how to remove nitrate using natural woodchips

1. CREDIT SEMINAR
SWE-591
WOOD CHIP BIOREACTORS FOR NITRATE
REMOVAL IN AGRICULTURAL LAND
DRAINAGE
PRESENTED BY:
MEHRAJ-U-DIN-DAR
L-2K14-AE-188-M
COURSE INSTRUCTOR:
DR.ANIL.BHARDWAJ
WELCOME TO…

2. LEARNING OBJECTIVE
Excess NITROGEN in the aquatic environment has led to
many environmental problems including acidification of
freshwater bodies, eutrophication and associated hypoxic
zones, adverse health effects for humans and aquatic
organisms, and N2O production, a greenhouse gas (
Camargo and Alonso, 2006 ). It is important to remediate
NITROGEN at the source in order to avoid multiple
adverse impacts as NITROGEN travels to downstream
water bodies (Galloway et al., 2003 ).
KNOWLEDGE GAP
A sort of "blue baby syndrome" can be caused
by methemoglobinemia.It is widely believed to be caused by nitrate
contamination in groundwater resulting in decreased oxygen
carrying capacity of hemoglobin in babies leading to death.The
groundwater can be contaminated by leaching of nitrate generated
from fertilizer used in agricultural lands,waste dumps or pit
latrines.Cases of blue baby syndrome have for example been
reported in villages in Romania and Bulgaria where
the groundwater has been polluted with nitrate leaching from pit
latrines.(SOURCE:WIKIPEDIA.COM)

3.  Introduction
 HISTORICAL BACKGROUND
 Bioreactor Basics
 Installation/Operation
 Research Areas
 Materials Used
 Parameters for Bioreactor Working
 Hydraulics Involved
 Factors Effecting Working Of a Bioreactor
 Performance Analysis
 Cost Benefit Analysis
 Conclusion
 References

4. INTRODUCTION
NITRATE
DEGRADES
WATER QUALITY
NITRATE LIMITS CAN
EXCEED 15mg/l* IN
SPRINGS AND EARLY
SUMMER
NITRATE CAUSES HYPOXIA
PROBLEM
CAN BE REDUCED BY
CHANGING FERTILIZER
APPLICATION RATES AND
TIMINGS BUT LOSS STILL
THERE
*(Baker et al., 1975; Gast et al.,
1978;Patni et al., 1996;Jaynes et
al.,1999; Kladivko et al.,2004;
Tomer et al., 2008)

5. HERALDING NITRATE CONTAMINATION AS A CONCERN
The International Nitrogen Initiative (INI)
 1998: First International Nitrogen Conference, The Netherlands.
 2001: Second International Nitrogen Conference, Maryland, USA
 2002/2003
Scientific Committee on Problems of the Environment (SCOPE)
and International Geosphere-Biosphere Program (IGBP) agreed to
sponsor INI.
 2004: Third International Nitrogen Conference, China
 2007: Fourth International Nitrogen Conference, Brazil
 2010: Fifth International Nitrogen Conference, New Dehli, India,
 December 3-7
http://initrogen.org/

6. DIFFERENT METHODS OF NITRATE REMOVAL
FROM WATER
ION EXCHANGE
DENITRIFICATION
BIOLOGICAL
DENITRIFICATION
HETEROTROPHIC
DENITRIFICATION
AUTOTROPHIC
DENITRIFICATION
OTHER METHODS
NO3
- →NO2→NO→N2O
→ N2
Membrane
separation
techniques
( Reverse osmosis,
Electro dyalysis )
COMBINATION PROCESSES

7. WOOD CHIP BIOREACTORS

9. WOOD CHIP BIOREACTOR BASICS
 Woodchip bioreactors
also are known as
denitrification
bioreactors, a name
that is slightly more
descriptive of the
actual process
occurring inside the
bioreactor.
 Denitrification is the conversion of nitrate (NO3
- ) to nitrogen gas (di nitrogen, N2) that is
carried out by bacteria living in soils all over the world and also in the bioreactor
 These good bacteria, called denitrifiers, use the carbon in the woodchips
as their food and use the nitrate as part of their respiration process.
Because these bacteria also can breathe oxygen, providing anaerobic
conditions through more constantly flowing tile water helps ensure that
the bacteria utilize the nitrate.
 A woodchip
bioreactor is
made by routing
drainage water
through a buried
trench filled with
woodchips

10. SIZE OF BIOREACTOR
Mostly ,100 to
120 feet long
and 10 to 25
feet wide.
Typically, no land is taken out of
production for a bioreactor.
Because bioreactors tend to have an
orientation that is long and narrow,
they fit well
in edge-of-field buffer strips and
grassed areas.
SOURCE:Iowa Soybean
Association Environmental
Programs and
Services)

11. TYPES OF WOOD AND SCOPE OF OTHER MATERIALS USED
FOR BIOREACTORS
Bioreactors are
designed based on a
specific flow rate of
water that the
woodchips allow (that
is, hydraulic
conductivity of the
woodchips).
Using chips that have
many fine materials,
shredded materials,
dirt, and
gravel can change this
allowable rate of
water flow, meaning
the bioreactor may not
work as intended
 Chips of sizes ¼ - inch to 1- inch size range are generally
used
 Chips made from treated or preserved wood are not
recommended effecting the bacteria’s ability to use the
carbon in the wood
 Green material such as leaves or conifer needles is not
recommended due to their relatively high nitrogen content
and their potential to quickly be degraded.
 Other carbon source materials such as corn cobs, corn
stalks, wheat straw, cardboard, and newspaper have
been investigated, but research has recommended woody
material because it provides a sustainable carbon source
that lasts longer.

12. LIFE OF BIOREACTOR
 The average life spans of 15 to 20
years, after which the woodchips
would be replaced if treatment was
to be continued. Because it is a new
practice, no bioreactors have been
in the ground long enough to have
direct evidence of longevity.
 The oldest working denitrification
system that treats septic waste
water was 15 years old in 2010.
SOURCE: Christianson et al,2011

13. EXTENT OF DRAINAGE AREA
TREATMENT
Most current bioreactor designs have
been successful at reducing the amount
of nitrate
in drainage from 30 to 80 acres. Some
larger designs have been installed and
are being
watched closely for performance.

14. POINTS TO PONDER UPON FOR INSTALLATION OF BIOREACTOR
Are certain
areas better
than others
for woodchip
bioreactors?
How do I manage
the bioreactor?
How much
management is
required?
Will my tile
back up
because of my
bioreactor?
Will this work
on an existing
drainage
system? Is there a yield or
soil impact, and
will a bioreactor
work with other
conservation
practices?
How much
nitrate will a
woodchip
bioreactor
remove? How big
an impact will I
have?
 How do bioreactors compare to wetlands and
other nitrate reduction strategies?
 Will the bioreactor remove other chemicals?
 Are there negative side effects?
 How much do they cost? Who will help pay?

15. RESEARCH AREAS
۞ University of Illinois,Department of Natural resources and Environmental
Sciences,W-503 Turner Hall,1102 S,Goodwin Av., Urbana,IL 61801,United States
۞ Department of Biological and Agricultural Engineering,NorthCarolina State
University,Campus Box 7625,Raleigh NC 27695-7625,USA
۞ Department of Natural Resources Science, University of Rhode Island, Kingston, RI
02881, USA
۞ National Laboratory for Agriculture and the Environment, USDA-ARS, 2110
University Blvd, Ames, IA 50011-3120, USA
۞ Department of Earth and Environmental Sciences, University of Waterloo,
Waterloo, ON N2L 3G1, Canada
۞ Department of Earth and Ocean Sciences, University of Waikato, Private Bag 3105,
Hamilton, New Zealand
۞ GNS Science, Private Bag 2000, Taupo, New Zealand
۞ ISERC, Visva-Bharati University, Santhinikethan 731235, India
۞ Department of Botany, Osmania University, Hyderabad 500007, Telangana, India
۞ Department of Civil Engineering, Faculty of Engineering and Technology, Annamalai
University, TamilNadu, India – 608 002.
۞ Department of Mechanical Engineering, A.V.C. College of Engineering,
Mayiladuthurai, TamilNadu, India - 609 305.

16. MATERIALS USED FOR DESIGNING A BIOREACOR
Pilot-scale reactors with identical volumes (0.71 M3 ) and depths (0.6 M), and three
cross sectional geometries – channel, rectangular and trapezoidal – were constructed
with plywood (Iowa State University’s Agricultural Engineering and Agronomy
research farm near Ames, Iowa)
The reactors
were 1:10 of
field-scale based
on surface
footprint
The inflow and outflow pipes (5 cm and
10 cm PVC, respectively) were placed in
the bottom center of the bioreactors.
The plywood boxes were lined
with polyethylene tarpaulin
and packed with woodchips.
The chips were a mixture of various local hard wood species and similar to those
used in field bioreactor installations.Particle size analysis showed a mean particle
size of 1.1 cm, an effective size ( D10, 10% by mass of woodchips was smaller than
this size) of 7 mm, and a uniformity coefficient( D60/D10) of 2 (Christianson et al.,
2010a)

17. CONT……………………
The layer of woodchips in the pilot reactors was covered
with a lightweight geo fabric and approximately 7 cm of
topsoil.
Control valves allowed manipulation of the flow rates and
outflow was measured with Neptune™ T-10 water meters.
Water depth within the reactor was set using a downstream flow control structure
consisting of an upturned PVC elbow at the reactor outlet.
Five to twelve PVC monitoring wells (2.5 cm diameter) were placed at pre
determined locations within the reactors to monitor flow depth and redox
conditions within the reactor.
Flow depth data were used to calculate the active reactor volumes at water
depths set by the downstream flow control structure. Feed water was obtained
from a 4000 L underground reservoir connected to a 30 cm diameter county main
drainage line that drained fields planted with corn and soybean.The rain volume
passing through the reactors during the testing period was less than 0.6% of the
total flow volume and was thus considered negligible.

18. ANALYSING PILOT BIOREACTOR WORKING
THE VARIOUS BIOREACTORS WERE ANALYSED IN THE FOLLOWING MANNER
Bromide Tracer Testing
Bromide tracer tests were conducted to determine the flow characteristics
and in situ HRTs of each bioreactor.
Nitrate Removal over a
Range Of Theoretical
Hydraulic Retention
Times (%)
Simulated Storm Event
Effects on Nitrate
Removal (@)
Impact of Influent Nitrate Concentration On Bioreactor
Performance

19. CONTROLLING FACTORS FOR NITRATE REMOVAL BY A WOOD CHIP BIOREACTOR
NITRATE CONCENTRATION
ALTERNATE C SOURCES
TEMPERATURE
PROCESSES COMPETING FOR
AVAILABLE C

20. HYDROLOGY ASSOCIATED WITH BIOREACTOR WORKING
Hydrological connections, limitation and potential approaches to overcoming limitations
in denitrifying bioreactors.

21. MECHANISM OF NITRATE REMOVAL
HETEROTROPHIC DENITRIFICATION
NITROGEN IMMOBILISATION INTO ORGANIC MATTER
DISSIMILATORY NITRATE REDUCTION TO AMMONIA
Immobilisation and
DNRA accounts for less
than 4% of total NO3
-
removed
(Greenan et al. 2006)
Less than 10% of NO3
-
removed was
attributable to
DNRA (and generally
this was less than 5%).
(Gibert et al. 2008)

22. HYDRAULICS INVOLVED IN BIOREACTOR
WORKING
TRACER
TESTING
RESIDENCE
TIME
TEMPERATURE
EFFECT ON
REACTION
RATE
NITRATE
REMOVAL
KINETICS

23. MODEL DEVELOPMENT
 The denitrification bed model is comprised of two components: water flow and
nitrate removal kinetics.
 Regarding the former,it was proved that Forchheimer's equation best describes
water flow through woodchips (Ghane et al., 2014) which is written as
where i is the hydraulic gradient (cm /cm), µ is the water dynamic
viscosity (g/cm s), k
in is the intrinsic permeability
 Hydraulic gradient was calculated as the measured head difference between the
inflow (hi) and outflow (ho) water heights divided by the bed length (L= 825 cm).
For the occasions where water height was not measured, recorded sensor water
levels were used instead. bed outflow temperature were used to determine water
dynamic viscosity. Solving the quadratic above equation, and replacing i= (ho-hi)/L
results in only one practical solution as

24. Cont…
Martinez and Wise, 2003

25. CONT…..

27. CONT…

28. FACTORS AFFECTING BIOREACTOR WORKING
MASS AND BED HEIGHT
LOSS
CHANGES IN POROSITY
CHANGES IN CARBON & NITROGEN
CONTENT OF MEDIA
COST OF MEDIA

30. PERFORMANCE EVALUATION OF A BIOREACTOR
NERF(NORTHEAST
RESEARCH AND
DEMONSTRATION
FARM)
PEKIN,IOWA
HAMILTON
COUNTY,IOWA
GREEN
COUNTY,IOWA

31. CONT…
Christianson et al

32. Christianson et al

33. Christianson et al

34. Christianson et al

35. Christianson et al

36. Christianson et al

37. Christianson et al

38. Christianson et al

40. FUTURE ENDEAVOURS

42. FINANCIAL COMPARISON OF DIFFERENT NITRATE REDUCTION
STRATEGIES
LAURA ET AL, 2009

43. CONT…
LAURA ET AL, 2009

44. LAURA ET AL, 2009

45. LAURA ET AL, 2009

46. CONCLUSIONS
 Designing agricultural drainage denitrification bioreactors for successful and
consistent nitrate reduction is challenging in consideration of variable drainage
flow rates, nitrate concentrations, and temperatures.
 However, the design process allows engineers to attempt to manage these
“uncontrollable” parameters with “controllable” factors like bioreactor design
geometry and length to width ratio.
 A key finding at the pilot-scale was that nitrate removal was not significantly
impacted by design geometry.
 This conclusion was confounded at the field-scale as the bioreactor with a
unique trapezoidal cross-section (NERF bioreactor) had poor performance in
general, perhaps unrelated to this design factor (e.g. management could be
optimized to route less water though the reactor).
 In reactor engineering, retention time is often an important design parameter
and this proved to be the case here

47. CONT..
 The hydraulics of water moving through a denitrification bioreactor was
shown to be important as, in controlled studies, increased flow rates during
drainage hydrographs caused decreased retention times and reduced nitrate
removal.
 This was also observed at the field-scale with high flow events at the NERF
bioreactor resulting in increased bioreactor effluent nitrate concentrations.
 Another important hydraulic issue at the field-scale was the occurrence of
bypass flow. This untreated water can greatly reduce the overall efficiency of
a bioreactor as mentioned (e.g. Greene Co. site).
 However, it may also not be desirable to treat all the drainage volume as
evidenced by the NERF bioreactor’s low nitrate removal percentages;this
bioreactor reduce bioreactor loads from 12% to 15% while treating 91% to 99%
of the drainage volume.
 The financial work presented here is the first of its kind for drainage water
quality practices in terms of its comprehensiveness and consistency.

48. REFERENCES
 Camargo, J.A., Alonso, A., 2006. Ecological and toxicological effects of inorganic
nitrogen pollution in aquatic ecosystems: a global assessment. Environ. Int. 32,
831–849.
 Galloway, J.N., Aber, J.D., Erisman, J.W., Seitzinger, S.P., Howarth, R.W.,
Cowling, E.B., Cosby, B.J., 2003. The nitrogen cascade. Bioscience 53 (4), 341–
356.
 Baker, J.L., Campbell, K.L., Johnson, H.P., Hanway, J.J., 1975. Nitrate,
phosphorous, and sulfate in subsurface drainage water. J. Environ. Qual. 4, 406–
412.
 Kladivko, E.J., Frankenberger, J.R., Jaynes, D.B., Meek, D.W., Jenkinson, B.J.,
Fausey, N.R., 2004. Nitrate leaching to subsurface drains as affected by drain
spacing and changes in crop production system. J. Environ. Qual. 33, 1803–1813.
 Patni, N.K., Masse, L., Jui, P.Y., 1996. Tile effluent quality and chemical losses
under conventional and no tillage: part 1. Flow and nitrate. Trans. Am. Soc.
Agric. Eng. 39, 1665–1672.

49.  Tomer, M.D., Moorman, T.B., Rossi, C.G., 2008. Assessment of Iowa River’s
South Fork watershed: part 1. Water quality. J. Soil Water Conserv. 63, 360–
370.
 Gast, R.G., Nelson, W.W., Randall, G.W., 1978. Nitrate accumulation in soils
and loss in tile drainage following nitrogen applications to continuous corn. J.
Environ.
Qual. 7, 258–261.
 Jaynes, D.B., Hatfield, J.L., Meek, D.W., 1999. Water quality in Walnut Creek
watershed: herbicides and nitrate in surface waters. J. Environ. Qual. 28, 45–
59.
 Jaynes, D.B., Kaspar, T.C., Moorman, T.B., Parkin, T.B., 2008. In situ bioreactors
and deep drain-pipe installation to reduce nitrate losses in artificially drained
fields. J. Environ. Qual. 37, 429–436.
 Christianson, L.E., Bhandari, A., Helmers, M.J., 2011. Pilot-scale evaluation of
denitrification drainage bioreactors: reactor geometry and performance. J.
Environ. Eng. 137, 213–220.
Greenan, C.M., Moorman, T.B., Kaspar, T.C., Parkin, T.B., Jaynes, D.B., 2006.
Comparing carbon substrates for denitrification of subsurface drainage water. J.
Environ.Qual. 35, 824–829.

51. QUESTIONS??

52. Schematic representation of an ion exchange plant

53. Generalized heterotrophic denitrification process

54. Generalised autotrophic sulphur-based denitrification
process

55. Plan and cross sectional views of pilot-scale denitrification bioreactors installed
near Ames, Iowa; All dimensions are in meters
Woodchip bioreactor after installation; circular sumps
and PVC wells used for research monitoring (Northeast
Iowa Research andDemonstration Farm)

56. BROMIDE TRACER TECHNIQUE

60. Impact of simulated hydrograph on NO3 --N removal in channel and
rectangular pilotreactors:(a) flow rates and percent mass reductions, and
(b) flow rates and percent massreductions normalized by retention time

61. Average percent reduction of NO3--N mass for two influent concentrations at four ranges of
theoretical retention times.Error bars indicate one standard deviation;No data was collected
for high concentration at the lowest retention time.