Shahab Ansari - Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, I. R. Iran
M. Heidarpour - Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, I. R. Iran.
S. F. Mousavi - Department of Water Engineering and Hydraulic Structures, Faculty of Civil Engineering, Semnan University, Semnan, I. R. Iran

ABSTRACT-Nowadays farmers often use N-fertilizers to increase crop yield, but they lost quickly by leaching causes environmental contaminations that reported as most important source of pollutant. Although biofilters are useful for removing nitrate from drainage water, but many researches show that they need an external carbon source to sustain denitrification. Many researchers study on different method, but most of them need equipment or material that becoming use in laboratory experiment. So this study describes laboratory experiments that investigated nitrate removal with barley straw in different percentages layered or mixed with soil. Results showed that layering method was more effective for removing nitrate. The percentage of optimum volume mixture of barley straw in layering and mixing methods was ۲۰% and ۳۰% respectively, both removing approximately ۸۰% of the influent nitrate. So barley straw can be used in a layered form as an effective, prompt, feasible and inexpensive method to remove nitrate.

Keywords: Barley straw, Biofilters, Contamination, N-fertilizers, Drainage water