Novel Production of Magnetite Particles via Thermochemical Processing of Digestate From Manure and Food Waste
18
Citation
17
Reference
10
Related Paper
Citation Trend
Abstract:
Sustainable management of food waste has become a global priority because of the significant environmental impacts associated with conventional disposal methods, including landfilling. Thermochemical processing is a food-waste-to-energy conversion technology in which food waste materials are converted to biofuel in a reduced O 2 environment at elevated temperatures. Another conversion technology is anaerobic digestion, in which microorganisms digest biodegradable material, producing biofuel and solid byproducts "digestate." We measured the physical properties of "biochar" produced by combining these approaches: digestate was used as feedstock for a commercial-scale thermochemical processing system. Magnetite (Fe 3 O 4 ) particles were produced during the food-waste-to-energy conversion process. This was particularly unexpected because none of the input materials were ferromagnetic, and no specific Fe precursors were introduced in the process. The Fe 3 O 4 was identified through a combination of X-ray fluorescence and dc magnetometry. Zero-field cooled magnetization-temperature curves reveal a Verwey transition at ~125 K across samples prepared under various conditions. Room temperature magnetization-field loops show a Langevin-like curve, technical saturation, and coercive fields of H C = 98-130 Oe across various samples. Clear Verwey transition, room temperature hysteresis, and an irreversibility temperature well above room temperature indicate that particles are multidomain. We attribute the presence of Fe 3 O 4 to the relatively high concentration of Fe naturally present in the solid digestate and the operating parameters of the thermochemical conversion process. High surface area magnetic biochar has a variety of potential applications, including the adsorption of heavy metals, wastewater treatment, supercapacitors, and conductive polymer composites.Keywords:
Digestate
Digestate
Biogas
Cite
Citations (58)
Summary This paper focuses on increasing quantities of digestate which is a final product of anaerobic digestion in biogas stations used as alternative sources of energy or as fermenting facilities which can reduce the quantities of biodegradable wastes on landfills. Digestate is a stabilised material produced by anaerobic digestion in a biogas station in addition to the main product - biogas. Potential use of digestate is limited due to its rather specific physical properties. In particular, individual components in digestate are extremely difficult to separate and its chemical or microbiological composition is special. The quality of digestate is affected mostly by the type of biomass. This paper presents current approaches to digestate and digestate management. It also includes taking and analysing digestate samples, processing of the samples in laboratory centrifuges and assessing the properties of digestate and separation products, i.e. the sludge liquor and separatum.
Digestate
Biogas
Cite
Citations (6)
The EU is currently addressing the problem of depletion of phosphate, which is a source of phosphorus. Due to the usage of modern digestate treatment enabling macroelements recycling, the digestate can be a suitable substitute for anorganic fertilizers. This experiment is focused on improving the soil properties due to digestate application in sugar beet growing region. Applicated digestate comes from a biogas plant of agricultural cooperative Velesovice. The obtained results show better physical properties (soil structure, stability of soil aggregates) and differences in pH values, Cox (%) and nutrient content between variants.
Digestate
Biogas
Cite
Citations (2)
Biogas plants are installations based on the anaerobic digestion process. As a result of the biodegradation of various substrates and waste from agriculture, biogas and digestate, which is the second product of the process, are produced. The most popular method of digestate management is its use as fertilizer, without prior processing. However, there are much more possibilities for the management of digestate and its fractions resulting from separation. The aim of the study was to discuss issues related to the properties and management of digestate from agricultural biogas plants. Due to its properties, digestate can be managed in many ways, in accordance with the circular bioeconomy and sustainable development rules. The paper discusses issues such as the production of digestate, separation into fractions, and the use of individual fractions, e.g. for fertilization and energy purposes. Analyzing the results from own research and other research available in the scientific literature, it was found that digestate is a valuable raw material with wide possibilities of its use.
Digestate
Biogas
Cite
Citations (0)
The aim of the present study was to investigate the amount of CH4, CO2 and NH3 in biogas digestate by laboratory experiments. For these experiments, fresh digestate (FD), solid fractions (SFD) and liquid fractions (LFD) of digestate as well as untreated digestate from the secondary fermenter (SD) were used. Gas release was measured by Fourier transform infrared spectrometry. Based on the total solids content, the highest amount of NH3 was released from LFD followed by SD. SFD and FD released similar amounts of NH3. CH4 was released from all digestates, with the exception of SFD. Stirring of digestates at 90 °C led to CH4 concentrations of 237.6 µg·gTS−1 released from LFD, 40.8 µg·gTS−1 from SD and 71.7 µg·gTS−1 from FD after 10 min. CO2 release from digestate is high compared to release of NH3 and CH4, although degassing was not completed within the experimental period. Digestate degassing experiments conducted while stirring at high temperatures are suitable to determine digestate gas-release potential.
Digestate
Biogas
Industrial fermentation
Cite
Citations (0)
Functioning of an agricultural biogas plant is connected with generating large amounts of post-digestion matter. After considering the physicochemical properties, the basic direction of digestate utilization should be its use as a fertilizer. A possibility of agricultural utilization of digestate as a fertilizer was investigated. Digestate obtained from an agricultural biogas plant was tested for the content of macroelements and heavy metals. The content of macroelements in the soil was also examined before and after digestate application. Digestate was used in alfalfa cultivation. The analysis showed an increase in macroelements content in alfalfa leaves. It was found that digestate can be used as a fertilizer.
Digestate
Biogas
Cite
Citations (196)
The aim of this study was to assess the feasibility of moderate thermal treatment (70 °C for one hour) of digestate in combination with post-digestion targeting residual biomethane potentials from three full-scale biogas plants digesting food waste (FW), agricultural waste (AW) and a mixture of AW and manure (AWM). Dissolved organic carbon (DOC), biomethane production, and digestate quality were investigated. For the study six laboratory-scale continuously stirred tank biogas reactors working as post-digesters, with thermally-treated and non-treated digestate were used. DOC for thermally-treated digestates increased significantly (t-test, p < 0.05); FW-digestate (110–200 %), AW-digestate (24–92 %) and for AWM-digestate (4–73 %). Indexes for corresponding DOC quality showed lower apparent organic molecular weights and decreased aromaticity (with the exception of FW-digestate). Thermal treatment of digestate improved the biomethane production during post-digestion by 21–22 % (FW-digestate) and 9 % (AW-digestate). For AMW-digestate no clear positive effect was observed, most likely due to biogas plant operational process disturbances.
Digestate
Biogas
Food Waste
Cite
Citations (0)
This study assessed how digestate and the liquid fraction (LF) of digestate would perform as candidate RENURE fertilisers (recovered nitrogen from manure) in nitrate vulnerable zones under the proposed criteria of the Joint Research Centre, namely, (i) a mineral nitrogen to total nitrogen ratio ≥ 90% (Nmin:TN ≥ 90%) or a total organic carbon to TN ratio ≤ 3 (TOC:TN ≤ 3); (ii) limits of ≤300 copper (Cu) mg kg−1 and ≤800 Zinc (Zn) mg kg−1. These criteria were applied to unpublished data (n = 2622) on digestate compositional properties, further amended with data from the literature (n = 180); digestate analysis from seven full-scale biogas facilities (n = 14); and biogas industry stakeholders (n = 23). The results showed that Cu and Zn mostly met the criteria, with compliance rates of 94.7% (of 1035 entries) and 95.0% (of 1038 entries), respectively. Just above 5% (of 1856 entries) met the Nmin/TN ≥ 90% criterion, while 36% (of 1583 entries) met the TOC/TN ≤ 3 criterion, while total compliance was 32% (of 1893 entries). When targeting the LF, total compliance increased noticeably, between 43 and 58% depending on DM range, indicating that LFs are better suited RENURE candidate fertilisers than unseparated digestate.
Digestate
Biogas
Cite
Citations (42)
Digestate
Biogas
Cite
Citations (6)
Substantial insight into the effect of ultrasound disintegration on the changes in biochemical parameters of manure digestate and digestate age is needed to understand the potential of digestate treatment. To address this knowledge gap, in this study, the effect of digestate age on the efficiency of ultrasound (US) disintegration was investigated. In this scope, dairy manure digestate samples were incubated in an oven at 37 °C for a predetermined amount of time to obtain simulated digestate ages of 15, 22, 29, 36 and 43 days. The results showed that US disintegration efficiency significantly affected the initial biochemical characteristics of digestate and that the digestate age had a significant effect on the US disintegration efficiency. This effect diminished when the applied specific energy (SE) was higher than 3000 kJ/kg total solids (TS). A numerical partial least squares (PLS) model was constructed to investigate the relative influences of the initial biochemical parameters on the soluble chemical oxygen demand (sCOD) and soluble carbohydrates (sCARB) solubilization. The results of the high-quality (R2 = 0.8) model indicated that the most influential parameters for the efficiency of US disintegration were the SE, the initial sCARB0, the TS, the initial sCOD0 and the volatile solids (VS).
Digestate
Cite
Citations (3)