Department of Plant and Environmental Sciences, P. D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
THT282 - 2012. Introduction to sustainable water and sanitation
Introduction to natural systems soil infiltration, wetlands, ponds
Professor Petter D. Jenssen
1
Department of Plant and Environmental Sciences,
Norwegian University of Life Sciences (UMB)
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Natural systems for
wastewater treatment There are three
main categories of
natural systems,
combinations
between
categories are also
possible
Ponds
Infiltration
Constructed
wetlands
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Natural systems can be
gravity and sun driven
and are thus energy
extensive. Recycling can
be enhances by reuse of
P-saturated media
Recycling
Systems with
source separation
Energy
intensive
Energy
extensive
Natural systems;
* Wetlands
* Ponds
* Soil infiltration
Conventional systems
3
Loss
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Natural systems for
wastewater treatment
Ponds
Infiltration
Constructed
wetlands
www.umb.no
Department of Plant and Environmental Sciences, P. D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Soil infiltration systems
Pretreatment
5
Infiltration unit called;
leachfield
or seepage bed/trenches
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P. D. Jenssen
Traditional buried soil infiltration system
6
Siegrist et al. 2000
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Infiltration of wastewater into soil
Open infiltration - dams
Subsurface systems trenches/beds
7
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Infiltration of wastewater into soil
AREA REQUIREMENT
Open infiltration - dams
1-5m2/person
Subsurface systems - trenches/beds
5-20m2/person
8
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Different buried infiltration
systems
Mound
Surface
infiltration
Septic
tank
Shallow
Deep
infiltration infiltration
Dosing
device
9
Source: www.avlop.no
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Setermoen infiltration system
5000pe
ONE PUMP IS THE ONLY MOVING
PART IN THE WHOLE
TREATMENT SYSTEM
66
THE INVESTMENT COST WAS 1/3
OF A CONVENTIONAL SYSTEM.
PAYBACK TIME 7 YEARS
www.umb.no
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Fecal
coli.
11
<100/100ml
Treatment results rapid infiltration Norway
COD
Phosphorus
www.umb.no
Nitrogen
(Kraft 1998)
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
TREATMENT*
Organic matter
(COD):
75 - 90 %
Suspended solids
(SS):
> 90%
Phosphorus (P):
>99 %
Nitrogen (N)
50 - 70%
Bacteria:
Groundwater
level
4-6 log reduction
12
*Renseeffekt i umetta sone ytterligere rensing
foregår
www.umb.no
i grunnvanssonen.
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Setermoen infiltration system
5000pe
ONE OF NORWAY´S BEST
PERFORMING
TREATMENT SYSTEMS
66
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Traditional buried soil infiltration system
TREATMENT*
Organic
matter(BOD):
> 90 %
Suspended solids
(SS):
•
> 90%
Phosphorus (P):
> 90 %
Nitrogen (N)
> 30% (20 - 60)
Bacteria:
4-6 log reduction
14
(Siegrist et al. 2000)
*Treatment preformance in the unsaturated zone, further treatment
will occur in the saturated zone
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Sandfilter
Sloping sides
Water level monitoring
pipe
•
Geotextile/insulation
Distribution layer
Sand
Bottom drainage
(PDJ 1999)
15
PDJ 99
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Sandfilter - performance
TREATMENT*
Organic matter
(COD):
Septic tank
effluent
>90%
Suspended solids
(SS):
> 90%
Phosphorus (P)*:
0 - 80%
Nitrogen (N)
30% (20 - 50%)
Bacteria:
Treated water
4-6 log reduction
64
16
* Based on 8 -10 years of
operation
www.umb.no
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Subsurface infiltration - Mound system
•
Peilerør
Water
level monitoring pipes
Sampling well
Sand
Natural soil
PDJ 1999
17
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Mound system
Mound systems are used
when the depth of the
local soil does not give
sufficient separation
distance to
ground-water and in
soils of low hydraulic
conductivity
18
PDJ 1999
P.D.J.
1990
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Infiltration systems - treatment
Shallow inflitration
Mound
Organic matter
BOD
Phosphorus
Nitrogen
(Køhler 1998)
19
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Subsurface infiltration - Mound system
TREATMENT*
•
Peilerør
Water
level monitoring pipes
Organic
matter(BOD):
> 90 %
Suspended
solids
Sampling well
(SS):
Sand
> 90%
Phosphorus (P):
> 90 %
Natural soil
Nitrogen (N)
> 50 - 80
PDJ 1999
Bacteria:
20
4-6 log reduction
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Different buried infiltration
systems
Mound
Surface
infiltration
Septic
tank
Shallow
Deep
infiltration infiltration
Dosing
device
21
Source: www.avlop.no
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
From Siegrist 2010
22
Drip irrigation systems
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Drip irrigation systems
23
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Drip irrigation systems
From Siegrist 2010
24
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Drip irrigation systems - treatment
Treatment
Organic
matter(BOD):
> 90 %
Suspended solids
(SS):
> 90%
Phosphorus (P):
> 90 %
Nitrogen (N)
> 30 - 70 %
25
From Siegrist 2010
Indicator bacteria:
4-6 log reduction
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Drip irrigation systems - treatment
Treatment
Organic
matter(BOD):
> 90 %
Suspended solids
(SS):
> 90%
Phosphorus (P):
> 90 %
Nitrogen (N)
> 30 - 70 %
26
From Siegrist 2010
Indicator bacteria:
4-6 log reduction
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Drip irrigation systems - treatment
Treatment
Organic
matter(BOD):
> 90 %
Suspended solids
(SS):
> 90%
Phosphorus (P):
> 90 %
Nitrogen (N)
> 30 - 70 %
Indicator bacteria:
27
et al. 2010)
4-6 log(Conn
reduction
www.umb.no
From Siegrist 2010
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Natural systems for
wastewater treatment
Ponds
Infiltration
Constructed
wetlands
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Constructed wetland
Dal primary school
29
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
30
www.umb.no
flow direction/purification
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Constructed wetland
31
High quality effluent
www.umb.no
Constructed wetland
treating wastewater from 2 homes
Septic tank
Pretreatment biofilter (P
Horizontal subsurface flow
constructed wetland (HSF)
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
33
Constructed wetland
Dal primary school
Parameter
Influent Effluent
mg/l
mg/l
Total - P
2,9
0,2
Total - N
29,0
12,0
COD
129
24
SS
<5
Fecal. coli. /100ml
< 2 www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Reuse of P-saturated filter material
34
More information
on reuse of filter media see: Jenssen et al.2010
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Constructed wetland - performance
TREATMENT*
Organic
matter(BOD):
> 90 %
Suspended solids
(SS):
> 90%
Phosphorus (P):
> 90 %
Nitrogen (N)
105
Designed accoding to Norwegian regulations
(VA-miljøblad no. 49) the service life for P-removal
is expected to be 10-15 years
www.umb.no
> 40 - 60
Bacteria:
>3 log reduction
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Natural systems for
wastewater treatment
Ponds
Infiltration
Constructed
wetlands
www.umb.no
Ponds are the worlds
most common
treatment system
Photo: W. Browne
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
38
Photo: W. Browne
www.umb.no
The worlds largest wastewater
treatment system ?
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Calcutta wetlands
39
www.umb.no
The primary pond
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Calcutta wetlands
40
www.umb.no
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Calcutta wetlands
84
41
Provides 15 - 20% of the fresh fish in Calcutta markets
www.umb.no
Ponds function in
cold climate if aerated
(Jenssen et al. 1991)
Aeration cascade
Photo: W. Browne
Typical removal:
* BOD
* Nitrogen
* Phosphorus
60 - 90%
20 - 40%
10 - 30%
Photo: W. Browne
Treatment
Organic
matter(BOD):
> 60 - 90 %
Suspended solids
(SS):
Typical removal:
* BOD
* Nitrogen
* Phosphorus
60 - 90%
20 - 40%
10 - 30%
80 - 90%
Phosphorus (P):
10 - 30 %
Nitrogen (N)
> 30 - 70 %
Indicator bacteria:
2-6 log reduction
Photo: W. Browne
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
A
pond/wetl
and
system in
Norway
148
www.umb.no
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
A
pond/wetl
and
system in
Norway
Parameter
Effluent conc.
mg/l
Removal
%
TOC
5
93
TSS
<5
< 90
Total - P
0.24
96
Total - N
4
91
148
Fecal Coli. /100ml
<100
>99.999
www.umb.no
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Removal
in a
pond/wetl
and
system in
Norway
Parameter
Norway´s best
performing
treatment
system?
Effluent conc.
mg/l
Removal
%
TOC
5
93
TSS
<5
< 90
Total - P
0.24
96
Total - N
4
91
148
Fecal Coli. /100ml
<100
>99.999
www.umb.no
More information see:
Browne and Jenssen 2005
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
48
Wastewater Treatment
Natural systems - processes
Biological
mineralization
Chemical/physical
precipitation/adsorption
Physical
straining/filtering
www.umb.no
Groundwater
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Removal mechanisms in
natural systems
•
•
•
•
Removal of organic matter
Removal of phosphorus
Removal of microorganisms
Removal of nitrogen
49
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Reduction of organic matter
Plastic particles as biofilm carrier
K1
K2
d= 9 mm
50
d= 15 mm
Natrix O
d= 60 mm
Biofilm media surface area 310 - 500 m2/m3
www.umb.no
Kaldnes TM
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
51
Reduction of organic matter
Expanded clay aggregates (FiltraliteHCTM) as
biofilm carrier
Particle size
2-5mm
Surface area
> 5000m2/m3
Bacteria on Filtralite
surface
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
52
Reduction of organic matter
Porous media as biofilm carrier
Sand
Filtralite
Particle size
0.06 - 2 mm
Particle size
2-5mm
Surface area
> 5000m2/m
Surface area
>> 5000m2/m
www.umb.no
Purification
through sand
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department
D
‹ epartment of Plant and Environmental Sciences, P.D. Jenssen
Septic tank
effluent
Treated water
53
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Removal mechanisms in
natural systems
•
•
•
•
Removal of organic matter
Removal of phosphorus
Removal of microorganisms
Removal of nitrogen
54
www.umb.no
Phosphorus removal in soils
Organic layer, Ohorizon
Oxidized layer, Bhorizon
Subsoil, Chorizon
Phosphorus removal in soils
Fe3(PO4)2
AlPO4
Ca3(PO4)2
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Phosphorus forms in soil - dependent on pH
57
(From Brady 1990)
www.umb.no
Groundwater level
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Fecal
coli.
59
<100/100ml
Treatment results rapid infiltration Norway
COD
Phosphorus
www.umb.no
Nitrogen
(Kraft 1998)
P-sorption capacity:
14 years under each basin
Groundwater level
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Phosphorus removal in soils
depth of infiltration trenches
Organic layer,
Ohorizon
Oxidized layer,
Bhorizon
62
Subsoil, Chorizon
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Removal mechanisms in
natural systems
•
•
•
•
Removal of organic matter
Removal of phosphorus
Removal of microorganisms
Removal of nitrogen
63
www.umb.no
•
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Small buried infiltration systems
(Siegrist et al. 2000)
64
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Pit toilets
65
A: Traditional pit latrine. B: VIP-latrine and
C: pour flush toilets with
twin soakpits.
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
66
Infiltration systems
bacteria removal
Soil surface
Depth cm
Infiltration trench
Bacteria/100ml or 100g of soil
E coli
Cloggede zone
Total coli
Total bacteria
(McCoy and Ziebell 1975)
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
The fate of microorganisms in soil
67
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Straining
68
The fate of microorganisms in soil
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Size of soil pores vs. size of microorganisms
Macropores
Pore sizes in sand
Virus
Bacteria
Parasites
69
( Edworthy 1979 in Englund 1980)
www.umb.no
Predation
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
The fate of microorganisms in soil
70
www.umb.no
Adsorption
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
The fate of microorganisms in soil
71
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
The fate of microorganisms in soil
Death by old age
72
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Removal mechanisms in
natural systems
•
•
•
•
Removal of organic matter
Removal of phosphorus
Removal of microorganisms
Removal of nitrogen
73
www.umb.no
Department of Plant and Environmental Sciences
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Fecal
coli.
74
<100/100ml
Treatment results rapid infiltration Norway
COD
Phosphorus
www.umb.no
Nitrogen
(Kraft 1998)
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Nitrogen transformations in soils
75
(Jenssen and Siegrist modified after Lance 1972)
www.umb.no
Ammonification
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
76
www.umb.no
ammonium
----> NH4
NH2
urea
Department of Plant and Environmental Sciences, P.D. Jenssen
Nitrogen transformations in soils
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Nitrogen transformations in soils
Nitrification
NH4 --> NO2--> NO3
ammonium
77
www.umb.no
nitrite
nitrate
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Nitrogen transformations in soils
Nitrification
NH4 --> NO2--> NO3
ammonium
nitrite
nitrate
Prerequisite:
Aerobic conditions
78
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Nitrogen transformations in soils
Denitrification
NO3 --> N2O --> N2
nitrate
nitrous oxide nitrogen gas
Prerequisites biological
denitrification:
79
1. Anerobic or anoxic
conditions
2. Carbon source
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Traditional buried soil infiltration system
Ammonification
•
Nitrification
Denitrification
80
Denitrification
(Siegrist et al. 2000)
www.umb.no
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Constructed wetland
81
www.umb.no
Denitrification
Nitrification
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
Department of Plant and Environmental Sciences, P.D. Jenssen
Constructed wetland
82
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
83
Natural systems
Conclusions
 Natural systems can be designed in many
different ways to accommodate local conditions
 Natural systems require relatively large area per
person
 Natural systems have stable and high treatment
performance
 Natural systems are simple in design, robust and
cost efficient
 The phosphorus removal of soil infiltration type
systems and constructed wetlands is dependent
on the P-removal capacity of the porous media
www.umb.no
Department of Plant and Environmental Sciences, P.D. Jenssen
NORWEGIAN UNIVERSITY OF LIFE SCIENCES
84
References

Browne, W. og P.D. Jenssen (2005). Exceeding tertiary standards with a pond/reed bed system in
Norway. Wat. Sci. Tech. 51(9), 299–306.

Conn KE, Siegrist RL, Barber LB, Meyer MT. 2010. Fate of Trace Organic Compounds during Vadose
Zone Soil Treatment in an Onsite Wastewater System. J. Environmental Toxicology and Chemistry.
29(2):285-293. Published online 8 October 2009. DOI:10.1002/ etc.40

Jenssen, P. D., T. Krogstad A. M. Paruch T. Mæhlum, K. Adam, C. A. Arias, A. Heistad, L. Jonsson, D.
Hellström, H. Brixd M. Yli-Halla, L. Vråle, M. Valve. 2010. Filter bed systems treating domestic
wastewater in the Nordic countries – performance and reuse of filter media. Ecol. Eng. 36, pp. 16511659.

Jenssen, P.D. og R.L. Siegrist (19). Nitrogen removal from wastewater in soil infiltration systems. I: H.
Ødegaard (red.): Fjerning av nitrogen i avløpsvann, 114– 12. Tapir. Trondheim

Lance, J.C. (1972). Nitrogen removal by soil mechanisms. J. Water Poll. Control Fed. 44(7), 1552–1561

McCoy, E. og Z.A. Ziebell (1975). Effects of effluents on ground water, bacteriol- ogical aspects. 2nd
Conf. on individual on-site wastewater systems. National Sanitation Foundation, Ann Arbor, Michigan,
67–76.

Siegrist R.L. 2010. Effluent Dispersal into Soil for Treatment and Disposal/Reuse: Principles and
Practices Sustainable Sanitation. Presentation at the summerschool: Decentralized, Natural and
Ecological Wastewater Treatment, Department of Plant and Environmental SciencesThe Norwegian
University of Life Sciences June 1 - 25, 2010

Siegrist RL. 2007. Engineering Soil Treatment Units as a Unit Operation in Onsite Wastewater
Reclamation Systems. Proc. 11th National Symposium on Individual and Small Community Sewage
Systems, Warwick, RI, October 21-24, 2007, American Society of Agricultural and Biological
Engineers, St. Joseph, MI.

Siegrist, R. L., E.J. Tyler og P.D. Jenssen (2000). Design and performance of onsite wastewater soil
absorption systems. Paper presented at National Research Needs Conference Risk-Based Decision
Making for Onsite Wastewate Treatment, St. Luis, Missouri, 19.–20. mai. USEPA, Electic Power Inst.
Community Env. Center, National Decentralized Water Recources Capasity Development Conference
Risk-Based Decision Making for Onsite Wastewate Treatment, St. Luis, Missouri, 19.–20. mai. USEPA,
Electic Power Inst. Community Env. Center, National Decentralized Water Recources Capasity
Development Project.
www.umb.no