Q15. As per carbon cycle about 110 billion ton C/yr (as CO2) is picked from atmosphere by photo synthesis. Of this 50 billion ton Carbon/yr (as CO2) is returned as respiration flux from 650 billion ton live carbon of land and the balance 60 billion ton Carbon/yr falls on soil as dead organic matter. This dead organic carbon due to soil respiration from typically 100 billion ton live carbon of soil returns to atmosphere as carbon dioxide thus completing the chain.
Water holds very little life stated as 1-5 billion ton measured as live carbon; in water algal respiration produces oxygen which is used by all organisms of water. Algal photosynthesis picks up 50 billion tons of carbon/yr from atmosphere and roughly the same amount 50 billion ton carbon/yr returns due respiration. It is now known that up to 40 billion ton carbon /yr additionally circulates due to physical mass transfer (due to temperature differences).
There is no dead organic carbon in water of this planet; yet all the wastes of human activities go into water by and large. But water does not support dead organic carbon — so says Carbon Cycle ?
Fossil combustion produces about 6 billion ton carbon/yr (as CO2) which enters atmosphere. The total carbon in litter respiration of soil is 10 times that in fossil fuels. There is so much energy in wastes. Why then do we not make better use of this energy ?
Nitrogen cycle is relatively less understood. It is now known that human activities release 400 million ton N/yr as oxides into atmosphere mostly due to high temperature combustion processes. In contrast natural N-fixation (N2 + H2O = NH3 + O2) generates 130 million ton – N/yr which is the prime source of N for life on soil. The disturbance to N- cycle seem as large as 300 plus % ; while fossil combustion contributes to about 5 % disturbance to C – cycle. Suggesting that green house problems currently engaging the world community must be understood in new ways so as to solve the problem on hand.
This exercise is about coming to grips with these foundational problems particularly fate of nitrogen through some lab measurements compiled below.
Experiments in a lab soil column are tabulated here. Typically soil columns 20 lit have been used in the experiments. Synthetic substrate containing sodium acetate (carbon source) , ammonium and nitrite – nitrogen (as N source). In addition some minerals are also used. Feed is pumped into reactor by peristaltic pumps at rates desired. Experiments have been conducted for different C/N. Inlet and outlet compositions are measured viz. pH, DO, SS, COD, Nitrite-N (A say), ammonium-N (B say), nitrate-N (C say) . Oxygen supply is as per whatever might be available naturally.
Q15.1. Plot nitrite-N loss versus ammonium-N loss (mg/L reactor/hr) for different C/N. Explain your results
Q15.2 Plot carbon loss versus,
a) total N loss,
b) ammonium-N loss and
c) Nitrite-N loss for different C/N.
Explain your results
Q15.3. Plot nitrate-N loss versus carbon loss for different C/N .Explain your results.
Let’s suppose that losses so observed arise from the following reactions
a) nitrite reduction to ammonia – X1 ,
b) nitrite oxidation to nitrate X2 ,
c) reaction between nitrite-N and ammonium-N to produce nitrogen gas and water ammonia and oxygen, X3 ,
d) reaction between nitrogen gas and water to give ammonia and oxygen.
In life processes carbon is used as energy source and also fixed as cell mass. Let X4 be cell mass and X5 be Carbon lost measured as COD. It may not be incorrect to assume that ammonia produced X1 is fixed in cell mass so X4 = α*X1 wherein α is the ratio COD of cell mass/N content of cell mass. Note that alpha data is available say for corn is 74.0 etc.
Q15.4 Set up the stoichiometry and determine the number of independent reactions and hence express X1, X2, X3 (mg/L reactor.hr) in terms of known measurements.
Q15.5. Plot X1 versus 2X3 for different C/N and comment
Q15.6 Plot 2X3 versus COD loss and comment
Q15.7 Plot slope (of COD loss/ 2X3) versus C/N and comment
Q15.8 Using results of Q15.7 predict productions from soil say for corn, sugarcane? Compare with available data for Corn (See Socolow 1999, Proc Natl Acad Sciences 96,6001-6008) and compare your predictions.
Q15.9 Estimate energy for cell synthesis assuming that exergonic reactions (nitrification & aerobic respiration) provide energy for endergonic reactions (protein synthesis & cell synthesis).
Table 7.12 Carbon and Nitrogen removal studies in 20 L CSF system
RUN |
Flow Rate |
C/N |
COD (mg/L) |
NH4+-N (mg/L) |
NO2--N (mg/L) |
NO3--N (mg/L) |
|
|
|
|
|
(L/hr) |
|
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
1 |
3 |
1.86 |
200 |
55.4 |
18.3 |
0.6 |
21.7 |
0.08 |
0 |
21.3 |
2 |
3 |
1.86 |
500 |
182.7 |
46.1 |
7.4 |
53.8 |
0.1 |
0 |
6.1 |
3 |
3 |
1.86 |
1000 |
385.5 |
90.4 |
15.4 |
107.5 |
0.02 |
0 |
1.1 |
4 |
3 |
3.32 |
200 |
77.5 |
10.1 |
0.4 |
12 |
0.09 |
0 |
8.7 |
5 |
3 |
3.32 |
500 |
230.1 |
25.9 |
4.5 |
29.9 |
0.15 |
0 |
5.6 |
6 |
3 |
3.32 |
1000 |
435.5 |
51.1 |
6.3 |
59.8 |
0.7 |
0 |
2.7 |
7 |
3 |
5.4 |
200 |
120.1 |
6.5 |
1.9 |
7.5 |
1.7 |
0 |
4.1 |
8 |
3 |
5.4 |
500 |
239.6 |
16 |
0.9 |
18.2 |
0.08 |
0 |
3 |
9 |
3 |
5.4 |
1000 |
505.6 |
31.1 |
2.4 |
36.8 |
0.7 |
0 |
1.7 |
10 |
6 |
1.86 |
200 |
78.2 |
18.3 |
3.4 |
21.7 |
0.3 |
0 |
13.7 |
11 |
6 |
1.86 |
500 |
207 |
46.1 |
10.3 |
53.8 |
2.3 |
0 |
5.6 |
12 |
6 |
1.86 |
1000 |
391.3 |
90.4 |
16.1 |
107.5 |
0.5 |
0 |
2.7 |
13 |
6 |
3.32 |
200 |
95.9 |
10.1 |
1.8 |
12 |
0.2 |
0 |
7 |
14 |
6 |
3.32 |
500 |
246.3 |
25.9 |
5.8 |
29.9 |
1.1 |
0 |
4.3 |
15 |
6 |
3.32 |
1000 |
482.7 |
51.1 |
10 |
59.8 |
1.1 |
0 |
2 |
16 |
6 |
5.4 |
200 |
142.5 |
6.5 |
3.2 |
7.5 |
3.3 |
0 |
5.4 |
17 |
6 |
5.4 |
500 |
285.2 |
16 |
3.5 |
18.2 |
2.5 |
0 |
3.3 |
18 |
6 |
5.4 |
1000 |
539.9 |
31.1 |
4.4 |
36.8 |
3.2 |
0 |
0.9 |
19 |
12 |
1.86 |
200 |
93.5 |
18.3 |
5.3 |
21.7 |
3 |
0 |
7.1 |
20 |
12 |
1.86 |
500 |
210.2 |
46.1 |
10.7 |
53.8 |
2.9 |
0 |
5.7 |
21 |
12 |
1.86 |
1000 |
400.7 |
90.4 |
17.2 |
107.5 |
2.2 |
0 |
4.1 |
22 |
12 |
3.32 |
200 |
131.8 |
10.1 |
4.7 |
12 |
4.3 |
0 |
3.9 |
23 |
12 |
3.32 |
500 |
272.4 |
25.9 |
7.8 |
29.9 |
4.1 |
0 |
3.1 |
24 |
12 |
3.32 |
1000 |
480.9 |
51.1 |
9.9 |
59.8 |
0.9 |
0 |
2.3 |
25 |
12 |
5.4 |
200 |
144.3 |
6.5 |
3.3 |
7.5 |
3.4 |
0 |
3 |
26 |
12 |
5.4 |
500 |
299.3 |
16 |
4.4 |
18.2 |
3.6 |
0 |
2.1 |
27 |
12 |
5.4 |
1000 |
600 |
31.1 |
7.9 |
36.8 |
7.6 |
0 |
0.2 |
28 |
3 |
0.93 |
200 |
48 |
35 |
10 |
41.20 |
0.3 |
0 |
25.6 |
29 |
3 |
0.93 |
500 |
172.8 |
87.5 |
15 |
103.3 |
0.56 |
0 |
8.6 |
30 |
3 |
0.93 |
1000 |
345.5 |
175 |
32.5 |
204.70 |
0.68 |
0 |
3.1 |
31 |
6 |
0.93 |
200 |
67.3 |
35 |
12.5 |
41.20 |
0.65 |
0 |
17.8 |
32 |
6 |
0.93 |
500 |
193.5 |
87.5 |
18.5 |
103.3 |
0.73 |
0 |
6.9 |
33 |
6 |
0.93 |
1000 |
362.7 |
175 |
34.1 |
204.70 |
0.96 |
0 |
2.6 |
34 |
12 |
0.93 |
200 |
79.6 |
35 |
14.2 |
41.20 |
4.3 |
0 |
11.2 |
35 |
12 |
0.93 |
500 |
197.4 |
87.5 |
19.7 |
103.3 |
4.6 |
0 |
5.8 |
36 |
12 |
0.93 |
1000 |
374.8 |
175 |
35.3 |
204.70 |
5.2 |
0 |
2.3 |
37 |
3 |
7.5 |
200 |
128 |
5.6 |
1.5 |
6.5 |
0.8 |
0 |
3.9 |
38 |
3 |
7.5 |
500 |
243 |
13.8 |
2.1 |
16.1 |
2.1 |
0 |
2.9 |
39 |
3 |
7.5 |
1000 |
527 |
26.6 |
2.7 |
30.3 |
3.4 |
0 |
1.6 |
40 |
6 |
7.5 |
200 |
149 |
5.6 |
3.1 |
6.5 |
1.45 |
0 |
3.4 |
41 |
6 |
7.5 |
500 |
301 |
13.8 |
3.6 |
16.1 |
3.3 |
0 |
2.5 |
42 |
6 |
7.5 |
1000 |
554 |
26.6 |
4.2 |
30.3 |
3.9 |
0 |
1.4 |
43 |
12 |
7.5 |
200 |
154 |
5.6 |
3.4 |
6.5 |
1.8 |
0 |
3.1 |
44 |
12 |
7.5 |
500 |
315 |
13.8 |
4.3 |
16.1 |
3.75 |
0 |
2.2 |
45 |
12 |
7.5 |
1000 |
616 |
26.6 |
7.2 |
30.3 |
6.6 |
0 |
1.1 |
46 |
3 |
10.8 |
200 |
138 |
4.5 |
0.7 |
4.85 |
0.85 |
0 |
3.8 |
47 |
3 |
10.8 |
500 |
253 |
12.4 |
6.1 |
13.5 |
2.54 |
0 |
2.8 |
48 |
3 |
10.8 |
1000 |
555 |
21.2 |
8.7 |
28.8 |
4.2 |
0 |
1.5 |
49 |
6 |
10.8 |
200 |
164 |
4.5 |
1.5 |
4.85 |
1.6 |
0 |
3.2 |
50 |
6 |
10.8 |
500 |
315 |
12.4 |
7.3 |
13.5 |
3.85 |
0 |
2.2 |
51 |
6 |
10.8 |
1000 |
579 |
21.2 |
9.6 |
28.8 |
4.95 |
0 |
1.2 |
52 |
12 |
10.8 |
200 |
168 |
4.5 |
3.1 |
4.85 |
1.92 |
0 |
2.9 |
53 |
12 |
10.8 |
500 |
332 |
12.4 |
8.2 |
13.5 |
4.77 |
0 |
2.0 |
54 |
12 |
10.8 |
1000 |
631 |
21.2 |
10.4 |
28.8 |
7.35 |
0 |
1.0 |
Table7.12 Carbon and nitrogen production & removal studies in 20 L CSF reactor
RUN |
Flow Rate
(l hr-1) |
C/N |
pH |
EC
(μS cm-1) |
TDS
(mg l-1) |
DO
(mg l-1) |
Turbidity
(mg l-1) |
|
|
|
|
|
|
|
|
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
1 |
3 |
1.86 |
7.1 |
7.7 |
872 |
812 |
887 |
821 |
4.2 |
4.8 |
6.8 |
0.6 |
2 |
3 |
1.86 |
7.2 |
7.8 |
874 |
814 |
889 |
815 |
4.3 |
5.1 |
7.2 |
0.8 |
3 |
3 |
1.86 |
7.1 |
7.9 |
875 |
810 |
890 |
818 |
4.4 |
5.2 |
6.7 |
0.6 |
4 |
3 |
3.32 |
6.9 |
7.4 |
966 |
890 |
980 |
845 |
4.6 |
5.1 |
6.5 |
0.5 |
5 |
3 |
3.32 |
6.8 |
7.2 |
967 |
891 |
982 |
848 |
4.7 |
5.2 |
6.7 |
0.6 |
6 |
3 |
3.32 |
6.8 |
7.2 |
969 |
892 |
985 |
847 |
4.8 |
5.1 |
6.4 |
0.5 |
7 |
3 |
5.4 |
6.5 |
8.2 |
973 |
895 |
995 |
856 |
4.9 |
5.5 |
6.6 |
0.5 |
8 |
3 |
5.4 |
6.4 |
8.2 |
974 |
894 |
998 |
855 |
4.8 |
5.3 |
6.7 |
0.6 |
9 |
3 |
5.4 |
6.5 |
8.1 |
971 |
891 |
992 |
852 |
5.1 |
5.6 |
6.7 |
0.6 |
10 |
6 |
1.86 |
7.2 |
7.8 |
871 |
809 |
887 |
720 |
4.4 |
5.2 |
6.8 |
0.8 |
11 |
6 |
1.86 |
7.1 |
7.9 |
873 |
808 |
889 |
716 |
4.3 |
5.2 |
7.2 |
0.9 |
12 |
6 |
1.86 |
7.2 |
7.9 |
874 |
811 |
890 |
717 |
4.4 |
5.3 |
6.7 |
0.8 |
13 |
6 |
3.32 |
7.1 |
7.3 |
965 |
885 |
980 |
730 |
4.8 |
5.3 |
6.5 |
0.7 |
14 |
6 |
3.32 |
6.9 |
7.5 |
968 |
887 |
982 |
732 |
4.7 |
5.1 |
6.7 |
0.8 |
15 |
6 |
3.32 |
6.9 |
7.8 |
968 |
890 |
985 |
734 |
4.8 |
5.2 |
6.4 |
0.8 |
16 |
6 |
5.4 |
6.6 |
8.1 |
973 |
893 |
995 |
728 |
4.9 |
5.4 |
6.6 |
0.8 |
17 |
6 |
5.4 |
6.5 |
8.2 |
975 |
896 |
998 |
730 |
4.8 |
5.3 |
6.7 |
0.9 |
18 |
6 |
5.4 |
6.4 |
8.4 |
970 |
889 |
992 |
731 |
5.1 |
5.6 |
6.7 |
0.9 |
19 |
12 |
1.86 |
7.2 |
7.8 |
870 |
805 |
887 |
740 |
4.1 |
4.9 |
6.8 |
1.1 |
20 |
12 |
1.86 |
7.1 |
7.8 |
872 |
810 |
889 |
745 |
4.3 |
5.1 |
7.2 |
1.1 |
21 |
12 |
1.86 |
7.2 |
7.8 |
873 |
812 |
890 |
742 |
4.3 |
5.2 |
6.7 |
0.9 |
22 |
12 |
3.32 |
7.1 |
7.6 |
965 |
884 |
980 |
760 |
4.6 |
5.2 |
6.5 |
0.9 |
23 |
12 |
3.32 |
6.9 |
7.5 |
966 |
886 |
982 |
762 |
4.8 |
5.1 |
6.7 |
0.9 |
24 |
12 |
3.32 |
6.9 |
7.4 |
968 |
890 |
985 |
763 |
4.8 |
5.4 |
6.4 |
0.9 |
25 |
12 |
5.4 |
6.7 |
7.9 |
972 |
892 |
995 |
765 |
4.9 |
5.4 |
6.6 |
1.1 |
26 |
12 |
5.4 |
6.6 |
8.1 |
975 |
895 |
998 |
764 |
4.9 |
5.6 |
6.7 |
0.9 |
27 |
12 |
5.4 |
6.8 |
8.3 |
970 |
890 |
992 |
765 |
5.1 |
5.7 |
6.7 |
1.1 |
Note: Inf: Influent; Eff: Effluent 20 L CSF reactor made up of aluminium contains media typically partially weathered Deccan trap basalt, under drain and distributor for the wastewater. The influent and effluent samples were analysed at regular interval.
Table7.12 Carbon and nitrogen production & removal studies in 20 L CSF reactor
RUN |
Flow Rate
(l hr-1 ) |
C/N |
pH |
EC
(μS cm-1) |
TDS
(mg l-1) |
DO
(mg l-1) |
Turbidity
(mg l-1) |
|
|
|
|
|
|
|
|
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
Inf |
Eff |
28 |
3 |
0.93 |
7.2 |
7.5 |
672 |
712 |
687 |
722 |
4.3 |
4.7 |
6.5 |
0.5 |
29 |
3 |
0.93 |
7.3 |
7.6 |
674 |
714 |
689 |
717 |
4.4 |
5.0 |
7.0 |
0.7 |
30 |
3 |
0.93 |
7.2 |
7.5 |
675 |
710 |
690 |
719 |
4.5 |
5.3 |
6.5 |
0.5 |
31 |
3 |
0.93 |
6.8 |
7.2 |
766 |
790 |
780 |
825 |
4.6 |
5.2 |
6.6 |
0.5 |
32 |
3 |
0.93 |
6.7 |
7.1 |
767 |
791 |
782 |
828 |
4.8 |
5.4 |
6.6 |
0.7 |
33 |
3 |
0.93 |
6.7 |
7.2 |
769 |
792 |
785 |
830 |
4.7 |
5.2 |
6.5 |
0.6 |
34 |
3 |
0.93 |
6.4 |
7.5 |
773 |
795 |
795 |
836 |
4.9 |
5.5 |
6.4 |
0.4 |
35 |
3 |
0.93 |
6.3 |
7.6 |
774 |
794 |
798 |
838 |
4.7 |
5.4 |
6.6 |
0.4 |
36 |
3 |
0.93 |
6.4 |
7.7 |
771 |
791 |
792 |
842 |
5.1 |
5.7 |
6.8 |
0.4 |
37 |
6 |
7.5 |
7.1 |
7.8 |
771 |
709 |
787 |
720 |
4.5 |
5.3 |
6.9 |
0.6 |
38 |
6 |
7.5 |
7.2 |
7.7 |
773 |
708 |
789 |
718 |
4.4 |
5.4 |
7.4 |
0.7 |
39 |
6 |
7.5 |
7.1 |
7.8 |
774 |
711 |
790 |
719 |
4.6 |
5.4 |
6.6 |
0.6 |
40 |
6 |
7.5 |
7.2 |
7.5 |
765 |
785 |
780 |
790 |
4.7 |
5.4 |
6.6 |
0.4 |
41 |
6 |
7.5 |
6.8 |
7.3 |
768 |
787 |
782 |
792 |
4.6 |
5.3 |
6.8 |
0.6 |
42 |
6 |
7.5 |
6.7 |
7.6 |
768 |
790 |
785 |
794 |
4.7 |
5.4 |
6.6 |
0. |
43 |
6 |
7.5 |
6.5 |
7.1 |
773 |
793 |
795 |
800 |
4.8 |
5.5 |
6.4 |
0.8 |
44 |
6 |
7.5 |
6.4 |
7.4 |
775 |
796 |
798 |
802 |
4.9 |
5.5 |
6.8 |
0.7 |
45 |
6 |
7.5 |
6.3 |
7.3 |
770 |
789 |
792 |
791 |
5.2 |
5.8 |
6.8 |
0.8 |
46 |
12 |
10.8 |
7.1 |
7.6 |
870 |
805 |
887 |
840 |
4.3 |
5.1 |
6.8 |
1.0 |
47 |
12 |
10.8 |
7.2 |
7.5 |
872 |
810 |
889 |
845 |
4.4 |
5.0 |
7.3 |
1.1 |
48 |
12 |
10.8 |
7.1 |
7.4 |
873 |
812 |
890 |
842 |
4.5 |
5.4 |
6.8 |
0.7 |
49 |
12 |
10.8 |
7.1 |
7.3 |
865 |
884 |
880 |
890 |
4.5 |
5.5 |
6.6 |
0.7 |
50 |
12 |
10.8 |
6.8 |
7.2 |
866 |
886 |
881 |
892 |
4.7 |
5.6 |
6.6 |
0.8 |
51 |
12 |
10.8 |
6.7 |
7.3 |
868 |
890 |
883 |
896 |
4.7 |
5.5 |
6.5 |
0.8 |
52 |
12 |
10.8 |
6.6 |
7.1 |
872 |
892 |
892 |
895 |
4.7 |
5.5 |
6.5 |
1.1 |
53 |
12 |
10.8 |
6.5 |
7.1 |
875 |
895 |
890 |
804 |
4.7 |
5.7 |
6.5 |
0.9 |
54 |
12 |
10.8 |
6.6 |
7.3 |
870 |
890 |
898 |
805 |
5.3 |
5.8 |
6.8 |
0.9 |
Note: Inf: Influent; Eff: Effluent 20 L CSF reactor made up of aluminium contains media typically partially weathered Deccan trap basalt, under drain and distributor for the wastewater. The influent and effluent samples were analysed at regular interval.