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Nutrient Removal Project: Chemical Phosphorus Removal Jill Crispell, Stephanie Wedekind, Sarah Rosenbaum.

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Presentation on theme: "Nutrient Removal Project: Chemical Phosphorus Removal Jill Crispell, Stephanie Wedekind, Sarah Rosenbaum."— Presentation transcript:

1 Nutrient Removal Project: Chemical Phosphorus Removal Jill Crispell, Stephanie Wedekind, Sarah Rosenbaum

2 Objectives Reduce the concentration of phosphorus in the effluent of the wastewater treatment plant by precipitating the phosphorus with varying concentrations of metallic salts Total phosphates should not exceed a concentration of 50ug/L in a stream entering a lake or reservoir

3 Hypothesis As the concentration of a metallic salt added increases, the concentration of phosphorus in the effluent should decrease from 4 mg/L to a value less than 50  g/L. The final phosphorus concentration will be independent from the concentration of metallic salts at high metallic salts concentrations. Metallic salts conc. Phosphorus Conc.

4 Setup

5 Setup Flow Rate: – 450 mL/min Reagents: – Phosphorus solution: 200 mg/L KH 2 PO 4 – Alum solution: 400 mg/L Al 2 (SO 4 ) 3 o 14H 2 O – Ferric Chloride: 200 mg/L FeCl 3

6 Methods First experiment: Effect of flocs – In each cycle, phosphorus and water added to bring concentration to 4 mg/L – Only in first cycle alum (12.5 mg/L) or ferric chloride (6.8 mg/L) Al 2 (SO 4 ) 3­ o 14H 2 O + 2PO 4 3-  2AlPO 4 + 3SO H 2 O FeCl 3 + PO 4 3-  FePO 4 + 3Cl -

7 Results: First experiment Alum was more effective than ferric chloride in removing phosphorus. Discovered original influent water contained ferric chloride Flocs remaining in tank continued to react with the phosphorus added

8 Results: First experiment cont.

9

10 Solutions to our Discoveries: – Decided to pump tap water into the plant from a large jug. – Completely drain the tank. – Added two new states, rinse and rinse effluent, to clean out the tank of all flocs.

11 Second experiment: Increasing concentration of alum Different concentrations, 10 mg/L, 12.5 mg/L, 15 mg/L and 25 mg/L, of alum were used to determine which concentration removes phosphorus most efficiently All samples were analyzed using the spectrophotometer to determine the amount of phosphorus remaining in the effluent.

12 Results: Second experiment As alum concentration in the plant increased, phosphorus concentration decreased and percent removal increased based on samples with 10 mg/L, 12.5 mg/L, 15 mg/L and 25 mg/L of alum respectively

13 Results: Second experiment cont.

14 Although we did not meet our goal of 50  g/L, our high percent removal indicates that the alum is effective Generally, the trend appears to be decreasing

15 Results: Second experiment cont. More testing is necessary to determine if the phosphorus reaches a minimum concentration There cannot be 100% removal (and thus a linear solution) because there is a saturation level in which additional alum no longer effects phosphorus removal

16 Results: Second experiment cont. According to the stoichiometry of the equations, we should have only needed to use a concentration of 12.5 mg/L of alum to completely react with the 4 mg/L of phosphorus, but much more is needed. Reasons: other reactants in water, more mixing time.

17 In the future we would… Test higher concentrations of alum Try mixing alum and FeCl 3 Adjust the pH to be in the optimum range of the coagulants (4.5-5 for FeCl 3, for Alum) – Our pH was between 8.3 and 8.4

18 THE END Have a great summer!


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