Transcript Document

Course 2 Unit 3
Storage and transport logistics
Lecturer: Mariska Ronteltap
[email protected]
Part A – Urine storage
Part B - Faeces storage
Part C – Transport logistics overview
Part D – Detailed analysis of transport options
2
This unit deals with which part of the sanitation
system?
+ storage at
household
or
community
level
+ storage at
household or
community
level
Course 2 Unit 3
Course 2 Unit 3
Part A: Urine storage
Note: Urine is normally stored pure, or with as little water added as
possible
All technical details presented in this Part A regarding urine pipes and
urine storage tanks are taken from Kvarnström et al. (2006), Appendix 2
Purposes of urine storage
1. Sanitisation of the urine, which will
occur over time (increased pH due to
urea conversion to ammonia; time itself
also results in pathogen kill – see
Course 2 Unit 1 Part A)
2. To bridge the time in between collection
events by transport vehicle
3. Farmers’ needs for urine fertiliser is not
constant all year round, but mostly just
before sowing and in the beginning of
the growth period (see also Course 3
“Reuse of ecosan products”)
Very simple urine collection
vessel:
Plastic 20 L jerrycan connected to
outlet of UDD toilet squatting pan
(may need frequent emptying
depending on number of users).
CREPA in Burkina Faso (seen
October 2006)
What is the required urine storage tank volume?
Equation based on household urine production and days between tank
emptying events:
Vstorage = Npeople · purine · temptying
Vstorage
Required storage volume at household level
Npeople
Number of people in household, e.g. 4.5
purine
Urine production per person and day
(see Course 1 Unit 2; e.g. 1.3 L/cap/d)
temptying
Time between emptying events, e.g. 30 days if emptied once
per month
Then in this example: Vstorage = 4.5 cap · 1.3 L/cap/d · 30 d = 176 L
Costs of urine storage
 Urine storage can be a major cost item in a large-scale urban
ecosan project!
 Often a trade-off is made between the theoretical storage time
required for complete sanitisation (see Course 2 Unit 1 Part A)
and the expenditure that is to be made for the urine storage
tanks
 The longer the urine storage time, the larger the urine storage
tank and the higher its cost
Key process during urine storage: degradation of
urea to ammonia in water
Urea
Ammonium
Hydroxyl ion (pH rise)
CO(NH2)2 + 3 H2O → 2 NH4+ + OH- + HCO3NH4+ + OH- ↔ NH3(aq) + H2O
Ammonia (aq = in solution)
Possible problems with urine storage
installations
1. Blockages in pipe from toilet to urine storage tank (see Course 1
Unit 3 Part A for details)
2. Odour (from ammonia)
3. Intrusion of groundwater (for underground tanks)
4. Nitrogen losses (in the form of ammonia)
A lot of the experience with urine storage comes from Sweden
because it is currently the country with the most wide-spread use
of urine-diversion toilets (see next slide)
A selection of places in Sweden where urine diversion is
installed for ten households or more
Since the middle of the 1990s at least
135,000 urine-diverting toilets have
been installed in different settings in
Sweden. Most of the installations are
urine-diverting liners made of plastic
for outhouses at summerhouses or
plastic urine diversion with dry
collection of faeces, but at least
15,000 are made of porcelain and
have either dry- or water-flushed
collection of faeces.
(Source: Kvarnström et al. (2006),
page 21)
Map of Southern part of Sweden
(Picture by Johan Palmcrantz & Co.)
Technical requirements for urine piping system
Parameter
Small systems with only
one toilet on each urine
pipe
Larger systems with
several toilets on one
urine pipe
U-bend required (for
odour control)
No
Yes
Pipe diameter inside
the house
At least 25 mm
At least 75 mma
Outdoor pipes
At least 110 mm
At least 110 mm
At least 4%
At least 1%
Slope
Pipe material
Plastic (e.g. PVC)
Need to avoid
Obstacles slowing down the flow, e.g. sharp
bends
Length of piping system
< 10 m
No limit but provide
possibility to inspect,
flush
and clean the
a Where the pipes can be easily cleaned and/or disassembled,
50 mm can be
accepted, at the expense of regular maintenance e.g. flushing every pipes
few years.
Guiding principles for urine pipes
 Piping in the system should be minimized as much as possible
(to limit the time the urine is in the piping system and thus the
degradation of urea and risk of precipitation in the system)
 To prevent odours, the piping system should be only sparingly
ventilated, pressure equalization is enough
 To maximize the flow rate of the urine and the sludge, the
insides of the pipes should be smooth and flow restrictions, e.g.
sharp 90º bends, should be minimized
 Remember: Long-distance piping for urine would not be a good
idea!
Course 2 Unit 3
Other specifications for the urine piping system
 The possibility to inspect, flush and clean the pipes in both
directions should be provided where there is a sharp bend in the
piping, at all transitions, e.g. from vertical to horizontal piping
and where the pipes leave the house.
 Manholes outside the house shall be equipped with child safe
lids that are water tight.
 When the collection container is outside of the toilet room, it is
also important that the pipe ends close to the bottom of the
collection container to avoid air flow through the pipe into the
toilet room.
 The urine pipe is preferably located in the same piping trench as
other wastewater pipes. It should be clearly marked, so that it is
clearly distinguishable from the other pipes.
 It is essential to avoid sedimentation pockets and thus it is
essential that a negative slope is avoided in all parts of the pipe
system.
Materials for urine storage
tanks
 Urine is very corrosive and if
possible metals should be
avoided altogether in the
system
 Possible options:
– Plastic tank, plastic drums
– Big rubber bags
– Digging a hole in the ground
and covering the ground
with polythene sheets to
create a basin (covered with
polythene sheets as well)
– High-quality concrete
(expensive)
– At the farmer’s end urine
could possibly be stored
directly in the ground itself
(without a plastic liner), see
EcosanRes Discussion
Forum on 10 April 2006 by
Håkan Jönsson, plus
This picture shows the plastic urine storage tanks at
Kullön, Sweden during the construction process. The
tanks will be covered with soil. Photo: Mats
Johansson.
(Source: Kvarnström et al. (2006), page 36)
Technical requirements for urine
storage tanks
 Tanks need to be water-tight and robust
 Care should be taken to prevent
groundwater leaking into the pipe system
– All connections in the ground must be
completely tight (i.e. welded or glued,
or if possible, avoided altogether) to
minimize the risk for intrusion of
groundwater
– If possible, connections in the ground
should be avoided all together
Very simple urine storage tank:
A number of plastic 20 L jerry-cans
(from UDD toilet shown in slide 4).
CREPA in Burkina Faso (seen
October 2006)
Urine storage tank (4 tanks of 2.5 m3 each) made of polyethylene in the basement of the GTZ head
office building in Eschborn, near Frankfurt in Germany, with sampling and level indicator devices
(installed in August 2006)
Level indicator for urine
Docking station for urine tankers
(insulated pipe for winter
temperatures in Germany)
Example: The first large-scale urine collection system with
urine diversion in Stockholm, Sweden
The system was established in 1997 and
urine from the Understenshöjden,
Palsternackan and Gebers residential
areas and the Bommersvik
conference centre is transported to
the Lake Bornsjön area where it is
stored and replaces chemical
fertilizer in agriculture.
Short facts:
 Connected households: 130 + 1
conference centre.
 Type of toilets: 50% Dubbletten,
25% Gustavsberg and 25% Wost
Man Ecology single flush.
 Glass-fibre tanks in each housing
area – 15 – 40 m3 each.
 Yearly volume of collected urine:
150 -170 m3.
 Storage tanks: 3 PVC balloon
tanks of 150 m3 each.
P. Jenssen
Storage takes place at Bornsjön, and the urine
is used on fields in the background owned by
the Stockholm Water Company.
Course 2 Unit 3
Course 2 Unit 3
Part B: Faeces storage
Different types of faeces collection require
different types of storage
Type of faeces
Toilet type
Type of storage
Type 1:
Faeces without water (but
with ash, sand, lime etc.,
and with or without toilet
paper)
UDD toilet;
composting toilet
 In the faeces vault
of a UDD toilet
 In smaller buckets
and then added to
composting process
Type 2:
Faeces with small amount
of water (one litre of water
per defecation)
= blackwater
 Vacuum toilets (with Intermediate storage
or without UD)
possible, e.g. in
septic tank
 Toilets where faeces
collected together with
anal washwater
Type 3:
 UD water-flush
 No storage toilets
usually discharged to
Faeces with large amount
the sewer
of water (e.g. several litres  Conventional waterof water
per is
defecation)
– easiest
flush toilets
(mixed
Could
be stored in
Type
1 faeces
certainly the
to store
and treat in
a low-income
also called brownwater
with urine)
septic tank
setting
Storage of Type 1 faeces
(faeces collected without water)
 Faeces volumes are much smaller
than urine volumes, hence its storage
is easier to realise
 For waterless systems: Can be
stored inside of faeces vault in a
UDD toilet (typically one year),
receiving primary treatment
 For secondary treatment, storage
and treatment are combined, e.g. in
anaerobic digestion or composting
(will be discussed in Course 2 Unit 4
and 6)
Example: Faeces storage in the vault of a
UDD toilet
Photo: Edward Guzha, Mvuramanzi Trust
in Harare, Zimbabwe
Storage of Type 2
faeces (blackwater
from vacuum toilets)
Top: Blackwater from vacuum toilets (without
UD) after the macerator pump; this is fresh
excreta – over time the colour would turn
black (anaerobic conditions).
Right: Storage tanks for blackwater of 80
persons (they produce ~ 5.6 L/cap/d)
Sneek, The Netherlands, March 2007
Course 2 Unit 3
Storage of Type 3 faeces (faeces plus water,
from UD water-flush toilets)
 In the case of UD water-flush toilets in Switzerland and Sweden,
the faeces-water mixture is not stored but discharged to the
sewer and wastewater treatment plant
 Research projects are ongoing to treat the faeces-water mixture
with membrane bioreactors and other high-tech processes
You can imagine that Type 3 faeces are quite difficult to store and
treat at low cost
What is the required faeces storage tank
volume?
Equation based on household faeces production and days between tank
or vault emptying events:
Vstorage = Npeople · pfaeces · temptying
Vstorage
Required storage volume at household level
Npeople
Number of people in household, e.g. 4.5
pfaeces
Faeces production per person and day (see Course 1
Unit 2; e.g. 50 L/cap/year – see also next slide)
temptying
Time between emptying events, e.g. 1 year
Then in this example: Vstorage = 4.5 cap · 50 L/cap/year · 1 yr. = 225 L
Specific faeces (or faeces-water) production to
be used in calculations
Type of faeces
Pfaeces to be used in
equation on previous
slide
Comments
Type 1:
Faeces without water
At excretion (wet): ~
50 L/cap/year *
Remember, faeces at excretion
are about 80% water
Using the wet amount would be
conservative for storage vault
sizing
After drying:
~ 10 L/cap/year
Type 2:
Faeces with small
amount of water
= blackwater
2044 L/cap/year
Using the value of 5.6 L/cap/d
measured in Sneek (remember 1
L per flush; therefore people flush
5.6 times per day)
Type 3:
Faeces with large
amount of water
= brownwater
12 264 L/cap/year
Assuming people flush 5.6 times
per day and 6 L per flush
* Value from Sweden – check for your country (see Course 1 Unit 2 Part B)
Course 2 Unit 3
Course 2 Unit 3
Part C: Transport logistics overview
Definition of the word “logistics”:
Logistics can be considered as a tool for getting resources, like products,
services, and people, where they are needed and when they are desired.
(www.wikipedia.org)
Urban ecosan logistical challenges:
flow movements into and out of the urban area
Arrows are indicating:
Food and water in to the city
Water, urine, faeces out of the city
27
The shorter the distances, the better
27
Safe transport options for different types of
materials derived from excreta
Consistency
of material
Types of excretabased material
Transport option
Comments
Dry
 Dried faeces from
UDD toilet vaults
 Compost
 Household solid
waste
Trucks, tractors,
trailers, tricycles
Similar to solid waste collection
systems
Liquid and
pumpable
 Faecal sludge (pit
latrines, septic
tanks)
 Digested sludge
from anaerobic
digesters
Vacuum tankers
Pipes and pumps
Vacuum tankers: see next slide
Pipes and pumps: in most cases
not cost-effective, unless distance
are very short
Urine
Barrels or tanks
on tricycle or truck
Pipes are not suitable for urine on
its own, but possibly together with
greywater
Greywater
Small-bore sewers
Greywater is too diluted to be
transported in any other way than
with pipes
Course 2 Unit 3
Pumping with vacuum tanker
 Commonly used to
remove faecal sludge from
septic tanks, pit latrines
 Direct contact of the
workers with the faecal
sludge is minimized 
quite a safe technique
 Tanks may be mounted on
carts pulled by tractor or
animals  smaller units
possible
A quick coupling at the
property line for rapid and
safe emptying of a
blackwater holding tank by
vacuum trucks
Source: ACTS
Truck with a vacuum pump for
blackwater removal,
Bangalore, India
Source: Heeb et al. (2007)
Example of a vacuum tanker operation in
industrialised country
 The photos on the next slide shows how a vacuum tanker is
used at a highway restaurant in Germany
– The task is to empty the holding tank which is used for all the
kitchen wastewater from the restaurant
– There is a grease trap for the kitchen wastewater
– The hose from the vacuum tanker is placed in an access
manhole
 On the photo top right, the worker is jetting water into the
storage tank to clean it out better and to allow better pumping
 The size of the vacuum tanker is 10 m3 plus 2 m3 of water for
the cleaning
 One can nicely see the safety precuations used, e.g. the bright
clothing, gloves, boots with steel toe caps
 Seen January 2007, photos by E. v. Münch
Course 2 Unit 3
Low-cost vacuum tanker for emptying faecal sludge from pit
latrines
Vacuum tank (500 L) and pump/tug assembly with 5.9 kW petrol
engine. For pit emptying with difficult access conditions. “Ideally suited
for micro-enterprise use”
Source: http://hq.unhabitat.org/cdrom/water/HTML/PDFs/vacutug.pdf
Safety precautions during excreta handling and
transport
 Critical points from a health risk
perspective
 Protection measures when
handling fresh and stored excreta:
– Gloves
– Shoes
– Wash hands afterwards
 Store material out of reach for
people or animals
 Manual handling should be
eliminated wherever it is possible
J. Heeb
Source: Heeb et al. (2007)
Main issues with transporting dry solid
material (faeces)


Transport logistics could be linked
to the city’s solid waste
management system
Amounts of dry faeces are much
smaller than conventional solid
waste
– Remember: dry mass of faeces ~
30 g/cap/d; but solid waste
production ~ 200 – 500 g/cap/d in
cities in India (see Course 1 Unit 2
Part B)


Could be a business opportunity
for small private enterprises
If containers are used inside of the
vault for faeces collection, keep in
mind the maximum weight that one
or two people can move, when the
full container is removed and
exchanged for an empty one
 Need to find suitable
vehicles to fit type of access
lanes
Dried faeces taken out of a double-vault UDD
toilet vault (Slob (2005), p. 111)
Main issues with transporting liquid material:
urine
 Pipes tend to block up, so cannot be transported by pipe over
longer distance
 Road based transport most common
 Distance to reuse site should be as short as possible
 Very rough rule of thumb: approx. 120 km is maximum
economical distance
 Disadvantages of road based transport: CO2 emissions, noise,
dust, increased traffic
 This is still a challenge for large scale ecosan in urban context
What transport distances would have to be covered in your city?
Course 2 Unit 3
Main issues with transporting liquid material:
greywater
 Small-bore sewers is most likely the best solution (see Course 2
Unit 8)
Main issues with transporting liquid material:
faecal sludge
 Vacuum tankers are best solution (privately operated or
operated by municipality)
 But in reality, manual emptying with buckets is still common in
low-income settings!
– Many people cannot afford to pay for a vacuum tanker
service and hence try to empty it themselves somehow
Unsafe, manual pit
emptying can look
like this!
The health risks for
this worker are
incredibly high let alone the lack of
human dignity!
Photo taken in Ouagadougou, Burkina Faso, by Doulaye Koné,
SANDEC/EAWAG, Switzerland
Course 2 Unit 3
Course 2 Unit 3
Part D: Detailed analysis of transport options
This part of the presentation builds on the work done by
Marieke Slob (2005): “Logistic aspects of ecological
sanitation in urban areas – Case study in low-income
community in Delhi, India”
All photos and numbers in this Part D are taken from that
excellent MSc thesis
Distinction between transport with a transfer (top row)
and direct transport (bottom row)
Slob (2005), p.43
 Transfer becomes necessary when haul distances increase to such
a distance that direct transport is no longer economical, or when the
destination can only be reached with a different means of transport
 It is cheaper to haul a large volume of waste in large increments
over a long distance than it is to haul a large volume of waste in
small increments over a long distance
Broad options for the logistics system
 Primary collection system
– Road
Only possible for greywater, not for urine
– Pipes
 Secondary collection system
– Road
Only relevant for longer distances
– Rail
– Water Only possible for greywater, not for urine
– Air
– Pipes
Overview of possibilities for main logistics system
Main logistics
system
Operator
of primary
collection
Means of collection
Analogy with existing
collection systems
Public toilets
Househol
d member
Inside the body of
household member
Household
member brings
urine and/or
faeces to a
collection point
Househol
d member
Household containers
Communal collection
(households discharge
their waste at
predetermined locations).
Refuse-collection vehicles
visit these sites at frequent
intervals to remove waste
(secondary collection)
Collection vehicles Collection
collect urine
service
and/or faeces at
each household
Piping system on
street/block level
Automatic
(collection
service)
Household container is
switched for empty
container or household
container is emptied into
collection vehicle
Door-to-door collection
service
Small diameter pipes
from households to a
large collection tank
Small bore sewerage
(small diameter sewers
laid at shallow gradients to
convey sewage)
Course 2 Unit 3
Overview of logistics chain with primary and
secondary collection
 The general logistics chain is the same for urine and faeces, although the
handling method and type of vehicles might be different for the two
excreta types (Slob (2005), p. 47)
 Each point of the logistics chain (numbers 1 to 8 above) has to be
designed and costed to make a cost estimate of the transport system
Factors affecting vehicle selection
 Housing density
 Waste generation per
household per period
 Waste density
 Haul distance
 Road surface (muddy,
sandy, stony, firm)
 Road widths
 Road gradient
 Availability of spare parts
and service
 Traffic type and density
 Waste corrosiveness and
abrasiveness
 Waste hazardousness
 Labour and fuel cost
 Available capital
 Strength of user in case
propulsion is (partly)
manually
 Risk of theft, damage and
abuse
Slob (2005), p. 48
Steps to design a transport system
1.
2.
3.
4.
Identify own situation (source, destination, roads, toilet system)
Adapt general criteria for the transport system to own situation
Identify possible vehicle and handling options
Organise group meetings with inhabitants, excreta and solid
waste collectors and farmers
5. Assess remaining options on the criteria of step 2 and conclude
which vehicles and equipment are the most suitable
6. Calculate the costs of the most suitable options as a result of
step 5
7. Make a suitable design
Source: Slob (2005)
Collection and transport options for urine
 Pouring the household containers into a collection container on
a small vehicle
 Pumping the urine with a hand pump from the household
container into a collection container on small vehicle
 Using a centrifugal pump mounted on a tractor-driven trailer with
a plastic tank on it (see next slide)
 Discarded options:
– Using a vacuum pump mounted on a tractor driven trailer
with a vacuum tank – too expensive
– Using gravity by constructing the containers at a high level –
too visible
– Switching the full household container for an empty one and
emptying them at a transfer station – double handling and
transport, and cleaning of containers required
Slob (2005), p. 80
Generator to operate a pump
(Slob (2005), p. 81)
Tractor with trailer to transport urine (in tanks) or faeces
(Slob (2005), p. 81)
Square plastic tank for urine
which could be fixed onto the
trailer (Slob (2006, p. 81)
Course 2 Unit 3
Vacuum pumps or centrifugal pumps?
 A vacuum pump is the standard to pump a
slurry (a vacuum pump can handle the
viscosity of the slurry and solid particles,
making it a robust pump)
 A vacuum tank construction needs thick
sheets of steel to be able to hold the
vacuum build-up in the tank
 Since urine is a liquid like water, it does
not need an expensive vacuuum
construction to pump it
– A centrifugal pump with a plastic tank
will be sufficient and cheaper
Hand pump (semi-rotary
pump): small and light,
seuction depth of 5 m and
capacity of 25 – 50 L/min.
(Slob (2005), p. 79)
Collection vehicle of solid waste collector: Tricycle without engine (Slob (2005), p. 56)
Course 2 Unit 3
Tricyle with engine
(Slob (2005), p. 79)
Tricyle with closed body to keep
faeces out of sight and to prevent
material from falling on the
ground
Calculations for urine transport
 The following equations are set up for urine transport in general
– The numbers used in the example are from Slob (2005), p.
89 for urine transport from 8,000 households with tricycles
with engine (no flush water added)
Calculation of number of vehicles required for
urine transport
1. Decide on work day factor (e.g. 1.17, see Table 1 on next slide)
2. Calculate urine quantity to be collected – Eqn. (1)
3. Decide on capacity of collection vehicle (e.g. 300 L, see Table
1)
4. Decide on days between collection events (e.g. 14 days)
5. Calculate the number of households covered in one trip (e.g.
3.5 – Eqn. (2))
6. Calculate duration of one trip (e.g. 49 min., see Table 2)
7. Calculate number of trips possible per day (e.g. 8.6) – Eqn. (3)
8. Decide on efficiency factor (e.g. 1.25, see Table 1)
9. Calculate the number of trips needed per day (e.g. 192) – Eqn.
(4)
10. Calculate number of vehicles required (with the numbers
above, the result is: 28) – Eqn. (6)
11. Go back to step 3 and 4 and change design figures to check if
better solution my be found (iterative procedure)
Table 1: Design parameters
(Values from Slob (2005), p. 88 – 89)
Parameter
Value (example)
Comments
Work day
factor
1.17
(= 7/6)
Collection service operates
six days out of seven
Efficiency
factor
1.25
(=100/80)
Efficiency factor of 80% is
assumed to allow for
breakdowns and
maintenance; number of
vehicles is multiplied with
100/80
Effective work
time
7 hours/day
Assume a workday of 8 hours
but allow 1 hour for breaks
Capacity of
collection
vehicle
Tricyle without engine: 100 L
Tricycle with engine: 300 L
Tractor with trailer: 3000 L
Size of common trailer for
tractor: 1.5 m wide and 2.5 m
long
In rainy season, the capacity
of vehicles may be reduced
Quantity to be collected per household
Vurine, HH = Npeople, HH · purine · tcollection
Eqn. (1)
Vurine, HH
Collection quantity per household (L/HH) – in this example
the value is 86 L/HH
Npeople, HH
Number of people in household, e.g. 5
purine
Urine production per person per day (see Course 1 Unit 2;
e.g. 1.23 L/cap/d)
tcollection
Time between collection events, e.g. 14 d
Course 2 Unit 3
Number of households covered in one trip
NHH, trip = Vvehicle / Vurine, HH
Eqn. (2)
NHH, trip
Number of households covered in one trip (in this
example the number is 3.5)
Vvehicle
Capacity of transport vehicle, e.g. 300 L
Vurine, HH
Collection quantity per household (L/HH) – in this
example the value is 86 L/HH
Table 2: Total duration of one trip
Activity
Example
(minutes)
Driving to first house
10
Handling per house and driving to next
house
12
(4 houses x 3
min.)
Total filling time of tank (= 300 L and
25 L per minute)
12
Driving to transfer point
10
Unloading
5
Total durating of one trip (ttrip)
49
Slob (2005), p. 89
Calculated from
equation on
previous slide
for NHH, trip
Number of trips possible per day
ftrips, poss = Nhours · ttrip
Eqn. (3)
ftrips, poss
Number of trips possible per day (in this example the
number is 8.6)
Nhours
Working hours per day, e.g. 7 h/d
ttrip
Duration of one trip, e.g. 49 min. = 0.82 h
Trips needed per day
ftrips, needed = Qurine / Vvehicle
Qurine = Npeople, HH · purine · fWD · NHH
Eqn. (4)
Eqn. (5)
ftrips, needed
Number of trips needed per day (in this example the
number is 192 trips/day)
Qurine
Quantity of urine to be collected per day (including work
day factor) – in this example, the number is 57,400 L/d
Vvehicle
Capacity of the vehicle, e.g. 300 L
Npeople, HH
Number of people per household, e.g. 5
Purine
Urine production per capita per day, e.g. 1.23 L/cap/d
FWD
Work day factor, e.g. 1.17 (see Table 1)
NHH
Number of housholds covered in the scheme, e.g. 8000
Course 2 Unit 3
Number of vehicles needed
Nveh., needed = ftrips, needed / ftrips, poss · h
Eqn. (6)
Nveh., needed
Number of vehicles needed (including efficiency factor)
– in this example, the number is 28
ftrips, needed
Number of trips needed per day, e.g. 192 trips per day
ftrips, poss
Number of trips possible per day, e.g. 8.6 trips per day
h
Efficiency factor, e.g. 1.25 (see Table 1)
Concluding remarks
 A worked example (using the same numbers as here) for urine
transport is given on page 89 of Slob (2005)
 The equivalent calculation can be made for faeces transport
(using the mass of faeces instead of volume, e.g. 50 kg/cap/year
of faeces)
– Only 2.4 vehicles (tricycle with engine) would be needed for
the faeces, see p. 121 of Slob (2005)
Example figures showing impact of flush water
 Some households in this case study area were insisting that
flush water should be added after urination
– This would increase the volume to be transported
considerably
 Urine volumes per household (5 people per household, 1.23
L/cap/d, assuming 3 urination events per day):
Urine storage
emptying frequency
No flush
water added
½ liter flush water added
after urination
daily
6 litres
14 litres
weekly
43 litres
96 litres
every 2 weeks
86 litres
191 litres
Example result for number of vehicles required for
faeces transport – comparing three different
options
Number of vehicles per option
5
Tractors
4
Tricycles
3
2
1
0
Tricycle without motor
Tricycle with motor
Tractor
Course 2 Unit 3
Example result: size of storage container and
number of vehicles versus emptying time period
Size of storage container
120
# Vehicles required
350
100
300
80
250
200
60
150
40
100
20
50
0
0
1
3
7
14
21
28
Collection frequency (days)
35
42
# Vechicles required
Size of storage container
(litre)
400
References

Heeb, J., Jenssen, P., Gnanakan, K. & K. Conradin (2007): ecosan
curriculum 2.0. In cooperation with: Norwegian University of Life
Sciences, ACTS Bangalore, Swiss Agency for Development and
Cooperation, German Agency for Technical Cooperation and the
International Ecological Engineering Society. Partially available from
www.seecon.ch and
http://www2.gtz.de/dokumente/oe44/ecosan/cb/en-m23-ecosanhuman-dignity-lecture-2006.ppt

Kvarnström, E., Emilsson, K., Richert Stintzing, A., Johansson, M.,
Jönsson, H., af Petersens, E., Schönning, C., Christensen, J.,
Hellström, D., Qvarnström, L., Ridderstolpe, P., and Drangert, J.-O.
(2006) Urine diversion: One step towards sustainable sanitation, Report
2006-1, EcoSanRes Programme, Stockholm Environment Institute,
Stockholm, Sweden. - of relevance here is in particular Appendix 2.
Available: http://www.ecosanres.org/pdf_files/Urine_Diversion_20061.pdf (also under extra reading)

Slob, M. (2005) Logistic aspects of ecological sanitation in urban areas.
Case study in low-income community in Delhi, India. MSc Thesis,
University of Twente, The Netherlands and WASTE, Gouda
([email protected]) (also under extra reading)