3. The concentrations of carbon, hydrogen, oxygen, nitrogen, and sulfur present in
cassava wastewater, wheat bran, and sewage sludge were calculated.
4. The gram atoms of carbon, hydrogen, oxygen, nitrogen, and sulfur present in
cassava wastewater, wheat bran, and sewage sludge were calculated.
5. Consider the overall reaction for biogas production,
C a H b O c N d S e þ f H 2 O ! p CH 4 þ q CO 2 þ r NH 3 þ s H 2 S
Writing balances for each element, we get
Carbon : a ¼ p þ q
ð6:E1Þ
Hydrogen : b þ 2f ¼ 4p þ 3r þ 2s
ð6:E2Þ
Oxygen : c þ f ¼ 2q
ð6:E3Þ
Nitrogen : d ¼ r
ð6:E4Þ
Sulfur : e ¼ s
ð6:E5Þ
Knowing the values of a, b, c, d, and e from step (4) above, the values of f, p, q, r,
and s can be calculated solving five simultaneous Eqs. (6.E1, 6.E2, 6.E3, 6.E4 and 6.
E5) (Tchobanoglous et al. 1991).
6.3
Results and Discussion (Tables 6.2, 6.3 and 6.4)
mg atom of carbon in cassava wastewater a 1
¼ 1139.37/12 ¼ 94.95
mg atom of hydrogen in cassava wastewater b 1 ¼ 88.25/1
¼ 88.25
mg atom of oxygen in cassava wastewater c 1
¼ 1380.83/16 ¼ 86.30
mg atom of nitrogen in cassava wastewater d 1
¼ 16.29/14
¼ 1.16
mg atom of sulfur in cassava wastewater e 1
¼ 1.09/32
¼ 0.03
mg atom of carbon in wheat bran a 2
¼ 115.51/12
¼ 9.63
mg atom of hydrogen in wheat bran b 2
¼ 9.94/1
¼ 9.94
mg atom of oxygen in wheat bran c 2
¼ 94.09/16
¼ 5.88
mg atom of nitrogen in wheat bran d 2
¼ 8.66/14
¼ 0.62
mg atom of sulfur in wheat bran e 2
¼ 0.58/32
¼ 0.02
mg atom of carbon in sewage sludge a 3
¼ 141.44/12
¼ 11.79
mg atom of hydrogen in sewage sludge b 3
¼ 12.34/1
¼ 12.34
mg atom of oxygen in sewage sludge c 3
¼ 101.49/16
¼ 6.34
mg atom of nitrogen in sewage sludge d 3
¼ 12.13/14
¼ 0.87
mg atom of sulfur in sewage sludge e 3
¼ 0.81/32
¼ 0.03
For cassava wastewater, substituting the mg atoms in Eqs. (6.E1, 6.E2, 6.E3, 6.E4
and 6.E5),
148
S. Sivamani et al.