Integration of Bio-Enzyme-Treated Super-Wood and AIE-Based Nonwoven Fabric for Efficient Evaporating the Wastewater with High Concentration of Ammonia Nitrogen

Abstract

The treatment of ammonia nitrogen wastewater (ANW) has garnered significant attention due to the ecology, and even biology is under increasing threat from over discharge ANW. Conventional ANW treatment methods often encounter challenges such as complex processes, high costs and secondary pollution. Considerable progress has been made in employing solar-induced evaporators for wastewater treatment. However, there remain notable barriers to transitioning from fundamental research to practical applications, including insufficient evaporation rates and inadequate resistance to biofouling. Herein, we propose a novel evaporator, which comprises a bio-enzyme-treated wood aerogel that serves as water pumping and storage layer, a cost-effective multi-walled carbon nanotubes coated hydrophobic/hydrophilic fibrous nonwoven mat functioning as photothermal evaporation layer, and aggregation-induced emission (AIE) molecules incorporated as anti-biofouling agent. The resultant bioinspired evaporator demonstrates a high evaporation rate of 12.83 kg m−2 h−1 when treating simulated ANW containing 30 wt% NH4Cl under 1.0 sun of illumination. AIE-doped evaporator exhibits remarkable photodynamic antibacterial activity against mildew and bacteria, ensuring outstanding resistance to biofouling over extended periods of wastewater treatment. When enhanced by natural wind under 1.0 sun irradiation, the evaporator achieves an impressive evaporation rate exceeding 20 kg m−2 h−1. This advancement represents a promising and viable approach for the effective removal of ammonia nitrogen wastewater.

1. Introduction

With the development of industry and agriculture, especially in the fields of biopharmaceuticals, fermentation and textile printing and dyeing, the clean water, ecology and even biology are under increasing threat from over discharge of ammonia nitrogen wastewater (ANW) [1–3]. However, the commonly ANW treatment methods primarily consist of gas stripping [4, 5], chemical precipitation [6, 7], biological treatment [8], adsorption [9] and breakpoint chlorination techniques [10], which suffer from low efficiency, high cost and secondary pollution. For example, gas stripping and chemical precipitation methods can effectively treat high concentrations ANW, but the formation of by-products and residues cause secondary pollution [11]. Therefore, it is urgent to explore a novel strategy for separating ammonia nitrogen from wastewater that is characterized by low carbon emission, high effective and eco-friendly.

Solar-driven interfacial evaporation (SIE) technology has emerged as a promising and sustainable method for desalination, garnering considerable attention due to its unique advantages, including the use of inexhaustible solar energy, low costs, and minimal environmental impact [12–16]. Unfortunately, the insufficient research on vapor collection strategies has long been considered a critical limitation of SIE technology, impeding its large-scale implementation and practical applications in desalination [17]. In the context of wastewater treatment, these limitations may be less impactful, as the primary focus is on achieving high evaporation rates and long-term operational stability, rather than vapor collection [18–20]. This makes SIE technology particularly suitable for treating wastewater, including ANW. Nevertheless, several challenges persist in the practical application of SIE, such as difficulty maintaining high evaporation caused by salt deposition and insufficient water supply.