Paper Details

Effects of wastewater irrigation on accumulation of heavy metals in soil and spinach; optimization by response surface methodology (RSM)

Solmaz Ahmadifard

DOI: https://dx.doi.org/10.12692/ijb/5.12.288-295

Int. J. Biosci. 5(12), 288-295. December, 2014. (PDF)

Abstract:

As a result of urbanization, urban wastewater has increased fast, so reusing urban wastewater has become a research topic for a long time. The goals of this study were effects of wastewater irrigation on accumulation of heavy metals in soil and spinach, and optimization by response surface methodology (RSM). The plants were transplanted into pots containing 7 kg of soil, and were irrigated with 400 mL of wastewater to water mixture (in different ratio) every day. The response surface methodology and central composite design have been used to clarify the experimental plan and determine the optimum settings of the independent variables and their responses. The independent factors were ratio of wastewater to water mixture (20, 40 and 60%; v/v) and different lengths of time for taking samples (10, 20 and 30 days). The results showed that the irrigation by wastewater led to accumulation of Mn and Ni in soil and plant. At the optimum time for taking samples (29.99 days) and ratio of wastewater to water mixture (59.85%; v/v) the maximum accumulation of Mn and Ni in soil, and roots and shoots of spinach were 3.25 mg/L (Mn in soil), 4.49 mg/L (Ni in soil), 2.99 mg/L (Mn in root), 1.59 (Mn in shoot), 3.36 mg/L (Ni in root) and 2.20 mg/L (Ni in shoot), respectively.