Comparison of two different ecological floating bio-reactors for pollution control in hyper-eutrophic freshwater

Naxin Cui,Yaqin Liu,Min Cai,Xiangfu Song,Guifa Chen,Guoyan Zou,Li Zhou

doi:10.1038/s41598-018-32151-5

Naxin Cui, Yaqin Liu + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-32151-5

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Journal: Scientific Reports	Publication Date: Sep 24, 2018
Citations: 12	License type: open-access

Affiliation: Shanghai Academy of Agricultural Sciences

Abstract

The use of ecological floating beds (EFBs) to control water pollution has been increasingly reported worldwide due to the severe situation of eutrophication in water bodies. In this study, two kinds of EFBs were set up under similar condition to compare their purification efficiency in hyper-eutrophic water. The conventional ecological floating bed (CEFB) was made of polystyrene foam board, and the enhanced ecological floating bio-reactor (EEFB) was designed as an innovative hollow, thin floating bed integrated with substrates of zeolite and limestone. The results showed that the EEFB increased treatment efficiency of total nitrogen (TN), total phosphate (TP), and ammonia nitrogen (NH4+-N) to 63.5%, 59.3%, and 68.0%, respectively. Plant accumulation was the main pathway for TN and TP removal in the CEFB. Microbial degradation played an increasingly important role in TN and TP removal in the EEFB. A higher concentration of nitrogen cycling bacteria was recorded in the EEFB than the CEFB (P < 0.05), suggesting that the substrates might enhanced the removal efficiency of the EEFB by promoting the growth of microorganisms rather than their absorption effect.

Highlights

Hyper-eutrophication leads to harmful cyanobacterial blooms, which is increasing worldwide, and represents a serious threat to drinking water supplies and the ecological and economical sustainability of freshwater ecosystems[1,2]
The results showed that adding substrates such as zeolite and limestone to ecological floating beds (EFBs) could effectively improve the nutrient removal efficiency
Its efficacy of water purification was analyzed comparing to the conventional ecological floating bed (CEFB) when applied to water pollution control in hyper-eutrophic water

Summary

Introduction

Hyper-eutrophication leads to harmful cyanobacterial blooms, which is increasing worldwide, and represents a serious threat to drinking water supplies and the ecological and economical sustainability of freshwater ecosystems[1,2]. The researches focused on ecological technologies such as artificial constructed wetlands and ecological floating beds (EFBs) for water purification in rivers or lakes[5,6]. As a common substrates that have been widely used in constructed wetlands, zeolite and limestone possess a good adsorption capacity for nitrogen and phosphate, and provide micro-environmental conditions for the growth of microorganisms. An enhanced EFB (EEFB) was designed by innovatively introducing the substrate mixture of zeolite and limestone to improve its purification efficacy when utilized in hyper-eutrophic water. Experiments were conducted to explore the nutrient removal mechanism in the EFBs. The objectives of this study are: (1) investigating the nutrient removal performance of the EEFBs that employ substrates in comparison with the CEFBs; (2) measuring the plant growth and the major microorganism www.nature.com/scientificreports/. 68.0 ± 2.37a 57.7 ± 2.02a related to nitrogen and phosphorus removal; and (3) exploring the pathway of nutrient removal in the EFBs system

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