Wastewater as a Non-conventional Resource: Impact of Trace Metals and Bacteria on Soil, Plants, and Human Health

Abstract

In many arid and semi-arid regions, farmers are often obligated to informally use raw wastewater for irrigating their crops. The impacts of wastewater irrigation on soil, crops, and human health were investigated, regarding trace metals and bacteria. Cr, Cu, Fe, Ni, and Zn were detected in wastewater. Cr, Cu, and Zn accumulated in soil and crops in the order rocket > clover > cabbage. The Health Risk Index reported risk from Cr and Zn in rocket. Fecal coliforms in wastewater and crops were detected along with Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The frequency (%) was 86.7% (cabbage), 66.7% (rocket), and 43.3% (clover). The multiple antibiotic resistance index (0.503) rendered crops high risk source for contamination. The comprehensive pollution index classified wastewater severely polluted (≥2.01). Conclusions deduced crops alternative reservoirs for trace metals and human pathogens. Recommendations included implementation of low cost treatment methods, holding irrigation 5–15 days before harvest, assuming citric and acetic acids reducing solutions for trace metals, and suggested ofloxacin, amoxycillin/clavulanate, and amikacin antibiotics against reported bacteria.

Keywords:

• irrigation
• wastewater
• trace metals
• bacteria
• environmental impacts

Acknowledgments

The authors are thankful for the support of the Central Laboratory for Environmental Quality Monitoring (CLEQM), National Water Research Center (NWRC), Egypt for giving them all the facilities to do this work.

Conflict of interest

The authors declare no conflict of interest.