XVII th World Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR) Hosted by the Canadian Society for Bioengineering (CSBE/SCGAB) Québec City, Canada June 13-17, 2010 NITRATE REMOVAL OF DRAINAGE WATER WITH BARLEY STRAW AS A BIOREACTOR FILTER S.E. HASHEMI 1 , M. HEIDARPOUR 1 , B. MOSTAFAZADEH-FARD 1 , A. MADANI 2 , S.-F. MOUSAVI 1 , M. GHEYSARI 1 , M. SHIRVANI 1 1 S.E. HASHEMI, Ph. D Student, Water Dep., College of Agriculture, Isfahan University of Technology, Isfahan, Iran, 84156-83111, sehashemi@gmail.com. 1 M. HEIDARPOUR, Associate Professor, heidar@cc.iut.ac.ir. 1 B. MOSTAFAZADEH-FARD, Professor, behrouz@cc.iut.ac.ir. 1 S.-F. MOUSAVI, Professor, mousavi@cc.iut.ac.ir. 1 M. GHEYSARI, Assistant Professor, gheysari@cc.iut.ac.ir. 1 M. SHIRVANI, Assistant Professor, Soil Dep., shirvani@cc.iut.ac.ir. 2 A. MADANI, Professors, Engineering Dep., NSAC. Canada, amadani@nsac.ca. CSBE100171 – Presented at ASABE's 9th International Drainage Symposium (IDS) ABSTRACT Nitrate is a widespread groundwater contaminant, which can cause pollution of receiving waters. Some of the highest losses of nitrate to surface waters come from drained agricultural land. Bioreactor filters are a useful approach for removing nitrate from drainage waters, but these systems require an external carbon supply to sustain denitrification. The ability of barley straw to serve as a carbon substrate for biofilters was evaluated in a laboratory model. In this study the effect of two heads (100 and 200 cm) and two thicknesses of bioreactor (300 and 600 mm) were also evaluated. The experiment was conducted in the polyethylene columns with 90 mm internal diameter. The influent nitrate concentration was 40 mg L-1. Addition of barley straw as a carbon source decreases significantly effluent nitrate concentrations. The rate of denitrification was affected by the water velocity and decreased at velocity about 0.04 m h-1. In the columns with 300 mm height, the average nitrate reduction at 100 and 200 cm heads were 63.49% and 60.22%, respectively. The average nitrate reduction at the 600 mm height columns with 100 and 200 cm heads were 69.97% and 67.1%, respectively. Keywords: Nitrate, Bioreactor filters, Denitrification, Drainage water, Barley straw. INTRODUCTION Drainage of agricultural lands is a mechanism for production growth, a safeguard for sustainable investment in irrigation, and a tool for conservation of land resources. During the second half of the 20 th century, drainage was implemented in about 150 million ha of under producing and naturally waterlogged or saline lands. This resulted in important improvements that contributed to a considerable increase of food production (Ritzema et al., 2006).The horizontal subsurface drainage system, in addition to controlling water table and leaching out harmful dissolved salt form the drained soil profile, may also cause losses of various form of nitrogen through the drainage effluent (singh, 2002). Such nitrogen losses, besides may leach and pollute both ground water and surface water, are also likely to cause environmental degradation that will be detrimental CIGR XVII th World Congress – Québec City, Canada – June 13-17, 2010 1