The Authors are grateful for the financial support received from the European Commission under the CharM and AdvCharM of the Climate-KIC Programme and from the Spanish Ministry of Science, Innovation and Universities under RTC-2017-6087-5 of the &#x201C;Investigaci&#x00F3;n, Desarrollo e Innovacion Orientada a los Retos de la Sociedad&#x201D; Programme and under the Severo Ochoa program (SEV-2016-0683).

1. Hydrothermal carbonization of household leftovers
<ol>
	<li>Calculation of the suitable amounts of water and biomass for the reaction mixture.
	<ol>
		<li>The reaction mixture must fill half of the volume of the autoclave. Assume that the density of the mixture is approximately 1 g/mL and calculate the amounts by weight. Approximately 80 wt% should be water and the rest solid matter. Overall water content is not crucial and may range from 70 to 85 wt%.</li>
		<li>Select the biomass from kitchen leftovers such as fruit peels or inedible vegetable parts. With the aim to calculate an exact mass balance for section 1, dry a sample of the biomass at 100&#8211;105 &#176;C in an oven for 2 h or overnight. The obtained mass is the solid matter of the biomass. Alternatively, use literature data (accuracy is reduced).</li>
		<li>Calculate how much wet biomass is required to charge the autoclave with 20 wt% of solid matter and how much of water is to be introduced together with it. Calculate how much water is required to reach the desired water amount in the reactor.</li>
	</ol>
	</li>
	<li>Charging the autoclave. 
	CAUTION: The autoclave has to be provided with a rupture disc with a burst pressure of 50 bar.
	<ol>
		<li>Weigh biomass and water as calculated in step 1.1.3 and introduce both into the autoclave.</li>
		<li>Close the autoclave and pressurize it with nitrogen up to 20 bar. Confirm that there is no pressure loss over 30 min. This ensures that the vessel is properly closed without any leaks. Release the pressure and close the vessel again.</li>
	</ol>
	</li>
	<li>Carbonization reaction.
	<ol>
		<li>Switch on the stirring. Heat the autoclave to 215 &#176;C within 30 min and maintain the temperature for at least 4 h or overnight.</li>
		<li>Monitor the pressure for the first 2 h. In general, it follows the vapor pressure curve of water up to 21 bar. If the pressure does not increase, either the heating is not working correctly, or the vessel is not closed properly. If this happens, stop the reaction and check the heating and sealing.</li>
		<li>In rare cases, e.g., if the biomass is prone to decarboxylation, the maximum pressure might be 5 to 10 bar higher than the 21 bar caused by steam pressure at 215 &#176;C. If the pressure exceeds 35 bar, switch off the heating and interrupt the reaction. After it has cooled down to room temperature carefully release the remaining pressure and start again from step 1.3.1.</li>
	</ol>
	</li>
	<li>Recovery of the raw hydrochar.
	<ol>
		<li>When the autoclave has cooled down to room temperature by natural cooling, carefully release any residual pressure and open the autoclave.</li>
		<li>Separate solid and liquid by vacuum filtration with a Buchner funnel. Dispose the of the liquid phase as aqueous solution among hazardous laboratory waste.</li>
		<li>Dry the solid at 100 to 105 &#176;C in an oven for 2 h or overnight. Calculate the mass balance of the first step, i.e. the hydrothermal carbonization (section 1). For this, take into account dry weight of the biomass and dry weight of the product.</li>
	</ol>
	</li>
</ol>
2. Thermal treatment of raw hydrochar in batch mode
<ol>
	<li>Weigh 1 g of dry raw hydrochar and place it on a glass frit of a tubular quartz reactor (batch reactor).</li>
	<li>For larger amounts such as 10 to 20 g, use pelletized material with a particle size of 0.2 to 6 mm. Otherwise, the occurrence of preferred channels might impede homogeneous treatment of the sample.</li>
	<li>Place the heating mantle of the reactor and connect a down-flow nitrogen stream of 20 mL/min. Place a small beaker below the reactor outlet to collect condensed liquids. Cooling is not required.</li>
	<li>Aspirate gases at the outlet and conduct them to the exhaust or place the whole reactor in an exhaust hood. Heat the reactor to 275 &#176;C with a ramp of 10 degrees/min. Maintain the temperature for 1 h.</li>
	<li>When cooled down to room temperature again, disconnect the gas flow. Discard the liquid collected in the beaker to the nonhalogenated organic residues. Recover the carbon material and weigh it. Calculate the mass balance for section 2, i.e. the thermal treatment, from the masses employed and obtained, and for the overall reaction from the mass obtained in the thermal treatment and the dry biomass employed in the carbonization step.</li>
</ol>
3. Analysis of the final product by thermogravimetry (TG)
<ol>
	<li>Crush the product in a mortar and weigh a 10 mg sample in a crucible of the apparatus.</li>
	<li>Place the crucible in the autosampler of the TG apparatus and select the analysis conditions: adjust the maximum temperature to 600 &#176;C and the employ air as sweep gas and a temperature ramp of 10 degrees/min.</li>
	<li>Start the analysis.</li>
	<li>Quantify the mass loss at 275 &#176;C in the TG curve by calculating the difference between initial weight and that observed at this temperature (see Figure 2). Express the mass loss as percentage of the initial weight. Compare the values of treated and raw samples. A clear reduction is observed.</li>
</ol>

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Marisa Hernandez and Borja Oliver-Tomas are employees of Ingelia SL that produced hydrochar samples used in this article. Maria Consuelo Hern&#x00E1;ndez-Soto, Estefan&#x00ED;a Ponce, and Michael Renz have nothing to disclose.

The hydrothermal carbonization is a very resilient method and always provides a carbonaceous product, i.e., the hydrochar. However, yield and properties of the hydrochar might vary, not only due to reaction conditions or reaction control, but rather due to heterogeneity and variation of the biomass. For instance, mass yield and C content might be higher for lignocellulosic biomass with a higher lignin content or woody materials.
In the case that a higher carbonization degree (quantified by elemental analysis) is desired, the hydrochar can be resubmitted to the carbonization reaction. Alternatively, in future reactions reaction time can be prolonged or reaction temperature can be increased (caution, autogenous water pressure increases exponentially with temperature).
The outcome of the thermal treatment also depends on the composition of the raw material. For instance, if the biomass involves other organic components such as vegetable oil, the thermal treatment will separate these volatile compounds from the solid and mass loss will be greater.
In the present protocol, both steps are carried out in batch mode. For industrial application, the whole production process has to be carried out in continuous mode. The hydrothermal carbonization is already carried out as a continuous process26,27, but the thermal treatment still has to be developed further. The final aim is to convert the OFMSW into a carbonaceous material with peat properties so that employing peat (considered to be a fossil material) increases in agriculture and horticulture with clear benefits for the environment and as a contributor to climate change mitigation.

Hydrothermal carbonization (HTC) is an emerging technology for waste management of wet, lignocellulosic resources. This technology was rediscovered by Antonietti and Titirici and applied to pine needles, pine cones, oak leaves and orange peels1. Thereby, the biomass is converted into hydrochar, a carbonaceous solid similar to lignite2,3 or peat4,5. Since then, many residual feedstocks have have processed such as agro-industrial waste6,7,8, the organic fraction of municipal solid waste (OFMSW)9, or paper mill sludge10. The technology is also used as biomass pretreatment for pyrolysis and gasification11. In addition, the procedure provides modern nanotechnology materials from homogeneous renewable resources such as sugars or cellulose. These advanced materials have potential for future applications as electrodes for rechargeable batteries, fuel cells or supercapacitators, gas storage, sensors or drug delivery12,13.
Hydrochar is a carbon material and as such it could be used as renewable solid fuel, especially when produced from low-value, heterogeneous resources with variable (seasonal or regional) composition. However, hydrochar production and its application to soil, instead of its immediate combustion, will have a triple contribution to climate change mitigation. First, choosing HTC as waste management technology avoids emission of the powerful greenhouse gas methane during composting or uncontrolled decomposition14,15. Second, avoiding combustion of hydrochar after a short period of time and applying it to soil, removes the carbon dioxide from the atmosphere for a longer period of time, i.e., it consists in real carbon capture and storage (CCS)16,17. Third, in general, char amended soils are more fertile soils (black soils) and plant growth is increased.18,19 This reduces fertilizer use and carbon dioxide emissions related to their production, besides preserving resources. Moreover, additional plant growth removes more carbon dioxide from the atmosphere.
Although it is quite clear that there are many apparent arguments for the application of hydrochar to soil, the material involves an inconvenience: raw hydrochar does not behave exactly as biochar that is produced by pyrolysis. Hydrochar does not clearly increase plant growth or even worse, frequently it causes a rather negative effect20,21,22. Therefore, farmers are not encouraged to apply it, and even less to pay money for it. Fortunately, this drawback can be mitigated or eliminated. The easiest approach is to simply wait for the second cultivation cycle22. Also washings20,21,22,23 or co-composting24 are successful treatments for this purpose. However, all these procedures require time or produce an aqueous stream that need further care.
Recently, it has been shown that raw hydrochar can be subjected to a soft thermal post-treatment25. The aim of this procedure is to simply desorb the undesired volatile and harmful substances. The resulting concentrated flow of mainly organic matter can be valorized thermally in situ. As such, the energy balance of the HTC plant is improved and any environmental risk of the side stream is prevented. Germination tests show that the treatment is successful when carried out at temperatures of 275 &#176;C or higher.
The present protocol (see Figure 1) involves two reaction steps and one straightforward analytical method for the evaluation of the reaction outcome. During the first step, biomass is converted into raw hydrochar in an autoclave at 215 &#176;C and at 21-bar pressure. Here, household leftovers are employed as starting material. These include all kinds of vegetable material such as fruit peels, fruit stones, inedible vegetable parts, coffee grounds, kitchen paper, compostable plastic bags, etc. The carbonaceous material is collected by filtration and dried. For the second step, it is placed on a glass frit of a vertical tubular reactor applying gas flow in a downward flow direction. The tube is heated to 275 &#176;C for 1 h. The resulting solid is analyzed by thermogravimetry (TG) in air. The material loss up to 275 &#176;C is quantified and compared to the loss observed with untreated hydrochar. The carbon material can be further characterized by elemental analysis (C, H, N, and S), ash content and ash composition (mainly Ca, Al, Si, and P).

<table><tbody><tr><td>Autoclave with a vessel volume of 100 to 500 mL</td><td></td><td></td><td></td></tr><tr><td>Continuous flow tubular calcination reactor with glass frit</td><td></td><td></td><td>Cuartz tube: 37 cm long, 20 mm outer diameter, glass frit (3 mm thickness) at 22 cm from the top of the tube</td></tr><tr><td>Vacuum filtration system</td><td></td><td></td><td>Buchner funnel, filter paper, filter flask</td></tr><tr><td>Oven for drying samples at 100 &amp;deg;C</td><td></td><td></td><td></td></tr><tr><td>Thermogravimetric analyzer</td><td></td><td></td><td>E.g. Netzsch STA 449F3 Jupiter with Netzsch STA 449F3 software and Netzsch ASC Manager software for autosampler control</td></tr><tr><td>Any king of vegetable biomass (for examples see tables 1 and 2) including:</td><td></td><td></td><td></td></tr><tr><td>Compostable plastic bags from BASF</td><td></td><td></td><td></td></tr><tr><td>Plastic bags for collection of the organic fraction in households, provided by local waste managers</td><td></td><td></td><td></td></tr><tr><td>Compostable coffee capsules ecovio (BASF)</td><td></td><td></td><td></td></tr></tbody></table>

transformation of organic household leftovers into a peat substitute

A two-step procedure is described for the synthesis of a carbon material with a similar composition and properties as peat. The produced hydrochar is made suitable for agricultural applications by removing plant growing inhibitory substances. Wet household waste such as fruit peel, coffee grounds, inedible vegetable parts, or wet lignocellulosic material in general, are treated in presence of water at 215 &#x00B0;C and 21 bar in an autoclave, i.e., by hydrothermal carbonization. All these leftovers have a considerable water content of up to 90 weight % (wt%). Adding water extends the procedure to drier materials such as nutshells or even garden prunings and compostable polymers, i.e., the plastic bag for collection of the leftovers.
Usually, the resulting carbon material, called hydrochar, produces a negative effect on plant growth when added to soil. It is supposed that this effect is caused by adsorbed phytotoxic compounds. A simple post-treatment under inert atmosphere (absence of oxygen) at 275 &#x00B0;C removes these substances. Therefore, the raw hydrochar is placed on a glass frit of a vertical tubular quartz reactor. A nitrogen gas flow is applied in down-flow direction. The tube is heated to the desired temperature by means of a heating mantle for up to one hour.
The success of the thermal treatment is easily quantified by thermogravimetry (TG), carried out in air. A weight loss is determined when the temperature of 275 &#x00B0;C is reached, since volatile content is desorbed. Its amount is reduced in the final material, in comparison to the untreated hydrochar.
The two-step treatment converts household leftovers, including compostable bags employed for their collection, into a carbon material that may serve as plant growth promoter and, at the same time, as a carbon sink for climate change mitigation.

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Transformation of Organic Household Leftovers into a Peat Substitute

A protocol for hydrothermal carbonization of vegetable food waste in an autoclave is presented, with subsequent dry thermal treatment at 275 &#x00B0;C in a continuous flow reactor desorbing volatile organic substances. The aim is to produce a carbon material suitable as soil amendment product or substrate component.

A two-step procedure is described for the synthesis of a carbon material with a similar composition and properties as peat. The produced hydrochar is made ...

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8.3K Views.  Universitat Politècnica de València-Consejo Superior de Investigaciones CientÍficas. Wij produceren een turfvervanger van resten. Deze procedure heeft een potentieel voor de organisatie van organisch afval. Exacte samenstelling doet er niet toe en seizoensvariaties worden getolereerd.Het biedt een alternatief voor het gebruik van hydrochar als vaste brandstof en helpt daarmee de klimaatverandering te beperken door koolstofafvang en -opslag en het besparen van fossiele meststoffen. Het is zeer belangrijk om de buitenste klemmen strak te sluiten of de samenstelling van d...

Video: Transformation of Organic Household Leftovers into a Peat Substitute

Methods for Facilitating Microbial Growth on Pulp Mill Waste Streams and Characterization of the Biodegradation Potential of Cultured Microbes

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor.

Industrial wastes can be collected and modified to analyze microbial growth. Lignocellulose extraction techniques provide components to analyze specific biodegradation ability. Gas chromatography-mass spectrometry identifies fermentation products of microorganisms grown on pulping waste. These methods determine the metabolic capacity of microorganisms to degrade pulping waste.

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high ...

Environment

Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production

Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 &#176;C) and thermophilic (55 &#176;C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 &#176;C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 LCH4/kgVS&#160;(VS: volatile solids) and 121 L CH4/kgVS&#160;at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kgdry_biochar was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only.

A novel Upflow Anaerobic Solid State (UASS) reactor was used for biogas production from fibrous feedstock. Digestate from UASS reactor was hydrothermally carbonized into HTC biochar in a pressurized batch reactor. The integration of the two bioenergy concepts was applied in this study to increase overall bioenergy production.

Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal ...

Single-throughput Complementary High-resolution Analytical Techniques for Characterizing Complex Natural Organic Matter Mixtures

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to characterize. However, to understand the thermodynamic and kinetic controls on greenhouse gas (carbon dioxide [CO2] and methane [CH4]) production resulting from the decomposition of NOM, a molecular-level characterization coupled with microbial proteome analyses is necessary. Further, climate and environmental changes are expected to perturb natural ecosystems, potentially upsetting complex interactions that influence both the supply of organic matter substrates and the microorganisms performing the transformations. A detailed molecular characterization of the organic matter, microbial proteomics, and the pathways and transformations by which organic matter is decomposed will be necessary to predict the direction and magnitude of the effects of environmental changes. This article describes a methodological throughput for comprehensive metabolite characterization in a single sample by direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), gas chromatography mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography mass spectrometry (LC-MS), and proteomics analysis. This approach results in a fully-paired dataset which improves statistical confidence for inferring pathways of organic matter decomposition, the resulting CO2 and CH4 production rates, and their responses to environmental perturbation. Herein we present results of applying this method to NOM samples collected from peatlands; however, the protocol is applicable to any NOM sample (e.g., peat, forested soils, marine sediments, etc.).

This protocol describes a single throughput for complementary analytical and omics techniques culminating in a fully-paired characterization of natural organic matter and microbial proteomics in different ecosystems. This approach permits robust comparisons for identifying metabolic pathways and transformations important for describing greenhouse gas production and predicting responses to environmental change.

Natural organic matter (NOM) is composed of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to ...

Reducing Willow Wood Fuel Emission by Low Temperature Microwave Assisted Hydrothermal Carbonization

Biomass is a sustainable fuel, as its CO2 emissions are reintegrated in biomass growth. However, the inorganic precursors in the biomass cause a negative environmental impact and slag formation. The selected short rotation coppice (SRC) willow wood has a high ash content (<img alt="Equation 1" src="/files/ftp_upload/58970/58970eq1.jpg" /> = 1.96%) and, therefore, a high content of emission and slag precursors. Therefore, the reduction of minerals from SRC willow wood by low temperature microwave assisted hydrothermal carbonization (MAHC) at 150 &#176;C, 170 &#176;C, and 185 &#176;C is investigated. An advantage of MAHC over conventional reactors is an even temperature conductance in the reaction medium, as microwaves penetrate the whole reactor volume. This allows a better temperature control and a faster cooldown. Therefore, a succession of depolymerization, transformation and repolymerization reactions can be analyzed effectively. In this study, the analysis of the mass loss, ash content and composition, heating values and molar O/C and H/C ratios of the treated and untreated SCR willow wood showed that the mineral content of the MAHC coal was reduced and the heating value increased. The process water showed a decreasing pH and contained furfural and 5-methylfurfural. A process temperature of 170 &#176;C showed the best combination of energy input and ash component reduction. The MAHC allows a better understanding of the hydrothermal carbonization process, while a large-scale industrial application is unlikely because of the high investment costs.

A protocol for the emission precursor depletion from low quality biomass by low temperature microwave assisted hydrothermal carbonization treatment is presented. This protocol includes the microwave parameters and the analysis of the biocoal product and process water.

Biomass is a sustainable fuel, as its CO2 emissions are reintegrated in biomass growth. However, the inorganic precursors in the biomass cause a negative ...

Carbon Sequestration and Soil Enhancement Through Onsite Biochar Production

Producing, Characterizing and Quantifying Biochar in the Woods Using Portable Flame Cap Kilns

One of the biggest challenges in utilizing non-commercial forest biomass is its widely distributed nature. The best solution to the biomass problem, to avoid expensive and carbon-intensive processing (chipping) and transportation costs, is to process it onsite. However, conventional burn piles have destructive impacts on forest soil and provide no benefits other than fuel reduction. Converting forest slash to biochar onsite has many ecological advantages over the current practice of slash disposal by incineration in burn piles, including reduced soil heating and particulate emissions, along with multiple benefits of the biochar to forest soil health and water holding capacity when left in place. Making biochar onsite in the woods is a way to return a pyrogenic carbon component to forest soils that has been missing due to the recent history of fire suppression. Biochar is also a leading method of carbon removal and sequestration for climate change mitigation. In this study, we document a method for making biochar using a portable biochar kiln. This low-cost method utilizes hand crews equipped with water for quenching kilns before the biochar burns to ash. Simple techniques for quantifying and characterizing the biochar produced are incorporated into the method for the purpose of measuring impact and qualifying for carbon removal certificates to help pay for the cost of the work. We describe the CM002 Component Methodology that provides standardized procedures for the quantification of GHG benefits during three stages of the process: waste biomass sourcing, biochar production, and biochar soil application. The CM002 Methodology is based on international best practices, including the most recent VCS methodology VM0044 Standards and EBC C-Sink Artisan Standards. Reliable quantification methods utilizing appropriate safety factors are the first essential step toward eligibility for carbon removal finance.

Author Spotlight: On-Site Biochar Production for Woody Debris Incineration in Forestry 

New methods for disposing of forestry slash piles in place produce pyrogenic carbon for restoring forest soil health and for carbon removal and sequestration. Here, we present a biochar production method integrating a new carbon removal accounting methodology and a digital application.

One of the biggest challenges in utilizing non-commercial forest biomass is its widely distributed nature. The best solution to the biomass problem, to ...

Microalgal Cultivation for Biomethane Obtention from Swine Waste Biogas

Biogas Purification through the use of a Microalgae-Bacterial System in Semi-Industrial High Rate Algal Ponds

In recent years, a number of technologies have emerged to purify biogas into biomethane. This purification entails a reduction in the concentration of polluting gases such as carbon dioxide and hydrogen sulfide to increase the content of methane. In this study, we used a microalgal cultivation technology to treat and purify biogas produced from organic waste from the swine industry to obtain ready-to-use biomethane. For cultivation and purification, two 22.2 m3 open-pond photobioreactors coupled with an absorption-desorption column system were set up in San Juan de los Lagos, Mexico. Several recirculation liquid/biogas ratios (L/G) were tested to obtain the highest removal efficiencies; other parameters, such as pH, dissolved oxygen (DO), temperature, and biomass growth, were measured. The most efficient L/Gs were 1.6 and 2.5, resulting in a treated biogas effluent with a composition of 6.8%vol and 6.6%vol in CO2, respectively, and removal efficiencies for H2S up to 98.9%, as well as maintaining O2 contamination values of less than 2%vol. We found that pH greatly determines CO2 removal, more so than L/G, during cultivation because of its participation in the photosynthetic process of microalgae and its ability to vary pH when solubilized due to its acidic nature. DO, and temperature oscillated as expected from the light-dark natural cycles of photosynthesis and the time of day, respectively. Biomass growth varied with CO2 and nutrient feeding as well as reactor harvesting; however, the trend remained primed for growth.

Author Spotlight: Scaling Microalgal Biotechnology for Enhanced Biomethane Production 

Air pollution impacts the quality of life of all organisms. Here, we describe the use of microalgae biotechnology for the treatment of biogas (simultaneous removal of carbon dioxide and hydrogen sulfide) and the production of biomethane through semi-industrial open high-rate algal ponds and subsequent analysis of treatment efficiency, pH, dissolved oxygen, and microalgae growth.

In recent years, a number of technologies have emerged to purify biogas into biomethane. This purification entails a reduction in the concentration of ...

Respirometry Protocol for Anaerobic Digestion of Food Waste and Sludge

Measuring Biomethane Potential of Food Scrap Waste Anaerobically Co&#45;Digested with Waste&#45;Activated Sludge Using Respirometry

The use of respirometry to study the biokinetics of microbiota treating wastewater or digesting wastewater sludges has become more prevalent over the last few decades. The use of respirometry to examine the biokinetics of anaerobic microbiota co-digesting organic waste streams such as wastewater sludge and food scrap is an area of active research. To date, no visualized protocol has been published on the topic. Accordingly, in this protocol, we configured a respirometer to measure methane production and flow rate over time using three different food-to-microorganism (F:M) ratios and food scrap waste and waste-activated sludge as substrates. The resulting data, coupled with substrate utilization measurements, provides the basis for understanding how different substrate concentrations influence the rate at which anaerobic microbiota produce methane. Additionally, this protocol presents a method to develop biokinetic parameters (e.g., methane production rate constant and yield). Others can use this respirometry protocol to examine organic degradation under anaerobic conditions and develop microbial parameters.

Author Spotlight: Advancing Anaerobic Microbiota Research Using a Novel Respirometry Protocol

This protocol describes a best practice for determining methane production and microbial kinetic parameters using respirometry for anaerobic microbiota co-digesting food scrap waste and waste-activated sludge.

The use of respirometry to study the biokinetics of microbiota treating wastewater or digesting wastewater sludges has become more prevalent over the last ...

Fast Pyrolysis of Biomass Residues in a Twin-screw Mixing Reactor

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for conversion with fast pyrolysis. In order to increase the synergies of food production and the energetic and/or material use of biomass, it is desirable to utilize residues from agricultural production, e.g., straw. The presented method is suitable for converting such a material on an industrial scale. The main features are presented and an example of mass balances from the conversion of several biomass residues is given. After conversion, fractionated condensation is applied in order to retrieve two condensates &#8212; an organic-rich and an aqueous-rich one. This design prevents the production of fast pyrolysis bio-oil that exhibits phase separation. A two phase bio-oil is to be expected because of the typically high ash content of straw biomass, which promotes the production of water of reaction during conversion.
Both fractionated condensation and the use of biomass with high ash content demand a careful approach for establishing balances. Not all kind of balances are both meaningful and comparable to other results from the literature. Different balancing methods are presented, and the information that can be derived from them is discussed.

A procedure for thermochemical conversion of biomass residues is presented that aims at maximizing the yield of liquid products (fast pyrolysis). It is based on a technology proven on an industrial scale and especially suitable for treating a straw type of biomass.

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for ...

Bioengineering

Ultrafast Lignin Extraction from Unusual Mediterranean Lignocellulosic Residues

Pretreatment is still the most expensive step in lignocellulosic biorefinery processes. It must be made cost-effective by minimizing chemical requirements as well as power and heat consumption and by using environment-friendly solvents. Deep eutectic solvents (DESs) are key, green, and low-cost solvents in sustainable biorefineries. They are transparent mixtures characterized by low freezing points resulting from at least one hydrogen bond donor and one hydrogen bond acceptor. Although DESs are promising solvents, it is necessary to combine them with an economic heating technology, such as microwave irradiation, for competitive profitability. Microwave irradiation is a promising strategy to shorten the heating time and boost fractionation because it can rapidly attain the appropriate temperature. The aim of this study was to develop a one-step, rapid method for biomass fractionation and lignin extraction using a low-cost and biodegradable solvent. 
In this study, a microwave-assisted DES pretreatment was conducted for 60 s at 800 W, using three kinds of DESs. The DES mixtures were facilely prepared from choline chloride (ChCl) and three hydrogen-bond donors (HBDs): a monocarboxylic acid (lactic acid), a dicarboxylic acid (oxalic acid), and urea. This pretreatment was used for biomass fractionation and lignin recovery from marine residues (Posidonia leaves and aegagropile), agri-food byproducts (almond shells and olive pomace), forest residues (pinecones), and perennial lignocellulosic grasses (Stipa tenacissima). Further analyses were conducted to determine the yield, purity, and molecular weight distribution of the recovered lignin. In addition, the effect of DESs on the chemical functional groups in the extracted lignin was determined by Fourier-transform infrared (FTIR) spectroscopy. The results indicate that the ChCl-oxalic acid mixture affords the highest lignin purity and the lowest yield. The present study demonstrates that the DES-microwave process is an ultrafast, efficient, and cost-competitive technology for lignocellulosic biomass fractionation.

Deep eutectic solvent-based, microwave-assisted pretreatment is a green, fast, and efficient process for lignocellulosic fractionation and high-purity lignin recovery.

Pretreatment is still the most expensive step in lignocellulosic biorefinery processes. It must be made cost-effective by minimizing chemical requirements ...

Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture

Fungi native to agricultural soils that colonized commercially available biodegradable mulch (BDM) films were isolated and assessed for potential to degrade plastics. Typically, when formulations of plastics are known and a source of the feedstock is available, powdered plastic can be suspended in agar-based media and degradation determined by visualization of clearing zones. However, this approach poorly mimics in situ degradation of BDMs. First, BDMs are not dispersed as small particles throughout the soil matrix. Secondly, BDMs are not sold commercially as pure polymers, but rather as films containing additives (e.g. fillers, plasticizers and dyes) that may affect microbial growth. The procedures described herein were used for isolates acquired from soil-buried mulch films. Fungal isolates acquired from excavated BDMs were tested individually for growth on pieces of new, disinfested BDMs laid atop defined medium containing no carbon source except agar. Isolates that grew on BDMs were further tested in liquid medium where BDMs were the sole added carbon source. After approximately ten weeks, fungal colonization and BDM degradation were assessed by scanning electron microscopy. Isolates were identified via analysis of ribosomal RNA gene sequences. This report describes methods for fungal isolation, but bacteria also were isolated using these methods by substituting media appropriate for bacteria. Our methodology should prove useful for studies investigating breakdown of intact plastic films or products for which plastic feedstocks are either unknown or not available. However our approach does not provide a quantitative method for comparing rates of BDM degradation.

Plastic films labeled "biodegradable" are commercially available for agricultural use as mulches. Tillage represents an attractive disposal method, but degradation under field conditions is poorly understood. The purpose of this study was to develop methods for isolating native soil fungi and bacteria that colonize plastic mulch films after field burial.

Fungi native to agricultural soils that colonized commercially available biodegradable mulch (BDM) films were isolated and assessed for potential to ...

Transformation of Organic Household Leftovers into a Peat Substitute

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