Trimetallic nanoparticles in anaerobic digestion process for biogas production

Nanoparticles (NPs) have emerged as an amazing class of materials with a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Metallic NPs can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. Nowadays, NPs are used in the anaerobic digestion (AD) process for enhancing biogas yield. However, NPs activity and electron exchange capacity depend on their interaction and inhibition effects on microbes in the AD process. Currently, to increase NPs activity and functionality, various organic and inorganic synthesis methods have been applied for the last two decades. In the same way, the co-precipitation method was used to prepare less hazardous, highly active NPs for microbes-to-microbes interaction compared to other methods. The present study focused on the trimetallic nanoparticles (TMNPs) made of iron (Fe), nickel (Ni), zinc (Zn), copper (Cu) and cobalt (Co) are considered the most effective materials for biomass conversion through the AD process. This study used palm oil mill effluent (POME) as biomass, and different concentrations of active TMNPs were used for biogas production. Fe-Ni-Zn, Fe-Co-Cu and Fe-Co-Zn TMNPs interact with microbes and help to degrade biomass under anaerobic conditions. At 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L and 50 mg/L TMNPs and POME-based mesophilic (37±1°C) AD was investigated for biogas production. Secondly, 20 mg/L Fe-Co-Zn TMNPs at pH 7.0 increased biogas production by 60.11% compared to the control AD. This work aims to determine ideal conditions for higher biogas with lesser TMNPs using response surface methodology (RSM). As a result, the mesophilic condition (250C -350C) of the POME-based AD process increased by 85% biogas production compared to the blank AD process (p < 0.05). However, The AD process has some limitations (TMNPs toxicity, antibacterial effects, less microbes interaction) and needs to focus on organic waste-to-energy production. Nevertheless, the biogas yield increased to 85% from moderate AD conditions with minimal Fe-Co-Zn TMNPs addition. Finally, other future perspectives worth investigating are reported to understand the microbial interaction and toxicity of TMNPs in deep for higher biogas production with lesser TMNPs concentration

The potential of poultry processing waste to generate renewable energy using Microbial Fuel Cells (MFCs)

Microbial Fuel Cell (MFCs) is a concept of applying microorganisms as catalyst in fuel cell. It works by oxidizing the electron and proton and transferred to the anode chamber under anoxic conditions to produce electricity. Microbial production of electricity might become an important form of bioenergy in future because MFCs extracting electric current from a wide range of soluble or dissolved complex organic wastes and renewable biomass. The poultry processing waste is collected from the Pusat Pemprosesan Ayam Kuantan. The double chamber MFC with three different concentration of substrate is used to generate the renewable energy from the waste. Analysis of data was performed by using a 1-way analysis-of-variance (1-way ANOVA). The significant ANOVA (P<0.05) studies shown the different in values of the monitored 4 parameters which indicates the data obtained is accurate. In this study, result analysis reveals that poultry processing waste is able to use as substrate in MFC hence able to produced energy. The maximum voltage that able to produce is 0.389V by using 1.2g of substrate concentration. Meanwhile, the MFC operation also is able to remove BOD and COD. These high levels of removal efficiency demonstrate the MFC system’s ability to treat poultry processing waste with the added benefits of generating energy

The role of iron-based nanoparticles (Fe-NPs) on methanogenesis in anaerobic digestion (AD) performance

Several strategies have been proposed to improve the performance of the anaerobic digestion (AD) process. Among them, the use of various nanoparticles (NPs) (e.g. Fe, Ag, Cu, Mn, and metal oxides) is considered one of the most effective approaches to enhance the methanogenesis stage and biogas yield. Iron-based NPs (zero-valent iron with paramagnetic properties (Fe0) and iron oxides with ferromagnetic properties (Fe3O4/Fe2O3) enhance microbial activity and minimise the inhibition effect in methanogenesis. However, comprehensive and up-to-date knowledge on the function and impact of Fe-NPs on methanogens and methanogenesis stages in AD is frequently required. This review focuses on the applicative role of iron-based NPs (Fe-NPs) in the AD methanogenesis step to provide a comprehensive understanding application of Fe-NPs. In addition, insight into the interactions between methanogens and Fe-NPs (e.g. role of methanogens, microbe interaction and gene transfer with Fe-NPs) beneficial for CH4 production rate is provided. Microbial activity, inhibition effects and direct interspecies electron transfer through Fe-NPs have been extensively discussed. Finally, further studies towards detecting effective and optimised NPs based methods in the methanogenesis stage are reported

Application of iron‐cobalt‐copper (Fe‐Co–Cu) trimetallic nanoparticles on anaerobic digestion (AD) for biogas production

Anaerobic digestion (AD) is a commercial technology for bioenergy technology, which is a naturally occurring process of various microbial actions that break down organic waste materials and produce energy as biogas. Nevertheless, AD efficiency can be reduced due to substrate loading, ammonia inhibition, low methane yield, and impure feedstock. The supplementation of various metal nanoparticles (NPs) has shown significant results for higher biogas production in the AD process. Iron (Fe)–based NPs are an essential complement to microbes for higher biogas production in the AD process. In this study, Fe-Co–Cu TMNPs were synthesized via the chemical co-precipitation method using metal salt (Fe(NO3)3, Co(NO3)2, Cu(NO3)2), and precipitants. The structure and morphology of the TMNPs are characterized by Fourier-transformation (FTIR) spectroscopy, X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM/EDX). Furthermore, the effect of Fe-Co–Cu trimetallic nanoparticles (TMNPs) in five different concentrations (0, 10, 20, 30, 40, and 50 mg/L) on palm oil mill effluent (POME)–based AD process for biogas production. The results showed that biogas yield increased by 5.66%, 7.54%, and 11.11% when using 20, 30, and 50 mg/L Fe-Co–Cu TMNPs. With the same TMNP concentration (10 mg/L and 40 mg/L), biogas yield was reduced by 26.41% and 11.11%, respectively. The economic feasibility and sustainability of Fe-Co–Cu TMNPs manufacturing and applying Fe-Co–Cu TMNPs in the AD process have been demonstrated. The assay showed the negative and positive effects of Fe-Co–Cu TMNPs in the POME-based AD process. The result of the present study indicates a possible new strategy for the preparation and design of NPs to enhance biogas production