Removal of abamectin and conventional pollutants in vertical flow constructed wetlands with Fe-modified biochar.

Nai-Qing Sha,Guo-Hao Wang,Shao-Yuan Bai,Yan-Hong Li

doi:10.1039/d0ra08265a

Abstract

To improve the ability of constructed wetlands to remove abamectin (ABM) and nutrients, the influence of four different substrates on constructed wetlands was studied. Four vertical up-flow constructed wetlands (UVCWs) were established to treat simulated agricultural wastewater: CW1 (quartz sand + pebbles), CW2 (pebbles + coke), CW3 (Fe-modified biochar + pebbles + coke), and CW4 (unmodified biochar + pebbles + coke). Under different combinations of hydraulic loading and organic loading, CW3 was extremely effective at removing nitrogen compared with CW1, CW2 and CW4. We found that CW3 was the most effective at treating ABM and conventional pollutants. The highest efficiency of removal of abamectin (99%), COD (98%), NH4+–N (65%), and TP (80%) was obtained in CW3. These results were directly verified by microbiological tests and microbial community analysis. The microbial diversity of CW3 and CW4 was significantly higher than those of CW1 and CW2. Fe-modified biochar provides a feasible and effective amendment for constructed wetlands to improve the nitrogen removal for C/N (2.5 : 1–5 : 1) wastewater by the ability of microbes to remove nitrogen. Fe-modified bamboo charcoal can be used in engineering as a new type of green environmental protection constructed wetland filler in the future.

Highlights

Pharmaceutical compounds have penetrated every aspect of our lives
Fe-modi ed biochar is a potential carrier of microbial agents
Under hypoxia and aerobic conditions, the microbial structure changes in the Fe cycle and the delta Proteobacteria and Methanomicrobia are abundant, which improves the ability of CW3 to remove ABM

Summary

Introduction

The abuse of pharmaceutical compounds has had a negative impact on the environment.[1] The detection and methods for the control of conventional pollutants have matured. Researchers have begun to pay attention to the harm and treatment of emerging pollutants (EOCs) in the environment.[2,3] The strong ability and persistence of personal-care products (PPCPs, such as antibiotics and sex hormones) and pesticides in the environment have become increasingly prominent.[4,5] Because of the low concentration of EOCs in the water (mg LÀ1 or ng LÀ1), most water treatment facilities cannot effectively eliminate them.[6] EOCs and PPCPs and other emerging pollutants have become new international research hotspots.[7,8] When pesticides are used in crops, they can reach the soil through rain and river water and enter the groundwater from the soil through osmosis.[9,10] This is especially true for antibiotics, since their indiscriminate use aGuangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541004, China. The occurrence of PPCPs and pesticides in the aquatic environment has become a worldwide issue of increasing environmental concern.[14]

Objectives

Results

Discussion

Conclusion