Sewage Treatment Terminology Explained A-Z Part 5; Nitrate to Primary Settlement Tank
Introduction
Welcome to Part 5 of our A-Z guide to sewage treatment terminology. In this installment, we cover terms starting with N-P, providing insights into essential concepts, processes, and components used in wastewater treatment systems, particularly package sewage treatment systems like the BMS Blivet.
29. Nitrate (NO₃):
A form of nitrogen found in aged sewage or after nitrification.
Although not as easily used as ammonia by plants, excessive levels can cause eutrophication.
Can be removed through denitrification.
30. Nitrite (NO₂):
A more unstable and toxic form of nitrate, harmful to aquatic species.
31. Nitrification:
A biological/chemical process where ammonia and amino acids are converted to nitrate under aerobic conditions.
Occurs after BOD and SS reduction.
Key considerations:
Temperature-sensitive nitrifying bacteria.
Requires 4x BOD capacity in temperate climates and 3x BOD capacity in warm climates.
32. Nitrogen (Total Nitrogen):
Exists in various forms:
Starts as plant/animal protein.
Degrades to ammonia.
Converts to nitrate through nitrification.
Converts to nitrogen gas (N₂) and oxygen gas (O₂) through denitrification in an anoxic environment.
Reenters the food chain via nitrogen-fixing bacteria, algae, and fertilisers.
33. Package:
Refers to an "all-in-one" sewage treatment system.
Includes:
Primary settlement.
Biological treatment.
Final settlement.
Fully self-contained and road-transportable, e.g., the BMS Blivet.
34. Phosphorus (P)/Orthophosphorus (OP):
An essential nutrient for algae and biological organisms, along with nitrogen.
Orthophosphates:
Immediately available for biological metabolism.
The most important polluting form of phosphorus.
Total Phosphorus (TP): Includes all forms of phosphorus in wastewater effluent.
35. Plug Flow:
A system where sewage moves through the treatment stages in the same sequence as it enters.
In the BMS Aerotor:
Sewage must pass through the Aerotor before proceeding to the next stage.
Prevents bypassing, ensuring full treatment even during flow variations.
97% of the surface area is inside the rotor, enhancing treatment efficiency.
Example of another plug flow system: Oxidation ditch.
36. Population Equivalent (PE):
Represents the BOD production and sewage flow equivalent of a fixed population.
Standard values:
60 g BOD/person/day.
200 litres/person/day.
37. Primary Settlement Tank (PST):
A tank designed to remove the majority of settleable solids from raw sewage.
Key Requirement:
Upward flow velocity of 0.9 m/s or less for effective settlement.
Additional Resources
For more detailed explanations of sewage treatment parameters, visit the BMS Education Blog/Customer Questions section, which covers:
Coming Up Next
The next article will explore terms starting with R to S, including Raw Sewage and Sewage Treatment Plant/System.
Questions?
If you have any questions of would like information on package wastewater treatment products, feel free to contact us.
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