Bacteria survival experiment for assessment of wastewater reuse in agriculture

摘要

Growth and survival of a strain of E. coli were investigated in laboratory-scale soil columnsnunder essentially static conditions in three Egyptian agricultural soils. One pore volumenof a buffer solution of known cell concentration was applied to a set of identical columnsnat time zero, and individual columns were analyzed for viable E. coli colony forming unitsnat times ranging from 1 hr to 7 d and at various soil depths. The resulting concentration-depthnprofiles yielded information that can promote proper application of wastewater reuse innagriculture and the assessment of associated health and environmental risks. Biomass growthnin soil occurred over the first 2 to 3 days after application, achieving biomass productionn40–70 times the number of cells applied depending on the soil. Culturable populations declinednto only a few viable cells at the end of 7 days. E. coli growth rate and total biomass productionnwere well correlated to the soil organic content. Indoor conditions resulted in slower but morenprolonged E. coli growth than in outdoor experiments, verifying the determinative rolesnof climatic factors and soil moisture.