Nutrient Addition Calculation in Biological treatment

[Farookengg]

I am designing a Water Water Treatment plant (with MBBR for Industrial Waste)

Metcalf & Eddy Says,

Based on Composition of Cell Biomass, about 12.2 g of Nitrogen & 2.3 g of Phosphorus are needed per 100 g Cell Biomass.

& it says in MBBR TSS Concentration may range from 12 g/m2 to 28 g/m2 of Media. (I have considered 20 g/m2 for my design)

In my design I have 160 m3 of Media, hence total biomass will be 160*20 = 3200 gm TSS, hence for maintaining Nitrogen, I have to add Nitrogen equivalent to 12.2*3200/100 = 390.4 gm, but it doesn't clear the requirement whether this amount of Nutrient need to be added in hourly basis or daily basis, hence please kindly suggest the Nutrient addition calculation based on your experience.

On the other hand we normally, calculate the nutrient addition to maintain a ratio of BOD:N = 100:5:1, which is simple for calculation, hence please help me to select the correct design calculation.

 

[bimr]

The amount of nutrient will depend on what is naturally present in the wastewater, which you have not said.

Nutrients are typically added continuously, so the feed rate is low.

 

[ashtree]

The BOD:N ratio is not typically used as a detailed design calculation but is more of a quick analysis for trouble shooting.
A plant that has influent where the N and P is less than this might expect to be having trouble due to nutrient limitations.

The Metcalf and Eddy quote i believe refers to the N and P required to grow and develop the biomass. So unless your design is going to grow and slough off the 20gm2 of biomass every day then the amount of P and N required the way you are calculating it may be excessively high.

What you need to know is what is the BOD to biomass conversion rate. How much biomass will you produce per day for a given amount of BOD applied. Without knowing the specifics of your plant and the characteristics of the influent its impossible to know to give a value for this conversion rate. Such data is often obtained by pilot testing.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"