Benefits and risks of wastewater use for vegetable production in Nairobi, Kenya

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Benefits and risks of wastewater use for
vegetable production in Nairobi, Kenya N.
Karanja, M. Njenga, G. Prain, K. Gathuru, E.
Kangethe, G. Kironchi, C. Githuku, P. Kinyari
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Problems for Low-income Urban Families

• Unemployment
• Lack of social and physical infrastructure
• Health and nutrition problems

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Wastewater farming in selected cities
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(No Transcript)
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Partnerships and Roles

• Urban Harvest-CIP
• -coordination and socio-economic survey
• -assessment of environmental benefits/risks in
  wastewater farming
• JKUAT
• -mapping sources types of pollutants and
  assessment of environmental risks in wastewater
  farming
• University of Nairobi
• -assessment of public health risks and assessment
  of environmental benefits/risks in wastewater
  farming
• Green Towns
• -Community mobilization
• Mailisaba and Kibera farmers
• Sampling, community mobilization, provision of
  sampling sites
• NEMA, NAWASCO, KEWI,
• -sampling and awareness creation and policy
  consultations

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Objectives

• Socio-economic study on benefits and practices of
  wastewater re-use for UA
• Characterize sources, types and contents of heavy
  metals and organic pollutants in wastewater.
• Develop strategies for reduced environmental and
  public health risks affecting men and women in
  communities involved in using wastewater for UA.
• Generate information for use in awareness raising
  among wastewater users especially women and
  policy makers for enhanced profitability and
  reduced risks.

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Methods and Approaches

• (i) Gender responsive socio-economic survey
• individual interviews with 26 and 206 households
  in Kibera and Maili Saba respectively
• focus group discussion

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(ii) Field sampling

• Environmental hazards nutrient, biological and
  heavy metal in wastewater, soil, vegetables from
  farms
• Public health faecal samples from farming and
  non farming household members, soil and
  vegetables from farm and informal markets

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Findings

• (i) Socio-economics
• Average size of farms lt0.5acre
• gt60 of labour was provided by women and hence
  more exposed to health risks
• Traditional African Vegetables (TAVs) and kale
  were the most preferred crops mainly for sale as
  only 20 were consumed at home. income and
  employment

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• Farmer experience
• Mary Has been farming for over 20 years, sells
  over 80 percent of her produce, employs 2
  fulltime workers and engage over 5 casuals.
  Supported and educated her children and bought
  half an acre farm in rural home and has
  diversified food supply throughout the year.

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(ii) Public health

• 20 of farmers were aware that use of wastewater
  could cause ill-health
• Farmers were not aware of the high heavy metal
  contents in the water
• 80 of the farmers applied unspecified pesticides

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Table 1. Parasite loads in faecal samples from
wastewater farmers and
non-farmers
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Table 2. Biological contaminants in vegetable
samples from wastewater farm and markets
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Marketing Chain Case Study of Leafy Vegetable in
Nairobi
Urban household production

• Traders and brokers
• Value addition
• Large volumes
• Consistent

Open-air urban markets
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Table 3. Characteristics of Wastewater Used for
Irrigation
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Heavy metal contaminants soils from Kibera and
Maili Saba
Critical Limits 84 mgPb/kg 4mgCd/kg, WHO 2006
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Heavy metal contaminants in vegetables (mg/kg)
Critical Limits 0.3mgPb/kg 0.2mgCd/kg EU
standards
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Capacity building

• Academic
• 2 M.Sc to be submitted at JKUAT
• Community
• Farmer representative sent to the World Water
  Forum
• Traditional African Vegetable seed production
• Farmers participation in policy for a in Nairobi

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Conclusions

• Benefits from wastewater re-use exists
• Knowledge on health risks is limited particularly
  on heavy metals in vegetables
• No difference in parasite load between farmers
  and non farmers was observed
• Heavy metal contamination in vegetables was high
  despite the fact that their concentration in
  water was low.
• Market vegetables were more contaminated with
  pathogens compared to those grown with wastewater

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What next?
Stabilization pond in Lima, Peru

• Research for development preferably regional on
• (i) potential of wastewater farming to urban food
  security and climate change (IWMI,2006-exploratory
  )
• (ii) gender responsive and cost effective
  technologies
• (iii) map out long-term impact of heavy metal
  pollution
• (iv) review and harmonize of agriculture-health-e
  nvironment policies and regulatory mechanisms

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Publications

• Nancy Karanja, Mary Njenga, Gordon Prain, Kuria
  Gathuru and Gerald Mutua (Forthcoming)
  Experiences in a collective community based
  wastewater Irrigation in urban and peri-urban
  areas in Nairobi, Kenya. In Canada and Research
  for Development Past, Present and Future (Ron
  Harpelle and Bruce Muirhead eds)
• Kinyari, P.K. et al (Forthcoming). Quantifying
  heavy metal contaminants in river and sewer
  water mapping pollutant sources and their
  environmental impacts along the Ngong river
  basin, Nairobi. In Innovations as Key to the
  Green Revolution in Africa Exploring the
  Scientific Facts. (Bationo et. al. eds)
  http//www.ciat.cgiar.org/tsbf_institute/index.htm
  
• Kuria Gathuru, Nancy Karanja and Mary Njenga
  (2007) Wastewater irrigation empowers Kenya's
  urban farmers. Story in the New Agriculturalist.
  www.new-agri.co.uk
• Mwangi, S Kimathi, M Kamore, M Karanja, N and
  Njenga, M. (2006) Creating Viable Markets
  Opportunities for Poor Women Farmers in Kenya.
  Article in the Urban Agriculture Magazine Vol.17.
  www.ruaf.org

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Safe food in all market outlets
Thank you
Healthy and happy families