Questions about nutrition
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I often see in many books the concept that the nutrient addition ratio should be BOD5:N:P=100:5:1. I’m a bit confused about this; is my understanding correct? For example, if there are 10 tons of wastewater in a tank with a BOD5 concentration of 1000 mg/L, then there are 10 kilograms of BOD5 in those 10 tons of wastewater. Does that mean I need to add 0.5 kilograms of nitrogen fertilizer and 0.1 kilograms of phosphorus fertilizer? This is a problem. Another question: do we mean that N-fertilizers are things like urea or compound fertilizers, and that P-fertilizers are things like glucose?
If the nitrogen and phosphorus levels in water are zero, 0.5 kilograms of N and 0.1 kilograms of P are required. Urea and phosphates are generally used to supplement nutrients. Glucose is used to replenish BOD and serves primarily as a carbon source.
When supplementing nitrogen and phosphorus, the concentration of nitrogen and phosphorus in the wastewater also needs to be taken into account. A phosphorus source is a fertilizer that contains phosphorus. The chemical formula of glucose does not contain P.
For nitrogen and phosphorus, the key factor is whether microorganisms can absorb them; urea and similar substances are not a concern in this regard. Also agree with the view above
Compound fertilizers available on the market contain nitrogen and phosphorus, but they are not as good as using urea, potassium dihydrogen phosphate, sodium sulfate, potassium hydrogen phosphate, etc., as these require less fertilizer and are easier to calculate in terms of dosage.
Glucose is a carbon source that replenishes BOD.