Human Excreta

7/28/2019 Human Excreta

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Excreta and Household

Wastewaters - Introduction

Margaret Katusiime Semakula


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Household Human Wastes and

Wastewaters


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Excreta and Graywater Definitions & Properties

Excreta: Human feces and urineManaged 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 useGraywater: Other wastewater from human activity

Not directly from human fecs and urine

Wastewater from washing, bathing, etc

Contains human wastes and exudates


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Managing Human Excreta - Options

Dry Collection: Open defecation

Collect in a container

e.g., chamber pot

Discharge to theenvironment w/ or w/o Rx

Latrines several kinds

Treat or dispose of or both

Separate feces and urine; Then, treat/store, use,

dispose to the

environment


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Semi-wet (or semi-dry)

Use some water

Pour-flush toilets and other low water usesystems


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Wet Systems

On-site Septic Systems

Other On-site systems

Soak pits

Sewerage

Sewage treatment systems


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Human Excreta Resource or Risk?

Nitrogen (N) 4.5

Phosphorous (P) 0.6

Potassium 1.0Organic matter

(as BOD)

35

Human excreta as a potential resource

Contains nutrients (N, P, K, and organicmatter)

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

Annual Amounts/Person, Kg


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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), ~ 10-12 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.


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0

20

Organicskg COD/ (Personyear)

12.3

3.6

14.1

VolumeLiter / (Personyear)

500 l 50 l

source:Otterpohl

0

6

Nutrient contentkg N,P,K / (Personyear)

N

P

K

0.8

5.3

1.0

Composition of Household

Waste and Wastewater

greywater urine faeces


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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

characteristicfraction

Characteristics of Human Wastes


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source:Drangert,

1998

Fertilizer Equivalence of Yearly per Capita ExcretedNutrients and Fertiliser Requirements for Producing

250 kg of Cereals

0

1

2

3

4

5

6

N N P P K K

N

utrient(kg)

cerealrequirements

faeces

urine

Fertilizer Potential of Human Excreta


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treatment

utilisation

substances 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

urine

(yellowwater)

liquid or dry

fertiliser

hygienisation by

storage or

drying

Options for Excreta and Greywater Utilization

Documents

Human Excreta