Groundwater and soil pollution with nitrate nitrogen by land disposal of wastewater, and a trial measure against the issues. Tomio Suzuki (Non Profit Organization, Institute of Ecological Engineering, Japan) Yutaro Anzai (Shinshu-University, Japan) Akito Matsumoto (Shinshu-University, Japan)

1. Tomio Suzuki
(Non Profit Organization, Institute of Ecological Engineering, Japan)
(E-mail: suzukit@wave.plala.or.jp)
Yutaro Anzai
(Shinshu-University, Japan)
Akito Matsumoto
(Shinshu-University, Japan)
(E-mail: amatsu1@shinshu-u.ac.jp)
Groundwater and soil pollution with nitrate
nitrogen by land disposal of wastewater,
and a trial measure against the issues
1

2. 6. An experimental result of removing NO3-N using
“the Lauric-Acid-Soil system” (LAS system)
2. Groundwater pollution with nitrate nitrogen (NO3-N)
by land disposal of wastewater
4.How long does NO3-N remain in soil
under the natural condition?
3. Soil pollution with NO3-N by land disposal of wastewater
5.How to remove NO3-N?
2
1. Back ground
Contents of this presentation

3. 1. Back ground
Following issues are worried in these areas
1)Groundwater pollution
2)Soil pollution
Measures against these issues are required from the
viewpoint of sustainable development.
These issues are worried not only in case of the dumping of raw
human waste but also that of treated water, because some kinds of
pollutants are usually still remaining even in the treated water.
3
Wastewater such as human waste has been dumped
into the ground at most of remote areas.

4. 4
The reason why NO3-N is taken in this presentation
1)The ill effect of NO3-N on human beings
 Methemoglobinemia symptom may be caused by the intake of water
containing NO3-N.
2) The value of the guidelines of NO3-N for drinking water quality
 The value of the guidelines for drinking water quality is set at 50 mgNO3
-/L
(about 11 mgNO3-N/L) by the World Health Organization (WHO)*.
3) Monitoring results of groundwater quality in Japan1)
 The exceeding ratio of NO3-N against the environmental quality standard
of groundwater (EQSgw)* has been showing the highest value among the
28 standard items of the EQSgw in Japan.
*The value of the WHO guidelines is set as a sum of nitrate ion (NO3
-) and nitrite ion (NO2
-),
and that of the EQSgw in Japan is set as a sum of NO3-N and nitrite nitrogen (NO2-N) .
However, only NO3-N is taken in this presentation in order to simplify the explanation.

5. 2. Worries of groundwater pollution with NO3-N
by land disposal of wastewater
Wastewater(A)
（mg/L）
Leachate(B)
（mg/L）
Removal efficiency
(A-B)/A☓100（%）
Biochemical Oxygen Demand (BOD) 53 0.6 98
Total Phosphorus (TP) 9.8 0.03 99
Ammonia Nitrogen (NH4-N) 125 8.6 93
Nitrate Nitrogen (NO3-N) 0.20 87 -430
Total Nitrogen (TN) 132 97 26
(The soil was volcanic ash soil. The permeation distance of the most of leachate through soil was 65cm)
2)Concentration of NO3-N increased remarkably in the leachate by the
oxidation of NH4-N.
1)Both BOD and TP were removed more than 90% in the leachate.
Results are summarized as follows.
Table 1 Comparison of water quality between wastewater and its leachate through soil2),3)
5
Worries of groundwater pollution with NO3-N

6. Research methods
1) Soil at a wastewater permeated area was dug twice, at the time of 2
months and 17 months after the end of wastewater loading, in the range
of 200cm deep, 600cm wide crossing a trench by which wastewater had
been loaded for 5 years.
2) Soil samples were collected twice, at the time of 2 months and 17
months after the end of wastewater loading, from each of corresponding
50cm mesh points in the vertical soil wall of the wastewater permeated
area (Fig.1 in the slide 7).
3) The concentration of NO3-N in the soil obtained from the twice researches
were compared at each corresponding sampling point with that of control
area (Fig.2 in the slide 8).
3. Soil pollution with NO3-N by land disposal of wastewater
Note that the investigated facility differs from the one shown in Table 1.
6

7. Water impervious layer
Fig.1 An outline of the soil sampling points
in the wastewater permeated area 3),4)
7
300 250 200 150 100 50 0 50 100 150 200 250 300
0 ○
Depth（cm）
50 ● ● ● ● ● ● ● ● ● ● ● ● ● ●
100 ● ● ● ● ● ● ● ● ● ● ● ● ● ●
150 ● ● ● ● ● ● ● ● ● ● ● ● ● ●
200 ● ● ● ● ● ● ● ● ● ● ● ● ● ●
Control area
Watering tube
Trench
Ground surface
Dots (● and ●) denote soil sampling points.
Horizontal distance from the trench（cm）

8. 50
100
150
200
0
50
100
150
200
300
200
100
0
100
200
300
Control
0
50
100
150
200
0
50
100
150
200
300
200
100
0
100
200
300
Control
●The concentration of NO3-N in the soil increased remarkably by wastewater
permeation as compared with that of control area.
● Increased No3-N in the soil rarely decreased even passing through 15
months under the natural condition except the root zone at a depth of 50cm.
Concentration of NO3-N in the soil at
the time of 2 months after the end of
wastewater loading (NO3-N2M)
Concentration of NO3-N in the soil at
the time of 17 months after the end of
wastewater loading (NO3-N17M)
Fig.2 Comparison of the concentration of NO3-N in the soil
between NO3-N2M and NO3-N17M
3),4)
An arrow
( ) denotes
the point of
wastewater
loading by
the trench
8

9. Fig.3 Relation of NO3-N concentration in the soil between NO3-N2M
and NO3-N17M at the corresponding sampling points3),4)
y = 0.78x + 4.1
r = 0.93
0
20
40
60
80
100
120
0 50 100 150
NO3-N 2M(mg/kg)
NO3-N17M(mg/kg)
The data of the root zone at a depth of 50cm were omitted taking into account of the
special condition of this area that the decrease of NO3-N based on the absorption by
plants might be proceeding.
9

10. Following results are obtained from Fig.3 3),4) in the slide 9.
1) The concentration of NO3-N in the soil decreased nearly in a same ratio at each corresponding
sampling point during 15 months.
2) It is considered that the value, 0.78 shown in the regression equation in Fig.3, shows the
decreasing coefficient of NO3- N in the soil during every 15 months under the natural condition.
3) It is estimated from the equation below that more than 10 years would be required in order to
decrease the amount of NO3-N in the soil of wastewater permeated area to that of control area.
∑ dN2M☓P0.8n=∑ dNc
d=100
200
d=100
200
P(=0.78): Natural decreasing coefficient of NO3-N in the
soil during every 15 months
n: Years required to decrease the amount of
NO3-N in the soil of the wastewater
permeated area to that of control area
∑ d N2M: Amount of NO3-N contained in the soil of the
wastewater permeated area, 200cm deep,
650cm wide and 100cm thick, at the time of 2
months after the end of wastewater loading
200
d=100
∑d NC: Amount of NO3-N contained in the soil
of the control area, 200cm deep,
650cm wide and 100cm thick
200
d=100
4.How long does NO3-N remain in soil
under the natural condition?
10

11. 5. How to remove NO3-N?
• Under coexistence of denitrifying bacteria→
Denitrifying bacteria are commonly living in soil under the
natural condition
• Under a proper temperature→Desirable more than 10℃
• Under a proper pH →Most of soil would have proper condition
• Under an anoxic condition→A submerged soil condition would
be available
• Under coexistence of an effective Hydrogen Donor (HD) →
Searches of effective HDs are required
It is well known that NO3-N would be removed as N2
under such proper conditions shown below.
11
A denitrifying method for wastewater treatment using soil would be
established under the coexistence of an effective HD.

12. Matters to be considered in the searching of
effective HDs
• To work effectively as a HD
• Not to induce a secondary pollution by the HD itself
• Low maintenance in operation
• Low cost in operation
• Harmless for human beings
A series of Higher Fatty Acids (HFAs) was examined for the
searching of effective HDs considering the factors described
above.
12

13. An anticipated
denitrification
effect
An anticipated
anti secondary
pollution effect
Small
Small
Large
Large
Which HFA does it work best as an effective HD?
Tests for the searching of effective HDs were performed among 5-kind HFAs from both sides,
a denitrification and an anti secondary pollution effect, anticipated from their water solubility.
Fig.4 Water solubility of 5-kind HFAs at 20℃5)
13
0
5
10
15
20
capric
acid
lauric
acid
myristic
acid
palmitic
acid
stearic
acid
Watersolubility(mg/100g)

14. Collection of
interstitial water
Fig.5 An experimental device and the method for the
searching of effective HDs using HFAs
A mixture of one kind
of HFAs and soil
( HFA : Soil = 1 : 10,
by weight)
A cylindrical filter
Research methods
●Each of 5-kind HFAs was mixed with soil at a ratio of 1(HFA) to 10(soil) by weight.
●Each mixture of 5-kind HFAs was submerged with 50mgNO3-N /L solution
and was incubated at a temperature of 5, 10, 15 and 20℃, respectively.
●Each interstitial water was collected and analyzed after 7-day incubation.
●A control, i.e. soil without HFAs, was examined in the same manner .
A solution of 50mgNO3-N/L
14

15. 0
10
20
30
40
50
60
capric
acid
lauric
acid
myristic
acid
palmitic
acid
stearic
acid
control
5℃
TN(mg/L)
0
10
20
30
40
50
60
capric
acid
lauric
acid
myristic
acid
palmitic
acid
stearic
acid
control
TN(mg/L)
0
10
20
30
40
50
60
capric
acid
lauric
acid
myristic
acid
palmitic
acid
stearic
acid
control
15℃
TN(mg/L)
0
10
20
30
40
50
60
capric
acid
lauric
acid
myristic
acid
palmitic
acid
stearic
acid
control
TN(mg/L)
10℃
20℃
Fig.6 Analytical results of TN concentration in the interstitial water
obtained from the research shown in the slide 146)
Lauric Acid (LA) was the most effective HD among 5-kind HFAs under
the experimental condition described in the slide 14.
15

16. SP3*, HRT**=34h
SP2*, HRT**=23h
SP1*, HRT**=12h
Substrate (a solution of 50mgNO3-N /L)Denitrified water
A pump
Over flow
Soil
LA ： Soil=1：9 mixture (by weight)
A submerged and anoxic condition
Fig.7 A schematic diagram of a continuous denitrifying device
under a submerged soil condition using the LAS system
*SP1, 2 and 3 show the sampling points of denitrified water.
**HRT shows the hydraulic retention time in the column.
●Soil was mixed with LA in a ratio of 1(LA) to 9(soil) by weight and the mixture was packed at L1 under
the soil layer, L2 and L3.
●A solution of 50mgNO3-N /L was led into the column from the bottom and was passed through it
upward in order to maintain the device an anoxic condition.
●Denitrified water was collected from each sampling point (SP1-3).
●The temperature had been kept at 20℃.
L1
L2
L3
A denitrification
and HD supply-
utilizing zone
A denitrification and HD
utilizing-removing zone
16
Denitrified
water

17. 0
10
20
30
40
50
60
Substrate SP1 SP2 SP3
TN
TOC
Fig.8 Changes of the average concentration of TN and TOC during one month in the
substrate and the denitrified water under the use of the LAS system
Supplied TN (a solution of 50mgNO3-N /L ) was removed 90% within 34h at SP3.
The secondary pollution based on the HD was scarcely observed keeping the concentration
of Total Organic Carbon (TOC) in the denitrified water at SP3 less than 5mgC/L.
Most of increased TOC at SP1 was supplied as LA ion isolated from LA by the action of OH
-
generated by denitrification, and was removed at SP2-SP3 as a HD in denitrification .
Additionally,
6. An experimental result of removing NO3-N using the LAS system
17
Denitrified water
TN,TOC(mg/L)

18. Summar
Both BOD and TP were removed more than 90%, however NO3-N increased
remarkably in the leachate by land disposal of wastewater .
Concentration of NO3-N in the soil increased at the wastewater permeated area,
and it was estimated that the increased NO3-N would remain in the soil more than
10 years under the natural condition.
Supplied TN as NO3-N was removed about 90% within 34h using the LAS system
keeping the concentration of TOC derived from the HD less than 5mgC/L.
Field researches on land disposal of wastewater and a laboratory
research on denitrification using the LAS system were performed.
18
Taking into account of these results , it is expected that the LAS
system would be applied to a system for removing most of TOC(or
BOD), TP and TN in land disposal of wastewater .
Results obtained are summarized as follows.

19. Improvements on better performance for removing
of both TN and TOC will be required.
Developments of techniques for the practical use
will be required.
Verification of the long term field test under the
practical use will be required.
An improvement on a easy removing method of N2
generated by denitrification will be required .
An improvement on a easy supplying method of the
HD will be required .
19

20. References
1)Ministry of the environment, Japan (2014) Monitoring results of groundwater quality in FY 2012,
p. 6 (Outline edition, in Japanese).
2)Suzuki, T., Katsuno, T. and Yamaura, G (1992) Land application of wastewater using three types of
trenches set in lysimeters and its mass balance of nitrogen, Water Research, 26, 1433-1444.
3)Suzuki, T. (1993) Land application of wastewater, in “Encyclopedia of environmental control
technology” (Edited by Cheremisinoff, P. N.), Vol.9, pp. 641-706, Gulf publishing Company, Houston.
4)Suzuki, T. and Yamaura, G. (1989) Natural recovery of chemical components accumulated in soil by
wastewater application, Water Research, 23, 1285-1291.
5) Japan oil chemists’ society (2001) Lipids and surfactants, The handbook of oil chemistry, 4th Ed.,
pp. 302-303, Maruzen, Tokyo (in Japanese).
6)Suzuki, T., Ishikawa, T. and Furihata, A. (2002) Denitrification of nitrate nitrogen using soil mixed
with solid fatty acid under flooding condition, Proceedings of the 36th annual conference of
Japan society on water environment (Okayama, 14-16 March), p. 402 (in Japanese).
20