Higher nitrogen removal achieved in constructed wetland with polyethylene fillers and NaOH-heating pre-treated corn stal
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RESEARCH ARTICLE
Higher nitrogen removal achieved in constructed wetland with polyethylene fillers and NaOH-heating pre-treated corn stalks for advanced treatment of low C/N sewage Zhengkai Tao 1 & Zhaoqian Jing 1
&
Yin Wang 1 & Mengni Tao 1 & Hui Luo 1
Received: 3 August 2020 / Accepted: 12 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Advanced processing of low C/N sewage faces the carbon sources shortage, while quantities of agricultural biomass wastes need to be disposed. This study investigated the potential of quantitative modified biomass addition in constructed wetlands (CWs) filled with polyethylene fillers. Results showed that the lignin in NaOH-heating pretreated corn stalks (NH-CSs) was destroyed, and the wrinkles on the stalks increased and became more soft after pretreatment, which was more conducive to the utilization of carbon sources and attachment of microorganisms. Compared with glucose and sodium acetate, the denitrification with mixed carbon source (glucose and NH-CSs) had the highest effective utilization percentage (61.37%) and NH-CSs were expected to become stable and fast-release carbon sources. After adding 30 g NH-CSs to the rear unit of CW with polyethylene fillers (CWA), TN removal efficiency was increased by 18.21%, and the average removal efficiency of COD, NH4+-N, TN, and TP reached 54.83%, 89.95%, 64.11%, and 45.04%, respectively. Compared with the traditional CW (CW-B), CW-A had a significant denitrification advantage (P < 0.05), but the removal efficiency and effluent stability of phosphorus were inferior to CW-B. These results indicate that the biomass carbon sources such as corn stalks and polyethylene fillers have a good potential to improve the denitrification in CWs. Keywords Agriculture waste . NaOH-heating pretreatment . External carbon dosage . Nitrogen removal . Constructed wetlands . Polyethylene fillers
Introduction Corn stalks are widespread with large quantities of biomass in the world. Especially in China, the annual output is up to 250 million tons (Hou et al. 2018). It is precisely because of the large-yield and easy availability of corn stalks that its comprehensive utilization has received extensive attention. For example, it can be used as the biomass fermentation substrate to generate electricity, and the residue can be used as a soil conditioner. It is an important attempt to consider using it as an additional carbon source to solve the carbon shortage in constructed wetlands (CWs) for wastewater treatment plant Responsible Editor: Alexandros Stefanakis * Zhaoqian Jing [email protected] 1
College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China
effluent, micropolluted water, and other water with a low C/ N (COD/nitrogen ratio), which is still identified as one of the major problems for the widespread application of CWs worldwide (Chen et al. 2019). Traditional carbon sources (methanol, acetic acid, etc.) are currently widely used and are classified as liquid low molecular carbon sources (Ga
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