Wang Zhong-Qiong, Zhang Rong-Bin, Chen Qing-Hua, Wei Hong-Bin, Wang Wei-Dong
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Huan Jing Ke Xue. 2012 Nov;33(11):3804-11.
Shijiuyang constructed wetland (SJY-CW) in Jiaxing City adopted plant-bed/ditch systems originated from the natural landscape as its major functioning unit. The constructed root channel technology (CRCT) is the core technique applied within the plant-bed/ditch systems. Monitoring results demonstrated that the wetland had the capability of improving water quality indexes by one rank grade according to the national environmental quality standards for surface water (GB 3838-2002). In order to optimize the water quality improvement function of plant-bed/ditch systems and CRCT, a pilot project in SJY-CW was constructed from May to October, 2010. The project contained 16 independent experimental cells. Orthogonal test design was applied to probe into the effects of constructed root channel layers, plant species combination, and reinforced physical substrates on promoting the water quality amelioration efficiency of the plant-bed/ditch systems. Comprehensively considering water treatment effects, construction difficulty, and construction and maintenance cost, the recommended optimal ways are as follows. Plant straws were preferably paved under subsurface zones by two layers with a gap of 20-30 cm. The preferable plant combination was reed (Phragmites australis) plus wild rice (Zizania caduciflora). Calcite might be applied as alternative reinforced media in some suitable sites of plant-bed/ditch systems. Water treatment effects were compared between pilot project and the whole wetland area of SJY-CW. The results showed that the reinforced pilot project exhibited higher treatment efficiency for nutrients than SJY-CW itself. The removal rates of total nitrogen, total phosphorus, and ammonia nitrogen were increased by about 20% - 40% in the pilot project. This suggested that SJY-CW could release its vast water treatment potential by means of increasing water flux through the subsurface root channel zones of plant beds. Therefore, some adjustment and control measures could be proposed to maintain the tradeoff balance between the potential release and maximization of wetland treatment efficiency and the treated water amount, such as constructing or modifying the hydraulic structures to regulate flow amount through large ditch, redistributing water flow and increasing the water head difference between the two sides of alternate small ditches.
嘉兴市的世纪阳人工湿地（SJY-CW）采用源于自然景观的植物床/沟渠系统作为其主要功能单元。构建根通道技术（CRCT）是应用于植物床/沟渠系统的核心技术。监测结果表明，根据国家地表水环境质量标准（GB 3838-2002），该湿地有能力将水质指标提升一个等级。为了优化植物床/沟渠系统和CRCT的水质改善功能，2010年5月至10月在SJY-CW开展了一个试点项目。该项目包含16个独立的实验单元。采用正交试验设计来探究构建根通道层、植物物种组合和强化物理基质对提高植物床/沟渠系统水质改善效率的影响。综合考虑水处理效果、施工难度以及建设和维护成本，推荐的最佳方法如下。植物秸秆最好在地下区域铺设两层，间隔20 - 30厘米。优选的植物组合是芦苇（Phragmites australis）加茭白（Zizania caduciflora）。在植物床/沟渠系统的一些合适部位，方解石可作为替代强化介质。对试点项目和SJY-CW的整个湿地区域的水处理效果进行了比较。结果表明，强化试点项目对营养物质的处理效率高于SJY-CW本身。试点项目中总氮、总磷和氨氮的去除率提高了约20% - 40%。这表明SJY-CW可以通过增加水流经植物床地下根通道区域的通量来释放其巨大的水处理潜力。因此，可以提出一些调整和控制措施，以维持湿地处理效率的潜力释放和最大化与处理水量之间的权衡平衡，例如构建或改造水工建筑物以调节通过大沟渠的流量、重新分配水流以及增加交替小沟渠两侧的水头差。
