1. Excreta and Household Wastewaters - Introduction
Global Water, Sanitation and Hygiene
ENVR 890 Section 003
ENVR 296 Section 003
Mark D. Sobsey
February, 2006

2. Household Human Wastes and Wastewaters

3. Excreta and Graywater– Definitions and Properties
Excreta: Human feces and urine
Managed in different ways:
Direct disposal on land or in water
Direct use as fertilizer, soil conditioner and for aquaculture
Pre-treatment prior to use
Dilution with water to convey (sewage) for disposal or use
Direct use of untreated (raw) sewage
Treatment and discharge to land or water
Treatment and reuse (agriculture, aquaculture, horticulture, industrial and civil use
Graywater: Other wastewater from human activity
Not directly from human feces and urine
Wastewater from washing, bathing, etc
Contains human wastes and exudates

4. Types of Human and Animal Wastes and their Systems
Feces & Urine = Excreta = “Nightsoil” = Slurry = Chamberpot Wastes
“Dry” Systems
Human (“sanitary”) waste in settings where water use is limited by preference or lack of indoor plumbing for water supply and liquid waste (sewage) disposal.
Sanitary or Municipal Sewage – Liquid or “Wet” Systems
Typical for human waste in settings where there is piped, household water supply and sanitary waste disposal using water.
Agricultural Animal Waste Systems:
Liquid or wet systems: use limited amounts of water for waste flushing from animal barns or other high animal density settings (dairy cattle
Dry systems: collect manure and urine, sometimes with bedding material by mechanical methods (movers) for storage and treatment
Pasture management is typically a dry system

5. Managing Human Excreta - Options
“Dry” Collection:
Open defecation
Collect in a container
e.g., chamber pot
Discharge to the environment w/ or w/o Rx
Latrines – several kinds
Treat or dispose of or both
Latrines, cesspools/waste pits
Separate feces and urine
Then, treat/store (latrines), use or dispose to the environment

6. Managing Human Excreta - Options
Semi-wet (or semi-dry)
Use some water
Pour-flush toilets/latrines and other low water use systems
Needed where water is used for anal cleansing
On-site systems needed handle additional water
Can be done by infiltration and on-site treatment of semi solid wastes in latrine pits, composting pits, twin-pit pour-flush latrine, etc.
Alternatively, collect waste onsite and removed for further centralized or decentralized Rx

7. Managing Human Excreta - Options
Wet Systems
On-site Septic Systems
Other On-site systems
Soak pits
Sand filters
Sewerage – liquid system to convey sewage off-site
Sewage treatment systems (off-site)
Subject sewage to physical, biological and chemical treatment processes
Separate settlable solids from remaining liquid
Biologically degrade ands stabilize organic matter
Biologically reduce pathogens
Physically and chemically disinfect pathogens

8. Domestic/Community Sanitary Sewage
Human feces and urine diluted in water + other “stuff”
~20-50 grams feces dry weight ( grams wet weight) L urine/ L raw sewage
Dry weight suspended matter is about % (~1-2 grams/L)
Most is organic
Contains many pathogens, especially larger but also smaller ones
Sewage also contains “soluble” organic matter
of ten measured directly/indirectly as carbon or biodegradable carbon
Smaller microbes are part of the “soluble” matter: viruses + bacteria

9. Human Excreta – Resource or Risk?
Human excreta as a potential resource
Contains nutrients (N, P, K, and organic matter)
Nutrients and organic matter are:
Detrimental in water, esp. surface water
Eutrophication, anoxia, fish kills
Beneficial on land
Fertilizer, soil conditioner, land stabilizer
Widely used as a fertilizer and soil amendment in both developed and developing countries
Potential for excreta misuse and environmental pollution is great without proper attention to management plans and human behavior considerations
Nitrogen (N)
4.5
Phosphorous (P)
0.6
Potassium
1.0
Organic matter
(as BOD) 35
Annual Amounts/Person, Kg

10. Nutrient Content of Human Excreta
Rich source of inorganic plant nutrients: N, P K and organic matter
Daily human excretion: ~30 g of C (90 g of organic matter), ~ g N, ~ 2 g of P and 3 g of K.
Most organic matter in feces most N and P (70-80 %) in urine. K equally distributed between urine and feces.

11. Composition of Household Waste and Wastewater
Organics
kg COD/ (Person·year)
12.3
3.6
14.1
Nutrient content
kg N,P,K / (Person·year) N P K
0.8
5.3
1.0
– l
500 l
50 l
Ca % of excreta nutrients are in urine as chemical compounds readily accessible to plants
source: Otterpohl
Volume
Liter / (Person·year)
greywater urine faeces

12. Characteristics of Human Wastes
of no major (or less) hygienic concern/risk
volumetrically the largest portion of wastewater
contains almost no (or less) nutrients (simpler treatment)
may contain spent washing powders etc.
3. greywater
less hygienically critical (less risk)
contains the largest proportion of nutrients available to plants
may contain hormones or medical residues
2. urine
hygienically critical (high risk)
consists of organics, nutrients and trace elements
improves soil quality and increase its water retention capacity
1. feces
characteristic
fraction

13. Fertilizer Potential of Human Excreta
source: Drangert, 1998

14. Ecological Sanitation – “Ecosan”
A reuse cycle and closed-loop system for excreta
Treats human excreta as a beneficial resource
Excreta are confined and processed on site until they are free of pathogenic (disease-causing) organisms
Sanitized excreta are then recycled by using them for agricultural purposes.
Key features of ecosan:
Prevent pollution and disease caused by human excreta
Manage human excreta as a resource rather than as a waste product
Recover and recycle water and nutrients
Ecological sanitation FAQs:

15. Options for Excreta and Greywater Utilization
urine
(yellowwater)
liquid or dry
fertiliser
hygienisation by
storage or
drying
faeces
(brownwater)
anaerobic
digestion,
drying,
composting
biogas,
soil
improvement
constructed wetlands, gardening,
wastewater ponds, biol. treatment, membrane- technology
greywater
(shower,
washing, etc.)
irrigation,
groundwater-
recharge or
direct reuse
substances
treatment
utilisation
Ecosan Book:

16. Conventional Domestic/Municipal Sewage Treatment Systems were not Originally Designed for the Purpose of Removing or Destroying Pathogens
Emphasis on reducing “nuisance” aspects of sewage: smell, biodegradability (putrescence), vector attraction, etc.
Remove settleable suspended matter as solids or “sludge”
biologically degrade and stabilize sludge organic matter
Oxidize and stabilize non-settleable organic matter and nitrogen in the remaining liquid
or denitrify (biologically convert nitrogen to N2 gas)
Later (1950s and 1960s), pathogen control was introduced:
Disinfect the remaining liquid fraction prior to release
Disinfect the remaining solid fraction prior to release
Wastewater Reuse – Emerged in the 1970s; water scarcity

17. Typical Sewage or Community/Municipal Wastewater Treatment Systems
Treated (or untreated) wastewater is often discharged to nearby natural waters; alternatively, it is applied to the land or reclaimed/reused

18. Land Application of Treated Wastewater:
an Alternative to Surface Water Discharge

19. Conventional Community (Centralized) Sewage Treatment
Pathogen Reductions Vary from: low (<90%) to Very High (>99.99+%)

20. Typical Dry Excreta Management
Conventional „drop and store“ sanitation
Retention of solids
Infiltration of liquids
Polluted groundwater
Nitrates
Viruses
Pathogens
When filled, abandon and build and new one.
Poses health risks and is ecologically unsound.

21. Overview of Ecosan Technologies

22. Examples of Urine Diverting Toilets
China
Wost-Man, Sweden
Roediger, Germany
Dubletten, Sweden 
dry/wet:
faeces without, urine with flush 
dry/wet:
faeces with, urine without flush 
wet:
faeces & urine with flush
GTZ, Mali 
waterless:
faeces and urine without flush

23. Examples of urine diversion toilet slabs
Urine diverting concrete slab
Composting toilet with urine separation (China)

24. Waterless Urinals vacuum urinal KfW-building, Germany Ethiopia
Mon Museum, Sweden
South Africa
Tepoztlan, Mexico

25. Examples of Composting Toilets
Promotes microbial activity at elevated temperature with air, heat, moisture, and some large particles
composting toilet, Germany
(Berger Biotechnik)
Schweden

26. Examples of Composting Toilets
‘Skyloo’, with above-ground vault, Zimbabwe

27. Examples of Dehydrating/Dessiccating Toilets
various dehydration systems (with and without urine separation)
“SolaSan”-prefabricated system, South Africa
“Enviroloo”-prefabricated system, South Africa
Prefabricated dry UD toilets - South Africa
Solar drying toilet, El Salvador

28. Dehydrating/Dessiccating Toilets/Latrines
Goal is to dry the waste, sometimes directing urine away from feces.
Use urine separately as a fertilizer.
Promote drying, keep the volume of material small; confine feces for 6–12 months.
Add ash, lime or other material to feces after each defecation to lower moisture content and raise pH to 9 or higher. Conditions of dryness and ↑ pH promote pathogen die-off.
Remove partly treated solid material removed from processing chamber after Rx and storage.
Possible further Rx (high temp., composting, alkaline Rx, storage, carbonization/incineration).

29. On-Site Septic Waste Treatment Systems
Wet system with collection into a subsurface tank, separation (settling) and digestion (biological Rx) of solids and discharge of liquid effluent via perforated into subsurface soil for additional Rx.
Widely used in rural areas of developed and developing countries.
Often fail (eventually) due to poor site conditions, poor installation, lack of maintenance over time.

30. Vacuum Systems elements:
vacuum toilets, vacuum urinals, vacuum conductions, pumping station
advantages:
water saving, concentrated black water collection, decentralised treatment possible (anaerobic)
manufacturer:
i.e. Roediger GmbH

31. Membrane Rx Technology
Highly effective removal of soluble and biodegradable materials in wastewater stream
Selective permeable membrane (pore sizes < viruses)
Treated water recycle potential for non-potable use
Compact, flexible system
Expensive, requires maintenance by trained operators and a supply chain for replacement membranes and other parts

32. Anaerobic Treatment with Biogas Production
small scale biogas plants:
decentralised treatment of household wastewater with or without agricultural waste

33. Aquaculture
Wastewater treatment by aquatic plants and fish with nutrient recyling by human consumption
Offers high quality protein at low cost
Predominantly in Asian countries
Fish production of 1-6 tons/ha·year) achieved
tilapia
carp
duckweed

34. Urine Storage Various containers for urine storage: Gebers, Schweden
Lambertsmühle, Deutschland

35. composting with organic waste
Agricultural Use
direct injection of liquid fertiliser
irrigation
urban agriculture
dried faeces - „soil amelioration“)
composting with organic waste
urban agriculture

36. Conventional Wastewater System

37. Urban Ecosan Concepts Periphery food faeces urine greywater
drinking water
Periphery

38. Urban Ecosan Concepts

39. Urban Ecosan Concepts Residential Area food faeces urine greywater
treated greywater
drinking water

40. Urban Ecosan Concepts

41. Urban Ecosan Concepts Downtown Area food faeces urine greywater
treated greywater
drinking water
irrigation
of urban green
vacuum
sewerage
biogas
plant

42. Titel des Vortrags, einzeilig
urban ecosan concepts
Titel des Vortrags, einzeilig
oder zweizeilig 42
WfB, Rom – 12.Jan.2005

43. Human Excreta, Sanitation and Pathogens – Some References