Laura E. Christianson , Reid D. Christianson , Christopher H. Hay , Anthony Seeman , Carolina Díaz-García , Gary W. Feyereisen , Lindsay Pease , Jeppe Kjaersgaard , Matthew J. Helmers , Michelle Soupir
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引用次数: 0
Abstract
Surface subsidence at denitrifying woodchip bioreactors treating subsurface drainage has been anecdotally noted but has not been consistently documented and is thus poorly understood. Subsidence is of concern due to safety and potential exacerbation of ponding within the bioreactor but could also indicate flow restrictions within the woodchip bed. This study used 3D light detection and ranging (LiDAR) surveying on handheld devices (iPhone 12 Pro, iPad Pro) to provide minimum estimates of surface subsidence at 17 full-size bioreactors across a range of ages (0.1 to 14 years). Bioreactors with woodchips extending to the surface subsided faster than bioreactors with soil covers with median subsidence rates over the entire surface of 7.3 and 1.0 cm/y, respectively. Maximum subsidence averaged 40 ± 14 cm across all sites and tended to occur near the inflow manifold where subsidence could disproportionately impact hydraulic performance. Although these findings are limited to the bioreactors in the present evaluation and other sites may show different trends, it may be that subsidence is not reducible to aerobicity alone. Subsidence is not necessarily, on its own, the best individual indicator of the end of design life. In practice, checking for a consistent reduction in the amount of outflow over time is the best way to assess the need for a bioreactor woodchip recharge. Nevertheless, in this study, subsidence at full-size bioreactors was successfully approximated using a hand-held LiDAR device, and use of this method at additional sites is suggested, especially following bioreactor construction.
期刊介绍:
Ecological engineering has been defined as the design of ecosystems for the mutual benefit of humans and nature. The journal is meant for ecologists who, because of their research interests or occupation, are involved in designing, monitoring, or restoring ecosystems, and can serve as a bridge between ecologists and engineers.
Specific topics covered in the journal include: habitat reconstruction; ecotechnology; synthetic ecology; bioengineering; restoration ecology; ecology conservation; ecosystem rehabilitation; stream and river restoration; reclamation ecology; non-renewable resource conservation. Descriptions of specific applications of ecological engineering are acceptable only when situated within context of adding novelty to current research and emphasizing ecosystem restoration. We do not accept purely descriptive reports on ecosystem structures (such as vegetation surveys), purely physical assessment of materials that can be used for ecological restoration, small-model studies carried out in the laboratory or greenhouse with artificial (waste)water or crop studies, or case studies on conventional wastewater treatment and eutrophication that do not offer an ecosystem restoration approach within the paper.