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Leachate Irrigation for Plants
Chapter 4
Leachate Irrigation for Plants 4.1 CHARACTERIZATION OF FRESH AND MATURE LEACHATE FOR IRRIGATION Characteristics of fresh and mature leachate used are shown in Table 4.1 and Table 4.2, respectively. Compared with fresh leachate, mature leachate (6 years) had much lower COD, BOD concentrations and biodegradation with higher TN, NH3-N concentrations. P concentrations in fresh leachate and
TABLE 4.1 Characterization of Fresh Leachate Used Parameters
1
2
3
Average value
pH
7.52
7.93
7.46
7.64
COD (mg/L)
14350
13600
14765
14238
BOD5 (mg/L)
6450
5712
6790
6317
BOD5/COD
0.45
0.42
0.46
0.44
NH3-N (mg/L)
1540
1467
1525
1510.67
TN (mg/L)
1665
1585
1670
1640
P (mg/L)
12
16
13
13.33
Cu (mg/kg)
0.05
0.05
0.05
0.05
Zn (mg/kg)
0.52
0.5
0.68
0.57
Pb (mg/kg)
, 0.2
, 0.2
, 0.2
, 0.2
Ni (mg/kg)
0.14
0.1
0.19
0.14
Cr (mg/kg)
0.15
0.19
0.17
0.17
Cd (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Hg (mg/kg)
70.3
68.5
79.6
72.8
Ca (mg/kg)
529
588
479
532
Mg (mg/kg)
272
219
385
292
K (mg/kg)
1540
2195
1479
1738
Pollution Control Technology for Leachate From Municipal Solid Waste. DOI: https://doi.org/10.1016/B978-0-12-815813-5.00004-8 © 2018 Elsevier Inc. All rights reserved.
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TABLE 4.2 Characterization of Mature Leachate (6 years) Used Parameters
1
2
3
Average value
pH
8.68
8.42
8.9
8.67
COD (mg/L)
2380
2492
2145
2339
BOD5 (mg/L)
366
402
260
342.67
BOD5/COD
0.15
0.16
0.12
0.15
NH3-N (mg/L)
2399
2250
2496
2381.67
TN (mg/L)
2526
2441
2635
2534
P (mg/L)
7
9
4.5
6.83
Cu (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Zn (mg/kg)
0.24
0.21
0.2
0.22
Pb (mg/kg)
, 0.2
, 0.2
, 0.2
, 0.2
Ni (mg/kg)
0.1
0.13
0.08
0.1
Cr (mg/kg)
0
0.01
0
0.01
Cd (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Hg (mg/kg)
32.5
42.5
28
34.33
Ca (mg/kg)
45.2
44.8
59
49.67
Mg (mg/kg)
110
87
132
109.67
K (mg/kg)
883
776
928
862.33
mature leachate (6 years) were both low. Heavy metal content of fresh leachate was approximately 10 times higher than that of mature leachate (6 years). Theoretically, mature leachate has nutritive elements like N, P, and K that are necessary in plant growth while it contains less heavy metal that may harm plants and soil. Thus, it is more appropriate to use mature leachate for irrigation as a nutrient source. Fundamental characterization of two soil samples is shown in Table 4.3. Although lower pH and slightly higher heavy metal contents, the soil II had higher hygroscopic moisture, organic content, total microbes, and nutrient concentration than that of soil I. Generally, soil II is more fertile for plant growth.
4.2 EFFECT OF LEACHATE IRRIGATION ON CHRYSANTHEMUM SEEDLINGS GROWTH It was shown that chrysanthemums of each group grew normally and leachate irrigation had no fatal effect on plant growth. Plant biomass increment of
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TABLE 4.3 Fundamental Characterization of Two Soils Before Planting Parameters
Soil I
Soil II
pH
8.18
7.99
Hygroscopic moisture (%)
0.59
1.07
Organic content (%)
2.30
7.90
12.19
15.17
Available P (mg/g)
2.04
4.44
Total microbes (absorbance)
0.481
0.534
TN (mg/g)
Zn (mg/kg)
51.00
66.63
Pb (mg/kg)
10.00
12.30
Cd (mg/kg)
2.50
4.60
Ni (mg/kg)
0.50
6.63
Cr (mg/kg)
21.95
26.43
K (mg/kg)
1230.00
1588.00
Ca (mg/kg)
9138.00
10212.00
FIGURE 4.1 Relationship of chrysanthemum biomass increment and leachate dilution ratio.
controlled sample (leachate irrigation) was 24.52 g, while 36.49 g, 39.97 g, 44.07 g in mature leachate at different dilution ratio of 1: 100, 1: 50, 1: 5, respectively. When using fresh leachate for irrigation, the biomass increment was 31.00 g, 47.94 g, and 40.07 g at different dilution ratio of 1: 100, 1: 50, 1: 5. Plant biomass increment under different conditions are shown in Fig. 4.1, chrysanthemum biomass increment in leachate irrigation groups is more than the control group, showing that leachate irrigation can accelerate chrysanthemum growth and increase biomass. The average biomass increase
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in three groups using mature leachate was 40.18 g, while 39.67 g for adopting fresh leachate irrigation. The statistics were close so that effects of two kinds of leachate on chrysanthemum growth were similar. For mature leachate irrigation, the higher the leachate concentration is, the higher chrysanthemum biomass increment will be obtained. When the dilution ratio was 1:5, the chrysanthemum biomass increment reached the highest. However, for fresh leachate irrigation, the highest chrysanthemum biomass increment was obtained at a dilution ratio of 1:50 and then it decreased at a dilution ratio of 1:5, which might be caused by following reasons. Leachate contains nutrients and pollutants, and the former promote and the latter hamper the growth. Since the two types of substances have opposite effects on chrysanthemum growth, there exists a balance point that leachate irrigation has a positive effect on biomass increase. When leachate concentration exceeds that balance point, adverse effect of leachate irrigation is more obvious. If choosing COD as the index for balance point and making full use of present statistics, the balance concentration is 1600 mg/L in fresh leachate irrigation. Theoretically, balance concentration in mature leachate irrigation is higher than that in fresh leachate irrigation.
4.2.1 Effect of Leachate Irrigation on Chrysanthemum Plant Height Test results of plant height variation are shown in Table 4.4.
4.2.1.1 Effect of mature leachate irrigation on chrysanthemum plant height Combining Table 4.1 and Fig. 4.2, it can be seen that plant height variations reaches the maximum at the dilution ratio of 1:50, followed by the group of 1:5. The least plant height variations occurred in leachate irrigation group of 1:100. If chrysanthemum growth cycle were divided into three periods according to growth condition and observation time, 1-46 d, 46 d-97 d, and after 97 d were the early stage, medium stage, and later stage, respectively. Obviously, medium stage was the rapidest growth stage of chrysanthemum. It was concluded that at the early stage, different concentration mature leachate irrigation had no obvious effect, since plants in each group had similar growth rate. At the medium stage, chrysanthemum growth rates started to vary, exhibiting most obvious effects of different dilution ratios. At the later stage, plant height variation rates of each group turn similar since plants were almost mature. At the medium stage of chrysanthemum growth, plant height increments of each group are shown in Fig. 4.3. Generally, mature leachate irrigation had an obvious effect on chrysanthemum plant height increment. It can be obtained that the dilution ratio of 1:50 can be contributed to the biggest plant height increment. The second
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329
TABLE 4.4 Test Results of Plant Height Variation (cm) Upon Leachate Irrigation Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L)
Planting time (d)
COD
BOD5
TN
0d
1:100
23
3
25
6.62
1:50
46
7
50
6.24
1:5
390
57
422
6.19
0
0
0
5.70
Water
46 d
64 d
97 d
110 d
9.20
14.50
29.83
36.00
11.05
21.35
41.20
48.75
11.15
21.25
35.25
40.81
12.10
19.94
31.56
37.06
Fresh leachate Dilution ratio
Leachate quality for irrigation (mg/L)
Planting time (d)
COD
BOD5
TN
0d
46 d
64 d
97 d
110 d
1:100
142
63
16
5.72
10.80
24.00
34.20
41.50
1:50
279
124
32
5.85
13.80
19.00
39.67
44.78
1:5
2343
1053
273
4.94
10.68
22.67
35.67
41.94
0
0
0
5.70
12.10
19.94
31.56
37.06
Water
FIGURE 4.2 Chrysanthemum plant height variation upon mature leachate irrigation.
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went to the dilution ratio of 1:5. When using clear water or the dilution ratio of 1:100 for irrigation, chrysanthemum plant height increment was the least.
4.2.1.2 Effect of fresh leachate irrigation on chrysanthemum plant height From Table 4.1 and Fig. 4.4, the plant height increment at the dilution ratio of 1:50 is the biggest, then followed by the ratio of 1:5 and 1:100. When using clear water for irrigation, the increment was the least. During the whole growth cycle of chrysanthemums, the variation at the dilution ratio of 1:5 and 1:100 were very similar. The rapid growth stage is still at the medium stage and similar with mature leachate irrigation. At the medium stage of chrysanthemum growth, plant height increments of each group are shown in Fig. 4.5. The dilution ratio of 1:50 got the highest plant height increment, 25.87 cm. The second
FIGURE 4.3 Relationship of chrysanthemum plant height increment at medium stage and leachate dilution ratio under mature leachate irrigation.
FIGURE 4.4 Chrysanthemum plant height variations upon fresh leachate irrigation.
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FIGURE 4.5 Relationship of chrysanthemum plant height increment at the medium stage and leachate dilution ratio under fresh leachate irrigation.
FIGURE 4.6 Relationship of chrysanthemum plant height increments at the medium stage and leachate dilution ratio under leachate irrigation.
was the dilution ratio of 1:5, with an increment of 24.99 cm; then the dilution ratio of 1:100 got an increment of 23.4 cm, while control group just got an increment of 19.46 cm. According to the results, fresh leachate irrigation had a great promotion on chrysanthemum plant height increment, with the best increment obtained at the dilution ratio of 1:50. The comparison of mature and fresh leachate irrigation for chrysanthemum plant height is shown in Fig. 4.6. It was indicated that plant height increment at dilution ratio of 1:50 in mature leachate irrigation was higher than that at same dilution ratio in fresh leachate irrigation, with the best growth condition among all the groups.
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4.2.2 Effect of Leachate Irrigation on Chrysanthemum Leaf Number Test results of leaf number variation are shown in Table 4.5.
4.2.2.1 Effect of mature leachate irrigation on chrysanthemum leaf number Chrysanthemum leaf number increment in mature leachate irrigation is shown in Fig. 4.7. Before the 64th day, leaf number increment of each group was similar. After that day, mature leachate irrigation, especially at dilution ratio of 1:5 and 1:50, was most beneficial to leaf number increment. 4.2.2.2 Effect of fresh leachate irrigation on chrysanthemum leaf number In Fig. 4.8, chrysanthemum leaf number increment in fresh leachate irrigation is given. Before 64th d, the difference between groups was not distinct. TABLE 4.5 Test Results of Leaf Number Variation Upon Leachate Irrigation Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L) COD
BOD5
1:100
23
3
1:50
46
1:5 Water
Planting time (d) TN
0d
46 d
64 d
110 d
25
2.09
15.50
28.67
59.67
7
50
2.09
13.50
25.20
82.90
390
57
422
2.27
18.20
25.75
84.63
0
0
0
2.36
18.40
28.56
41.89
Fresh leachate Dilution ratio
1:100
Leachate quality for irrigation (mg/L) COD
BOD5
142
63
Planting time (d) TN 16
0d
46 d
64 d
110 d
1.91
16.00
29.78
68.89
1:50
279
124
32
2.64
20.90
24.20
81.44
1:5
2343
1053
273
2.09
17.55
28.00
84.89
0
0
0
2.36
18.40
28.56
41.89
Water
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FIGURE 4.7 Chrysanthemum leaf number increment under mature leachate irrigation.
FIGURE 4.8 Chrysanthemum leaf number increment under fresh leachate irrigation.
Subsequently, the results started to vary obviously. Faster growths were observed in the dilution ratio of 1:5 and 1:50. In other words, fresh leachate irrigation was beneficial to chrysanthemum leaf number increment with the dilution ratio of 1:5 and 1:50.
4.2.2.3 Comparison of mature and fresh leachate irrigation on chrysanthemum leaf number Relationship of chrysanthemum leaf number increase and leachate dilution ratio is shown in Fig. 4.9. Mature and fresh leachate irrigation had similar effects on chrysanthemum leaf number variation. When the leachate dilution ratio was 1:50 or 1:5, the effect was most distinct. Generally, regardless of leachate type, diluted leachate irrigation benefitted the chrysanthemum leaf number increment.
4.2.3 Effect of Leachate Irrigation on Chrysanthemum Leaf Area Test results of leaf area variations which are used as the index of chrysanthemum growth are presented at Table 4.6.
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FIGURE 4.9 Relationship of chrysanthemum leaf number increment and dilution ratio upon leachate irrigation.
TABLE 4.6 Test Results of Leaf Area Variations (cm2) Leachate Irrigation on Chrysanthemum Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L) COD
BOD5
1:100
23
3
1:50
46
1:5 Water
Planting time (d) TN
0d
46 d
64 d
110 d
25
20.14
25.75
30.69
42.90
7
50
19.65
33.48
42.89
54.63
390
57
422
18.02
30.58
37.79
45.72
0
0
0
18.16
26.27
27.18
32.40
Fresh leachate Dilution ratio
1:100
Leachate quality for irrigation (mg/L) COD
BOD5
142
63
Planting time (d) TN
0d
46 d
64 d
110 d
16
17.38
27.14
41.67
40.28
1:50
279
124
32
16.22
37.98
38.13
51.64
1:5
2343
1053
273
15.87
29.13
34.75
41.74
0
0
0
18.16
26.27
27.18
32.40
Water
Leachate Irrigation for Plants Chapter | 4
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4.2.3.1 Effect of mature leachate irrigation on chrysanthemum leaf area Observation results of leaf area variations under different leachate irrigation condition are shown in Fig. 4.10. The sample of the dilution ratio 1:50 had the fastest growth rate, and the control group had the slowest growth rate. Generally, leachate irrigation benefitted chrysanthemum leaf growth and the best leaf growth was obtained at the dilution ratio of 1:50. 4.2.3.2 Effect of fresh leachate irrigation on chrysanthemum leaf area Fresh leachate irrigation had an obvious effect on chrysanthemum leaf growth. In Fig. 4.11, the variations of chrysanthemum leaf area at different dilution ratios are shown. The sample of the dilution ratio 1:50 had the fastest growth rate, while the second and the third were 1:100 and 1:5, respectively. Leachate irrigation groups generally had a higher rate than the control group. Thus, fresh leachate irrigation had a positive effect on chrysanthemum leaf growth, with the best result obtained at the dilution ratio of 1:50. 4.2.3.3 Comparison of mature and fresh leachate irrigation on chrysanthemum leaf area Fig. 4.12 shows leaf area increment results, from which two types of leachate irrigation both had positive effects on chrysanthemum leaf growth. The best result was obtained at the dilution ratio of 1:50.
4.2.4 Effect of Leachate Irrigation on Chrysanthemum Root Length Chrysanthemum root length before and after planting is shown in Fig. 4.13. When using mature leachate for irrigation, the root length increased to some extent. The biggest increment occurred at the dilution ratio of 1:100. The
FIGURE 4.10 Chrysanthemum leaf area variations under mature leachate irrigation.
FIGURE 4.11 Chrysanthemum leaf area variations under fresh leachate irrigation.
FIGURE 4.12 Chrysanthemum leaf area variation with different leachate types and dilution ratios upon leachate irrigation.
FIGURE 4.13 Effect of leachate irrigation on chrysanthemum root length.
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337
effects of fresh leachate irrigation were obvious, and the dilution ratio 1:5 still got the best growth, while ratio of 1:100 had a little negative effect.
4.2.5 Effect of Leachate Irrigation on Chrysanthemum Peroxidase Activity Peroxidase, existing in every organ of plants, is related to plant respiration intensity. Peroxidase activity has some relationship with plant growth to some extent so that peroxidase activity can reflect plant growth. Test method for peroxidase is spectrophotometry with characteristic wavelength of 470 nm. The absorbance variation in the same time can be used to judge the activity of peroxidase. Peroxidase activity variations of the collected samples at the 64th and 110th day in mature and fresh leachate irrigation respectively are shown in Figs. 4.14 4.17. From Fig. 4.14, it can be found that peroxidase activity is strongest when adopting clear water irrigation, followed by 1:100 group, 1:50 group, 1:5 group, in turn, which means that mature leachate irrigation has an adverse effect on chrysanthemum peroxidase activity. From Fig. 4.15, it can be found that peroxidase activity is strongest when adopting clear water irrigation, then 1:100 group, 1:50 group, and 1:5 group is done, in turn, which also means that fresh leachate irrigation has the same adverse effect on chrysanthemum peroxidase activity with fresh leachate. When testing the peroxidase activity at the 110th day, the results were different. Although the control group still got the highest peroxidase activity, the second highest was 1:5 and then 1:100, 1:50 dilution in turn, meaning chrysanthemum tended to adapt to the leachate irrigation; especially the experimental group of ratio 1:5 had almost the same peroxidase activity with the control group. At the 110th planting day, for fresh leachate irrigation, the sample of ratio 1:100 had a higher peroxidase activity than the control group. Peroxidase
FIGURE 4.14 Test results of chrysanthemum peroxidase activity under mature leachate irrigation at 64th day.
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FIGURE 4.15 Test results of chrysanthemum peroxidase activity under fresh leachate irrigation at the 64th day.
FIGURE 4.16 Test results of chrysanthemum peroxidase activity under mature leachate irrigation at the 110th day.
FIGURE 4.17 Test results of chrysanthemum peroxidase activity under fresh leachate irrigation at the 110th day.
activity of 1:50 sample was slightly lower than that of the control group while the 1:5 sample almost reached 0. It meant that fresh leachate irrigation with a dilution ratio of 1:5 was hazardous to peroxidase activity in chrysanthemum.
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TABLE 4.7 Growth Status of Five Plants after 46 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
1:10
1:5
Clean water
1:10 control
34
44
56
54
57
64
Plant height (cm) Salvia plebeia Manila
31
32
31
29
31
32
Chrysanthemum
22
18
19
23
23
21
Aster novi-belgii
32
46
51
38
35
37
39
19
32
37
43
Stem perimeter (mm) Ophiopogon japonicus
TABLE 4.8 Growth Status of Five Plants After 101 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
1:10
1:5
Clean water
1:10 control
Salvia plebeia
90
65
70
76
83
91
Manila
33
30
27
29
39
32
Chrysanthemum
37
50
53
40
56
48
Aster novi-belgii
34
38.5
35
37
32
33
Little leaf box
28
28.5
33
30
33.5
30
52
38
40
52
58
Plant height (cm)
Stem perimeter (mm) Ophiopogon japonicus
4.3 PLANTS GROWTH UPON LEACHATE IRRIGATION 4.3.1 Effect of Leachate Irrigation on Growth Status The growth status of five plants using mature leachate after 46 days or 101 days are shown in Tables 4.7 and 4.8, Table 4.9.
TABLE 4.9 Difference Between the Growth Status of Five Plants After 101 days Compared with 46 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
Salvia plebeia
56
21
Manila
2
22
Chrysanthemum
15
32
Aster novi-belgii
2
Little leaf box
1:10
1:5
Clean water
1:10 control
14
22
26
27
24
0
8
0
24
17
32
27
27.5
2 16
21
23
24
29
35
34.5
35
35.5
35
13
19
8
15
15
Plant height (cm)
Stem perimeter (mm) Ophiopogon japonicus
FIGURE 4.18 The peroxidase activity of chrysanthemum after 46 days’ leachate irrigation.
FIGURE 4.19 The peroxidase activity of chrysanthemum after 101 days’ leachate irrigation.
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4.3.2 Effect of Leachate Irrigation on Peroxidase Activity The peroxidase activity of chrysanthemum after 64 and 101 days is shown in Figs. 4.18 and 4.19. It was shown that the strongest peroxidase activity among Ch1BCh6 (representing 1:100, 1:50, 1:10, 1:5, clear water, and 1:10 control group of chrysanthemum, respectively) was Ch3 after 46 days, followed by Ch1, Ch2, Ch4, Ch6, and the control group had the lowest peroxidase activity. Peroxidase activity of chrysanthemum varied even more irregularly. Peroxidase activity of Ch1 and Ch4 remained high, followed by Ch6, and that of the three others were very low. The peroxidase activity of Manila after 64 and 97 days are shown in Figs. 4.20 and 4.21, respectively. M1 M6 represented 1:100, 1:50, 1:10, 1:5, and clean water, and 1:10 control group of Manila growth, respectively. It was shown that the strongest peroxidase activity was D2 after 64 days, followed by M1, M3, M6, and M5,
FIGURE 4.20 Peroxidase activity of Manila after 64 days’ leachate irrigation.
FIGURE 4.21 Peroxidase activity of Manila after 97 days’ leachate irrigation.
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FIGURE 4.22 Peroxidase activity of salvia plebeia after 101 days’ leachate irrigation.
FIGURE 4.23 Peroxidase activity of little leaf box after 110 days’ leachate irrigation.
which had little difference, and the control had the lowest peroxidase activity. It can be seen from Fig. 4.21 that the difference between the peroxidase activity of chrysanthemum after 64 and 97 days is obvious. And the strongest peroxidase activity was M2, followed by M3, M5, then M4, M1, and M6 had the lowest peroxidase activity. The peroxidase activity of salvia plebeia after 101 days is shown in Fig. 4.22.
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TABLE 4.10 pH of Soil for Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
8.35
8.54
8.55
8.51
8.54
8.10
8.19
8.09
8.28
2
8.36
8.51
8.27
8.41
8.41
8.37
8.33
8.21
8.42
3
8.59
8.44
8.54
8.50
7.89
8.33
8.10
8.15
8.47
4
8.46
8.39
8.57
8.37
8.50
8.29
8.06
8.10
8.61
5
8.39
8.46
8.25
8.42
8.43
8.44
8.20
8.08
8.41
6
8.37
8.51
8.55
8.46
8.39
8.50
8.16
8.48
Salvia plebeian was irrigated using diluted mature leachate. S1 S6 were on behalf of 1:100, 1:50, 1:10, 1:5, and clean water, and 1:10 control group, respectively. And the strongest peroxidase activity was S4, followed by S5, S1, then S2, S3, and S6 had the lowest peroxidase activity. The peroxidase activity of little leaf box after 110 days irrigation is shown in Fig. 4.23. L1 L6 represented 1:100, 1:50, 1:10, 1:5, clean water, and 1:10 control group of little leaf box growth, respectively. Six-year leachate had a certain impact on the peroxidase activity of little leaf box. And the strongest peroxidase activity was L4, followed by L1, L5, then L6, and L3, L2 had the lowest peroxidase activity, showing great difference with others.
4.4 SOIL PROPERTIES CHANGE UPON LEACHATE IRRIGATION ON PLANTS 4.4.1 Soil pH pH is an important chemical property for soil and also one of the key impact factors of soil fertility. It not only affects soil formation, properties, and the existence status, transformation and effectiveness of soil nutrient, but also the microbial activity and normal growth of crops. pH of soil is shown in Table 4.10, in which No.1B6 refer to the dilution ratios of 1:100, 1:50, 1:10, 1:5, clean water, and 1:10 control group, respectively, while {ABD} and {EBH} represent the soil I and soil II, respectively, meanwhile, {A, C, E, G} denoted the soils irrigated by mature leachate, {B, D, F, H} for fresh leachate, and {J} for the soil sample collected in the same place with soil A at different time. pH of soils I and II were 8.18 and 7.99. respectively. before irrigation. It was weak alkaline. pH of soils after leachate irrigation increased a little, which was also the weak alkaline. pH varied irregularly because the randomness of test results was large after irrigated by different leachate or different
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TABLE 4.11 The Soil Hydroscopic Properties (%) for Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
1.34
1.04
2.18
0.90
1.65
1.60
1.67
0.98
0.71
2
1.53
2.17
1.88
2.24
1.64
1.28
1.37
2.07
0.91
3
1.35
2.26
2.23
1.86
4.31
1.84
1.33
1.78
0.84
4
2.04
2.04
2.38
2.20
2.20
1.78
1.38
1.42
0.72
5
1.96
2.07
1.24
2.13
2.37
1.69
1.60
1.49
0.84
6
1.86
1.84
0.90
1.77
1.70
1.29
1.46
0.77
TABLE 4.12 The Increment of Soil Hydroscopic Properties (%) for Leachate Irrigation No.
A
B
C
D
1
127.1
76.3
269.5
52.5
2
159.3
267.8
218.6
3
128.8
283.1
4
245.8
245.8
5
232.2
6
215.3
E
F
G
H
J
54.2
49.5
56.1
2 8.4
20.3
279.7
53.3
19.6
28.0
93.5
54.2
278.0
215.3
302.8
72.0
24.3
66.4
42.4
303.4
272.9
105.6
66.4
29.0
32.7
22.0
250.8
110.2
261.0
121.5
57.9
49.5
39.3
42.4
211.9
52.5
200.0
58.9
20.6
36.4
30.5
dilution ratios. Soil pH will not make a big difference after leachate irrigation in a certain period.
4.4.2 Soil Hygroscopic Properties Soil hydroscopic properties are an important component and fertility factor for soil, affected by air relative humidity, soil texture, organic matter content, etc. The status of the soil hydroscopic water is shown in Table 4.11. The increment of soil hydroscopic properties is shown in Table 4.12. As shown in Table 4.12, as a whole, the soil hydroscopic properties significantly increased after leachate irrigation for a period of time, as well as soil moisture retention and adjusting ability. It can be found that hygroscopic properties after leachate irrigation were higher than water irrigation. Leachate absorption of soil had no obvious correlation with dilution ratio of
345
Leachate Irrigation for Plants Chapter | 4
FIGURE 4.24 The leachate absorption of soil B and J upon irrigation.
TABLE 4.13 Soils Organic Matter Contents (%) of Tests No.
A
B
C
D
E
F
G
H
J
1
7.20
4.80
4.80
4.95
11.11
11.69
13.13
10.85
5.05
2
4.29
5.55
5.11
4.43
9.57
12.34
12.99
7.95
5.59
3
7.20
4.32
5.61
5.85
7.54
11.67
15.21
10.91
4.90
4
7.84
4.82
5.27
7.00
8.18
11.60
12.35
10.61
5.36
5
7.35
5.22
5.61
5.63
8.83
10.50
13.07
13.32
6.59
6
7.40
5.80
6.33
6.65
8.72
10.80
12.92
6.24
leachate. Besides, leachate absorption of soils {A, C, E, G} after mature leachate irrigation and soils {B, D, F, H} after fresh leachate irrigation had no obvious difference. The leachate absorption of soil I (A, B, C, D) were almost the same with soil II (E, F, G, H), but due to original high hygroscopic properties in soil II, increment of hygroscopic properties in soil I was larger than soil II (soil J and B were taken from the same place, but soil I was measured on the 46th day). As shown in Fig. 4.24, the leachate absorption of soil B was higher than soil J, which fully indicated that leachate absorption of soil can be facilitated by leachate irrigation.
TABLE 4.14 Increment Rate of Soil Organic Matter After Leachate Irrigation (%) No.
A
B
C
D
1
213.04
108.70
108.70
115.22
2
86.52
141.30
122.17
3
213.04
87.83
4
240.87
5
219.57
6
221.74
E
F
G
H
J
40.63
47.97
66.20
37.34
119.57
92.61
21.14
56.20
64.43
0.63
143.04
143.91
154.35
2 4.56
47.72
92.53
38.10
113.04
109.57
129.13
204.35
3.54
46.84
56.33
34.30
133.04
126.96
143.91
144.78
11.77
32.91
65.44
68.61
186.52
152.17
175.22
189.13
10.38
36.71
63.54
171.30
347
Leachate Irrigation for Plants Chapter | 4
TABLE 4.15 Classification of Soil Organic Matter Content and Fertility Level Fertility level
Low
Lower
Medium
Higher
High
Soil organic matter content (g/kg)
,5
5 2 10
10 2 12
12 2 15
.15
TABLE 4.16 Soil Total Nitrogen Content (mg/g) No.
A
B
C
D
E
F
G
H
1
17.81
11.19
11.04
10.13
13.67
25.01
24.59
25.85
J 6.28
2
16.01
10.70
12.71
13.71
16.91
21.24
22.64
19.00
13.44
3
20.24
13.27
11.23
13.93
15.06
25.57
27.54
23.03
11.90
4
16.58
17.76
13.54
18.59
18.58
23.09
26.56
27.12
12.57
5
17.44
12.55
13.40
11.39
19.92
19.87
32.56
23.90
12.57
6
19.77
12.26
17.93
13.34
20.99
24.74
25.59
11.68
4.4.3 Soil Organic Matters Soil organic matters mainly derive from plants and microorganisms, including living and dead organisms, as well as its secretion and derivatives. Soil organic matter, the essence of the fertility of soil, which has a great effect on physical, chemical, and biological properties of soil, is an indicator of good or bad, rich or poor soil. Content, composition, and properties of organic matter varies with climate and biological conditions regularly. The soil organic matter is determined by potassium dichromate colorimetric method as shown in Table 4.13. The original organic matter content of soil I was 2.30%, with lower fertility, whereas that of soil II was 7.90%, good fertility. Increment rate of soil organic matter after leachate irrigation is shown in Table 4.14. It can be seen from Tables 4.13 4.15 that a dramatic increment in soil organic matter content appears. Leachate irrigation could obviously promote soil organic matter content and soil fertility. Classification of soil organic matter content and fertility level is shown in Table 4.15. Soil I was poor, only containing 2.3% organic matter, low fertility, but organic matter content had been raised more than one time after leachate irrigation for four months, basically reaching the lower level. Soil II was relatively good, of which organic matter content was 7.90%, belonging to low fertility, while organic matter content had certain improvement after leachate
TABLE 4.17 Increments of Soil TN Content After Leachate Irrigation (%) No.
A
1
46.10
2
B
C
D
E
F
2 8.20
2 9.43
2 16.90
2 9.89
64.86
31.34
2 12.22
4.27
12.47
11.47
3
66.04
8.86
2 7.88
14.27
4
36.01
45.69
11.07
5
43.07
2.95
9.93
6
62.18
0.57
47.09
9.43
G
H
J
62.10
70.40
2 48.48
40.01
49.24
25.25
10.25
2 0.73
68.56
81.54
51.81
2 2.38
52.50
22.48
52.21
75.08
78.77
3.12
2 6.56
31.31
30.98
114.63
57.55
3.12
38.37
63.09
68.69
2 4.18
349
Leachate Irrigation for Plants Chapter | 4
irrigation for a period. Organic matter content of F, G, H were more than 10%, mostly reached the medium level and some reached the higher or high level. Organic matter content of soils after mature leachate irrigation {A, C, E, G} and fresh leachate irrigation {B, D, F, H}, had no obvious difference in addition to A. A had the greatest increase in organic matter among all.
4.4.4 Soil Total Nitrogen Content The soil fertility can be judged by soil total nitrogen content, which can also be taken as reference to the soil fertilization, as shown in Table 4.16. The original soil I TN was 12.19 mg/g, and soil II TN was 15.17 mg/g. Increments of soil TN content after leachate irrigation is shown in Table 4.17. It can be seen from Table 4.16 and Table 4.17 that a dramatic increase in soil TN content occurs. Relatively, increment in soil II TN was more obvious than soil I. Other soil I TN content changed little in addition to A, as most of them fluctuated near 6 10% of the original soil. And there was a relatively large increment in soil II TN content, as most of soils TN had increased by about 40% in addition to E. Soils TN of A had only increased by about 30%. Besides, TN of soil {A, C, E, G} after mature leachate irrigation and soil {B, D, F, H} after fresh leachate irrigation had no obvious difference. There was no obvious correlation between TN content and dilution ratio of leachate.
4.4.5 Soil Effective Phosphorus Phosphorus easy to be absorbed by plants can be judged by effective phosphorus, which can be taken as reference to the soil fertilization, as shown in Table 4.18. TABLE 4.18 The Effective Phosphorus in Soils (mg/g) No.
A
B
C
D
E
F
G
H
J
1
1.04
1.26
1.58
0.94
2.40
2.17
3.85
1.65
1.60
2
1.57
1.79
1.57
2.17
2.53
2.60
3.34
2.46
1.57
3
1.21
0.73
1.11
1.34
2.05
3.24
3.02
2.00
1.54
4
1.64
1.98
1.38
2.00
2.84
3.32
3.32
1.91
1.46
5
1.85
2.07
1.15
1.70
4.08
2.74
4.33
1.39
1.31
6
1.22
1.59
1.11
1.58
2.33
4.34
3.17
1.44
TABLE 4.19 Decrements of Effective P in Soil After Leachate Irrigation (%) No.
A
B
C
D
E
F
G
H
J
1
2 49.02
2 38.24
2 22.55
2 53.92
2 45.95
2 51.13
2 13.29
2 62.84
2 21.57
2
2 23.04
2 12.25
2 23.04
6.37
2 43.02
2 41.44
2 24.77
2 44.59
2 23.04
3
2 40.69
2 64.22
2 45.59
2 34.31
2 53.83
2 27.03
2 31.98
2 54.95
2 24.51
4
2 19.61
2 2.94
2 32.35
2 1.96
2 36.04
2 25.23
2 25.23
2 56.98
2 28.43
5
2 9.31
1.47
2 43.63
2 16.67
2 8.11
2 38.29
2 2.48
2 68.69
2 35.78
6
2 40.20
2 22.06
2 45.59
2 22.55
2 47.52
2 2.25
2 28.60
2 29.41
TABLE 4.20 Total Soil Microbial Amount (Absorbance) No.
A
B
C
D
E
F
G
H
J
1
0.575
0.585
0.573
0.582
0.604
0.585
0.623
0.627
0.578
2
0.593
0.553
0.548
0.633
0.622
0.559
0.590
0.558
0.570
3
0.595
0.577
0.611
0.587
0.638
0.660
0.674
0.570
0.567
4
0.559
0.526
0.575
0.606
0.554
0.728
0.620
0.666
0.570
5
0.562
0.592
0.577
0.548
0.545
0.597
0.674
0.616
0.575
6
0.511
0.567
0.580
0.592
0.676
0.616
0.664
0.567
TABLE 4.21 Increments of Microbial Amount in Soil After Leachate Irrigation (Absorbance) No.
A
B
C
D
E
F
G
H
J
1
19.54
21.62
19.13
21.00
13.11
9.55
16.67
17.42
20.17
2
23.28
14.97
13.93
31.60
16.48
4.68
10.49
4.49
18.50
3
23.70
19.96
27.03
22.04
19.48
23.60
26.22
6.74
17.88
4
16.22
9.36
19.54
25.99
3.75
36.33
16.10
24.72
18.50
5
16.84
23.08
19.96
13.93
2.06
11.80
26.22
15.36
19.54
6
6.24
17.88
20.58
23.08
26.59
15.36
24.34
17.88
Leachate Irrigation for Plants Chapter | 4
353
Effective P in soil I was 2.04 mg/g, and effective P in soil II was 4.44 mg/g. Decrements of effective P in soil after leachate irrigation is shown in Table 4.19. It can be seen from Table 4.18 and Table 4.19 that a dramatic decrease in effective P in soil after leachate irrigation for four months appears. The decrement rate of effective P in the two soils was almost the same. There was no obvious correlation between effective P in soil and dilution ratio of leachate or types of leachate. Because of low P content in leachate, it was impossible to provide the soil with P during the growth. While plant growth required a lot of P, effective P content in the soil was bound to decrease.
4.4.6 Total Soil Microbial Amount Total soil microbial is shown in Table 4.20. Microbial amount in soil I was 0.481, and microbial amount in soil II was 0.534. Increments of microbial amount in soil after leachate irrigation are shown in Table 4.21. It can be seen from Table 4.20 and Table 4.21 that the microbial amount in soil after leachate irrigation increases considerably. The increment rate of the microbial amount in two soils was almost the same. There was no obvious correlation between microbial amount in soil and dilution ratio of leachate or types of leachate. There existed a complex microbial community in the soil, and it became more prosperous and more conducive to plant growth, thus increasing soil fertility.
4.4.7 Heavy Metals Contents in Soil Due to a certain amount of metal ions (such as Zn, Pb, Cd, Ni, Cr) in leachate, the risk of metal ions content into soil increased using leachate irrigation. If metal ions in soil accumulated to a relatively high concentration, it would do harm to the plant growth as well as soil fertility. Zn content in soil is shown in Table 4.22 and Pb content in soil is shown in Table 4.23. Zn content in soil I was 51 mg/kg and Zn content in soil II was 66.63 mg/kg. Mostly zinc content in soils after leachate irrigation was fair or less than that before leachate irrigation, and only a few were extremely high. There was no obvious correlation between zinc content in soil and dilution ratio of leachate or types of leachate. Therefore, zinc content in soil would not change obviously after leachate irrigation. Pb content in soil I was 10 mg/kg and Pb content in soil II was 12.3 mg/ kg before irrigation. It can be seen from Table 4.23 that an increase in Pb content in soil after leachate irrigation occurs, and some even reaches
TABLE 4.22 Zn Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
32.34
49.20
0.92
51.94
57.10
18.15
72.27
49.81
77.00
2
54.66
0.00
44.81
43.87
22.28
100.70
56.19
1.54
56.00
3
57.62
39.13
35.89
42.69
64.02
57.14
66.90
47.42
53.50
4
38.16
22.10
7.01
0.92
61.46
103.40
59.66
58.22
63.50
5
47.74
47.42
52.50
33.52
52.40
54.01
76.71
80.88
66.50
6
52.26
4.95
30.94
2.48
52.40
68.18
10.73
54.00
TABLE 4.23 Pb Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
1
43.10
49.60
41.67
47.83
13.04
2
56.04
43.65
48.61
50.00
3
50.93
53.88
44.25
4
45.26
35.71
44.25
5
50.00
45.65
6
34.78
44.25
F
G
H
J
44.25
55.56
56.04
17.75
39.82
100.45
46.88
51.59
12.35
47.41
20.83
51.34
46.30
13.04
10.45
43.65
50.93
48.61
49.11
51.73
13.55
39.35
51.59
60.27
47.41
51.34
51.59
14.40
13.27
46.46
49.11
46.30
58.04
18.85
356
Pollution Control Technology for Leachate From Municipal Solid Waste
TABLE 4.24 Cd Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
1
6.49
6.67
6.18
7.35
8.58
2
6.74
6.67
7.25
7.11
3
7.01
5.99
4.92
4
6.24
4.81
4.18
5
6.37
6.62
6
6.86
5.17
F
G
H
J
5.41
6.92
7.49
3.00
5.17
15.96
7.60
6.67
3.00
6.99
7.74
8.36
6.04
6.13
2.50
6.42
7.98
7.50
6.59
5.74
3.00
7.01
7.91
7.60
7.24
6.33
7.16
2.50
4.43
5.41
7.60
6.53
7.60
2.50
TABLE 4.25 Ni Content in Soil (mg/kg) After Leachate Irrigation No.
A
D
E
F
G
H
J
1
18.60
B 4.96
C 4.25
19.40
22.09
19.60
17.71
23.52
, 0.50
2
20.24
5.67
20.51
17.78
24.89
44.70
22.08
5.67
, 0.50
3
23.28
18.60
20.66
20.79
21.06
24.28
22.73
21.01
, 0.50
4
19.69
13.80
18.54
14.87
24.39
26.05
21.52
20.79
, 0.50
5
18.32
21.01
19.40
19.12
23.73
22.98
22.08
9.21
, 0.50
6
17.78
19.07
17.48
19.60
23.18
24.39
23.73
, 0.50
40 50 mg/kg. Pb content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Pb content in soil I was lower than soil B, suggesting that Pb content in soil had some relationship with irrigation time. The longer the irrigation time, the greater chance of increased Pb content appeared. Cd content in soil is shown in Table 4.24. Cd content in soil I was 2.5 mg/kg and Cd content in soil II was 4.6 mg/kg before irrigation. It can be seen from Table 4.24 that a large increase in Cd content in soil after leachate irrigation occurs, and some even reaches 6 mg/kg. Cd content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Cd content in soil I was lower than soil B, suggesting that Cd content in soil had some relationship with irrigation time.
357
Leachate Irrigation for Plants Chapter | 4
TABLE 4.26 Cr Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
22.12
26.58
23.87
26.15
29.93
27.88
26.21
25.57
22.05
2
25.94
23.69
23.95
24.59
27.97
51.30
29.37
25.86
23.60
3
27.63
24.82
24.21
26.69
27.16
30.70
26.69
23.67
23.30
4
22.30
16.40
22.56
4.61
30.65
29.89
26.79
27.06
23.85
5
24.22
48.25
23.29
26.31
29.42
25.38
28.22
28.12
36.90
6
33.70
29.90
23.57
24.95
25.36
34.52
30.80
22.15
TABLE 4.27 K Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
1
1673.90
1147.43
1297.37
1541.20
2051.63
1610.72
1831.77
1371.25
2
1697.67
1413.44
1084.05
1579.42
1197.74
3026.53
1915.55
1188.23
3
1694.11
1435.23
1432.26
1653.90
1116.73
2021.32
1486.73
1358.97
4
1471.47
992.93
1614.79
1611.31
2230.74
1745.61
1218.93
1454.64
5
1208.83
1362.73
1390.86
1591.90
1683.41
1834.94
1452.26
1261.92
6
1419.38
1531.49
1425.92
1706.19
1246.86
1691.14
1742.83
The longer irrigation time led to the greater chance of increased Cd content. Ni content in soil is shown in Table 4.25. Ni content in soil I was 0.5 mg/kg and Ni content in soil II was 6.63 mg/kg before irrigation. It can be seen from Table 4.26 that a large increase in Ni content in soil after leachate irrigation is observed, and some even reaches 18 mg/kg. Ni content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Ni content in soil I was lower than soil B, suggesting that Ni content in soil had some relationship with irrigation time. The longer irrigation time led to the greater chance of increased Ni content. Cr content in soil is shown in Table 4.26. Cr content in soil I was 21.95 mg/kg and Cr content in soil II was 26.43 mg/kg. Mostly Cr content in soils after leachate irrigation was fair or below that before leachate irrigation, and only a few were extremely high. There was no obvious correlation between Cr content in soil and dilution ratio of leachate or types of leachate. Therefore, Cr content in soil would not change obviously after leachate irrigation from the overall.
TABLE 4.28 Ca Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
1
8045.00
9381.50
9061.00
11169.00
12251.00
8566.00
9918.00
8535.50
2
8930.50
10371.00
9498.00
10758.00
8885.00
17347.00
12104.00
9063.50
3
8401.00
7981.50
8517.50
8769.00
9092.50
12431.00
9076.00
11145.00
4
8472.50
8452.00
8601.50
8329.50
9342.00
9233.50
11830.50
9776.00
5
10259.00
10684.00
8736.50
9640.50
12991.50
8828.50
11542.50
9855.50
6
11609.00
6676.00
9120.00
8884.50
9378.50
9782.00
13399.00
Leachate Irrigation for Plants Chapter | 4
359
4.4.8 K, Ca Contents Besides a certain amount of heavy metal ions, leachate contains other metal ions, like Ca and K, which can also accumulate in the soil after leachate irrigation, having certain effects on soil properties. K content in soil is shown in Table 4.27. K content in soil I was 1230 mg/kg and K content in soil II was 1588 mg/kg. Mostly K content in soils after leachate irrigation was fair or higher than that before leachate irrigation. Increase in K content in soil II was higher than soil I overall. There was no obvious correlation between K content in soil and dilution ratio of leachate or types of leachate. Therefore, K content in soil remained stable or got a small increase after leachate irrigation. Considering the importance of K element for plants, it indicated that K provided by leachate irrigation can meet the needs of plant growth. Ca content in soil is shown in Table 4.28. Ca content in soil I was 9138 mg/kg and Ca content in soil II was 10212 mg/kg. Mostly Ca content in soils after leachate irrigation was fair or higher than that before leachate irrigation. There was no obvious correlation between Ca content in soil and dilution ratio of leachate or types of leachate. Therefore, Ca content in soil remained stable or got a small increase after leachate irrigation from the overall.
Leachate Irrigation for Plants 4.1 CHARACTERIZATION OF FRESH AND MATURE LEACHATE FOR IRRIGATION Characteristics of fresh and mature leachate used are shown in Table 4.1 and Table 4.2, respectively. Compared with fresh leachate, mature leachate (6 years) had much lower COD, BOD concentrations and biodegradation with higher TN, NH3-N concentrations. P concentrations in fresh leachate and
TABLE 4.1 Characterization of Fresh Leachate Used Parameters
1
2
3
Average value
pH
7.52
7.93
7.46
7.64
COD (mg/L)
14350
13600
14765
14238
BOD5 (mg/L)
6450
5712
6790
6317
BOD5/COD
0.45
0.42
0.46
0.44
NH3-N (mg/L)
1540
1467
1525
1510.67
TN (mg/L)
1665
1585
1670
1640
P (mg/L)
12
16
13
13.33
Cu (mg/kg)
0.05
0.05
0.05
0.05
Zn (mg/kg)
0.52
0.5
0.68
0.57
Pb (mg/kg)
, 0.2
, 0.2
, 0.2
, 0.2
Ni (mg/kg)
0.14
0.1
0.19
0.14
Cr (mg/kg)
0.15
0.19
0.17
0.17
Cd (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Hg (mg/kg)
70.3
68.5
79.6
72.8
Ca (mg/kg)
529
588
479
532
Mg (mg/kg)
272
219
385
292
K (mg/kg)
1540
2195
1479
1738
Pollution Control Technology for Leachate From Municipal Solid Waste. DOI: https://doi.org/10.1016/B978-0-12-815813-5.00004-8 © 2018 Elsevier Inc. All rights reserved.
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TABLE 4.2 Characterization of Mature Leachate (6 years) Used Parameters
1
2
3
Average value
pH
8.68
8.42
8.9
8.67
COD (mg/L)
2380
2492
2145
2339
BOD5 (mg/L)
366
402
260
342.67
BOD5/COD
0.15
0.16
0.12
0.15
NH3-N (mg/L)
2399
2250
2496
2381.67
TN (mg/L)
2526
2441
2635
2534
P (mg/L)
7
9
4.5
6.83
Cu (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Zn (mg/kg)
0.24
0.21
0.2
0.22
Pb (mg/kg)
, 0.2
, 0.2
, 0.2
, 0.2
Ni (mg/kg)
0.1
0.13
0.08
0.1
Cr (mg/kg)
0
0.01
0
0.01
Cd (mg/kg)
, 0.05
, 0.05
, 0.05
, 0.05
Hg (mg/kg)
32.5
42.5
28
34.33
Ca (mg/kg)
45.2
44.8
59
49.67
Mg (mg/kg)
110
87
132
109.67
K (mg/kg)
883
776
928
862.33
mature leachate (6 years) were both low. Heavy metal content of fresh leachate was approximately 10 times higher than that of mature leachate (6 years). Theoretically, mature leachate has nutritive elements like N, P, and K that are necessary in plant growth while it contains less heavy metal that may harm plants and soil. Thus, it is more appropriate to use mature leachate for irrigation as a nutrient source. Fundamental characterization of two soil samples is shown in Table 4.3. Although lower pH and slightly higher heavy metal contents, the soil II had higher hygroscopic moisture, organic content, total microbes, and nutrient concentration than that of soil I. Generally, soil II is more fertile for plant growth.
4.2 EFFECT OF LEACHATE IRRIGATION ON CHRYSANTHEMUM SEEDLINGS GROWTH It was shown that chrysanthemums of each group grew normally and leachate irrigation had no fatal effect on plant growth. Plant biomass increment of
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TABLE 4.3 Fundamental Characterization of Two Soils Before Planting Parameters
Soil I
Soil II
pH
8.18
7.99
Hygroscopic moisture (%)
0.59
1.07
Organic content (%)
2.30
7.90
12.19
15.17
Available P (mg/g)
2.04
4.44
Total microbes (absorbance)
0.481
0.534
TN (mg/g)
Zn (mg/kg)
51.00
66.63
Pb (mg/kg)
10.00
12.30
Cd (mg/kg)
2.50
4.60
Ni (mg/kg)
0.50
6.63
Cr (mg/kg)
21.95
26.43
K (mg/kg)
1230.00
1588.00
Ca (mg/kg)
9138.00
10212.00
FIGURE 4.1 Relationship of chrysanthemum biomass increment and leachate dilution ratio.
controlled sample (leachate irrigation) was 24.52 g, while 36.49 g, 39.97 g, 44.07 g in mature leachate at different dilution ratio of 1: 100, 1: 50, 1: 5, respectively. When using fresh leachate for irrigation, the biomass increment was 31.00 g, 47.94 g, and 40.07 g at different dilution ratio of 1: 100, 1: 50, 1: 5. Plant biomass increment under different conditions are shown in Fig. 4.1, chrysanthemum biomass increment in leachate irrigation groups is more than the control group, showing that leachate irrigation can accelerate chrysanthemum growth and increase biomass. The average biomass increase
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in three groups using mature leachate was 40.18 g, while 39.67 g for adopting fresh leachate irrigation. The statistics were close so that effects of two kinds of leachate on chrysanthemum growth were similar. For mature leachate irrigation, the higher the leachate concentration is, the higher chrysanthemum biomass increment will be obtained. When the dilution ratio was 1:5, the chrysanthemum biomass increment reached the highest. However, for fresh leachate irrigation, the highest chrysanthemum biomass increment was obtained at a dilution ratio of 1:50 and then it decreased at a dilution ratio of 1:5, which might be caused by following reasons. Leachate contains nutrients and pollutants, and the former promote and the latter hamper the growth. Since the two types of substances have opposite effects on chrysanthemum growth, there exists a balance point that leachate irrigation has a positive effect on biomass increase. When leachate concentration exceeds that balance point, adverse effect of leachate irrigation is more obvious. If choosing COD as the index for balance point and making full use of present statistics, the balance concentration is 1600 mg/L in fresh leachate irrigation. Theoretically, balance concentration in mature leachate irrigation is higher than that in fresh leachate irrigation.
4.2.1 Effect of Leachate Irrigation on Chrysanthemum Plant Height Test results of plant height variation are shown in Table 4.4.
4.2.1.1 Effect of mature leachate irrigation on chrysanthemum plant height Combining Table 4.1 and Fig. 4.2, it can be seen that plant height variations reaches the maximum at the dilution ratio of 1:50, followed by the group of 1:5. The least plant height variations occurred in leachate irrigation group of 1:100. If chrysanthemum growth cycle were divided into three periods according to growth condition and observation time, 1-46 d, 46 d-97 d, and after 97 d were the early stage, medium stage, and later stage, respectively. Obviously, medium stage was the rapidest growth stage of chrysanthemum. It was concluded that at the early stage, different concentration mature leachate irrigation had no obvious effect, since plants in each group had similar growth rate. At the medium stage, chrysanthemum growth rates started to vary, exhibiting most obvious effects of different dilution ratios. At the later stage, plant height variation rates of each group turn similar since plants were almost mature. At the medium stage of chrysanthemum growth, plant height increments of each group are shown in Fig. 4.3. Generally, mature leachate irrigation had an obvious effect on chrysanthemum plant height increment. It can be obtained that the dilution ratio of 1:50 can be contributed to the biggest plant height increment. The second
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TABLE 4.4 Test Results of Plant Height Variation (cm) Upon Leachate Irrigation Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L)
Planting time (d)
COD
BOD5
TN
0d
1:100
23
3
25
6.62
1:50
46
7
50
6.24
1:5
390
57
422
6.19
0
0
0
5.70
Water
46 d
64 d
97 d
110 d
9.20
14.50
29.83
36.00
11.05
21.35
41.20
48.75
11.15
21.25
35.25
40.81
12.10
19.94
31.56
37.06
Fresh leachate Dilution ratio
Leachate quality for irrigation (mg/L)
Planting time (d)
COD
BOD5
TN
0d
46 d
64 d
97 d
110 d
1:100
142
63
16
5.72
10.80
24.00
34.20
41.50
1:50
279
124
32
5.85
13.80
19.00
39.67
44.78
1:5
2343
1053
273
4.94
10.68
22.67
35.67
41.94
0
0
0
5.70
12.10
19.94
31.56
37.06
Water
FIGURE 4.2 Chrysanthemum plant height variation upon mature leachate irrigation.
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went to the dilution ratio of 1:5. When using clear water or the dilution ratio of 1:100 for irrigation, chrysanthemum plant height increment was the least.
4.2.1.2 Effect of fresh leachate irrigation on chrysanthemum plant height From Table 4.1 and Fig. 4.4, the plant height increment at the dilution ratio of 1:50 is the biggest, then followed by the ratio of 1:5 and 1:100. When using clear water for irrigation, the increment was the least. During the whole growth cycle of chrysanthemums, the variation at the dilution ratio of 1:5 and 1:100 were very similar. The rapid growth stage is still at the medium stage and similar with mature leachate irrigation. At the medium stage of chrysanthemum growth, plant height increments of each group are shown in Fig. 4.5. The dilution ratio of 1:50 got the highest plant height increment, 25.87 cm. The second
FIGURE 4.3 Relationship of chrysanthemum plant height increment at medium stage and leachate dilution ratio under mature leachate irrigation.
FIGURE 4.4 Chrysanthemum plant height variations upon fresh leachate irrigation.
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FIGURE 4.5 Relationship of chrysanthemum plant height increment at the medium stage and leachate dilution ratio under fresh leachate irrigation.
FIGURE 4.6 Relationship of chrysanthemum plant height increments at the medium stage and leachate dilution ratio under leachate irrigation.
was the dilution ratio of 1:5, with an increment of 24.99 cm; then the dilution ratio of 1:100 got an increment of 23.4 cm, while control group just got an increment of 19.46 cm. According to the results, fresh leachate irrigation had a great promotion on chrysanthemum plant height increment, with the best increment obtained at the dilution ratio of 1:50. The comparison of mature and fresh leachate irrigation for chrysanthemum plant height is shown in Fig. 4.6. It was indicated that plant height increment at dilution ratio of 1:50 in mature leachate irrigation was higher than that at same dilution ratio in fresh leachate irrigation, with the best growth condition among all the groups.
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4.2.2 Effect of Leachate Irrigation on Chrysanthemum Leaf Number Test results of leaf number variation are shown in Table 4.5.
4.2.2.1 Effect of mature leachate irrigation on chrysanthemum leaf number Chrysanthemum leaf number increment in mature leachate irrigation is shown in Fig. 4.7. Before the 64th day, leaf number increment of each group was similar. After that day, mature leachate irrigation, especially at dilution ratio of 1:5 and 1:50, was most beneficial to leaf number increment. 4.2.2.2 Effect of fresh leachate irrigation on chrysanthemum leaf number In Fig. 4.8, chrysanthemum leaf number increment in fresh leachate irrigation is given. Before 64th d, the difference between groups was not distinct. TABLE 4.5 Test Results of Leaf Number Variation Upon Leachate Irrigation Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L) COD
BOD5
1:100
23
3
1:50
46
1:5 Water
Planting time (d) TN
0d
46 d
64 d
110 d
25
2.09
15.50
28.67
59.67
7
50
2.09
13.50
25.20
82.90
390
57
422
2.27
18.20
25.75
84.63
0
0
0
2.36
18.40
28.56
41.89
Fresh leachate Dilution ratio
1:100
Leachate quality for irrigation (mg/L) COD
BOD5
142
63
Planting time (d) TN 16
0d
46 d
64 d
110 d
1.91
16.00
29.78
68.89
1:50
279
124
32
2.64
20.90
24.20
81.44
1:5
2343
1053
273
2.09
17.55
28.00
84.89
0
0
0
2.36
18.40
28.56
41.89
Water
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FIGURE 4.7 Chrysanthemum leaf number increment under mature leachate irrigation.
FIGURE 4.8 Chrysanthemum leaf number increment under fresh leachate irrigation.
Subsequently, the results started to vary obviously. Faster growths were observed in the dilution ratio of 1:5 and 1:50. In other words, fresh leachate irrigation was beneficial to chrysanthemum leaf number increment with the dilution ratio of 1:5 and 1:50.
4.2.2.3 Comparison of mature and fresh leachate irrigation on chrysanthemum leaf number Relationship of chrysanthemum leaf number increase and leachate dilution ratio is shown in Fig. 4.9. Mature and fresh leachate irrigation had similar effects on chrysanthemum leaf number variation. When the leachate dilution ratio was 1:50 or 1:5, the effect was most distinct. Generally, regardless of leachate type, diluted leachate irrigation benefitted the chrysanthemum leaf number increment.
4.2.3 Effect of Leachate Irrigation on Chrysanthemum Leaf Area Test results of leaf area variations which are used as the index of chrysanthemum growth are presented at Table 4.6.
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FIGURE 4.9 Relationship of chrysanthemum leaf number increment and dilution ratio upon leachate irrigation.
TABLE 4.6 Test Results of Leaf Area Variations (cm2) Leachate Irrigation on Chrysanthemum Mature leachate Dilution ratio
Leachate quality for irrigation (mg/L) COD
BOD5
1:100
23
3
1:50
46
1:5 Water
Planting time (d) TN
0d
46 d
64 d
110 d
25
20.14
25.75
30.69
42.90
7
50
19.65
33.48
42.89
54.63
390
57
422
18.02
30.58
37.79
45.72
0
0
0
18.16
26.27
27.18
32.40
Fresh leachate Dilution ratio
1:100
Leachate quality for irrigation (mg/L) COD
BOD5
142
63
Planting time (d) TN
0d
46 d
64 d
110 d
16
17.38
27.14
41.67
40.28
1:50
279
124
32
16.22
37.98
38.13
51.64
1:5
2343
1053
273
15.87
29.13
34.75
41.74
0
0
0
18.16
26.27
27.18
32.40
Water
Leachate Irrigation for Plants Chapter | 4
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4.2.3.1 Effect of mature leachate irrigation on chrysanthemum leaf area Observation results of leaf area variations under different leachate irrigation condition are shown in Fig. 4.10. The sample of the dilution ratio 1:50 had the fastest growth rate, and the control group had the slowest growth rate. Generally, leachate irrigation benefitted chrysanthemum leaf growth and the best leaf growth was obtained at the dilution ratio of 1:50. 4.2.3.2 Effect of fresh leachate irrigation on chrysanthemum leaf area Fresh leachate irrigation had an obvious effect on chrysanthemum leaf growth. In Fig. 4.11, the variations of chrysanthemum leaf area at different dilution ratios are shown. The sample of the dilution ratio 1:50 had the fastest growth rate, while the second and the third were 1:100 and 1:5, respectively. Leachate irrigation groups generally had a higher rate than the control group. Thus, fresh leachate irrigation had a positive effect on chrysanthemum leaf growth, with the best result obtained at the dilution ratio of 1:50. 4.2.3.3 Comparison of mature and fresh leachate irrigation on chrysanthemum leaf area Fig. 4.12 shows leaf area increment results, from which two types of leachate irrigation both had positive effects on chrysanthemum leaf growth. The best result was obtained at the dilution ratio of 1:50.
4.2.4 Effect of Leachate Irrigation on Chrysanthemum Root Length Chrysanthemum root length before and after planting is shown in Fig. 4.13. When using mature leachate for irrigation, the root length increased to some extent. The biggest increment occurred at the dilution ratio of 1:100. The
FIGURE 4.10 Chrysanthemum leaf area variations under mature leachate irrigation.
FIGURE 4.11 Chrysanthemum leaf area variations under fresh leachate irrigation.
FIGURE 4.12 Chrysanthemum leaf area variation with different leachate types and dilution ratios upon leachate irrigation.
FIGURE 4.13 Effect of leachate irrigation on chrysanthemum root length.
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effects of fresh leachate irrigation were obvious, and the dilution ratio 1:5 still got the best growth, while ratio of 1:100 had a little negative effect.
4.2.5 Effect of Leachate Irrigation on Chrysanthemum Peroxidase Activity Peroxidase, existing in every organ of plants, is related to plant respiration intensity. Peroxidase activity has some relationship with plant growth to some extent so that peroxidase activity can reflect plant growth. Test method for peroxidase is spectrophotometry with characteristic wavelength of 470 nm. The absorbance variation in the same time can be used to judge the activity of peroxidase. Peroxidase activity variations of the collected samples at the 64th and 110th day in mature and fresh leachate irrigation respectively are shown in Figs. 4.14 4.17. From Fig. 4.14, it can be found that peroxidase activity is strongest when adopting clear water irrigation, followed by 1:100 group, 1:50 group, 1:5 group, in turn, which means that mature leachate irrigation has an adverse effect on chrysanthemum peroxidase activity. From Fig. 4.15, it can be found that peroxidase activity is strongest when adopting clear water irrigation, then 1:100 group, 1:50 group, and 1:5 group is done, in turn, which also means that fresh leachate irrigation has the same adverse effect on chrysanthemum peroxidase activity with fresh leachate. When testing the peroxidase activity at the 110th day, the results were different. Although the control group still got the highest peroxidase activity, the second highest was 1:5 and then 1:100, 1:50 dilution in turn, meaning chrysanthemum tended to adapt to the leachate irrigation; especially the experimental group of ratio 1:5 had almost the same peroxidase activity with the control group. At the 110th planting day, for fresh leachate irrigation, the sample of ratio 1:100 had a higher peroxidase activity than the control group. Peroxidase
FIGURE 4.14 Test results of chrysanthemum peroxidase activity under mature leachate irrigation at 64th day.
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FIGURE 4.15 Test results of chrysanthemum peroxidase activity under fresh leachate irrigation at the 64th day.
FIGURE 4.16 Test results of chrysanthemum peroxidase activity under mature leachate irrigation at the 110th day.
FIGURE 4.17 Test results of chrysanthemum peroxidase activity under fresh leachate irrigation at the 110th day.
activity of 1:50 sample was slightly lower than that of the control group while the 1:5 sample almost reached 0. It meant that fresh leachate irrigation with a dilution ratio of 1:5 was hazardous to peroxidase activity in chrysanthemum.
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TABLE 4.7 Growth Status of Five Plants after 46 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
1:10
1:5
Clean water
1:10 control
34
44
56
54
57
64
Plant height (cm) Salvia plebeia Manila
31
32
31
29
31
32
Chrysanthemum
22
18
19
23
23
21
Aster novi-belgii
32
46
51
38
35
37
39
19
32
37
43
Stem perimeter (mm) Ophiopogon japonicus
TABLE 4.8 Growth Status of Five Plants After 101 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
1:10
1:5
Clean water
1:10 control
Salvia plebeia
90
65
70
76
83
91
Manila
33
30
27
29
39
32
Chrysanthemum
37
50
53
40
56
48
Aster novi-belgii
34
38.5
35
37
32
33
Little leaf box
28
28.5
33
30
33.5
30
52
38
40
52
58
Plant height (cm)
Stem perimeter (mm) Ophiopogon japonicus
4.3 PLANTS GROWTH UPON LEACHATE IRRIGATION 4.3.1 Effect of Leachate Irrigation on Growth Status The growth status of five plants using mature leachate after 46 days or 101 days are shown in Tables 4.7 and 4.8, Table 4.9.
TABLE 4.9 Difference Between the Growth Status of Five Plants After 101 days Compared with 46 days Upon Leachate Irrigation Growth index / Plant
1:100
1:50
Salvia plebeia
56
21
Manila
2
22
Chrysanthemum
15
32
Aster novi-belgii
2
Little leaf box
1:10
1:5
Clean water
1:10 control
14
22
26
27
24
0
8
0
24
17
32
27
27.5
2 16
21
23
24
29
35
34.5
35
35.5
35
13
19
8
15
15
Plant height (cm)
Stem perimeter (mm) Ophiopogon japonicus
FIGURE 4.18 The peroxidase activity of chrysanthemum after 46 days’ leachate irrigation.
FIGURE 4.19 The peroxidase activity of chrysanthemum after 101 days’ leachate irrigation.
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4.3.2 Effect of Leachate Irrigation on Peroxidase Activity The peroxidase activity of chrysanthemum after 64 and 101 days is shown in Figs. 4.18 and 4.19. It was shown that the strongest peroxidase activity among Ch1BCh6 (representing 1:100, 1:50, 1:10, 1:5, clear water, and 1:10 control group of chrysanthemum, respectively) was Ch3 after 46 days, followed by Ch1, Ch2, Ch4, Ch6, and the control group had the lowest peroxidase activity. Peroxidase activity of chrysanthemum varied even more irregularly. Peroxidase activity of Ch1 and Ch4 remained high, followed by Ch6, and that of the three others were very low. The peroxidase activity of Manila after 64 and 97 days are shown in Figs. 4.20 and 4.21, respectively. M1 M6 represented 1:100, 1:50, 1:10, 1:5, and clean water, and 1:10 control group of Manila growth, respectively. It was shown that the strongest peroxidase activity was D2 after 64 days, followed by M1, M3, M6, and M5,
FIGURE 4.20 Peroxidase activity of Manila after 64 days’ leachate irrigation.
FIGURE 4.21 Peroxidase activity of Manila after 97 days’ leachate irrigation.
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Pollution Control Technology for Leachate From Municipal Solid Waste
FIGURE 4.22 Peroxidase activity of salvia plebeia after 101 days’ leachate irrigation.
FIGURE 4.23 Peroxidase activity of little leaf box after 110 days’ leachate irrigation.
which had little difference, and the control had the lowest peroxidase activity. It can be seen from Fig. 4.21 that the difference between the peroxidase activity of chrysanthemum after 64 and 97 days is obvious. And the strongest peroxidase activity was M2, followed by M3, M5, then M4, M1, and M6 had the lowest peroxidase activity. The peroxidase activity of salvia plebeia after 101 days is shown in Fig. 4.22.
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TABLE 4.10 pH of Soil for Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
8.35
8.54
8.55
8.51
8.54
8.10
8.19
8.09
8.28
2
8.36
8.51
8.27
8.41
8.41
8.37
8.33
8.21
8.42
3
8.59
8.44
8.54
8.50
7.89
8.33
8.10
8.15
8.47
4
8.46
8.39
8.57
8.37
8.50
8.29
8.06
8.10
8.61
5
8.39
8.46
8.25
8.42
8.43
8.44
8.20
8.08
8.41
6
8.37
8.51
8.55
8.46
8.39
8.50
8.16
8.48
Salvia plebeian was irrigated using diluted mature leachate. S1 S6 were on behalf of 1:100, 1:50, 1:10, 1:5, and clean water, and 1:10 control group, respectively. And the strongest peroxidase activity was S4, followed by S5, S1, then S2, S3, and S6 had the lowest peroxidase activity. The peroxidase activity of little leaf box after 110 days irrigation is shown in Fig. 4.23. L1 L6 represented 1:100, 1:50, 1:10, 1:5, clean water, and 1:10 control group of little leaf box growth, respectively. Six-year leachate had a certain impact on the peroxidase activity of little leaf box. And the strongest peroxidase activity was L4, followed by L1, L5, then L6, and L3, L2 had the lowest peroxidase activity, showing great difference with others.
4.4 SOIL PROPERTIES CHANGE UPON LEACHATE IRRIGATION ON PLANTS 4.4.1 Soil pH pH is an important chemical property for soil and also one of the key impact factors of soil fertility. It not only affects soil formation, properties, and the existence status, transformation and effectiveness of soil nutrient, but also the microbial activity and normal growth of crops. pH of soil is shown in Table 4.10, in which No.1B6 refer to the dilution ratios of 1:100, 1:50, 1:10, 1:5, clean water, and 1:10 control group, respectively, while {ABD} and {EBH} represent the soil I and soil II, respectively, meanwhile, {A, C, E, G} denoted the soils irrigated by mature leachate, {B, D, F, H} for fresh leachate, and {J} for the soil sample collected in the same place with soil A at different time. pH of soils I and II were 8.18 and 7.99. respectively. before irrigation. It was weak alkaline. pH of soils after leachate irrigation increased a little, which was also the weak alkaline. pH varied irregularly because the randomness of test results was large after irrigated by different leachate or different
344
Pollution Control Technology for Leachate From Municipal Solid Waste
TABLE 4.11 The Soil Hydroscopic Properties (%) for Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
1.34
1.04
2.18
0.90
1.65
1.60
1.67
0.98
0.71
2
1.53
2.17
1.88
2.24
1.64
1.28
1.37
2.07
0.91
3
1.35
2.26
2.23
1.86
4.31
1.84
1.33
1.78
0.84
4
2.04
2.04
2.38
2.20
2.20
1.78
1.38
1.42
0.72
5
1.96
2.07
1.24
2.13
2.37
1.69
1.60
1.49
0.84
6
1.86
1.84
0.90
1.77
1.70
1.29
1.46
0.77
TABLE 4.12 The Increment of Soil Hydroscopic Properties (%) for Leachate Irrigation No.
A
B
C
D
1
127.1
76.3
269.5
52.5
2
159.3
267.8
218.6
3
128.8
283.1
4
245.8
245.8
5
232.2
6
215.3
E
F
G
H
J
54.2
49.5
56.1
2 8.4
20.3
279.7
53.3
19.6
28.0
93.5
54.2
278.0
215.3
302.8
72.0
24.3
66.4
42.4
303.4
272.9
105.6
66.4
29.0
32.7
22.0
250.8
110.2
261.0
121.5
57.9
49.5
39.3
42.4
211.9
52.5
200.0
58.9
20.6
36.4
30.5
dilution ratios. Soil pH will not make a big difference after leachate irrigation in a certain period.
4.4.2 Soil Hygroscopic Properties Soil hydroscopic properties are an important component and fertility factor for soil, affected by air relative humidity, soil texture, organic matter content, etc. The status of the soil hydroscopic water is shown in Table 4.11. The increment of soil hydroscopic properties is shown in Table 4.12. As shown in Table 4.12, as a whole, the soil hydroscopic properties significantly increased after leachate irrigation for a period of time, as well as soil moisture retention and adjusting ability. It can be found that hygroscopic properties after leachate irrigation were higher than water irrigation. Leachate absorption of soil had no obvious correlation with dilution ratio of
345
Leachate Irrigation for Plants Chapter | 4
FIGURE 4.24 The leachate absorption of soil B and J upon irrigation.
TABLE 4.13 Soils Organic Matter Contents (%) of Tests No.
A
B
C
D
E
F
G
H
J
1
7.20
4.80
4.80
4.95
11.11
11.69
13.13
10.85
5.05
2
4.29
5.55
5.11
4.43
9.57
12.34
12.99
7.95
5.59
3
7.20
4.32
5.61
5.85
7.54
11.67
15.21
10.91
4.90
4
7.84
4.82
5.27
7.00
8.18
11.60
12.35
10.61
5.36
5
7.35
5.22
5.61
5.63
8.83
10.50
13.07
13.32
6.59
6
7.40
5.80
6.33
6.65
8.72
10.80
12.92
6.24
leachate. Besides, leachate absorption of soils {A, C, E, G} after mature leachate irrigation and soils {B, D, F, H} after fresh leachate irrigation had no obvious difference. The leachate absorption of soil I (A, B, C, D) were almost the same with soil II (E, F, G, H), but due to original high hygroscopic properties in soil II, increment of hygroscopic properties in soil I was larger than soil II (soil J and B were taken from the same place, but soil I was measured on the 46th day). As shown in Fig. 4.24, the leachate absorption of soil B was higher than soil J, which fully indicated that leachate absorption of soil can be facilitated by leachate irrigation.
TABLE 4.14 Increment Rate of Soil Organic Matter After Leachate Irrigation (%) No.
A
B
C
D
1
213.04
108.70
108.70
115.22
2
86.52
141.30
122.17
3
213.04
87.83
4
240.87
5
219.57
6
221.74
E
F
G
H
J
40.63
47.97
66.20
37.34
119.57
92.61
21.14
56.20
64.43
0.63
143.04
143.91
154.35
2 4.56
47.72
92.53
38.10
113.04
109.57
129.13
204.35
3.54
46.84
56.33
34.30
133.04
126.96
143.91
144.78
11.77
32.91
65.44
68.61
186.52
152.17
175.22
189.13
10.38
36.71
63.54
171.30
347
Leachate Irrigation for Plants Chapter | 4
TABLE 4.15 Classification of Soil Organic Matter Content and Fertility Level Fertility level
Low
Lower
Medium
Higher
High
Soil organic matter content (g/kg)
,5
5 2 10
10 2 12
12 2 15
.15
TABLE 4.16 Soil Total Nitrogen Content (mg/g) No.
A
B
C
D
E
F
G
H
1
17.81
11.19
11.04
10.13
13.67
25.01
24.59
25.85
J 6.28
2
16.01
10.70
12.71
13.71
16.91
21.24
22.64
19.00
13.44
3
20.24
13.27
11.23
13.93
15.06
25.57
27.54
23.03
11.90
4
16.58
17.76
13.54
18.59
18.58
23.09
26.56
27.12
12.57
5
17.44
12.55
13.40
11.39
19.92
19.87
32.56
23.90
12.57
6
19.77
12.26
17.93
13.34
20.99
24.74
25.59
11.68
4.4.3 Soil Organic Matters Soil organic matters mainly derive from plants and microorganisms, including living and dead organisms, as well as its secretion and derivatives. Soil organic matter, the essence of the fertility of soil, which has a great effect on physical, chemical, and biological properties of soil, is an indicator of good or bad, rich or poor soil. Content, composition, and properties of organic matter varies with climate and biological conditions regularly. The soil organic matter is determined by potassium dichromate colorimetric method as shown in Table 4.13. The original organic matter content of soil I was 2.30%, with lower fertility, whereas that of soil II was 7.90%, good fertility. Increment rate of soil organic matter after leachate irrigation is shown in Table 4.14. It can be seen from Tables 4.13 4.15 that a dramatic increment in soil organic matter content appears. Leachate irrigation could obviously promote soil organic matter content and soil fertility. Classification of soil organic matter content and fertility level is shown in Table 4.15. Soil I was poor, only containing 2.3% organic matter, low fertility, but organic matter content had been raised more than one time after leachate irrigation for four months, basically reaching the lower level. Soil II was relatively good, of which organic matter content was 7.90%, belonging to low fertility, while organic matter content had certain improvement after leachate
TABLE 4.17 Increments of Soil TN Content After Leachate Irrigation (%) No.
A
1
46.10
2
B
C
D
E
F
2 8.20
2 9.43
2 16.90
2 9.89
64.86
31.34
2 12.22
4.27
12.47
11.47
3
66.04
8.86
2 7.88
14.27
4
36.01
45.69
11.07
5
43.07
2.95
9.93
6
62.18
0.57
47.09
9.43
G
H
J
62.10
70.40
2 48.48
40.01
49.24
25.25
10.25
2 0.73
68.56
81.54
51.81
2 2.38
52.50
22.48
52.21
75.08
78.77
3.12
2 6.56
31.31
30.98
114.63
57.55
3.12
38.37
63.09
68.69
2 4.18
349
Leachate Irrigation for Plants Chapter | 4
irrigation for a period. Organic matter content of F, G, H were more than 10%, mostly reached the medium level and some reached the higher or high level. Organic matter content of soils after mature leachate irrigation {A, C, E, G} and fresh leachate irrigation {B, D, F, H}, had no obvious difference in addition to A. A had the greatest increase in organic matter among all.
4.4.4 Soil Total Nitrogen Content The soil fertility can be judged by soil total nitrogen content, which can also be taken as reference to the soil fertilization, as shown in Table 4.16. The original soil I TN was 12.19 mg/g, and soil II TN was 15.17 mg/g. Increments of soil TN content after leachate irrigation is shown in Table 4.17. It can be seen from Table 4.16 and Table 4.17 that a dramatic increase in soil TN content occurs. Relatively, increment in soil II TN was more obvious than soil I. Other soil I TN content changed little in addition to A, as most of them fluctuated near 6 10% of the original soil. And there was a relatively large increment in soil II TN content, as most of soils TN had increased by about 40% in addition to E. Soils TN of A had only increased by about 30%. Besides, TN of soil {A, C, E, G} after mature leachate irrigation and soil {B, D, F, H} after fresh leachate irrigation had no obvious difference. There was no obvious correlation between TN content and dilution ratio of leachate.
4.4.5 Soil Effective Phosphorus Phosphorus easy to be absorbed by plants can be judged by effective phosphorus, which can be taken as reference to the soil fertilization, as shown in Table 4.18. TABLE 4.18 The Effective Phosphorus in Soils (mg/g) No.
A
B
C
D
E
F
G
H
J
1
1.04
1.26
1.58
0.94
2.40
2.17
3.85
1.65
1.60
2
1.57
1.79
1.57
2.17
2.53
2.60
3.34
2.46
1.57
3
1.21
0.73
1.11
1.34
2.05
3.24
3.02
2.00
1.54
4
1.64
1.98
1.38
2.00
2.84
3.32
3.32
1.91
1.46
5
1.85
2.07
1.15
1.70
4.08
2.74
4.33
1.39
1.31
6
1.22
1.59
1.11
1.58
2.33
4.34
3.17
1.44
TABLE 4.19 Decrements of Effective P in Soil After Leachate Irrigation (%) No.
A
B
C
D
E
F
G
H
J
1
2 49.02
2 38.24
2 22.55
2 53.92
2 45.95
2 51.13
2 13.29
2 62.84
2 21.57
2
2 23.04
2 12.25
2 23.04
6.37
2 43.02
2 41.44
2 24.77
2 44.59
2 23.04
3
2 40.69
2 64.22
2 45.59
2 34.31
2 53.83
2 27.03
2 31.98
2 54.95
2 24.51
4
2 19.61
2 2.94
2 32.35
2 1.96
2 36.04
2 25.23
2 25.23
2 56.98
2 28.43
5
2 9.31
1.47
2 43.63
2 16.67
2 8.11
2 38.29
2 2.48
2 68.69
2 35.78
6
2 40.20
2 22.06
2 45.59
2 22.55
2 47.52
2 2.25
2 28.60
2 29.41
TABLE 4.20 Total Soil Microbial Amount (Absorbance) No.
A
B
C
D
E
F
G
H
J
1
0.575
0.585
0.573
0.582
0.604
0.585
0.623
0.627
0.578
2
0.593
0.553
0.548
0.633
0.622
0.559
0.590
0.558
0.570
3
0.595
0.577
0.611
0.587
0.638
0.660
0.674
0.570
0.567
4
0.559
0.526
0.575
0.606
0.554
0.728
0.620
0.666
0.570
5
0.562
0.592
0.577
0.548
0.545
0.597
0.674
0.616
0.575
6
0.511
0.567
0.580
0.592
0.676
0.616
0.664
0.567
TABLE 4.21 Increments of Microbial Amount in Soil After Leachate Irrigation (Absorbance) No.
A
B
C
D
E
F
G
H
J
1
19.54
21.62
19.13
21.00
13.11
9.55
16.67
17.42
20.17
2
23.28
14.97
13.93
31.60
16.48
4.68
10.49
4.49
18.50
3
23.70
19.96
27.03
22.04
19.48
23.60
26.22
6.74
17.88
4
16.22
9.36
19.54
25.99
3.75
36.33
16.10
24.72
18.50
5
16.84
23.08
19.96
13.93
2.06
11.80
26.22
15.36
19.54
6
6.24
17.88
20.58
23.08
26.59
15.36
24.34
17.88
Leachate Irrigation for Plants Chapter | 4
353
Effective P in soil I was 2.04 mg/g, and effective P in soil II was 4.44 mg/g. Decrements of effective P in soil after leachate irrigation is shown in Table 4.19. It can be seen from Table 4.18 and Table 4.19 that a dramatic decrease in effective P in soil after leachate irrigation for four months appears. The decrement rate of effective P in the two soils was almost the same. There was no obvious correlation between effective P in soil and dilution ratio of leachate or types of leachate. Because of low P content in leachate, it was impossible to provide the soil with P during the growth. While plant growth required a lot of P, effective P content in the soil was bound to decrease.
4.4.6 Total Soil Microbial Amount Total soil microbial is shown in Table 4.20. Microbial amount in soil I was 0.481, and microbial amount in soil II was 0.534. Increments of microbial amount in soil after leachate irrigation are shown in Table 4.21. It can be seen from Table 4.20 and Table 4.21 that the microbial amount in soil after leachate irrigation increases considerably. The increment rate of the microbial amount in two soils was almost the same. There was no obvious correlation between microbial amount in soil and dilution ratio of leachate or types of leachate. There existed a complex microbial community in the soil, and it became more prosperous and more conducive to plant growth, thus increasing soil fertility.
4.4.7 Heavy Metals Contents in Soil Due to a certain amount of metal ions (such as Zn, Pb, Cd, Ni, Cr) in leachate, the risk of metal ions content into soil increased using leachate irrigation. If metal ions in soil accumulated to a relatively high concentration, it would do harm to the plant growth as well as soil fertility. Zn content in soil is shown in Table 4.22 and Pb content in soil is shown in Table 4.23. Zn content in soil I was 51 mg/kg and Zn content in soil II was 66.63 mg/kg. Mostly zinc content in soils after leachate irrigation was fair or less than that before leachate irrigation, and only a few were extremely high. There was no obvious correlation between zinc content in soil and dilution ratio of leachate or types of leachate. Therefore, zinc content in soil would not change obviously after leachate irrigation. Pb content in soil I was 10 mg/kg and Pb content in soil II was 12.3 mg/ kg before irrigation. It can be seen from Table 4.23 that an increase in Pb content in soil after leachate irrigation occurs, and some even reaches
TABLE 4.22 Zn Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
32.34
49.20
0.92
51.94
57.10
18.15
72.27
49.81
77.00
2
54.66
0.00
44.81
43.87
22.28
100.70
56.19
1.54
56.00
3
57.62
39.13
35.89
42.69
64.02
57.14
66.90
47.42
53.50
4
38.16
22.10
7.01
0.92
61.46
103.40
59.66
58.22
63.50
5
47.74
47.42
52.50
33.52
52.40
54.01
76.71
80.88
66.50
6
52.26
4.95
30.94
2.48
52.40
68.18
10.73
54.00
TABLE 4.23 Pb Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
1
43.10
49.60
41.67
47.83
13.04
2
56.04
43.65
48.61
50.00
3
50.93
53.88
44.25
4
45.26
35.71
44.25
5
50.00
45.65
6
34.78
44.25
F
G
H
J
44.25
55.56
56.04
17.75
39.82
100.45
46.88
51.59
12.35
47.41
20.83
51.34
46.30
13.04
10.45
43.65
50.93
48.61
49.11
51.73
13.55
39.35
51.59
60.27
47.41
51.34
51.59
14.40
13.27
46.46
49.11
46.30
58.04
18.85
356
Pollution Control Technology for Leachate From Municipal Solid Waste
TABLE 4.24 Cd Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
1
6.49
6.67
6.18
7.35
8.58
2
6.74
6.67
7.25
7.11
3
7.01
5.99
4.92
4
6.24
4.81
4.18
5
6.37
6.62
6
6.86
5.17
F
G
H
J
5.41
6.92
7.49
3.00
5.17
15.96
7.60
6.67
3.00
6.99
7.74
8.36
6.04
6.13
2.50
6.42
7.98
7.50
6.59
5.74
3.00
7.01
7.91
7.60
7.24
6.33
7.16
2.50
4.43
5.41
7.60
6.53
7.60
2.50
TABLE 4.25 Ni Content in Soil (mg/kg) After Leachate Irrigation No.
A
D
E
F
G
H
J
1
18.60
B 4.96
C 4.25
19.40
22.09
19.60
17.71
23.52
, 0.50
2
20.24
5.67
20.51
17.78
24.89
44.70
22.08
5.67
, 0.50
3
23.28
18.60
20.66
20.79
21.06
24.28
22.73
21.01
, 0.50
4
19.69
13.80
18.54
14.87
24.39
26.05
21.52
20.79
, 0.50
5
18.32
21.01
19.40
19.12
23.73
22.98
22.08
9.21
, 0.50
6
17.78
19.07
17.48
19.60
23.18
24.39
23.73
, 0.50
40 50 mg/kg. Pb content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Pb content in soil I was lower than soil B, suggesting that Pb content in soil had some relationship with irrigation time. The longer the irrigation time, the greater chance of increased Pb content appeared. Cd content in soil is shown in Table 4.24. Cd content in soil I was 2.5 mg/kg and Cd content in soil II was 4.6 mg/kg before irrigation. It can be seen from Table 4.24 that a large increase in Cd content in soil after leachate irrigation occurs, and some even reaches 6 mg/kg. Cd content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Cd content in soil I was lower than soil B, suggesting that Cd content in soil had some relationship with irrigation time.
357
Leachate Irrigation for Plants Chapter | 4
TABLE 4.26 Cr Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
J
1
22.12
26.58
23.87
26.15
29.93
27.88
26.21
25.57
22.05
2
25.94
23.69
23.95
24.59
27.97
51.30
29.37
25.86
23.60
3
27.63
24.82
24.21
26.69
27.16
30.70
26.69
23.67
23.30
4
22.30
16.40
22.56
4.61
30.65
29.89
26.79
27.06
23.85
5
24.22
48.25
23.29
26.31
29.42
25.38
28.22
28.12
36.90
6
33.70
29.90
23.57
24.95
25.36
34.52
30.80
22.15
TABLE 4.27 K Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
1
1673.90
1147.43
1297.37
1541.20
2051.63
1610.72
1831.77
1371.25
2
1697.67
1413.44
1084.05
1579.42
1197.74
3026.53
1915.55
1188.23
3
1694.11
1435.23
1432.26
1653.90
1116.73
2021.32
1486.73
1358.97
4
1471.47
992.93
1614.79
1611.31
2230.74
1745.61
1218.93
1454.64
5
1208.83
1362.73
1390.86
1591.90
1683.41
1834.94
1452.26
1261.92
6
1419.38
1531.49
1425.92
1706.19
1246.86
1691.14
1742.83
The longer irrigation time led to the greater chance of increased Cd content. Ni content in soil is shown in Table 4.25. Ni content in soil I was 0.5 mg/kg and Ni content in soil II was 6.63 mg/kg before irrigation. It can be seen from Table 4.26 that a large increase in Ni content in soil after leachate irrigation is observed, and some even reaches 18 mg/kg. Ni content in soil had no obvious correlation with type of leachate, dilution ratio of leachate, and plant species. Ni content in soil I was lower than soil B, suggesting that Ni content in soil had some relationship with irrigation time. The longer irrigation time led to the greater chance of increased Ni content. Cr content in soil is shown in Table 4.26. Cr content in soil I was 21.95 mg/kg and Cr content in soil II was 26.43 mg/kg. Mostly Cr content in soils after leachate irrigation was fair or below that before leachate irrigation, and only a few were extremely high. There was no obvious correlation between Cr content in soil and dilution ratio of leachate or types of leachate. Therefore, Cr content in soil would not change obviously after leachate irrigation from the overall.
TABLE 4.28 Ca Content in Soil (mg/kg) After Leachate Irrigation No.
A
B
C
D
E
F
G
H
1
8045.00
9381.50
9061.00
11169.00
12251.00
8566.00
9918.00
8535.50
2
8930.50
10371.00
9498.00
10758.00
8885.00
17347.00
12104.00
9063.50
3
8401.00
7981.50
8517.50
8769.00
9092.50
12431.00
9076.00
11145.00
4
8472.50
8452.00
8601.50
8329.50
9342.00
9233.50
11830.50
9776.00
5
10259.00
10684.00
8736.50
9640.50
12991.50
8828.50
11542.50
9855.50
6
11609.00
6676.00
9120.00
8884.50
9378.50
9782.00
13399.00
Leachate Irrigation for Plants Chapter | 4
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4.4.8 K, Ca Contents Besides a certain amount of heavy metal ions, leachate contains other metal ions, like Ca and K, which can also accumulate in the soil after leachate irrigation, having certain effects on soil properties. K content in soil is shown in Table 4.27. K content in soil I was 1230 mg/kg and K content in soil II was 1588 mg/kg. Mostly K content in soils after leachate irrigation was fair or higher than that before leachate irrigation. Increase in K content in soil II was higher than soil I overall. There was no obvious correlation between K content in soil and dilution ratio of leachate or types of leachate. Therefore, K content in soil remained stable or got a small increase after leachate irrigation. Considering the importance of K element for plants, it indicated that K provided by leachate irrigation can meet the needs of plant growth. Ca content in soil is shown in Table 4.28. Ca content in soil I was 9138 mg/kg and Ca content in soil II was 10212 mg/kg. Mostly Ca content in soils after leachate irrigation was fair or higher than that before leachate irrigation. There was no obvious correlation between Ca content in soil and dilution ratio of leachate or types of leachate. Therefore, Ca content in soil remained stable or got a small increase after leachate irrigation from the overall.