Department of Civil Engineering, Queen's University, 58 University Ave., Kingston, ON K7L 3N6, Canada.
Department of Civil Engineering, Queen's University, 58 University Ave., Kingston, ON K7L 3N6, Canada.
Sci Total Environ. 2019 Mar 10;655:720-729. doi: 10.1016/j.scitotenv.2018.11.278. Epub 2018 Nov 19.
The discharge from food production greenhouses (greenhouse effluent) contains high nutrient and salt concentrations, which, if directly released, can have adverse effects on the environment. Wood-chip bioreactors are increasingly popular passive water treatment systems favoured for their economical denitrification in treating agricultural field tile drainage. Microbial communities are central to denitrification; however little is known about the maturation of microbial communities in wood-chip bioreactors treating greenhouse effluents. In this study, multiple subsurface flow wood-chip bioreactors, each vegetated with a different plant species, together with an unplanted unit, received synthetic greenhouse effluent with elevated nitrate concentrations. The hybrid bioreactors were operated for over 2 years, during which time water samples were collected from the inlet, outlet and within the reactors. The increasing denitrification rate in the bioreactor planted with Typha angustifolia (narrowleaf cattail) correlated with increasing microbial activity and metabolic richness, measured by the carbon utilization patterns in Biolog® EcoPlates. Increased denitrifying gene (nirS) copies (determined by quantitative polymerase chain reaction, qPCR), and near-complete nitrate removal were observed in the T. angustifolia and unplanted reactors after 16 and 23 months of operation respectively. The findings suggested that an acclimation period of at least one year can be expected in unseeded bioreactors planted with T. angustifolia, while bioreactors without vegetation may require a longer time to maximize their denitrification capacity. These results are important for the design and operation of wood-chip bioreactors, which are expected to be more commonly applied in the future.
从食物生产温室（温室废水）中排出的水含有高浓度的营养物质和盐分，如果直接排放，会对环境产生不利影响。木屑生物反应器是一种越来越受欢迎的被动水处理系统，因其在处理农业领域排水中的经济脱氮而受到青睐。微生物群落是脱氮的核心；然而，对于处理温室废水的木屑生物反应器中微生物群落的成熟过程，我们知之甚少。在这项研究中，多个地下水流木屑生物反应器，每个反应器都种植了不同的植物物种，以及一个未种植的单元，接收了含有高浓度硝酸盐的合成温室废水。混合生物反应器运行了超过 2 年，在此期间，从入口、出口和反应器内部收集了水样。种植狭叶香蒲（Typha angustifolia）的生物反应器中的脱氮率不断增加，这与微生物活性和代谢丰富度的增加有关，这是通过 Biolog® EcoPlates 中的碳利用模式来衡量的。在 16 和 23 个月的运行后，分别在种植狭叶香蒲和未种植的反应器中观察到脱氮基因（nirS）拷贝数的增加（通过定量聚合酶链反应，qPCR 确定）和硝酸盐的近乎完全去除。研究结果表明，在未播种的种植狭叶香蒲的生物反应器中，预计需要至少一年的适应期，而没有植被的生物反应器可能需要更长的时间来最大限度地提高其脱氮能力。这些结果对于木屑生物反应器的设计和运行非常重要，预计未来它们将得到更广泛的应用。
