F. YANG, R. ZHU
Copyright © 2013 SciRes. ENG
manganate index determination” (GB11892-89).
3.5. Microorganism Culture
1) Seed culture media
Seed culture media for Bacillus subtilis, photosynthet-
ic bacteria, lactobacillus bacteria, nitrifying bacteria and
were beef extract peptone medium.
2) Proliferation mediu m (g/L): glucose 1, yeast extract
0.7, peptone 1, (NH4)2SO4 0.2, MgSO4·7H2O 0.2, KH2PO4
1, and agar 18 g, pH 7.2.
3.6. Screening of Lake Wat er Rest oration and
Purification Bacteria
According to information reported in literature, microor-
ganisms with w ater restoration and purification functions,
Bacillus subtilis, photosynthetic bacteria, lactobacillus
bacteria, nitrifying bacteria 1, nitrifying bacteria 2 and
oligotrophic bacteria, w ere sel ected, and total phosphorus,
total nitrogen and COD value in lake water were meas-
ured. Lake water from same position was selected and
aliquoted into 7 1L-flasks. The adding amount of micro-
organisms were: 6 g /L Bacillus subtilis, 2 g/L photosyn-
thetic bacteria, 0.4 g/L lactobacillus, 0.2 g/L nitrifying
bacteria 1, 0.2 g/L nitrifying bacteria 2, and 0.4 g/L oli-
gotrophic bacteria, with plain water as control. Different
water indicators in lake wa ter wer e determined 20 d after
adding agents, a nd the measure temperature was 20˚C.
3.7. Design of Orthogonal Experiment for
Complex Agent s Ratio
According to relevant experimental reports and conven -
tional value, orthogonal experiments were preformed
mainly using Bacillus subtilis with five other supple-
mental microorganisms, each containing three concentra-
tions (L1873). The level of orthogonal design factors was
shown in Table 1.
4. Results and Discussion
4.1. Screening of Lake Wat er Rest oration and
Purification Bacteria
According to relevant literature, six kinds of microor-
ganisms with lake water purification and r estoration abil -
ity were selected for pilot study. Related indicators were
measured, and the re sults were shown in Figure 1.
As shown in Figure 1, 20 d after adding agents, total
phosphorus, total nitrogen and COD values in each water
sample revealed that all six bacteria had different levels
of water pur ification and restor ation ability. Bacillus s ub-
tilis had strongest purificatio n ability of total phosphorus
purification, lactobacillus had higher ability of nitrogen
purification, and photosynthetic bacteria higher ability
Table 1. L18(37) orthogonal experimental design.
level Factors
A(g/L) B(g/L) C(g/L) D(g/L) E(g/ L) F(g/L) G
1 6 1 0.4 0.2 0.2 0.4 1
2 8 2 0.6 0.4 0.4 0.6 2
3 10 3 0.8 0.6 0.6 0.8 3
Notes: A: Bacillus subtilis; B: Photosynthetic bacteria; C: Lactic acid bac-
teria; D: Nitroba cte ria 1; E : Nitrobacteria 2; F: Oligotrophic bacteria; G: Error.
The total phosphorus
The total nitrogen
COD
The total phosphorus (mg/L). The total nitr ogen (mg/L). COD (mg/L)
A: The initial quality of lake water
B: The quality for lake water of adding Bacillus subtilis
C: The quality for lake water of adding Photosynthetic bacteria
D: The quality for lake water of adding Lactic acid bacteria
E: The quality for lake water of adding Nitrobacteria 1
F: The quality for lake water of adding Nitrobacteria 2
G: The quality for lake water of adding Oligotrophic bacteria
Figure 1. The purifying and repairing bacteria screening
for lake water.
of COD purification. Comprehensive analysis of three
measured indicators to compare to the purification ability
of each bacterium showed that Bacillus subtilis group
exhibited strongest water purification capability. Ac-
cording to the purification characteristics of each bacte-
rium, we used a complex agent based on Bacillus subtilis
with five other supplemental bacteria as purification
agents for studies.
4.2. Ratio of Complex Agent
Using COD value as L1873 orthogonal experiment results,
complex agent was added and the results were deter-
mined 20 d later, as shown in Table 2.
As shown in Tables 2 and 3, the ratio difference of
various agents had high impacts on the measured COD
values. Among each agent ratio, Bacillus subtilis and
nitrifying bacteria displayed highly significant impacts,
and lactobacillus and oligotrophic bacteria had signifi-
cant impacts. According to the F value, the order of im-
pacts of each bacteria on COD was: Bacillus subtilis >