Abstract

Microbial contamination of vegetables due to irrigation with wastewater-polluted streams is a common problem around most cities in developing countries because wastewater is an available source of water and nutrients but wastewater treatment is often inadequate. On-farm treatment of polluted water is a feasible option to manage microbial risks in a multi-barrier approach. Current evidence indicates good suitability of biochar filters for microbe removal from wastewater using the hydraulic loading rate (HLR) designed for sand filters, but their suitability has not been tested under on-farm conditions. This study evaluated the combined effect of several variables on removal of microbial indicators from diluted wastewater by biochar filtration on-farm and the correlations between removal efficiency and HLR. Columns of biochar with three different effective particle diameters (d(10)) were fed with diluted wastewater at 1x, 6x, and 12x the design HLR and two levels of water salinity (electrical conductivity, EC). Influent and effluent samples were collected from the columns and analyzed for bacteriophages (phi X174 and MS2), Escherichia coli, Enterococcus spp., and Saccharomyces cerevisiae. Microbe removal decreased with increasing HLR, from 2 to 4 to 1 log in for bacteria and from 2 to 0.8 login for viruses, while S. cerevisiae removal was unaffected. Effective particle diameter (d(10)) was the main variable explaining microbe removal at 6x and 12x, while EC had no effect. Correlation analysis showed removal of 2 log(10 )bacteria and 1 log(10) virus at 3x HLR. Thus biochar filters on-farm would not remove significant amounts of bacteria and viruses. However, the design HLR was found to be conservative. These results, and some technical and management considerations identified, can assist in the development of a scientific method for designing biochar filters for on-farm and conventional wastewater treatment.

Keywords

Pathogens; Biochar filtration; Wastewater irrigation; Nutrient recycling; On-farm treatment

Published in

Journal of Environmental Management
2019, Volume: 248, article number: 109295
Publisher: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

SLU Authors

• Perez Mercado, Luis Fernando

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • University of San Simón (UMSS)

• Lalander, Cecilia

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

• Joel, Abraham

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Dalahmeh, Sahar

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

• Vinnerås, Björn

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

Associated SLU-program

SLU Plant Protection Network


Sustainable Development Goals

Ensure healthy lives and promote well-being for all at all ages
Ensure availability and sustainable management of water and sanitation for all
Make cities and human settlements inclusive, safe, resilient and sustainable
Ensure sustainable consumption and production patterns


UKÄ Subject classification

Water Treatment


Publication identifier

DOI: https://doi.org/10.1016/j.jenvman.2019.109295

Permanent link to this page (URI)

https://res.slu.se/id/publ/101740