or engineered bacteria (e.g., Pseudomonas, Bacillus, Alcaligenes) are chosen for their ability to degrade specific pollutants (like oil, nitrates, or heavy metals).
- 31. Continued... • Application: Thesemicrobes are added directly to wastewater treatment plants, rivers, lakes, or groundwater. • Action: The introduced microbes boost biodegradation, working alongside native microbes to remove toxins faster and more completely.
- 32. Case Study: Bioremediation •A study conducted in Harare assessed the effectiveness of a bio gel containing indigenous microorganisms in degrading petroleum hydrocarbons in contaminated soils. The bio gel was applied to sites such as old generator areas and fuel storage zones. The bio gel contains bacterial species such as Pseudomonas, Acinetobacter, Rhodococcus, Gordonia, and Bacillus. They are known for their ability to produce enzymes like monooxygenases, dioxygenases, and dehydrogenases, which facilitate the breakdown of complex hydrocarbons into simpler, less harmful compounds.Results showed a significant reduction in Total Petroleum Hydrocarbons (TPH), with the highest degradation observed between weeks 6 and 8 at soil depths of 0–30 cm.
- 33. Bioremediation Case study •Details: The Shagashe River, polluted by raw sewage from Masvingo City's treatment works, was studied for bioremediation using the water hyacinth (Eichhornia crassipes). While laboratory experiments indicated the plant's potential in absorbing pollutants like nitrates and phosphates, field studies showed limited effectiveness, possibly due to factors like water flow reducing contact time between the plant and pollutants.
- 34. Bioaugmentation • The studyinvestigated the potential of Chlorella vulgaris to eliminate Vibrio cholerae from raw sewage collected in Chegutu. The sewage was inoculated with C. vulgaris cultures and monitored over a three-week period. Results indicated a continuous decrease in V. cholerae concentrations, with complete elimination observed within 21 days. This suggests that C. vulgaris can be effectively used in bioaugmentation strategies to treat sewage contaminated with pathogenic bacteria.
- 35. References • Sharma, R.,Kumar, R., Satapathy, S.C., Al-Ansari, N., Singh, K.K., Mahapatra, R.P., Agarwal, A.K., Le, H.V. and Pham, B.T. (2022) 'Analysis of water pollution using different physicochemical parameters: a study of Yamuna River', Environmental Chemistry Letters, 20(4), pp. 2349-2366. Available at: https://doi.org/10.1007/s10311-022-01447-4 (Accessed: 1 May 2025).
- 36. Continued... • Khan, S.,Naushad, M., Iqbal, J., Bathula, C. and Al-Muhtaseb, A.H. (2022) 'Emerging contaminants of high concern for the environment: current trends and future research', Frontiers in Environmental Science, 10, 880246. Available at: https://doi.org/10.3389/fenvs.2022.880246 (Accessed: 1 May 2025).
- 37. Continued... • International Journalof Chemical and Biochemical Sciences (IJCBS) (2023) 'Impact of industrial effluents on water quality and human health: a review', International Journal of Chemical and Biochemical Sciences, 23, pp. 23-24. Available at: https://www.iscientific.org/wp- content/uploads/2023/05/19-IJCBS-23-23-24.pdf (Accessed: 1 May 2025).
- 38. Continued... • Sreedevi, P.R.,Suresh, K. and Jiang, G., 2022. Bacterial bioremediation of heavy metals in wastewater: a review of processes and applications. Journal of Water Process Engineering, 48, p.102884. • Irvine, K.N., Ho, H.L. and Chua, L.H., 2023. Dynamics of runoff quality associated with an urban park and WSUD treatment train in a tropical climate. Environmental Technology, 44(4), pp.512-527.
- 39. Continued... • Violet, D.,Masamha, B., Mapfaire, L., Machingure, B., and Chivuraise, G., 2013. Environmental Management and Sustainable Development: Onsite Bioremediation Using Bio Gel on Petroleum Hydrocarbons Contaminated Soil in Zimbabwe. 2, 10.5296/emsd.v2i1.3472