Question

urgent

A wastewater treatment bioreactor is designed to conduct phosphorus removal by using organisms A and B. Given that with the following parameters: Heterotrophic synthesis yield, Y = 0,40 g VSSIG COD Endogenous decay coefficient, Kd = 0.08 g VSS/g VSS day SRT = 5 days Biomass produced = [Y/(1+(K.) SRT)] x (bCOD or bsCOD) Phosphorus content of organism A: 0.30 g Plg VSS Phosphorus content of organism B: 0.02 g Plg VSS Clarifier effluent VSS concentration = 8 g/m3 Wastewater characteristics: Influent COD = 300 g/m Influent bCOD = 200 g/m² Influent bsCOD = 50 g/m² Phosphorus = 6 g/m3 (a) By using organism A, describe the principle and operational design of a biological phosphorus removal process. (2 marks) (b) Determine the phosphorus removal obtained from organisms A and B respectively (Given that all the influent Page 5 of 7 bsCOD is consumed solely by the organism A as it grows much faster than organism B in the bioreactor). (5 marks)

Answer 1

Principle of biological phosphorous removal process is that Phosphorus-accumulating organisms (PAOs) can absorb dissolved phosphorus from wastewater and stores it in granules within their cells, doubling the phosphorus content of the solids.PAOs are aerobic and similar to other activated-sludge bacteria.
In an anaerobic environment, PAOs have the ability to sequester readily biodegradable biochemical oxygen demand.

Operational Considerations during design
Dissolved Oxygen: Avoid over aeration. Maintain 0.5
to 1.0 mg/L DO concentrations at the end of the aeration zone. This will allow the activated sludge process to perform adequately and ensure that excessive dissolved oxygen concentrations are not recycled back to the anaerobic phase.

Filamentous Control: Avoid over chlorination.
Excessive RAS chlorination can harm the EBPR
process. The Cloud WWTF has reported that more
frequent, but less intense,RAS chlorination
successfully controls the growth of filamentous
bacteria while minimizing adverse impacts on the
biological treatment system.

Influent BOD:P Ratios: A minimum of 25:1 ratio of
influent BOD to phosphorus has been reported to be
critical for successful EBPR. Source reduction of
phosphorus loads can help to decrease influent
phosphorus loads and improve EBPR efficiency..

1 tkaSAT For organism (Biomass produred in Papo - 0.141 (1+ Bake On) . AcoD 0.14% Itkadu. where on SRT 5 days Po influent phosphorous concentration=691 m3 ka=0.08. Y=0.4 influent cos= 300 + 200 Assume fd = 003 g rss lg rss • COD semoral - 80% do ACOD=$100 g/m3 so P= 6- 0.148 0.41 +0.3x0.08x57400 1+ 0.0845 6 -4.48 . 11.52 g/m3 I NOTE 8 AD CAMERA