Wastewater in urban agriculture Resource or threat?

A look inside

Concentrations of micro-organisms excreted in one litre of wastewater

Cryptosporidium parvum

Waterborne disease risk

Entamoeba histolytica

Giardia intestinalis

Wastewater treatment

Ascaris lumbricoides

No need of added fertilizers Costs of treatment

Inefficent crops Low quality output

Anchilostoma duodenale

Trichuris trichiura

Nutrients Soil enrichment Pharmaceuticals Heavy metals

Ecosystem destruction

Nutrients Eutrophication

Number of organisms Logaritmic scale

1 000 000 10 000 100

Wastewater reuse in agriculture: blackwater and graywater discharge

Food provision Contamined food provision

Pollutant discarge on soils and ecosystems

Source: Drechser, P., et al.Wastewater Irrigation and Health. Assessing and Mitigating Risk in Low-Income Countries, IWMI-IDRC, 2009.

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Figure 12a: Is reuse of wastewater a benefit or a threat for agri- culture? Figure 12b looks at what one litre of wastewater might contain in terms of pathogens.

100 000

1 000 10

Source: WHO, Guidelines for the Safe Use of Wastewater, Excreta and Greywater, Volume 2 Wastewater use in agriculture, 2006.

Enteric visuses Rotavirus

Salmonella Shighella

Vibrio cholerae