Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review (original) (raw)
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The Influence of Trace Elements on Anaerobic Digestion Process
Civil and Environmental Engineering Reports, 2018
The article is the literature review on the importance of trace elements supplementation in the methane fermentation process. The production of biogas, including methane, as well as the efficiency of the process depend on the substrates to be fermented. Substances supplied with the substrate as well as products generated in the decomposition phases can inhibit the process. The factor limiting fermentation is the rate of enzymatic hydrolysis of substrates. Certain compounds, such as alkanes, alkenes, biphenol, aromatic hydrocarbons, alcohols and ketones, are not directly susceptible to hydrolysis. They undergo this process in the presence of extracellular enzymes. The instability of the methane fermentation process described in the literature may be related to the lack of trace elements or micronutrients. Trace elements (Co, Ni, Cu, Mn, Fe, Zn, Se and Mo) are components of enzymes, some bacterial nucleic acids and essential for the synthesis of vitamins. The role of some trace elemen...
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Demirel B. and Scherer P. (2011). Trace element requirements of agricultural biogas digesters during biological conversion of renewable biomass to methane. Biomass and Bioenergy 35(3), 992-8. Evranos B. and Demirel B. (2015). The impact of Ni, Co and Mo supplementation on methane yield from anaerobic mono-digestion of If you have any queries, ideas or interest in the TE supplementation work please contact the COST ES1302 representatives in your country:
The Role of Trace Elements on Anaerobic Co-digestion in Biogas Production
In this study, we investigated the concentration of trace elements in the digestates in a laboratory batch anaerobic digester. Many of these trace elements are important macro and micro nutrients. The availability of these nutrients for microbes responsible for anaerobic digestion and substrate toxicity have to be controlled in biogas production. The analyzed substrates were characterized at various concentrations in the following trace elements; potassium, phosphorus, manganese, copper, calcium, molybdenum, zinc, cobalt, iron, aluminum, silver, nickel and cadmium. Trace elements like copper, silver, nickel, cadmium, zinc have been reported to be inhibitory and toxic under certain conditions in biochemical reaction depending on their concentrations. These trace elements lower biogas production above threshold concentration due to accumulation of organic acid as a result of methanogenic bacterial inhibition. There was no deficit of nutrients detected in the anaerobic digesters analysis.
Trace metals are essential for the enzyme cofactors involved in the biochemistry of methane formation and are needed in a balanced anaerobic digestion process. Food and kitchen waste generally contains low concentrations of trace elements, especially metals. As a consequence the anaerobic digestion process may result instable. The aim of this study is to evaluate the effect of metals addition on mesophilic anaerobic digestion of food waste, both in batch tests and in laboratory scale CSTR reactors. Batch anaerobic trials using source-separated food waste as substrate with inoculums of different origins were carried out under mesophilic conditions. Reactions were operated both with and without trace elements (Co, Mo, Ni, Se, W) supplementation. Supplementation with trace metals had either neutral or slightly negative effects with inoculums originating from reactors with a high background level of metals, such as those for the co-digestion of biowaste and waste activated sludge. For i...
Frontiers in Environmental Science, 2016
This paper discusses the potential to enhance the anaerobic digestion of food waste FW by supplementing trace elements (Fe, Co, Ni, Zn, Mn, Cu, Se, and Mo) individually as well as in cocktails. A series of batch experiments on the biomethane potential of synthetic food waste were performed with low (FW-A) and high (FW-B) trace element background concentrations prepared in, respectively, Delft (The Netherlands) and Tampa (Florida, USA). The most effective trace elements for FW-A were Fe with an increase of 39.2 (±0.6)% of biomethane production, followed by Se (34.1 ± 5.6% increase), Ni (26.4 ± 0.2% increase) and Co (23.8 ± 0.2% increase). For FW-B supplementing these trace elements did not result in enhancement of the biomethane production, except for Se. FW-B had a Se concentration of 1.3 (±0. 5) µ g/gTS, while it was below the detection limit for FW-A. Regardless of the FW source, Se resulted in 30-35% increase of biomethane production at a concentration range of 25-50 µg/L (0.32-0.63 µM). Volatile fatty acids analysis revealed that TE supplementation enhances their consumption, thus yielding a higher biomethane production. Moreover, additional experiments on sulfide inhibition showed the enhancing effects of trace elements on the anaerobic digestion of food waste were not related with sulfide toxicity, but with the enzymatic reactions and/or microbial biomass aggregation.
Environmental science and pollution research international, 2018
Trace elements (TEs) play an indispensable role in enhancing the stability of anaerobic digestion (AD) of food waste (FW). Significant research on AD of FW with TE supplementation has been conducted with low Fe content inoculum. However, the use of Fe-rich inoculum is inevitable due to chemical phosphorous removal from wastewater in North America. We conducted comprehensive mesophilic batch tests to investigate the effect of TEs (Fe, Ni, Co, Se, and Mo) on FW digestion inoculated with Fe-rich sludge (≥ 1000 mg Fe L). This paper presents the impact of supplementing various concentrations of TEs on specific methanogenic activity (SMA), maximum specific methane production rate (SMPR), and apparent hydrolysis rate constant (K). The addition of TEs adversely impacted methanogenic activity by 20 to 58% in the SMA tests. The effects of individual and mixed supplementation of TEs on the SMPR and K during FW digestion were negligible; exceptions include Fe, Mo, and Co. Final soluble TE conce...
Trace metals are essential for the growth of anaerobic microorganisms, however, in practice they are often added to anaerobic digesters in excessive amounts, which can lead to inhibition. The concept of bioavailability of metals in anaerobic digestion has been poorly understood in the past, and a lack of deep understanding of the relationship between trace metal speciation and bioavailability can result in ineffective metal dosing strategies for anaerobic digesters. Sequential extraction schemes are useful for fractionating trace metals into their different forms, and metal sulfides can serve as a store and source for trace metals during anaerobic digestion, while natural/synthetic chelating agents (soluble microbial products-SMPs, extracellular polysaccharides-EPS, and EDTA/NTA) are capable of controlling trace metal bioavailability. Nevertheless, more work is needed to: investigate the speciation and bioavailability of Ca, Mg, Mn, W, and Se; compare the bioavailability of different forms of trace metals e.g. carbonates, sulfides, phosphates to different anaerobic trophic groups; determine what factors influence metal sulfide dissolution; investigate whether chelating agents can increase trace metal bioavailability; develop and adapt specialized analytical techniques, and; determine how trace metal dynamics change in an anaerobic membrane bioreactor (AnMBR).
Enhancement of Thermophilic Digestion of Food Waste (FW) via Trace Element Supplementation
Journal of Chemical Engineering Research Updates, 2019
In this study, the role of trace element (TE) supplementation and performance characteristics of a thermophilic anaerobic digester fed by food wastes (FW) is investigated in the long run, and a representative operational data set for field application is reported over the whole experimental period. Continuous feeding of food wastes with a dry matter of 5% for 150 days was carried out using a 100 L pilot-scale CSTR type anaerobic digester under thermophilic operation conditions. Hydraulic retention time (HRT) and organic loading rate (OLR) were kept around 28 days and less than 3.0 kg oDM m 3 day-1 , respectively. Volumetric biogas production values were reported to be 0.32 m 3 m-3 day-1 during the period where there is no TE supplementation; on the other hand, biogas production was doubled (0.69 m 3 m-3 day-1) following TE supplementation. This corresponds to an average unit biogas production of 317 and 443 L kg-1 oDM, during TE supplementation and no TE supplementation periods, respectively. Statistical analysis indicated that Co, As, Se, and Al were the most significant trace elements affecting the digester performance.
Bioavailability and Toxicity of Metal Nutrients during Anaerobic Digestion
Journal of Environmental Engineering, 2007
This paper investigates the effect of chelating agents on the bioavailability of Fe and Cu during anaerobic digestion. The results on metal speciation and methane production in anaerobic serum bottles showed that biomass was able to grow in the presence of citrate 1 mM and nitrilotriacetic acid ͑NTA͒ 1 mM, suggesting that the binding sites at the cell surface competed efficiently for the metals with the chelating agents added. The presence of free ethylenediaminetetraacetic acid 1 mM inhibited methanogenesis, and this seemed to be related to a loss in metal uptake capacity. Although the addition of soluble microbial products ͑SMP͒ did not change metal distribution in anaerobic systems, it caused an increase in the rate of methane production, and it is believed that direct uptake of Cu-SMP complexes was responsible for this increase. The best protection against Cu toxicity occurred when stoichiometric amounts of NTA, which should complex and solubilize most of the Cu, was added, and it is likely that NTA prevented lethal concentrations of Cu from being adsorbed onto the cell and hence internalized.