fuel potential of faecal sludge
TRANSCRIPT
FUEL POTENTIAL OF FAECAL SLUDGE Calorific value results from Uganda, Ghana, and Senegal
Teddy Nakato
T. Nakato*, L. Strande**, C. Niwagaba*, H. Dione***, N. Baawuah****, A . Murray****
*College of Engineering, Design Art and Technology
Makerere University, Kampala Uganda
**Eawag - Swiss Federal Institute of Aquatic Science & Technology
Sandec – Department of Water and Sanitation in Developing Countries, Switzerland
***Dakar University, Senegal
****Waste Entreprisers Ltd. – Accra, Ghana
Faecal Sludge Management Conference (FSM2) - 29-31 October 2012, Durban
FAECAL MANAGEMENT ENTERPRISES (FaME)
Senegal:
Seydou Niang
Dakar University
Ghana:
Ashley Murray
Waste
Enterprisers
Switzerland:
Linda Strande
Eawag/Sandec
Austria:
Gerald Eder
hydrophil iC
Uganda:
Charles Niwagaba
Makerere University
Senegal:
Papa Samba Diop
Senegal National Sanitation
Utility (ONAS)
when pits become full, FS is dumped in environment
users of these systems cannot afford to pay emptying fees
access to sanitation not provided, even with «improved» systems
THE SANITATION CHALLENGE
Need to find way to manage faecal sludge from onsite
systems when they become full
Added value endproducts could provide financial
driver for entire service chain
provide a means to remove FS from community, and
ensure adequate treatment
One possibility, using FS as an industrial fuel, as there
is a huge demand for biomass fuels, especially in
Kampala
INTRODUCTION
Test the technical viability of converting FS to
solid fuel by
evaluating the effect of source on fuel potential
(e.g. pit latrine, septic tank, lagoon)
evaluating the effect of age on calorific value
evaluating COD as a predictor of calorific value
evaluating the effect of dryness when using
faecal sludge as a fuel
RESEARCH OBJECTIVES
Calorific Value
The calorific value of a fuel is the quantity of heat
produced by its combustion - at constant pressure and
under "normal" ("standard") conditions (i.e. to 0oC and
under a pressure of 1,013 mbar).
Calorific value was used as a metric of the potential
energy of FS that would be released during combustion
DEFINITION
Three cities in three countries
METHODOLOGY
Characteristics Kampala,
Uganda
Kumasi,
Ghana
Dakar,
Senegal
Population of the city 1.72 million 1.50 million 2.51 million
Population connected to
sewers
7% 8% 25%
Population using on-site
sanitation
86% 86% 72%
Population open
defecating
7% 6% 3%
CHARACTERISTICS OF STUDY SITES
Faecal sludge source Kampala Kumasi Dakar
Fully lined pit latrine 23 20 1
Unlined pit latrine 14
Partially lined pit latrines 22
Septic tank 15 10 19
Drying beds - Raw FS 28 28
Drying beds - WWTP Sludge 28
Anaerobic ponds 80
Fresh and Dry heaps 16
Non Functional Ponds 8
Sampling scheme
METHODOLOGY
SAMPLING METHODS
Sampling Methods
From trucks: 1-L composite of samples collected at the
beginning, middle and end of emptying
From ponds and drying beds: I-L composite of
samples from five pre-defined locations
Sampling from drying beds Faecal sludge sampling
SAMPLING METHODS
Laboratory assessments
Calorific value (MJ/kg TS)
Water content (as %)
Total solids (mg/L)
Chemical Oxygen
Demand (COD) (mg/L TS)
METHODOLOGY
Calorific Value of FS from septic tanks and fully lined pit latrines did not differ
significantly by type or by location, even though the FS is quite different
Calorific Value is reported as MJ / kg – dry matter
RESULTS
Faecal sludge is high in organic matter, organic carbon bonds release energy
upon combustion
(EUBIONET II, 2007)
RESULTS
Age of faecal sludge did
not have a significant
impact on calorific value
Maybe fuel value comes
from recalcitrant organic
molecules that are
degraded more slowly???
Type of samples include:
Septic tank
Unlined pit latrines
Fully lined pit latrines
Partially lined pit latrines
-> need for further research
RESULTS
COD was not a predictor of
calorific value
Even in the drying beds,
where the COD decreased
with time from 80 to 40
mg/L, the calorifc value
was consistent
COD is measured as
concentration, calorific
value as solids, so
compared COD/TS to CV
Maybe fuel value comes
from recalcitrant organic
molecules that are not
oxidized during COD???
-> need for further research
RESULTS
Total solids content depends on onsite collection and storage
system, and treatment methods
Need a product that the enduser can and will use
To
tal S
oli
ds
(%
)
Faecal sludge needs to be dry to burn well!!
RESULTS
If energy is used to dry sludge, at a calorific value of 17.2
MJ/kg TS, the sludge must be ≥ 27 % dry solids before there
is a net benefit in energy (theoretical calculation)
Any increase in dryness, produces an increase in the net
benefit
Passive processes such as drying beds can also be used,
but require additional time and space, need to find a balance
In addition to dryness, the form of the final product is also
important
There will be different treatment needs for each specific
context
RESULTS
The calorific value of FS did not vary
significantly with source
The age of FS was not a predictor of calorific
value
The calorific value of FS is similiar to other
commonly used biomass fuels
COD was also not a predictor of CV
The dryness and form of final FS product is
important if it is to be accepted and used as a
profitable industrial fuel
CONCLUSIONS
FUNDERS
SPLASH (EU water initiative)
EPP (Eawag Partnership Programme)
NCCR (National Centre for Competence in Research)
GIZ (Deutsche Gesellschaft für Internationale
Zusammenarbeit)
MEMD(Ministry of Energy and Mineral Development –
Uganda)
ACKNOWLEDGEMENTS
Any questions?
THANK YOU FOR YOUR ATTENTION!
Teddy Nakato – FSM2, 31st October, 2012
E-mail: [email protected], [email protected]