A diverse community of bacteria, archaea, protozoa, and fungi acts as a living, dynamic ecosystem responsible for several critical purification processes:
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Organic Compound Degradation: Various microbial groups specialize in breaking down different organic compounds (e.g., carbohydrates, fats, and proteins) into simpler substances and ultimately into carbon dioxide and water.
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Nutrient Removal: Specific specialized bacteria are essential for removing key nutrients that can cause environmental problems like eutrophication (excessive plant growth in water bodies).
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Nitrogen Removal: Processes like nitrification (converting ammonia to nitrate by microbes like Nitrosomonas and Nitrobacter) and denitrification (converting nitrate to nitrogen gas by various heterotrophs) are carried out by distinct microbial populations. Some systems utilize Anammox (Anaerobic Ammonium Oxidation) bacteria for more energy-efficient nitrogen removal.
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Phosphorus Removal: Certain bacteria, known as Polyphosphate-Accumulating Organisms (PAOs), are essential for removing phosphorus by storing it inside their cells as polyphosphate.
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Pathogen and Contaminant Removal: While the primary goal is often to remove organic matter, the microbial community also plays a role in decreasing the concentration of pathogens and degrading various micropollutants, pharmaceuticals, and industrial contaminants.
Importance to Operations (Stability and Efficiency)
Microbial diversity is essential to the successful and stable operation of a wastewater treatment plant for several reasons:
| Importance Factor | Explanation |
| Resilience and Stability | A high-diversity community, like a strong polyculture (versus a monoculture), is more robust and better able to handle fluctuations in the composition, concentration, and flow of influent wastewater. If one group of microbes is inhibited (e.g., by a toxic shock load), others can take over or compensate, preventing system failure. |
| Complete Pollutant Breakdown (Efficiency) | Wastewater contains a complex mixture of pollutants. A diverse community ensures that multiple metabolic pathways are available, maximizing the breakdown of the entire spectrum of contaminants, leading to a higher quality effluent. |
| Functional Redundancy | Having multiple species that can perform the same crucial function (like organic degradation) provides a backup system. This functional redundancy ensures that the overall process efficiency remains high even when environmental conditions change or a subset of the community dies off. |
| Floc Formation and Settling | A healthy, diverse microbial community forms flocs (clumps of microbes) in the activated sludge process. The structure and integrity of these flocs are vital for the sludge to settle efficiently in the secondary clarifiers, separating the clean water from the microbial biomass. Poor diversity can lead to issues like “bulking,” where the sludge doesn’t settle, disrupting the entire operation. |
Using Aster Bio’s MCA Testing to Check for Microbial Diversity
MCA relies primarily on Next-Generation Sequencing (NGS), often targeting the 16S rRNA gene for bacteria and archaea (and sometimes the ITS region for fungi). This gene is universally present in these organisms but contains variable regions that act as a unique genetic “barcode” for identification.
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Sample Collection: A sample of activated sludge or mixed liquor suspended solids (MLSS) is collected from the bioreactor.
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DNA Extraction: DNA is extracted from the entire microbial community within the sample.
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Gene Amplification (PCR): The 16S rRNA gene is amplified using Polymerase Chain Reaction (PCR).
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Sequencing (NGS): The amplified DNA fragments are sequenced to determine the exact genetic code (the “barcode”).
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Bioinformatics Analysis: The millions of sequence reads are compared against massive public and proprietary microbial databases.
What MCA Reveals About Diversity and Function
MCA provides a comprehensive report that maps the entire ecosystem within the wastewater plant, which is crucial for operational decision-making.
Checks for Diversity and Structure
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Taxonomic Profile: It identifies all microbes present, classifying them from the broadest categories (Phylum) down to the genus level. Common dominant phyla in wastewater are often Proteobacteria, Bacteroidetes, and Firmicutes.
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Diversity Indices: It calculates key metrics like the Shannon Index, which provides a quantitative measure of the community’s richness (number of different species) and evenness (how evenly distributed their populations are). High diversity indicates a more resilient and stable system.