Plant species as a significant factor in wastewater treatment in constructed wetlands

Abstract

Constructed wetlands are one of the newest wastewater treatment technologies. They should reduce the Biochemical Oxygen Demand (BOD) and utilize a large amount of the influent. The BOD determines how much oxygen is used bymicro organisms while oxidizing organic matter. If BOD is high, the effluent is high in organic material, which clogs the soil of the drainfield. Reductions in the BOD can increase the life of a drainfield. The water usage of wetlands is important to drainfields. Reducing the amount of effluent through water uptake can result in smaller drainfields. This study was conducted using Arrowhead (Sagittaria lancifolia), Umbrella Palm (Cyperus alternifolius), Dwarf Umbrella Palm (Cyperus isoclaudus), and Cattail (Typha latifolia) in microcosms fed rural septic influent. The water parameters studied were water usage, ammonium-nitrogen, phosphorus, coliforms, suspended solids, BOD, pH, and turbidity. The BOD for all plants was reduced below the standard levels but none were significantly different. The Umbrella Palm utilized an average of 30% of the wastewater it received over a two-day period and its water usage was significantly different from the others. The Umbrella Palm reduced the BOD and influent volume, making it the best plant choice for use in constructed wetlands.