Transcript
8/13/2019 Septic Tanks _ SSWM
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Concept Understand your System Planning & Process Tools Implementation Tools Specific Topics Backg
Home Implementation tools W astewater Treatment Hardware (Semi-)Centralised W astewater Treatments S eptic Tanks
Implementation Tools
Introduction
Water Sources
Water Purification
Water Distribution
Water Use
Wastewater Collection
WastewaterTreatment
Reuse and Recharge
Compiled by:
Septic Tanks
Dorothee Spuhler (seecon international
gmbh)
Executive SummaryA septic tankis an underground watertight chamber made of brick work,
concrete, fibreglass, PVC or plastic that receives both blackwaterfrom
cistern or pour-flush toiletsand greywaterthrough a pipe from inside a
building. Settlingand anaerobic digestionreduce solids and organics.
Septic tanks areprimary treatmentmethods, and the only moderately
treated effluentis infiltrated intothe ground or transported via a sewer.
Accumulating faecal sludgeneeds to be dug out the chamber and correctly
disposed regularly.
In Out
Blackwater, Brownwater, Excreta, (Organic
Solid Waste)Blackwater(settled), Faecal Sludge, (Biogas)
The septic tank is the most common small-scale decentralised treatment unit for grey water
and blackwaterfrom cistern or pour-flush toilets. It is basically a sedimentationtank (physical
treatment) in which settled sludge(solids and organics) is stabilisedby anaerobic digestion
(biological treatment). Dis solved and suspended (unsettleable) matter leaves the tank more or
less untreated. Its shape can be rectangular or cylindrical.
Septic tanks are used for wastewaterwith a high content of settleable solids, typically for
effluentfrom domestic sources, but they are also suitable for other wastewaterof similar
properties (SASSE 1998). Typical basic systemsincluding septic tanks at household or school
level are pourflush toilets, followed by two-chamber septic tanks and a soak pit, a leach field,
or an evapo-transpiration mound(www.schoolsanitation.org). In densely populated areas, on-
site inf iltration should not be used because the saturation of the soil with the only moderately
treated effluentcan cause a serious healthrisk. In these cases, septic tanks should be
connected to a simplified seweror solids-free sewerto transport the effluentsto a secondary
treatment(e.g. surface flow, horizontalor vertical flowconstructed wetlands). When septic
tanks are used as a primary settlingtreatment in DEWATSsystems, they are generally followed
by anaerobic filters, anaerobic baffled reactors(ABRs), constructed wetlands(planted gravel
filters) and maturation ponds. In any case, water is needed to pour and bring the wastes to the
septic tank (5 to 40 L of water per day per person, DFID2003).
Overview scheme of a septic tank. Solids settle out and undergo anaerobic digestion, the effluent
Related Topic
Sustainable Sanitati
Grasp what Sustaina
Sanitation actuallySustainable Sanitatio
Health and Hygiene
Background informat
health and hyg iene i
water management
sanitation.
Health and Hygiene I
Anaerobic Digestion
I f septic tanks are cl
biogas recovered, th
become anaerobic bi
settlers:
Biogas SettlerAnaerobic Digestion
Toilet Systems
Septic tank typically
blackwater from:pou
flush toilet; UD flush
flush
Pour-Flush ToiletFlush ToiletLow-flush ToiletUrine Diversion Flush
Effluent Infiltration
The effluent can eit
infiltrated on-site or
for fertigation, if is
heavely polluted. Ch
Soak PitsLeach FieldsFertigation
Faecal Sludge
Sludge that has been
settled in septic tan
called faecal sludge.
contains a lot of pat
and needs to be trea
before reuse. See al
Anaerobic DigestionDrying BedsSettling / Thickening(Co-)composting (La
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Septic Tanks _ SSWM
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A septic tank asprimary treatment, followed by a leach field.
Source: U.S. EPA (n.y.)
Septic tank receiving black- and grey water from a housing (left)
and a septic tank collecting wastewaterfrom several housing as a
primary treatmentbefore a small bore sewersystem (right).
Sources: http-//cfpub.epa.gov/owm/septic/septic.cfm?
page_id=265 (left) and SANIMAS (2005) (right).
with suspended and dissolved pollutants flows through. A venting pipecan evacuate the biogas
formed during anaerobic digestion. Source: adapted from TILLEY et al. (2008).
Treatment Process and Basic Design Principles
A septic tank consis ts at minimum of 2 compartments made out of concrete or bricks. Pre-
fabricated concrete rings, PVC or fibreglass septic tanks are also available and may be less
expensive in some contexts (WSP2008). The first compartment occupies at least the half the
total volume, because most of the sludgeaccumulates here (SASSE 1998), while scum(oil and
fat) floats to the top. W hen there are only two chambers, the firs t one should be 2/3 of the
total length (TILLEY et a l. 2008). The following chamber(s) are provided to calm the turbulent
liquid. The baffle, or the separation between the chambers, is to prevent scumand solids from
escaping with the effluent(TILLEY et al. 2008). A T-shaped outlet pipe, the lower arm of which
dives 30 cm below water level (SASS E 1998), will further reduce the scumand solids that are
discharged. Normally, the chambers are all of the same depth (between 1.5 to 2.5 m), but
sometimes the first chamber is made deeper as the others.
Over time, anaerobicbacteriaand microorganismsstart to digest the settled sludge
anaerobically, transforming it into CO2 and CH4 (biogas) and some heat. Optimal physical
treatment by sedimentationtakes place when the flow is smooth and undisturbed. Biological
treatmentby anaerobic digestionis optimised by a quick and intensive contact between the
new inflow and old sludge, particularly when the flow is turbulent. Depending on the way the
new influentflows through the tank, different treatment effect predominate. With a turbulent
flow, the degradation of suspended and dissolved solids starts more quickly; however, more
suspended solids are discharged with the effluent. This leadsto bad odours, as active solids
that are not completely fermented leave the tank (SASSE 1998). The contact and hence
degradation is slower when the flow is less turbulent, but also less s uspended solids leave the
tank. The gases produced during anaerobic digestionmust be allowed to escape. If the
drainage system of the house or other building has a ventilationpipe at the upper end, gases
can escape from the septic tank along the drains. If the drainage system is not ventilated, a
screened vent pipe should be provided from the septic tank itself (WHO1992).The size of the first chamber
is calculated to be at least
twice the accumulating
sludgevolume. The sludge
volume depends on different
factors: the number of users;
the portion of settleable
solids of the influent; the
amount of water used per
capita; the average annual
temperatureand on de-
sludging intervals (SASS E
1998). Approximately 80 to
100 L should be provided per
domestic user (SASSE 1998),
but most countries provide a national standard for tank volume per domestic user. The
retention time should be designed for 48 hours to achieve at least a moderate treatment
(TILLEY et al. 2008). For help on dimensioning of septic tank, an exercise is given in
Eawag/Sandec (2008, Sanitation Systemsand Technologies. Exercise Septic Tank) and Excel
spreadsheets are available in SASSE (1998).
A septic tank will remove 30
to 50% of BOD(Biological
Oxygen Demand), 40 to 60%
of TSS(Total Suspended
Solids) (UNEP 2004) and
result in an abatement of 1
log units E. coli(afaecal
indicator bacteria) (TILLEY
et al. 2008) a lthough
efficiencies vary greatly
depending on the influent
concentrations and climatic
conditions. Hydraulic
Retention Times(HRT) are
generally 24 hours (MOREL &
DIENER 2006).
Aqua privyThe aqua privyis a variation of the septic tank and consists of a simple storage and settling
tank immediately under the latrine floor. Excretadrop directly into the tank through a pipe.
The bottom of the pipe is submerged in a liquid in the tank, forming a water sealto prevent
escape of flies, mosquitoes and smell (WHO1992). The tank functions like a septic tank. The
effluentusually infiltrates into the ground through a soak pit and accumulated solids (sludge)
must be removed frequently (WHO1992). In any case, the accumulating sludgemust be
treated.
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Toilet with aqua privyand soak pit. Source: WAaF (2002)
Costs considerations
Construction costs of septic tank are relatively low compared to other water based systems.
However, they are much more expensive than for dry or composting toiletsand unlikely to be
affordable by poorer people in society. They also require sufficient piped water to flush all the
wastes through the drains and manual or mechanical (vacuumorgulper) de-sludging needs tobe done periodically. Engineers mus t prepare design and layout, while unskilled labourers can
carry out construction if a mason supervises the work.
Operation and Maintenance
To start up a s eptic tank it should be "seeded" with sludgefrom a tank that has been operating
for some time to ensure that the necessary microorganismsresponsible for anaerobic
digestionare present (WHO1992).
Routine inspection is necessary to remove floating debris such as coarse materials and grease,
to ensure that there are no blockages at the inlet or outlet and to check whether de-sludging is
needed. De-sludging is needed when 1/2 to 2/3 of the total depth between the water level and
the bottom of the tank are occupied by sludgeand scum(WHO1992). One of the difficulties
with septic tanks is that when the tank is almost full of solids, the inflow scours a channel
through the sludgeand pass through the tank in a matter of minutes rather than remaining in
the tank for the required retention time (SASSE 1998). The most satisfactory method of sludge
removal is by vacuum tanker. If a vacuumtanker is not available, the sludgemust be bai led
out manuallyusing buckets or agulper. This is an unpleasant work and care must be taken to
ensure that sludgeis not spilled around the tank during emptying, as the removed sludgefrom
a septic tank includes fresh excrete and presents a risk of transmission of diseases of faecal
origin (TILLEY et al. 2008). Thefaecal sludgeneeds to be correctly disposed and further
treated (e.g. smallor large scalecomposting, anaerobic digestion). Before that, thefaecal
sludgecan also be further separated from the liquid in drying bedsor settling. The separated
effluentsfrom these s ystems should be treated in waste stabilisation ponds(WSP) or
constructed wetlands(surface flow, horizontalor vertical flow).
Generally, septic tanks should be emptied every 1 to 5 years. A small amount of sludgeshould
be left in the tank to ensure continuing rapid digestion. When opening the tank, gas produced
in anaerobic digestioncould escape and therefore, open fi re should be avoided when opening
the septic tank. Regular de-sludging activities require well-organised community or
public/private serv ice provider (TILLEY et al. 2008). Because of the delicate ecology, care
should also be taken not to discharge hars h chemicals into the septic tank (TILLEY et al. 2008).
Health Aspects
Since the effluentfrom septic tanks is anaerobic, it is likely to contain large numbers of
pathogens, which can be a potential source of infection (WHO1992). Many of the problems
with septic tank systems arise because no adequate consideration is given to the disposal of
the tank effluent. However, the entire tank is below the surface so direct contact of users with
any wastewateris avoided (TILLEY et al. 2008). But because of the microbial healthrisk which
arises from both the effluentand thefaecal sludgecare should be taken during inspections
and emptying. Mechanical emptying in a vacuum truckor a manual technology like a sludge
gulpercan decrease the healthrisks (TILLEY et al. 2008).
At a Glance
Working Principle
Basically a sedimentationtank (physical
treatment) in which settled sludgeis
stabilisedby anaerobic digestion(biological
treatment). Dissolved and suspended matter
leaves the tank more or less untreated.
Capacity/Adequacy
Household and community level; Primary
treatmentfor domestic grey- and
blackwater. Depending on the following
treatment, septic tanks can also be used for
industrial wastewater. Not adapted for areas
with highgroundwatertable or prone to
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flooding.
Performance
BOD: 30 to 50%; TSS: 40 to 60 %; E. coli: 1
log units
HRT: about 1 day
CostsLow-cost, depending on availability of
materials and frequency of de-sludging.
Self-help CompatibilityRequires expert design, but can be
constructed with locally available material.
O&M
Should be checked for water tightness , scum
and sludgelevels regularly. Sludgeneeds tobe dug out every 1 to 5 years and dis charged
properly (e.g. in compostingor drying bed).
Needs to be vented.
Reliability
When not regularly emptied, wastewater
flows through without being treated.
Generally good res istance to s hock loading.
Main strength Simple to construct and to operate.
Main weaknessEffluentand sludgerequire further
treatment. Long start-up phase.
ApplicabilitySeptic tanks can be installed in every type of climate, although the efficiency will be affected
in colder climates (TILLEY et al. 2008).
Septic tanks are used for wastewaterwith a high percentage of settleable solids, typically for
effluentfrom domestic sources (S ASSE 1998). They can be introduced as a decentralized, on-
site treatment system at household, block or school level(UNEP 2004). Effluentsstill contain
pathogensand should therefore not be used for crop irrigationnor should it be discharged to
canals or surface waterdrains (WHO1992). Effluentsform septic tanks can be soil infiltrated
in soak pits, a leach fieldor mounds. In more dense areas, the effluentsshould not be
infiltrated but the septic tank may be integrated as individual pre-treatment units for a
community into a small bore sewersystem transporting the wastewatersto a secondary
treatment. Even though the septic tank is watertight, it should not be constructed in areas
with highgroundwatertables or where there is frequent flooding (TILLEY et al. 2008).Aqua privies can be built indoors and above ground and are appropriate for rocky or flood
prone areas where pits or other technologies would not be appropriate, but they require
frequent emptying and constant maintenance (TILLEY et al. 2008).
AdvantagesCan be built and repaired with locally available materials
No real problems with f lies or odours if used correctly
Long service life
Little space required due to underground construction
Low investment costs, low operation and maintenance costs depending on the
availability of water and the requirement for emptying
No energy required
DisadvantagesHigh cost compared to dry or composting toilet systems
Constant and suff icient amounts of piped water required to bring the waste to the
treatment unit
Low reduction in pathogens, solids and organics: Secondary treatmentfor both
effluent and faecal sludge required
De-sludging required: Manual de-sludging is hazardous to health and mechanical de-
sludging (vacuum trucks) requires the infrastructure and may be rather costly
Only suitable for low-density housing in areas with low water table and not prone to
flooding
Manual cleaning of the tank is highly hazardous and an inhumane task, while
mechanical cleansing (vacuum trucks) requires sophisticated instruments
References
EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Exercises: Septic
Tank. Duebendorf: Swiss Federal Institute of Aquatic Science (Eawag), Department of Water
and Sanitation in Developing Countries (Sandec). PDF
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WHO (Editor) (1992): A Guide to the Development of On-site
Sanitation. Geneva: World Health Organisation (WHO). URL[Accessed: 14.04.2010]. PDF
The publication presents appropriate technologies for sanitation
and highlights socio-economic aspects of planning and
implementing. Emphasis is g iven to household-level sanitation
improvements for urban areas, as well as rural areas and small
communities. Background information on sanitation, in-depth
technical information on the design, construction, operation and
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http://www.sswm.info/sites/default/files/reference_attachments/WHO%201992%20A%20Guide%20to%20the%20development%20of%20on-site%20sanitation.pdfhttp://whqlibdoc.who.int/publications/1992/9241544430_eng.pdfhttp://www.sswm.info/library/214http://www.sswm.info/sites/default/files/reference_attachments/NATURGERECHTE%20TBW%202001%20Decentralised%20wastewater%20treatment%20methods%20for%20developing%20countries.pdfhttp://www.sswm.info/library/158http://www.sswm.info/sites/default/files/reference_attachments/ECOSAN%20CLUB%202012%20Faecal%20Sludge%20Management.pdfhttp://www.ecosan.at/ssphttp://www.sswm.info/library/6160http://www.sswm.info/sites/default/files/reference_attachments/IDAHO%20DEQ%202001%20A%20Homeowners%20Guide%20to%20Septic%20Systems.pdfhttp://www.deq.state.id.us/WATER/assist_citizen_comm/septic/septic_homeowners_guide.pdfhttp://www.sswm.info/library/33http://www.sswm.info/libraryhttp://www.sswm.info/sites/default/files/reference_attachments/WSP%202008%20Technology%20Options%20for%20Urban%20Sanitation%20in%20India.pdfhttp://www.wsp.org/UserFiles/file/Urban_Sanitation.pdfhttp://www.sswm.info/library/131http://www.sswm.info/sites/default/files/reference_attachments/WHO%201992%20A%20Guide%20to%20the%20development%20of%20on-site%20sanitation.pdfhttp://whqlibdoc.who.int/publications/1992/9241544430_eng.pdfhttp://www.sswm.info/library/214http://www.sswm.info/sites/default/files/reference_attachments/WAaF%202002%20Sanitation%20Technology%20Options.pdfhttp://www.sswm.info/library/219http://www.sswm.info/sites/default/files/reference_attachments/UNEP%202004%20Improving%20Municipal%20Wastewater%20Management%20in%20Coastal%20Cities.pdfhttp://esa.un.org/iys/docs/san_lib_docs/tsc_training_manual_wastewater_english.pdfhttp://www.sswm.info/library/225http://www.sswm.info/sites/default/files/reference_attachments/TILLEY%202008%20Compendium%20of%20Sanitation%20Systems%20and%20Technologies-FRENCH_0.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/TILLEY%202008%20Compendium%20of%20Sanitation%20Systems%20and%20Technologies_0.pdfhttp://www.eawag.ch/forschung/sandec/publikationen/indexhttp://www.sswm.info/library/34http://www.sswm.info/sites/default/files/reference_attachments/SASSE%201998%20DEWATS%20Decentralised%20Wastewater%20Treatment%20in%20Developing%20Countries_0.pdfhttp://www.sswm.info/library/129http://www.sswm.info/sites/default/files/reference_attachments/SANIMAS%202005%20Informed%20Choice%20Catalogue.pdfhttp://www.sswm.info/library/187http://www.sswm.info/sites/default/files/reference_attachments/MOREL%20and%20DIENER%202006%20Greywater%20Management.pdfhttp://www.eawag.ch/forschung/sandec/publikationen/ewm/dl/Morel_Diener_Greywater_2006.pdfhttp://www.sswm.info/library/649http://www.sswm.info/sites/default/files/reference_attachments/DFID%202003%20Handbook%20for%20the%20Assessment%20of%20Catchment%20Water%20Demand%20and%20Use.pdfhttp://www.hrwallingford.co.uk/downloads/projects/handbook_catchment_water.pdfhttp://www.sswm.info/library/224http://www.sswm.info/sites/default/files/reference_attachments/U.S%20EPA%20n.%20y.%20Planning%20for%20Septic%20Systems%20-%20Use%20of%20Online%20Decentralized%20Systems%20in%20Developing%20Areas.pdfhttp://www.epa.gov/owm/septic/pubs/planning_for_septic_systems.pdfhttp://www.sswm.info/library/2238/13/2019 Septic Tanks _ SSWM
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maintenance and project planning and development processes
involved in projects and programmes complement the book.
U.S.EPA (Editor) (1980): Onsite Wastewater Treatment Systems
Manual. United States Environmental Protection Agency, Office of
Water Office of Research and Development. PDF
Rather old design manual for onsite was tewater treatment options.
However, valuable information on established sys tems such as
septic tanks, sand filters, aerobic treatment units (suspended
growth and fixed film), disinfection, nutrient removal as well as
wastewater segregation and recycling are given. Additional
information is given on disposal methods and appurtenances.
UNEP (Editor); Murdoch University (Editor) (2004): Environmentallysound technologies in wastewater treatment for the implementation
of the UNEP/GPA "Guidelines on M unicipal Wastewater
Management". The Hague: United Nations Environment Programme
Global Programme of Action (UNEP/GPA), Coordination Office. PDF
Technical information on environmentally sound technologies in
wastewater treatment.
WSP (Editor) (2007): Philippines Sanitation Source Book and
Decision Aid. pdf presentation. Washington: Water and Sanitation
Program. PDFThis Sanitation Sourcebook distils some of the core concepts of
sanitation in a user-friendly format so that the book can serve as a
practical reference to sanitation professionals and investment
decision-makers, particularly the local governments. The annexe
contains a practical collection of factsheets on selected sanitation
system options.
WSP (Editor) (2008): Technology Options for Urban Sanitation in
India. A Guide to Decision-Making. pdf presentation. Washington:
Water and Sanitation Program. URL[Accessed: 26.03.2010]. PDF
These guidance notes are designed to provide state governments
and urban local bodies with additional information on available
technologies on sanitation. The notes also aid in making an
informed choice and explain the suitability of approaches.
MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010):
How to Select Appropriate Technical Solutions for Sanitation.
Cotonou and Paris: Partenariat pour le Dveloppement Municipal
(PDM) and Programme Solidarit Eau (pS-Eau). URL[Accessed:
19.10.2011]. PDF
The purpose of this guide is to assi st local contracting authorities
and their partners in identifying those sanitation technologies best
suited to the different contexts that exist within their town. The
first part of the guide contains aplanning process and a set of
criteria to be completed; these ass ist you in characterizing each
area of intervention so that you are then in a position to identify
the most appropriate technical solutions. The second part of the
guide consists of technical factsheets which give a practical
overview of the technical and economic characteristics, the
operating principle and the pros and cons of the 29 sanitation
technology options mos t commonly used in sub-Saharan Africa.See document in FRENCH
LEMOS CHERNICHARO, C.A. de (2007): Anaerobic Reactors.
London: International Water Association (IWA) Publishing. URL
[Accessed: 01.11.2013]. PDF
Anaerobic Reactors is the forth volume in the series Biological
Wastewater Treatment. The fundamentals of anaerobic treatment
are presented in detail, including its applicability, microbiology,
biochemistry and main reactor configurations. Two reactor types
are analysed in more detail, namely anaerobic filters and especially
UASB (upflow anaerobic sludge blanket) reactors. Particular
attention is also devoted to the post-treatment of the effluents
from the anaerobic reactors. The book presents in a clear and
informative way the main concepts, working principles, expected
removal efficiencies, design criteria, design examples,
construction aspects and operational guidelines for anaerobic
reactors.
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SPERLING, M. von; LEMOS CHERNICHARO, C.A. de (2005):
Biological Wastewater Treatment in Warm Climate Regions Volume
1. London: International Water Association (IWA) Publishing. URL
[Accessed: 01.11.2013]. PDF
Biological Wastewater Treatment in Warm Climate Regions gives a
state-of-the-art presentation of the s cience and technology of
biological wastewater treatment, particularly domestic s ewage.
The book covers the main treatment processes used worldwide
with wastewater treatment in warm climate regions given a
particular emphasis where simple, affordable and sustainable
solutions are required. The 55 chapters are divided into 7 parts
over two volumes: Volume One: (1) Introduction to wastewater
characteristics, treatment and disposal; (2) Bas ic principles of
wastewater treatment; (3) Stabilisation ponds; (4) Anaerobic
reactors; Volume Two (also available in the SSWM library): (5)
Activated sludge; (6) Aerobic biofilm reactors; (7) Sludge treatment
and disposal.
Case Studies
MOREL, A.; DIENER, S. (2006): Greywater treatment systems for
hotel premises, S ri Lanka. In: MOREL, A.; DIENER, S. (2006):
Greywater Management in Low and M iddle-Income Countries,
Review of different treatment systems for households or
neighbourhoods. Duebendorf, 80-84.
This case study presents different cost-effective on-site treatment
technologies with main focus on hotel greywater and blackwater
treatment systems. The first greywater treatment plant was
constructed for the Swiss Res idence Hotel. Based on the experience
gained by the Swiss Residence Hotel, further systems were
implemented at the hotels Ivy Banks and Coral Sands.
ROBBINS, D.; STRANDE, L.; DOCZI, J. (2012): Opportunities in
Fecal Sludge Management for Cities in Developing Countries:
Experiences from the Philippines. North Carolina: RTI International
. URL[Accessed: 15.01.2013]. PDF
In July 2012, a team from RTI International deployed to the
Philippines to evaluate four FSM programs with the goal of
reporting on best practices and lessons learned. The four cases
Dumaguete City, San Fernando City, Maynilad Water for the west
zone of metro Manila, and Manila Water from the east zone of
metro Manilawere chosen to highlight their different approaches
to implementing FSM.
Awareness Raising MaterialU.S. EPA (Editor) (1987): It's Your Choice: A Guidebook for Local
Officials on Small Community Wastewater Management Options .
United States Environmental Protection Agency, Office of Water
Office of Research and Development. PDF
This booklet was prepared by the United States Environmental
Protection Agency U.S. EPA for officials from communities of less
than 10000 people to present them available options and thus to
enable an informed choice.
U.S. EPA (Editor) (2000): Decentralized Systems Technology Fact
Sheet - Septic System Tanks. Washington, D.C.: United States
Environmental Protection Agency, Office of Water Off ice of
Research and Development (US EPA). URL[Accessed: 15.04.2010].
PDF
Four-page factsheet by the United States Environmental ProtectionAgency (U.S. EPA), describing septic tanks, their applicability and
the design of septic tank systems for household-level black and
greywater treatment.
U.S. EPA (Editor) (2000): Decentralized Systems Technology Fact
Sheet - Septic Tank Leaching Chamber. Washington, D.C.: United
States Environmental Protection Agency, Office of W ater Office of
Research and Development.. URL[Accessed: 15.04.2010]. PDF
Seven-page factsheet by the United States Environmental Protection
Agency (U.S. EPA), describing the system, its applicability and the
design of a leaching field following a septic tank.
U.S. EPA (Editor) (2000): Decentralized Systems Technology Fact
Sheet: Septic Tank Systems for Large Flow Application.
Washington, D.C.: United States Environmental Protection Agency,Office of Water Office of Research and Development.. URL
[Accessed: 15.04.2010]. PDF
Ten-page factsheet by the United States Environmental Protection
Agency (U.S. EPA), describing the system, its applicability and
design of a septic tanks for large-flow applications.
http://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20Tank%20Systems%20for%20Large%20Flow%20Application.pdfhttp://www.epa.gov/owm/septic/pubs/septic_tank_large_flow_app.pdfhttp://www.sswm.info/library/217http://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20Tank%20Leaching%20Chamber%20.pdfhttp://nepis.epa.gov/Exe/ZyNET.exe/P1006DD9.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2000+Thru+2005&File=D%3A%5CZYFILES%5CINDEX+DATA%5C00THRU05%5CTXT%5C00000022%5CP1006DD9.TXT&User=anonymous&Password=anonymous&ImageQuality=r85g16%2Fr85g16%2Fx150y150g16%2http://www.sswm.info/library/216http://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20System%20Tanks.pdfhttp://www.epa.gov/owm/mtb/septic_system_tank.pdfhttp://www.sswm.info/library/215http://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%201987%20%20%20It's%20Your%20Choice-%20A%20Guidebook%20for%20Local%20Officials%20on%20Small%20Community%20Wastewater%20Management%20Options%20.pdfhttp://www.sswm.info/library/262http://www.sswm.info/libraryhttp://www.sswm.info/sites/default/files/reference_attachments/ROBBINS%20et%20al.%202012%20Opportunities%20in%20Fecal%20Sludge%20Management%20for%20Cities%20in%20Developing%20Countries.%20Experiences%20from%20the%20Philippines.pdfhttp://www.eawag.ch/forschung/sandec/publikationen/ewm/dl/IWA_Water21_Philippines.pdfhttp://www.sswm.info/library/7133http://www.sswm.info/library/880http://www.sswm.info/libraryhttp://www.sswm.info/sites/default/files/reference_attachments/SPERLING%20and%20LEMOS%20CHERNICHARO%202005%20Biological%20Wastewater%20Treatment%20in%20Warm%20Climate%20Regions%20Volume%201.pdfhttp://www.iwawaterwiki.org/xwiki/bin/view/Articles/DevelopingCountriesTitlesfromIWAPublishingFreetoDownload?utm_source=WaterWiki+Connect&utm_campaign=81b910d928-wikinews_june13&utm_medium=email&utm_term=0_65bedfee7b-81b910d928-89879641http://www.sswm.info/library/232http://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20Tank%20Systems%20for%20Large%20Flow%20Application.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20Tank%20Leaching%20Chamber%20.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%202000%20Decentralized%20Systems%20Technology%20Fact%20Sheet-%20Septic%20System%20Tanks.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/US%20EPA%201987%20%20%20It's%20Your%20Choice-%20A%20Guidebook%20for%20Local%20Officials%20on%20Small%20Community%20Wastewater%20Management%20Options%20.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/ROBBINS%20et%20al.%202012%20Opportunities%20in%20Fecal%20Sludge%20Management%20for%20Cities%20in%20Developing%20Countries.%20Experiences%20from%20the%20Philippines.pdfhttp://www.sswm.info/sites/default/files/reference_attachments/SPERLING%20and%20LEMOS%20CHERNICHARO%202005%20Biological%20Wastewater%20Treatment%20in%20Warm%20Climate%20Regions%20Volume%201.pdf8/13/2019 Septic Tanks _ SSWM
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