Objectives

1. Nitrogen Removal ProjectHJR IncorporatedHeather NelsonJeannette Harduby Rudi SchuechFor Sparkling Clean Water Every Time

2. Objectives • Test Bardenpho Method for efficiency in nitrate removal • Test nitrate concentrations in waste using method of Karlsson et al. • Test the nitrate concentrations in waste using Hach cadmium test kit • Test for nitrate accumulation in the aeration stage

3. Background Nitrogen Removal Steps organic nitrogen (proteins, aka casein) → ammonia NH4+ Ammonia → nitrite NO2- Nitrite → nitrate NO3- Nitrate → nitrogen gas N2

4. Nitrifying Bacteria • Chemolithotrophic – “burn” ammonia and nitrite for energy • Cannot use organic carbon or nitrogen • Many are non-motile • May require a solid substrate to attach themselves to for optimum growth • Secrete a sticky slime matrix for adhesion • Clump together to avoid light (vampiric?!)

5. Nitrifying Bacteria Continued… • Obligate aerobes - Require DO above 2 mg/L • Slow growth and long generation times • In the time it takes one Nitrosomonas to divide, one E. coli will produce 35 trillion offspring! • Very pH sensitive - thrives at pH slightly above 7

6. Still More on Nitrifying Bacteria • Optimal temperature between 77-86°F • Growth rate decreased by 50% at 64°F Ahh! The light, it burns!

7. Bardenpho Process

8. Barnard Sequencing Batch Reactor ammonia + organic N TKN0 BOD0 BOD0 TKN0 Biomass 3 h 3 h 2 h 0.33 h 0.67 h

9. HJR Original State Times

10. Karlsson et al Method • Make standard curve of nitrate absorbancies at 220 nm vs. concentration • Take samples of effluent waste water • Filter samples • Run samples through UV spectrophotometer • Use correction factor to find [NO3-] of samples • Correction factor = 2 (absorbance @ 275)

11. Karlsson et al results

12. Karlsson et al. conclusions • Since the correction factor @ 275 nm was greater than 10% of the absorbance @ 220 nm, this test is inaccurate for our wastewater

13. Cadmium Test Method • Take samples of waste water periodically throughout different stages • Settle and filter sample • Dilute 0.5 mL of sample to 5 mL with distilled water (to 25 mL for 50X dilution) • Mix in contents of cadmium test packets • Run through spectrophotometer • Concentrations calculated from 542 nm absorbancies

14. Anaerobic One Nitrate Concentrations

15. Aerobic One Nitrate Concentrations

16. Long Aeration Test for Nitrate Accumulation

17. Cadmium Test Reality Check

18. Cadmium Test Reality Check continued… Using a 10 mg/L nitrate standard

19. Email to Hach HJR Inc. told Hach that their testing kit was both difficult to use and inaccurate We suggested a safer packaging method such as capsules rather than packets and reported the discrepancies obtained in our results through their test kit.

20. Hach’s Response and follow up • Claims working in a fume hood is not necessary according to MSDS. But… • MSDS calls cadmium compounds carcinogenic and “highly toxic if inhaled” - PEL – 0.05 mg/m3 air • Hach said, “Best practice is to work in a still air environment” so powder doesn’t blow away • A capsule does not work in terms of longevity and shipping. • Indicated that inaccuracy may be due to not enough reagent getting into sample • Asked for documentation of our results.

21. Conclusions • New way for testing nitrate concentrations needs to be researched • It likely took many hours for nitrate to form because the population of nitrifying bacteria was too small • Method of Karlsson et al. did not work for this experiment.