Sick water?

A look inside Concentrations of micro-organisms excreted in one litre of wastewater

Wastewater in urban agriculture Resource or threat?

Cryptosporidium parvum Entamoeba histolytica Giardia intestinalis

Waterborne disease risk

Salmonella

Shighella

Wastewater treatment

Vibrio cholerae

Ascaris lumbricoides

Anchilostoma duodenale

No need of added fertilizers Costs of treatment

Inefficent crops

Low quality output

Trichuris trichiura

Enteric visuses

Rotavirus

Pharmaceuticals

Nutrients

Heavy metals

Soil enrichment

Nutrients

Ecosystem destruction

Number of organisms Logaritmic scale

Eutrophication

100 10 000 1 000 000

1 000 10 100 000

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

Wastewater reuse in agriculture: blackwater and graywater discharge Food provision Contamined food provision

Pollutant discarge on soils and ecosystems

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.

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

34