Abstract

To achieve the universal target of 'safely managed sanitation' set out in UN Sustainable Development Goal 6, the world needs to increase its rate of progress, since e.g. Phnom Penh, the capital of Cambodia, currently has zero percent safely managed sanitation. One way to promote safer faecal sludge management is to shift to a more circular system with nutrient recycling, but this carries the risk of heavy metal accumulation in the environment. This study analysed the concentrations of heavy metals in raw faecal sludge from various sources and assessed the appropriateness of resource recovery and reuse in relation to the heavy metal and nutrient loads in faecal sludge. A total of 42 samples collected from sludge disposal sites in Phnom Penh during the dry and rainy seasons were analysed for heavy metals and physicochemical parameters. Mean measured concentrations of heavy metals in faecal sludge samples decreased in the order Zn > Cu > Pb > Cr > Ni > Hg > As > Cd in both seasons but were higher in the rainy season, probably due partly to inflow from stormwater drains and run-off from roads during storm events. All elements analysed were within the permissible limits for application to land according to EU standards and USEPA. However, Hg and Zn concentrations exceeded the tolerance limits for local organic fertiliser and Swedish limits for compost. Faecal sludge is thus not an appropriate fertiliser considering the risk of heavy metal accumulation in relation to phosphorus recovered. Options to avoid recirculating pollutants to the environment include upstream prevention of pollution, source separation of household wastewater fractions and use of biosolids as a soil conditioner together with other fertilisers or for soil production. Additional studies are needed on these options if sanitation stakeholders are to close the nutrient loop.

Keywords

Faecal sludge management; Heavy metals; Low and middle-income country; Nutrient recovery; Onsite sanitation; Sustainable agriculture

Published in

Journal of Environmental Management
2024, Volume: 349, article number: 119436

SLU Authors

• Eliyan, Chea

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • Royal University of Phnom Penh

• Mcconville, Jennifer

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

• Zurbrügg, Christian

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • Eawag, Swiss Federal Institute of Aquatic Science and Technology

• Vinnerås, Björn

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure sustainable consumption and production patterns
Ensure availability and sustainable management of water and sanitation for all


UKÄ Subject classification

Environmental Management


Publication identifier

DOI: https://doi.org/10.1016/j.jenvman.2023.119436

Permanent link to this page (URI)

https://res.slu.se/id/publ/126942