Soil fertilization with wastewater biosolids -monitoring changes in the 'soil-fertilizer-plant' system and phosphorus recovery options

Nicholas Kathijotes, Elena Zlatareva, Svetla Marinova, Vera Petrova

Research output: Contribution to journalArticlepeer-review


The aim of this study is to establish changes that may occur after a prolonged application of wastewater sludge treated to biosolids, in the 'soil-fertilizer-plant' system. Thirteen experimental plots with different soil types planted with experimental crops were investigated in order to evaluate the suitability of these biosolids as soil conditioners and fertilizers. The biosolids were incorporated in soil starting in 2006 in different quantities (from 6 tons per ha) for various arrays. The rate of application was calculated on the basis of imported nitrogen and was consistent with the characteristics of the sludge, soil diversity, growing crop requirements, and other factors. In 2013 (after 7 years of land use) average soil samples from the same arrays were taken and analyzed. No chemical fertilizer was applied during the experimental period. The results show that the use of sewage biosolids as a soil improver in accordance with local legislation does not pose any serious environmental risks but can maintain and improve soil fertility and crop yield. A slight increase in Cu and Zn in plants was detected, however the content of heavy metals in all soil samples was below maximum allowable limits and no signs of phytotoxicity were observed.

Original languageEnglish
Pages (from-to)1499-1508
Number of pages10
JournalWater Science and Technology
Issue number6
Publication statusPublished - 1 Sept 2016


  • Biosolids
  • Fertilization
  • Heavy metals
  • Organic matter
  • Phosphorus recovery
  • Wastewater sludge


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