An Initial Assessment of a Wetland-Reservoir Wastewater Treatment and Reuse System Receiving Agricultural Drainage Water in Nova Scotia

Abstract

A wetland-reservoir wastewater treatment and reuse systems is an integrated water management system constructed on farms to conserve water and to help mitigate water pollution from agricultural drainage. This research assesses such a system in Nova Scotia and provides recommendations for adapting its location, design, construction, and operation to a cold climate. Water quality, hydraulic, and meteorological data was collected between November 2007 and January 2009. The system collected approximately 15500 m 3 (8700 m 3 ha-1 of drained land) annually, potentially enough water to irrigate more than the drained area. A tracer study was conducted in the constructed treatment wetland to assess residence time. Little difference was observed between the actual residence time (15.0 d) and the nominal residence time (14.5 d). This is attributed to a high length to width ratio (10:1). Annual nitrate-nitrogen and E. coli reductions by the constructed treatment wetland were 52% and 33%, respectively. Significant monthly variation was observed, and is attributed to the dynamic hydraulic and pollutant loading of tile drainage water. Total phosphorus and soluble reactive phosphorus concentrations were typically below detectable levels (0.10 mg L-1 and 0.05 mg L-1 respectively) at all sampling locations. Reservoir water quality exceeded irrigation water quality guidelines for E. coli (100 CFU 100 mL-1) during summer months and is attributed to environmental factors. At a cost of approximately $50,000 ha-1 the system may require economic incentives or drainage water disposal regulations before it can be adopted by farmers.

Performance of an Agricultural Wetland-Reservoir-Irrigation Management System

“…Effluent from each cell was discharged via a 150 mm diameter underground pipe and water level control structure leading to a sampling hut (where Q was measured) and then flowed into the reservoir. Full details on CW design and construction are provided in [33].…”

“…The design capacity of the reservoir was less than the estimated inputs because the dam location was limited by land availability, topography, and cost. [33]. The reservoir was situated in a gully south of the 5 ha field and was formed by constructing a dam across the gully.…”

Drainage Water Storage for Improved Resiliency and Environmental Performance of Agricultural Landscapes

“…In Missouri and Ohio, corn grain yields increased up to 50% (Nelson and Smoot, 2012;Allred et al, 2014), while soybean yields increased up to 29% (Nelson et al, 2011;Allred et al, 2014). Water quality benefits have also been demonstrated, since nutrients in both subsurface drainage and surface runoff can be recycled back onto the crop field during the growing season (Tan et al, 1993;Haverstock et al, 2010;Wesstrom and Joel, 2010). Allred et al (2003) included both a wetland and a reservoir in a system they called the Wetland-Reservoir Subirrigation System (WRSIS) for additional ecological benefits (Smiley and Allred, 2011).…”

Constructed Wetlands for Agricultural Wastewater Treatment in Northeastern North America: A Review

“…Applications include the treatment of milkhouse wash water and farmyard runoff [19][20][21][22][23][24][25][26][27], tile drainage outflow [28][29][30][31]), aquaculture wastewater [32,33] abattoir wastewater [34], and winery process water [35]. CWs are engineered to optimize naturally occurring biological, chemical, and physical processes to treat wastewaters.…”