The application status, development and future trend of nano-iron materials in anaerobic digestion system

doi:10.1016/j.chemosphere.2020.129389

Chemosphere

Volume 269, April 2021, 129389

https://doi.org/10.1016/j.chemosphere.2020.129389 Get rights and content

Highlights

•
The summary of nZVI and Fe₃O₄ NPs added anaerobic digestion mechanisms.
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The effect of pollutants digestion in nZVI and Fe₃O₄ added anaerobic system.
•
The microbial community changes in different anaerobic digestion system.
•
The theory basis for experiments and applications in nZVI and Fe₃O₄ added system.

Abstract

Growing environment problem and emphasis of environmental protection motivate intense research efforts in exploring technology to improve treatment efficiency on refractory organic pollutants. Hence, finding a method to make up for the deficiency of anaerobic digestion (AD) is very attractive and challenging tasks. The recent spark in the interest for the usage of some nanomaterials as an additive to strengthen AD system. The adoption of iron compounds can influence the performance and stability in AD system. However, different iron species and compounds can influence AD system in significantly different ways, both positive and negative. Therefore, strengthening mechanism, treatment efficiency, microbial community changes in Nanoscale Zero Valent Iron (nZVI) and Fe₃O₄ nanoparticles (Fe₃O₄ NPs) added AD systems were summarized by this review. The strengthening effects of nZVI and Fe₃O₄ NPs in different pollutants treatment system were analyzed. Previous study on the effects of nZVI and Fe₃O₄ NPs addition on AD have reported the concentration of nZVI and Fe₃O₄ NPs, and the types and biodegradability of pollutants might be the key factors that determine the direction and extent of effect in AD system. This review provides a summary on the nZVI and Fe₃O₄ NPs added AD system to establish experiment systems and conduct follow-up experiments in future study.

Introduction

In recent years, due to the growing serious water pollution problem, efficient technology development for contamination removal from wastewater attracts much more attention and interest. Among different treatment technologies, anaerobic digestion (AD) presents higher advantages due to its high organic load treatment, low cost, low energy demand, low sludge formation, energy recovery and efficiently resource utilization of pollutants (Zouari, 1998; Chen et al., 2008; Khalid et al., 2011; Uzuh et al., 2019). Hence, AD is widely used to treat different kinds of wastewater, municipal pollutants and agricultural solid wastes with additional methane generation (Zouari, 1998; Maciascorral et al., 2008; Khalid et al., 2011; Antonopoulou et al., 2015). Anaerobic digestion process mainly consists of four phases (Salminen and Rintala, 2002; Pan et al., 2016b): hydrolysis, acidogenesis phase, acetogenesis phase and methanogenesis. In the whole AD process, the main metabolites are methane, CO₂, volatile fatty acids (VFAs) and other low molecular weight organic matters.

However, there are some bottlenecks, limiting the efficiency and wide application of AD system for different pollutants treatment. The main drawbacks are low transformation efficiency and poor stability of AD system (Chen et al., 2008; Rajagopal et al., 2013). To solve these shortcomings, different approaches have been used to strengthen AD system. These methods mainly include microbial structure improvement (Hu et al., 2016; Li et al., 2018; Yang et al., 2019), reactor regulation (Cui et al., 2017; Zhang et al., 2018a; Pereira et al., 2019), parameter optimization (Rajasimman et al., 2017; Huang et al., 2019) nanoparticles (NPs) addition (Abdelsalam et al., 2017; Beiki and Keramati, 2019; He et al., 2019).

Specifically, nanoparticles show promising application in AD system for stability enhancement and transformation improvement. Nanoparticles addition in anaerobic treatment system could affect the microbial growth, pollutants degradation and biogas yields, such as nZVI (Khatri et al., 2015; Zhang et al., 2015; Abdelsalam et al., 2017), Fe₃O₄ NPs (Ali et al., 2017), ZnO NPs (Lunadelrisco et al., 2011; Mu et al., 2011; Nguyen et al., 2015), CuO NPs (Lunadelrisco et al., 2011; Ünşar et al., 2016), Ag NPs (Miller et al., 2013; Ünşar et al., 2016), CeO₂ NPs (Nguyen et al., 2015; Ünşar et al., 2016), TiO₂ NPs (Demi̇;Rel, 2016), Ni NPs (He et al., 2019). These literatures proved that NPs had good biocompatibility (Shukla et al., 2005; Abdul and Zhang, 2008; Aggarwal et al., 2009) when applied in AD system. After adding NPs, the biodegradability of pollutants was improved in biological treatment system, and the growth of microorganism was also strengthened. Comparing with above NPs, nZVI and Fe₃O₄ NPs had lower toxicity to microorganism in biological treatment systems (Ye et al., 2020). Additionally, Fe₃O₄ NPs was easy to prepared with low cost. It was also reported that nZVI and Fe₃O₄ NPs were greatly applied in wastewater treatment system ((Mueller et al., 2012); Fan et al., 2019; Xu et al., 2020) for environment protection and environmental modification (Chang et al., 2014; Zhu et al., 2014; Beiki and Keramati, 2019; Liu et al., 2019; Noonari et al., 2019). The NPs addition could enhance microbial activity and electron transfer efficiency in biological system, which provided a novel idea and direction for AD system in hard-biodegradable pollutants treatment process. From the search result, the number of literatures with nZVI and AD increased from about 136 in 2016 to 276 in 2019, and the number of literatures with Fe₃O₄ NPs and AD increased from about 75 in 2016 to 137 in 2019. Hence, there were more researchers paying attention on nZVI and Fe₃O₄ NPs in AD system to strengthen anaerobic system.

According to the above information, the present review aimed to summarize the advance and application of nZVI and Fe₃O₄ NPs coupling with of AD system. In addition, it also reviewed the mechanism of nanoparticles addition for AD system enhancement during treating different wastes as well as their effect to microbial community. Moreover, main conclusion and future trend were also presented in this review. Through summarizing the treatment effect, digestion mechanism, economic analyzation and influence on microbial community in nZVI and Fe₃O₄ NPs added AD system, the present work systematically provided theoretical basis and direction of AD system for following research and summarized practical application in future waste pollutants treatment system.

Section snippets

The properties of nZVI and Fe₃O₄ NPs

The different physical and chemical properties of NPs pointed out their wide application in different fields. Previous research has deeply characterized the properties of nZVI and Fe₃O₄ NPs via different methods (Table 1).

Among all the properties, biocompatibility is one of the most important property in biological treatment system due to its effect on microorganism. Therefore, due to the lower biocompatibility, nZVI and Fe₃O₄ NPs were widely applied to enhance the treatment efficiency and

nZVI synthesis method

Due to the better performance of nZVI in pollutants treatment process, researcher had investigated different synthesis methods, including physical and chemical methods (Table S1). According to the synthesis method, synthetic nZVI had good purity, especially the chemical synthesis method. Among the different synthesis methods, ball milling was the main physical method for nZVI production due to its simple process, high production efficiency and low cost (Kang et al., 2017). However, the

Fe₃O₄ NPs synthesis method

Fe₃O₄ NPs has wide application in environmental modification. Hence, different synthesis methods and mechanisms of Fe₃O₄ NPs were summarized in Table S2.

Among the above methods, precipitation synthesis method was the most commonly used method (Madankumar et al., 2018; Sivakumar et al., 2018) with following mechanism:Fe²⁺ + 2Fe³⁺ + 8OH⁻→Fe₃O₄ + 4H₂O

This method had some advantages, including mild reaction conditions, low price of raw materials and easy to achieve industrial manufacture. The

The change of microbial community in nZVI and Fe₃O₄ NPs added AD system

With addition of nZVI or Fe₃O₄ NPs, the microbial communities could be significantly changed in AD system (Wang et al., 2016, 2017; Zhang et al., 2018d). The main influenced microorganisms are listed in Table 4.

In nZVI added system, there were some differences on archaea and bacteria under different conditions. The abundances of Chloroflexi, Firmicutes in phylum decreased as shown in Fig. 2-A (Yu et al., 2016; He et al., 2017). And the abundance of Euryarchaeota increased in nZVI added system.

Economic and environmental consideration

Although the benefits of utilizing nZVI and Fe₃O₄ NPs in AD system are alluring, it is important to evaluate the economic and environmental influence of nZVI and Fe₃O₄ NPs addition in AD system. The previous studies mainly concerned the nZVI and Fe₃O₄ NPs addition on digestion efficiency on different pollutants. There were few researches considering the economic and environmental consideration. From the economic evaluation of iron power added in AD, the treatment system could save 272400 US$

Future perspective

nZVI and Fe₃O₄ NPs are usually used in anaerobic treatment system for their biocompatibility. The mechanism of nZVI and Fe₃O₄ NPs added AD system was summarized above. Some reaction conditions in anaerobic biological treatment process needed deeper investigation. These conditions might influence treatment effect, biogas yield and microbial communities in anaerobic treatment system. Dosage is the most important factor, which might restrict the activity of anaerobe with high dosage in AD process.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledge

This work was supported by the National Natural Science Foundation of China (grant numbers: 51678553, 21876167, 52070176),the Opening Project of the key Laboratory of Energy Utilization of Agricultural Wastes of the Ministry of Agriculture and Villages (KLERUAR2020-01), the National Key Research and Development Program of China (grant number: 2017YFD0800804-03, 2018YFD0500202-04).

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ReviewThe application status, development and future trend of nano-iron materials in anaerobic digestion system

Highlights

Abstract

Introduction

Section snippets

The properties of nZVI and Fe3O4 NPs

nZVI synthesis method

Fe3O4 NPs synthesis method

The change of microbial community in nZVI and Fe3O4 NPs added AD system

Economic and environmental consideration

Future perspective

Declaration of competing interest

Acknowledge

Renew. Energy

Energy

Adv. Drug Deliv. Rev.

J. Colloid Interface Sci.

Process Biochem.

Journal of Environmental Chemical Engineering

Appl. Catal. B Environ.

Bioresour. Technol.

Int. J. Hydrogen Energy

Chemosphere

Chemosphere

Process Biochem.

Microchem. J.

Sci. Total Environ.

Chemosphere

Process Biochem.

Anaerobe

J. Hazard Mater.

J. Hazard Mater.

Water Res.

Chemosphere

Waste Manag.

Water Res.

Water Res.

Adv. Powder Technol.

Journal of Environmental Chemical Engineering

Waste Manag.

Bioresour. Technol.

Appl. Energy

Chem. Eng. J.

Bioresour. Technol.

Bioresour. Technol.

J. Hazard Mater.

J. Hazard Mater.

Bioresour. Technol.

Bioresour. Technol.

Bioresour. Technol.

Int. Biodeterior. Biodegrad.

Renew. Energy

Bioresour. Technol.

Chem. Eng. J.

Chem. Eng. J.

Bioresour. Technol.

Int. J. Hydrogen Energy

Water Res.

Journal of Environmental Chemical Engineering

Bioresour. Technol.

Journal of the Taiwan Institute of Chemical Engineers

Phys. B Condens. Matter

Biocompatibility of silica coated NaYF(4) upconversion fluorescent nanocrystals

Biomaterials

Review
The application status, development and future trend of nano-iron materials in anaerobic digestion system

The properties of nZVI and Fe₃O₄ NPs

Fe₃O₄ NPs synthesis method

The change of microbial community in nZVI and Fe₃O₄ NPs added AD system