1. Factors Regulating Environmental Transformation of
Organic P – Nutrient Resource Ratio
By Sayantani Ghosh (51444937)
MSc Environmental Microbiology
Supervised by Professor Graeme Paton

2. Introduction
• Phosphorus is the basis of all living forms which cannot be replaced and is a non-renewable resource.
• 90% of global demand for phosphorus is directed to agriculture for its use as fertilizer
in food production.
• The P present in the wastewater is a major threat to the environment.
• Therefore, P recovery from wastewater system is likely to become a sustainable option to meet
current and future P demands in agriculture.

3. Establish the relationship between P transformation and
nutrient resource ratio. The main objective of the work was
manipulation of nutrient resource ratio expecting to notice a
change in P mineralization capacities.
The C:N:P ratio was manipulated to measure the
difference of aryl – phosphatase activity and its
effect on the biomass and pH .

4. Methods
Samples were taken each time to determine the effect of the varied ratio on the aryl-phosphatase activity.
The phosphatase assay was used but in a microtiter plate so that a large number of samples could be
analysed over a short period of time.
Skimmed milk was used as the source of organic P where the inoculum was added and C:N ratio was
varied and placed on the shaker incubator to carry on the experiment.
The samples were also digested by acetic acid and analysed using FIA (flow injection analysis) to
determine the production of PO4
3- .
The cfu and the pH was also calculated to determine its effect.

5. Results
Fig. 1 • C:N 9.2:.5; • C:N 18.4:.5; • C:N 23:.5; • 46:.5
0
1E+09
2E+09
3E+09
4E+09
5E+09
6E+09
7E+09
7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9
colonyformingunits/ml
mM pnp /hr
49
50
51
52
53
54
55
56
7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9
PO4
3-
mM PNP/HR
Fig. 1 • C:N 9.2:.5; • C:N 18.4:.5; • C:N 23:.5; • 46:.5

6. Results
0.00E+00
1.00E+09
2.00E+09
3.00E+09
4.00E+09
5.00E+09
6.00E+09
7.00E+09
11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5
colonyformingunits/ml
mM pnp/hr
50
52
54
56
58
60
62
10 11 12 13 14 15 16 17 18 19 20
PO4
3-
mM PNP/HR
Fig. 1 • C:N 4.6:1; • C:N 4.6:2 • C:N 4.6:2.5; • 4.6:5 Fig. 1 • C:N 4.6:1; • C:N 4.6:2 • C:N 4.6:2.5; • 4.6:5

7. Future prospects
It was seen that the assay could be performed in a microtiter plate if possible modifications are done
accordingly.
In the future, the efficiency of the microtiter plate method can be tested at commercial level and with
wastewater samples.
Comparing the results of different C:N ratios, the appropriate ratio for the maximum activity will be
challenging to determine as the wastewater will have highly varied C:N ratios.

8. ASHLEY, K., CORDELL, D. and MAVINIC, D., 2011. A brief history of phosphorus: From the philosopher’s stone to
nutrient recovery and reuse. Chemosphere, 84(6), pp. 737-746.
References
KARUNANITHI, R., SZOGI, A.A., BOLAN, N., NAIDU, R., LOGANATHAN, P., HUNT, P.G., VANOTTI, M.B.,
SAINT, C.P., OK, Y.S. and KRISHNAMOORTHY, S., Phosphorus Recovery and Reuse from Waste Streams. Advances
in Agronomy, (0).
GATERELL, M., GAY, R., WILSON, R., GOCHIN, R. and LESTER, J., 2000. An economic and environmental
evaluation of the opportunities for substituting phosphorus recovered from wastewater treatment works in existing UK
fertiliser markets. Environmental technology, 21(9), pp. 1067-1084.
TABATABAI, M.A. and BREMNER, J.M., 1969. Use of p-nitrophenyl phosphate for assay of soil phosphatase
activity. Soil Biology and Biochemistry, 1(4), pp. 301-307.

9. Thank you