The objective of this study was to evaluate the treatment efficiency of a short rotation willow coppice (SRWC) vegetation filter for the treatment of wastewater from a municipal primary effluent in a humid continental climate context. The experimental work was carried out at pilot scale on a willow plantation located in Québec, Canada. The experimental design included nine plots that were irrigated with groundwater (L0 = 14 mm/d) or two primary effluents (L1 = 10 and L2 = 16 mm/d) for 111 days. This research showed that SRWCs operated on coarse-textured soils allow efficient removal of organic matter (91 % of COD for L1 and L2) and nitrogen (98 % of TKN for L1 and L2) from wastewater. It was also shown, in this case, that the total nitrogen loading should be used as the limiting design parameter to minimize the risk of contaminating underground drinking water sources with nitrates. Almost complete removal of total phosphorus was observed during this experiment (98 % for L1 and L2). However, a significant increase in soil available phosphorus was observed following the L2 treatment, which suggests an eventual phosphorus soil profile saturation in the event of continued wastewater irrigation. Avoiding such a saturation would require chemical phosphorus removal upstream of SRWC vegetation filters. Finally, an imbalance between irrigation and willows needs was observed as a result of irrigating plots at a constant hydraulic loading rate. Thus, irrigation of an SRWC with wastewater should be modulated according to willow seasonal transpiration trends to allow a better allocation of water and nutrients according to plant needs, and in doing so, increase treatment efficiency and resources valorization. Highlights • Efficient removal of OM and nitrogen (TKN) by coarse textured SRWC vegetation filter • TN should be used as the limiting design parameter of SRWC vegetation filter • Eventual P soil profile saturation in the event of continued wastewater irrigation • Irrigation should be modulated according to willow seasonal transpiration trends

No abstract

No abstract

The treatment of leachate by vegetative filters composed of short-rotation willow coppice (SRWC) has been shown to be a cost-effective alternative to conventional and costly methods. However, few studies have considered the treatment capability of willow filters at a scale large enough to meet the industrial requirements of private landfill owners in North America. We report here on a field trial (0.5 ha) in which a willow plantation was irrigated with groundwater (D0) or aged leachate at two different loadings (D1 and D2, which was twice that of D1). Additionally, half of the D2-irrigated plots were amended with phosphorus (D2P). The system, which operated for 131 days, was highly efficient, causing the chemical oxygen demand concentration to drop significantly with the total removal of ammonia (seasonal average removal by a concentration of 99–100%). D2P efficacy was higher than that of D2, indicating that P increased the performance of the system. It also increased the willow biomass 2.5-fold compared to water irrigation. Leaf tissue analysis revealed significant differences in the concentrations of total nitrogen, boron, and zinc, according to the treatment applied, suggesting that the absorption capacity of willows was modified with leachate irrigation. These results indicate that the willow plantation can be effective for the treatment of landfill leachate in respect of environmental requirements.

With today’s environmental challenges, developing sustainable energy sources is crucial. From this perspective, woody biomass has been, and continues to be, a significant research interest. The goal of this research was to develop new technology for mapping willow tree yield grown in a short-rotation forestry (SRF) system. The system gathered the physical characteristics of willow trees on-the-go, while the trees were being harvested. Features assessed include the number of trees harvested and their diameter. To complete this task, a machine-vision system featuring an RGB-D stereovision camera was built. The system tagged these data with the corresponding geographical coordinates using a Global Navigation Satellite System (GNSS) receiver. The proposed yield-mapping system showed promising detection results considering the complex background and variable light conditions encountered in the outdoors. Of the 40 randomly selected and manually observed trees in a row, 36 were successfully detected, yielding a 90% detection rate. The correctly detected tree rate of all trees within the scenes was actually 71.8% since the system tended to be sensitive to branches, thus, falsely detecting them as trees. Manual validation of the diameter estimation function showed a poor coefficient of determination and a root mean square error (RMSE) of 10.7 mm.