Cellulosic Waste Research Articles

Revalorization of cellulosic wastes from Posidonia oceanica and Arundo donax as catalytic materials based on affinity immobilization of an engineered β-galactosidase

Catalytic materials obtained by enzyme immobilization have multiple potential applications in the food industry. The choice of the immobilization method and support may be critical to define the properties of the immobilized enzyme compared to the soluble form. Although the use of immobilized enzymes shows multiple advantages, their catalytic efficiency is compromised in many instances. Molecular engineering techniques have been used to generate hybrid proteins where the enzyme of interest is fused to a module with affinity to a specific biopolymer. Binding of the hybrid TmLac-CBM2 protein, in which the β-galactosidase from Thermotoga maritima is fused to a carbohydrate-binding module from Pyrococcus furiosus, to cellulosic material from aquatic biomass wastes (such as Posidonia oceanica and Arundo donax) has been assayed. Both species generate environmental wastes that could be revalorized if converted into bioactive materials. Cellulose cryogels, but not films, from P. oceanica were able to bind the TmLac-CBM2 hybrid, with a higher immobilization yield (90%) than that from A. donax cellulose cryogels (60%). However, fractions containing also hemicellulose were less effective as immobilization supports in both cases, with yields of 47% and 30%, respectively. Cellulose cryogels loaded with β-galactosidase were able to hydrolyse lactose with the same efficiency as the free form of the enzyme. In contrast, enzyme-loaded cellulose films were inactive. This study represents a proof of concept for the valorisation of cellulosic wastes as bioactive materials. Furthermore, it provides information about the interaction specificity between the binding module and the cellulosic support, useful for other enzymes.

Superabsorbent Hydrogel from Extracted Oil Palm Frond Waste Cellulose Using Microwave Irradioation for Cadmium Ion Removal from Aqueous Solution

Проведено диспергування целюлозного волокна, екстрагованого з відходів листя олійної пальми в «зеленому розчині», одержаному з сечовини та гідроксиду натрію. Для синтезу гідрогелів застосовано реакцію полімеризації з використанням мікрохвилього випромінення. Вплив додавання целюлози визначено внаслідок порівняння ступеня набухання гідрогелю з 0% і 2 % целюлози. Показано, що коефіцієнт набухання збільшується за наявності целюлози. За допомогою скануючої електронної мікроскопії доведено, що гідрогель з целюлозою має нерівну поверхню в порівнянні з гідрогелями без неї. Методами рентгено-структурного аналізу та сканувальна калориметрії встановлено, що гідрогелі з целюлозою втрачають кристалічність при полімеризації, а полімеризований гідрогель має кращу термостабільність, порівняно з необробленим целюлозним волокном. Результати Фур‘є-спектроскопії свідчать про полімеризацію між поліакриламідом та целлюлозою, з посиланням на смугу при 1657,99 см-1, характерної для N–H. Досліджено здатність гідрогелю з різним вмістом целюлози до адсорбції кадмію як функції рН. Встановлено, що максимальну кількість кадмію адсорбує гідрогель з 2 % целюлози за рН 4. Показано, що такий сорбент може бути використаний для видалення йонів Cd з водного розчину.

Enhanced production of cellulosic butanol by simultaneous co-saccharification and fermentation of water-soluble cellulose oligomers obtained by chemical hydrolysis

Butanol attracted interests as a drop-in biofuel obtainable from cellulosic wastes. However, the process typically used for cellulose bioconversion, i.e., separate hydrolysis and fermentation (SHF) of pretreated cellulose (Process I), is insufficient for energy-efficient production of fuel grade butanol due to the limited obtainable butanol titer. Recently, post-hydrolysis of chemically formed water-soluble cellulose oligomers was suggested for acetone-butanol-ethanol (ABE) production in SHF mode of operation (Process II). In this study, it was found that simultaneous saccharification and fermentation of the soluble oligomers (oligomeric-SSF) (Process III) and simultaneous co-saccharification and fermentation (SCSF) of soluble oligomers along with regenerated cellulose (Process IV) are promising alternatives for upgrading the titer and yield of cellulosic butanol production by Clostridium acetobutylicum. In Process III, utilizing the oligomeric hydrolysate obtained through dilute acid hydrolysis at 120 °C for 60 min using 1% acid through oligomeric-SSF led to 14.2 g/L ABE production, i.e., 65% higher than Process I. In addition, using the oligomeric hydrolysate in SCSF resulted in 24 g/L ABE (16 g/L butanol) production with an overall yield of 182 g ABE/kg cellulose. Process IV showed 191% higher titer and 14% higher yield of ABE production, compared with Process I.

Feasibility of enhancing production of 5-hydroxymethylfurfural using deep eutectic solvents as reaction media in a high-pressure reactor

5-hydroxymethylfurfural (HMF) is a versatile biomass-derived chemical for synthesizing useful compounds. In this work an attempt is made to produce HMF by developing a low-cost process for doing that using cellulosic waste and deep eutectic solvents (DESs). The most effective DES was choline chloride/citric acid (ChCl/citric acid, 2/1), which provided a greater glucose conversion percentage (around 100 mol%), HMF yield (8 mol%), and HMF selectivity (8 %) than other DESs with 0.1 g of pure glucose. To increase the HMF yield further, the species of catalyst, reaction time and reaction temperature were varied. The highest glucose conversion percentage (91.76 mol%), HMF yield (15.02 g/g) and HMF selectivity (8%) were obtained with a reaction time of five minutes, a reaction temperature of 130 ℃, sulfuric acid as the catalyst, and a ChCl/citric acid ratio of the DES of 2/1. These optimal conditions were used with the enzymatic hydrolysate of pretreated wood dusts as a substrate. The experimental results thus obtained revealed a glucose conversion percentage, HMF yield and HMF selectivity of 34.86 mol%, 16.46 g/g and 67.43 %, respectively, under these conditions. These results reveal that using enzymatic hydrolysate from pretreated wood in the production of HMF can yield approximately as much (16.46 g/g) as the use of pure glucose, indicating that this low-cost process may be commercially feasible.

Sodium polyacrylate inhibits fermentative hydrogen production from waste diaper‐like material

AbstractBACKGROUNDThe inhibitory effect of a moisture‐absorbent sodium polyacrylate (SPA), that is commonly used in disposable diapers, on the bio‐hydrogen (H2) generation from waste diaper‐like material (WDM) was assessed in dark fermentation studies. Three types of treatments were evaluated in batch bioreactors at 37 °C: mixture of bond paper and filter paper (WDM, no SPA), SPA alone (only SPA or control), and WDM spiked with SPA [paper plus sodium polyacrylate hydrogel (WDM‐SPA)]. The WDM simulated the cellulosic fraction of diaper composition.RESULTSThe units with only SPA did not produce H2. The WDM‐SPA units exhibited H2production 25% lower than those of bioreactors loaded with only WDM but no SPA. Cumulative H2 production was 0.03, 4.22 and 5.50 mmolH2 gTS–1 for the SPA, WDM‐SPA and WDM reactors, respectively (0.04, 5.90 and 8.77 mmolH2 gVS–1; 0.89, 132.19 and 196.45 NmLH2 gVS–1). BioH2 generation was related to predominance of the fermentation route that produces 1 mol L–1 of butyric acid (HBu) plus 2 mol L–1 H2 in the WDM and WDM‐SPA units, as suggested by the ratio A:B (acetic: butyric acids; A:B < 0.79 mg HAc‐COD mg HBu‐COD–1 in both cases).CONCLUSIONIt seems that this is the first documented result on the inhibitory effect of SPA on the bioH2 fermentation of cellulosic wastes. However, further research should be carried out at different levels of SPA to determine, for instance, the half‐inhibition value of SPA, that is, the concentration of SPA that would cause a 50% drop in H2 generation of the non‐SPA treatment. © 2019 Society of Chemical Industry

Effect of Cellulosic Waste Derived Filler on the Biodegradation and Thermal Properties of HDPE and PLA Composites

Composites with high density polyethylene (HDPE) and poly(lactic) acid (PLA) matrix have been tested to analyze the effect of natural fillers (wood flour, recycled wastepaper and a mix of both fillers) and temperature on polymer degradation. Composting tests have been performed in both mesophilic (35 °C) and thermophilic (58 °C) conditions. Degradation development has been evaluated through mass variation, thermogravimetric analysis and differential scanning calorimetry. HDPE, as expected, did not display any relevant variation, confirming its stability under our composting conditions. PLA is sensibly influenced by temperature and humidity, with higher reduction of Mw when composting is performed at 58 °C. Natural fillers seem to influence degradation process of composites, already at 35 °C. In fact, degradation of fillers at 35 °C allows a mass reduction during composting of composites, while neat PLA do not display any variation.

Microbial reduction of Fe(III) coupled to the biodegradation of isosaccharinic acid (ISA)

Isosaccharinic acid (ISA) forms through alkaline hydrolysis of cellulose in intermediate level nuclear waste and is a strong complexant of metals with the potential to mobilize priority radionuclides in an underground geological disposal facility (GDF). In this study, microbial ISA degradation was studied under anaerobic conditions with Fe(III) oxyhydroxide as the terminal electron acceptor at pH 7 to 10, representative of conditions in the geosphere surrounding a geological disposal facility. A multidisciplinary approach was used to study the fate and limits of ISA biodegradation, including mineralogical analyses (XRD, ESEM and TEM), alongside geochemical profiling of ISA and its biodegradation products, and microbial community analysis by 16S rRNA gene sequencing. Under the conditions imposed, ISA degradation was constrained to a pH limit of ≤9 and was degraded via Fe(III) reduction and fermentation. Biominerals, resulting from ISA degradation, were analyzed. These revealed two Fe(II) minerals, siderite [FeCO3] and vivianite [(Fe3PO4)2·8H2O], not normally associated with the microbial reduction of ferrihydrite in laboratory cultures, possibly as a result of chelation of ISA with Fe(III) that made the electron acceptor more soluble. After the enrichment at pH 7, a complex microbial consortium, including Clostridia and close relatives to known Fe(III)-reducing bacteria Geobacter sp. and Rhodoferax ferrireducens, was associated with these activities. The results are discussed in the context of geological disposal safety case development, including the potential impact on priority radionuclides including U(VI), Np(V), and Tc(VII), which are highly susceptible to reductive immobilization when in contact with Fe(II)-bearing biominerals.

Recycled Cellulose Polypropylene Composite Feedstocks for Material Extrusion Additive Manufacturing.

Many types of consumer-grade packaging can be used in material extrusion additive manufacturing processes, providing a high-value output for waste plastics. However, many of these plastics have reduced mechanical properties and increased warpage/shrinkage compared to those commonly used in three-dimensional (3D) printing. The addition of reinforcing materials can lead to stiffer parts with reduced distortion. This paper presents work in the reinforcement of recycled polypropylene using cellulose waste materials to generate a green composite feedstock for extrusion-based polymer additive manufacturing. Recycled polypropylene/waste paper, cardboard, and wood flour composites were made using a solid-state shear pulverization process. Fourier transform infrared and thermogravimetric analysis were utilized to qualitatively analyze the amount of filler incorporated into the 3D-printed materials. Recycled polymer composites had increased levels of filler incorporated in the printed parts compared to the virgin polymer composites based on the thermal gravimetric analysis. The dynamic mechanical analysis showed a ca. 20–30% increase in storage modulus with the addition of cellulose materials. Tensile strength was not significantly increased with the addition of 10 wt % cellulose, but the elastic modulus increased 38% in virgin polypropylene. The analysis of fracture surfaces revealed that failure initiates at the interface, suggesting that the interfacial strength is weaker than the filler strength.

Humic acid coated cellulose derived from rice husk: A novel biosorbent for the removal of Ni and Cr

Biosorption using cellulosic wastes has been considered as a clean technology for the uptake of heavy metals. In this study, a novel biosorbent was synthesized by extracting the cellulose from the waste rice husk using soda bleaching technique followed by its coating using humic acid. The biosorbent was found to be very effective for the removal of nickel and chromium from the aquatic medium. Various physicochemical conditions for uptake like pH (5–6), contact time (8 h) were optimized using batch method.The sorption capacity enhanced significantly by providing humic acid coating. Experiment data were fitted in sorption isotherm and kinetic modelstodescribe the sorption process.Sorption capacity of developed biosorbent was 12.41 mg g−1 and 19.39 mg g−1for nickel and chromium respectively and the sorption followed the Langmuir isotherm for both the elements.

Synthesis and Characterization of Cellulose Derivatives from Industrial Towel Waste

AbstractThe paper covers the synthesis and characterization of cellulose derivatives from waste cellulose, namely, towel wastes. For this purpose, the cellulose acetate derivatives were synthesized from towel waste by applying the conventional chemical synthesis process. To clarify the structure of synthesized materials, some spectroscopic methods (FT‐IR, XRD, 1H‐NMR, 13C‐NMR) were used. Furthermore, thermal behavior and surface morphology of prepared materials were investigated by DTG‐TG and SEM, respectively. It was found that the degree of substitution values decreased as the duration of hydrolysis increased in cellulose diacetate synthesis. It was also understood that cellulose diacetate was dissolved in acetone differently from cellulose triacetate. Degree of substitution values of cellulose diacetate were compared by using 1H‐NMR and titrimetric method. These helped elucidate the expected reaction. The proposed method was easy compared with the conventional method.

Исследование биосинтеза бактериальной наноцеллюлозы продуцентом Medusomyces gisevii Sa-12 на ферментативном гидролизате продукта щелочной делигнификации мискантуса

A high demand for bacterial nanocellulose (BNC) in various economic sectors has resulted in intensification of studies aimed at searching for ways of reducing the cost of its production. BNC on an industrial scale is obtained using synthetic nutrient media, the cost of which may amount to 30–60% of the total cost of the process. Therefore, the study of BNC biosynthesis using low-cost nutrient media, such as food and cellulosic waste and other alternative sources of raw materials, seems to be highly relevant. The biomass of miscanthus currently used as a raw material for biofuels may become such an alternative source. Miscanthus is characterised by availability, low cost and annual renewability on an industrial scale. This study was aimed at investigating the BNC biosynthesis process from the enzymatic hydrolyzate obtained by alkaline delignification of miscanthus. The delignification process involved treatment of the plant with a dilute sodium hydroxide solution at ambient pressures. Enzymatic hydrolysis of the obtained substrate was carried out in a 11L-fermenter. For the first time, BNC was successfully obtained in a nutrient medium from an enzymatic hydrolyzate produced by alkaline delignification of miscanthus. The symbiotic culture of Medusomyces gisevii Sa-12 characterised by a high adaptive potential was used as a producer. The maximum specific growth rates were 0.360 and 0.384 day -1 for yeast and acetic acid bacteria, respectively. Consumption of reducing substances was observed to proceed in two stages: the rate constant of substrate utilisation at the first and the second stages were equal to 0.464 day and 0.034 day -1 , respectively. The highest yield of BNC was 5.14% on the 14th day of cultivation, which is 1.8 times lower than that on a synthetic nutrient medium. Although the nutrient medium of the enzymatic hydrolyzate obtained by alkaline delignification of miscanthus is not biologically pure, Medusomyces gisevii Sa-12 shows a high technological potential and ability to synthesize a chemically pure BNC even under adverse conditions.

Biodegradable and transparent cellulose film prepared eco-friendly from durian rind for packaging application

Abstract High purity cellulose was isolated from durian rind in this study. Cellulose films were successfully regenerated from cellulose solution in lithium chloride/N,Ndimethylacetamide using water as regeneration solvent. The X-ray diffraction and FTIR results revealed that the durian-rind cellulose (DC) fiber was similar to commercial cellulose derived from cotton linters. The regenerated cellulose film exhibited good appearance with smooth surface and excellent transparency. The tensile tests results showed that DC film possessed high rigidity and tensile strength. The biodegradation analysis indicated that DC film could be 100% broken down in soil in 4 weeks, higher biodegradation percentage than that of cellophane, suggesting outstanding biodegradability of DC film. This work provides a potential application of conversion of durian rind as well as other cellulosic waste resource into biodegradable packaging and other functional materials.

Recycling of pre-consumer viscose waste fibers for the removal of cationic dye from aqueous solution

Recycling of textile waste materials has attracted significant attention for fabrication low-cost dye adsorbent from aqueous solutions. Viscose cellulosic waste fibers are supposed to give an answer to the finding low-cost adsorbent materials. In this research work, viscose waste fibers (VF) were modified by selective oxidation to improve the ability to absorb cationic dyes during wastewater treatment. For this purpose, different treatment parameters were investigated such as sodium periodate concentration, and time of selective oxidation with sodium chlorite. Then, unmodified and oxidized viscose fibers (OVF) were ball milled to produce viscose powder (VP) and oxidized viscose powder (OVP), respectively. The morphology of obtained viscose powders was characterized by scanning electron microscopy. Furthermore, methylene blue adsorption onto viscose cellulose fiber waste (VF) and oxidized viscose fibers (OVF) was studied as a function of contact time (0–80 min), adsorbent dosage (1–9 g/L), MB solution initial pH (3–9) and MB initial concentration (20–80 mg/L). The results showed that MB adsorption onto VF and OVF is a rapid favorable chemisorption process that can be well described by the Langmuir model. The higher adsorption capacity of OVF than VF was related to the increase of the carboxylic group. The oxidized viscose fiber can be used as a potential adsorbent for water treatment.

Reducing sugars production from cellulosic wastes by subcritical water hydrolysis in a continuous lab scale unit

Second generation biofuels are those produced from lignocellulosic biomass or crops that do not compete with food production. Cellulose and hemicellulose in plants can be transformed to building blocks, pentoses and hexoses, by hydrolysis. However, most processes require a physic-chemical pretreatment to remove lignin, which acts as a barrier for chemicals during hydrolysis. In fact, pretreatment for removal of lignin or lignin byproducts formed during hydrolysis can be considered as limiting steps for subsequent sugar transformation processes. Alternatively, industrial cellulosic residues, in which lignin and most of hemicellulose have been previously removed through chemical treatment, could be used as raw material for the production of reducing sugars without the drawbacks related to pretreatment and purification steps. Such is the case for diaper industry, which generates a polyacrylate-cellulose dust (POCEL), which cannot be recycled to the process. POCEL is comprised by around of 60 wt. % cellulose and 40 wt. % super absorbent polymer sodium polyacrylate. Due to the high content of cellulose in comparison to lignocellulosic biomass, in which the cellulose content usually oscillate between in the range 20 to 40 wt.%, POCEL could be used as a low cost raw material for glucose production, that can be subsequently fermented to produce bioethanol.In this work, experimental results of POCEL suspensions hydrolysis under subcritical water conditions in a continuous laboratory scale unit are presented. POCEL suspensions in water at 1.2 wt. % were prepared by adding a few drops of hydrochloric acid up to pH 2 to prevent sodium polyacrylate jellification with water. The hydrolysis unit in subcritical water at continuous laboratory scale consisted of a high pressure pump, preheater, a tubular reactor immersed in an electrical oven, heat exchanger and needle valve to regulate system pressure. Experiments were carried out in the temperature range 350 to 420 °C, pressures of 100 to 136 atm and suspension flowrates of up to 6.4 mL/min. Reactor effluent samples were characterized by means of dinitrosalicylic acid (DNS) colorimetric method. The highest concentration of reducing sugars was obtained at 390 °C and a water flowrate of 1.9 mL/min, which corresponds to a residence time of 126.7 s in the reactor. The estimated productivity of sugar production based on a cellulose content of 60 wt.% in POCEL was 85.4%, which indicates this kind of cellulosic waste could be used to obtain high reducing sugars concentration in hydrolysates through a continuous subcritical water process.

Low-cost Bio-Adsorbent based on Amorphous Carbon Thin Film/chitosan composite for removal of Methylene Blue Dye: Kinetic and Isotherm

In this article, we focused on using low cost bio-adsorbents such as chitosan from shrimp & crabs shells waste and amorphous carbon thin film ACTF from micro crystalline cellulose waste to prepare a new composite (ACTF/C) for removal of methylene blue (MB) dye from aqueous solution. ACTF/C composite was prepared via a novel ultrasonic co precipitation method instead of traditional chemical vapour deposition (CVD) method. The morphological and structural descriptions are performed using XRD, FTIR, TEM, TGA, SAED and SEM analysis. The analysis results showed that ACTF/C composite was prepared successfully. The effects of several parameters such as adsorbent doses (0.05–0.2 g/100 ml), temperatures (25–45 oC), initial solution pH (3–9), dye concentrations (10,25, 50, and 100 ppm) and contact time (20-80 min) on the adsorption process were examined. The kinetics, thermodynamic analyses and adsorption isotherm models were examined to estimate the empirical results. The empirical facts are properly equipped with the Langmuir isotherm (R2 = 0.997), giving an absorption capacity of more than 85 mgg-1. From kinetic details, we found that adsorption of methylene blue day across ACTF/C composite is represented by pseudo second-order model. In general, these outcomes suggest that the new ACTF/C composite provides great potential to get rid of methylene blue dye from contaminated water

HYRON-An Installation to Produce High Purity Hydrogen and Soft Iron Powder from Cellulose Waste.

The paper aims to describe a new technology of producing a gaseous mixture of type H2 + CO from cellulose waste that generates high purity hydrogen, without using technical oxygen. The physico-chemical process takes place in an installation designed and built for this purpose, namely HYRON, whose scheme and functionality are presented in the article, as well. The process relies on natural decomposition of cellulose waste into H2, CO, CO2 and water vapor, as a result of overheating. In subsidiary, the HYRON installation allows producing soft iron powder, with very low carbon content, from shredded iron ore, by using part of the obtained hydrogen as reducing agent. The chemical reactions underlying the gasification and redox processes, as well as the design approach of the various parts of the HYRON plant, are described in the article at length. The experimental tests made with the installation prototype (after proper calibration) showed that the resulted hydrogen had a purity of at least 99%, while the soft iron powder had over 88% pure iron in the composition. After a short economical analysis, it turned out that the costs of such products are reasonable.

White Root Fungus Capability (Rigidoporus microporus (Swartz: Fr.) Van Ov.) in Degrading Cellulose Waste

Cellulose is one of abundance natural biopolymer with limited usage. The common found waste cellulose are waste straw, sawdust, and pineapple pit. Rigidoporus microporus is a white root fungi groups that often attack the roots of plants that rot and die. This study was conducted to assess the ability of white root fungi (R. microporus) to degrade waste cellulose, according to cellulolitic activity index of potential R. microporus isolate. The medium used was Carboxy Methyl Cellulose (CMC) with dye Congo Red (0,1%). The results obtained that R. microporus has cellulotic index 3,23 which indicated as potential cellulose degrade.

Production of nanocellulose from waste cellulose

Nanocellulose obtained from waste cellulose has a promising wide range of opportunities to obtain the superior material properties towards various end-products. Here, we report on waste cellulose material from used diapers subjected to an acid hydrolysis using sulfuric acid to obtain nanocellulose. The prepared nanocellulose was further characterized with the aid of different techniques to elucidate crystallinity (85% degree), purity and morphology of the obtained product.

Waste-cellulose-derived porous carbon adsorbents for methyl orange removal

High-performance nitrogen-doped porous carbon adsorbents were prepared from waste cellulose fibers using the spray-drying method and used to remove methyl orange (MO) from water. The carbon adsorbents possessed a honeycomb-like turbostratic microstructure with hierarchical pores. Such waste-cellulose-derived carbon adsorbents were found to exhibit a fast adsorption rate towards MO. A sample thermally treated at 800 °C with the highest specific surface area (about 1259.4 m2/g) and total pore volume (about 2.7 cm3/g) exhibited the best MO adsorption capacity (337.8 mg/g), which is significantly higher than that of ZnCl2-activated carbon. The effect of MO initial concentration, pH and temperature on the carbon adsorption was investigated systematically. It was found that the adsorption system is heterogeneous while the isotherm data on the carbon sample can be well described by both Langmuir and Freundlich isotherm models. The high-performance and cost-effective carbon adsorbent described in this paper holds a great promise for dye removal from aqueous solutions.

LABORATORY BIODEGRADATION OF POTENTIAL CELLULOSE WASTES GENERATED DURING LONG-TERM MANNED SPACE MISSIONS

Anaerobic microbial biodegradation of cellulose containing wastes generated during the long-term manned space missions is a key technological approach for resolving the problem of wastes accumulated onboard of the spacecraft. Herewith are presented data on the possibilities of structurally stable multispecies microbial consortia originating from methanogenic bioreactors to decompose different cellulose substrates – filter paper, medical gauze and vegetable mix as potential cellulose wastes during space missions. The rates of biodegradation processes carried out at mesophilic and thermophilic conditions are not only measured and compared but are providing new opportunities for development of technology for microbial biodegradation of cellulose-rich organic wastes. Moreover, the studies have shown that paper and gauze hydrolysis with the help of cellulolytic bacterial communities can be an effective component of utilization of cosmonaut hygiene items. Biodegradation of plant wastes by community of anaerobic bacteria is promising and applicable tool also under terrestrial conditions. Light microscopy of bacterial communities reveals the presence of Gram-positive spore forming bacilli (short and long forms, bipolar and dividing cells) and typical clostridia forms.