Abstract
In this study, a novel lab-scale biofortification-combination system (BCS) of Oenanthe javanica and Bacillus series was developed to improve the treatment ability of vertical subsurface flow constructed wetlands (VSFCW) at low temperatures (0–10 °C). The results showed that BCS-VSFCW overcame the adverse effects of low temperature and achieved the deep removal of nutrients. In addition, the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) by BCS-VSFCW were 38.65%, 28.20%, 18.82%, and 14.57% higher than those of blank control, respectively. During the experiment, Oenanthe javanica and low temperature tolerant Bacillus complemented each other in terms of microbial activity and plant uptake. Therefore, VSFCW combined with Oenanthe javanica and low temperature tolerant Bacillus has a promising future in low temperature (<10 °C) areas of northern China.
Highlights
The existence and activity of plants and microorganisms are important for vertical subsurface flow constructed wetlands (VSFCW) [7,8], which can improve their effectiveness in the treatment of wastewater [9,10]
The results show that there was a significant difference in the removal ability of chemical oxygen demand (COD) between plants and microorganisms in the VSFCW
The results show that the removal effect of total nitrogen (TN) by planting Oenanthe javanica and adding microorganism agent was much better than that of the blank control group
Summary
Eutrophication in micro-polluted lake ecosystems has an increasing trend worldwide due to unreasonable anthropogenic activities [1]. Constructed wetlands (CWs) are an efficient, economical, and eco-friendly sewage purification technology, especially suitable for the treatment of micro-polluted lake and river water [2–4]. Among these types of wetlands, the vertical subsurface flow constructed wetlands (VSFCW) require less area and strong oxygen transfer capability and have been widely used in the treatment of micro-polluted lake water [5,6]. In the low-temperature season, some aquatic plants have difficulty in adapting to low temperature, and microbial activity is reduced, leading to a reduced removal efficiency of VSFCW [15,16] Species such as Phragmites australis and Typha orientalis are commonly used in VSFCW for an improved performance in the warmer environment; in the low-temperature season, these species would deteriorate or wither [17]
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