Raw Substrate Research Articles

TRIBOLOGICAL CHARACTERISTICS OF POLYURETHANES USED FOR THE SOLES OF FOOTWEAR

The inability to take into account the type of base material (floor, pavement, soil), as well as the inability to take into account the variable friction conditions – load, intermediary medium (water, loose abrasive, sand or other soil particles), sliding velocity, and ambient temperature – is a significant limitation the use of friction methods and devices used so far in the footwear industry to precisely anticipate the behavior of the bottom materials in the actual operating conditions of the footwear. These limitations prompted the authors to adapt a tribological tester for this purpose, used in the area of construction and operation of machines and material engineering. A research methodology was developed and, in order to verify it, measurements of the coefficient of friction and wear of polyurethane used for shoe soles in combination with a raw and varnished wooden substrate were carried out. The obtained test results are characterized by diversity, which proves the high research resolution of the developed method. It allows determining the coefficient of friction of associations influencing the slip of the footwear and the wear and tear that determines the length of use of the footwear.

Bio-fertilizers issued from anaerobic digestion for growing tomatoes under irrigation by treated wastewater: targeting circular economy concept

Tomatoes (Solanum lycopersicum) plant were provided with bio-fertilizers issued from anaerobic digestion of olive mill wastewater without and with 1%, 5% of phosphate residues in mesophilic conditions for 25 days. 1% of raw substrates (OMW raw; OMW + 1%PR raw; olive mill wastewater + 5%phosphate residues raw; and phosphate residues) and digestates (olive mill wastewater digestate, olive mill wastewater + 1%phosphate residues digestate and olive mill wastewater + 5%phosphate residues digestate) was provided fortnightly to the plants. Reclaimed water from a wastewater treatment plant located in the study site was used for automatically controlled irrigation. It contained a low level of chemical fertilizers to compare tomato plant growth, leaf analysis, steam water potential, production yield and fruit quality results to plants fed with bio-fertilizers. Generally, parameters and results were progressively increased during the growing and harvesting stage, which refer to the essential elements that cover the plant’s needs. Plants fed with bio-fertilizers showed the most extended plant height (olive mill wastewater + 5% phosphate residues raw), and the best accumulation of essential elements in leaves (olive mill wastewater + 1% phosphate residues digestate and olive mill wastewater + 5%phosphate residues digestate). The maximum average fruit weight per treatment (35.5 g) was obtained when applying the digestates mixture of olive mill wastewater raw and olive mill wastewater + 5% phosphate residues. The maximum yield production per plant was obtained when applying phosphates residues. Bio-fertilizers (digestates) showed good performances, high fruit quality and perfect tomato yield production compared to the control plants. Results obtained during this study are considered promising regarding environmental framework. However, this study was done in a laboratory scale and needs to be applied in a large scale to provide more data on the effectiveness of the digestates application. It is also recommended to apply these bio-fertilizers on different crops and various soils for a better evaluation.

PHOTOCATALYTIC TiO2FILMS SYNTHESIZED BY REACTIVE CHEMICAL SPRAYING

Titanium tetrachloride was used to synthesize titanium dioxide emulsion by the hydrolysis process. The semiconductor was deposited on raw unglazed ceramic and silicon substrate by the reactive chemical spraying process. The experimental conditions were chosen to ensure film adhesion. Obtained films were calcined at different temperatures ranging from 600∘C to 680∘C and characterized by X-ray diffraction, atomic force microscopy, optical measurement, contact angle measurement, and scratch test. The photocatalytic test was carried out under UV irradiation using an azo dye. The silicon substrate allowed to show the film structure. The AFM observation indicated that film roughness increased from 12[Formula: see text]nm to 32[Formula: see text]nm. Roughness growth corresponds to a large active surface and enhanced photocatalyst activity. During the photocatalyst test under UV irradiation, the sample calcined at 660∘C shows the best result with a degradation efficiency of 140[Formula: see text]mg[Formula: see text][Formula: see text][Formula: see text][Formula: see text]. The same sample was characterized by hydrophilic behavior and adhesion strength.

Isolation of Potential Extracellular Cellulase Producer and Determination of Cellulase Production Efficiency with Various Raw Substrates

Cellulase is one of the important groups of enzyme for many industrial applications. It is applied in various processes of food industries, paper and pulp industry, fabric industry, medicine and pharma industry, agriculture industries etc. Microorganisms are among the most potential source for large scale production of this enzyme. The current study is aimed to isolate microorganisms which are capable of producing cellulase and to determine its efficiency for production of cellulase with different raw materials. For this study, bacteria microorganisms were isolated on CMC containing media. Screening was done using congo red (0.1%) and NaCl (1%) solution. Among various isolated species, Bacillus amyloliquefaciens was identified as the most potential strain and hence selected for further study, various raw materials which are rich in cellulose were used for cellulase production. These raw materials were sugarcane bagasse, paper pulp, molasses, orange peel, wheat bran, cassava waste, tea waste and agriculture waste. Cellulase activity was determined by using dinitrosalicylic acid (DNSA) method. Results of the study have shown that among all the raw materials, sugarcane bagasse, molasses and paper pulp were found as the most potential sources for enzyme production. DNSA have shown 0.97 IU/mL, 0.98IU/mL and 0.88 IU/mL of enzyme activity respectively for all the three raw materials. Results have also shown that agriculture waste alone is not found suitable for production of cellulase as it has shown only 0.32 IU/mL of enzyme activity. From the entire study, it was concluded that for large scale production of cellulase, sugarcane bagasse and molasses are the best sources using Bacillus amyloliquefaciens.

Combined Pretreatment by Ultrasound and Struvite Precipitation of Raw Substrates: A Strategy to Overcome C/N Ratio Unbalance in Nitrogen-Rich Anaerobic Co-Digestion Systems

The present study aimed to optimize the struvite chemical precipitation process in nitrogen-rich anaerobic co-digestion systems. Struvite precipitation experiments were carried out using a mixture of cattle slurry liquid fraction and sewage sludge, with and without ultrasound pretreatment. Marine salt or MgCl2 were used as magnesium source in NH4+:Mg2+ stoichiometric proportions of 1:1.5 and 1:3. Under the tested conditions, ammonium nitrogen and orthophosphate were removed from the mixed liquor with a maximum observed efficiency of 43% and 92%, respectively, when the ultrasound treatment was applied prior to struvite precipitation, using MgCl2 as source of magnesium (NH4+:Mg2+ of 1:3). The operating time was 40 min. Different pretreatments were tested prior to the biomethanization experiments, struvite precipitation, ultrasound and a combination of both pretreatments. The application of ultrasound (with an energy input of 218 kJ L−1) and struvite precipitation (NH4+:Mg2+ of 1:3) increased the methane content in the biogas by 82% and reduced hydraulic retention time by 28%, when compared to the anaerobic co-digestion assays without pretreatment. The hydrolytic pretreatment increased the bioavailability of nitrogen by 5%, thus enhancing the removal efficiency of ammonium nitrogen by 20%. Consequently, an increase in the carbon to nitrogen ratio was observed, favoring the methanogenesis process.

Integrated production of edible mushroom (Auricularia auricular-judae), fermentable sugar and solid biofuel

This study aimed to develop an energy- and resource-efficient process for the coproduction of edible mushroom, fermentable sugar and solid biofuel from wood residues. A promising potential was revealed for wood ear fungus (Auricularia auricular-judae), which yielded about 200 g mushroom per kg dry birch-based substrate, with concomitant degradation of 76.8 and 85.7% of lignin and xylan, respectively, in the substrate. Substrate pasteurisation by hot-air (85–100 °C) was as effective as by energy intensive autoclaving (121 °C), resulting comparable mushroom growth and degradation of lignocellulose. The spent mushroom substrate (SMS) contained 28–33% glucan, which upon analytical enzymatic saccharification released around 46% of the potentially-achievable glucose, corresponding to a 2.3–fold enzymatic digestibility compared with that of the raw substrate. The solid leftover generated after enzymatic hydrolysis revealed high thermal energy value and promising combustion characteristics, showing a plausibility to be recycled as solid fuel for self-supporting energy system and space heating.

Quantitative Changes in the Biochemical and Mineral Composition of the Substrate in Solid-State Cultivation of Enoki Mushroom

This study, for the first time, investigated the pattern of changes in a range of macromolecules and minerals of a lignocellulosic substrate utilized for cultivation of Enoki mushroom. Five different phases of a lignocellulosic substrate (consisting of 40% wheat straw + 40% sawdust + 18% wheat bran) were examined, including raw, mycelia-filled, pinning, fruiting, and the spent substrates. A well-authenticated native strain of Enoki mushroom, Flammulina velutipes, was used for cultivation in the substrate. The results exhibited a significant 1.35-fold, 1.18-fold, and 1.30-fold increase in nitrogen, soluble carbohydrates, and ash contents of the spent substrate, respectively, compared to the raw substrate. Conversely, a remarkable reduction was observed in holocellulose (27%), insoluble lignin (27%), insoluble carbohydrates (33%), and C:N ratio (33%) in the spent substrate, compared to the raw substrate. Soluble lignin increased by 23% in the mycelia-filled phase compared to the raw substrate, but it returned to its initial level in the spent substrate. Further HPLC coupled with GC–MS confirmed the lignin changes and demonstrated that the ratio of syringyl to guaiacyl (as lignin monolignols) increased towards the fructification phases. There was also a significant increase in the contents of elements in the spent substrate compared to the raw substrate. The data presented here provide evidences for understanding how biochemical changes in macromolecules of a lignocellulosic substrate could lead to optimum vegetative growth and fructification of Enoki mushroom, leaving a high-value non-toxic spent substrate.

Anaerobic Co-Digestion of Fish Processing Waste with Cow Manure and Waste of Market (Rests of Fruits and Vegetables): A Lab Scale Batch Test

The aim of this work was to use fish processing waste (FW) as main substrate for anaerobic digestion. To enhance the biogas production of FW, co-digestion was done with two other substrates: cow dung (CD) and waste of market (MW). Batch test was carried out in an 1 L glass digester in a temperature controlled chamber at 38°C. The following mixtures were carried out: FW with CD respectively at different ratios 100:0% (A), 80:20% (B) and 60:40% (C); FW with MW at the following ratio 80:20% (D); FW with CD and MW respectively at these ratios 80:10:10% (F) and 60:20:20% (G). The biogas produced was measured using a milligas counter® and the volume of gas was recorded. The gas composition was determined using gas chromatography. With a pH stable for raw substrates and mixtures, TS and VS (%TS) contents for FW were respectively 31.01% and 91.55%. Between 3 to 13 days of experimentation, the highest flow rate was observed. The percentage of methane was more important for mixtures B and D, 61% and 59% respectively. pH and VOA/TIC were stable at the end of the batch test for all mixtures, meaning that the organic matter was already well digested. The highest values of Volatile Solid Removal (VSR) were found for mixtures C, D, F and G. Therefore, the promising mixtures for next experimentations in large scale are B and D.

Effect of methanol-organosolv pretreatment on anaerobic digestion of lignocellulosic materials

Lignocellulosic materials are the most abundant biomass on the planet, representing a great opportunity for energy valorisation. This work investigated the effect of methanol-organosolv pretreatment on the methane production from hazelnut skin (HS), spent coffee grounds (SCG), and almond shell (AS). The pretreatment on the three lignocellulosic materials was performed at 130, 160, and 200 °C for 60 min using a 50% (v/v) methanol solution, with and without the addition of sulfuric acid as a catalyst. The biomethane potential of raw and pretreated substrates was evaluated under wet-mesophilic conditions in batch reactors, achieving 17.3 (±32.3), 293.4 (±46.6), and 23.2 (±9.6) mL CH4/g VS for HS, SCG, and AS, respectively. The methanol-organosolv pretreatment was particularly effective on HS, increasing its biomethane potential up to 310.6 (±22.2) CH4/g VS. On the contrary, all pretreatment conditions were ineffective on SCG and AS in terms of cumulative methane production. Among the three substrates, only HS showed significant composition changes due to the pretreatment, with the lignin content decreasing from 39.66 to 34.73% and the amount of bioavailable sugars increasing. An energy assessment confirmed the pretreatment efficacy on HS, with a maximum net positive energy recovery of 1.35 kWh/kg VS.

The effect of torrefaction on the thermo‐kinetics of thermally processed black pine

AbstractThis paper investigates the kinetic behaviour of thermal decomposition of pre‐treated pine needles. The model‐free methods of Flynn‐Wall‐Ozawa (FWO), Kissinger‐Akahira‐Sunose (KAS), and Kissinger, are used to determine the kinetic parameters of the processed pine needles. For a comparative analysis, the kinetic characteristic of the pre‐treated pine needles is equated to the thermal decomposition of the raw pine needles. For torrefaction of the raw substrate, some changes related to the design have been made to the furnace. The raw material has been thermally pre‐treated at a temperature of 523 K for 5 minutes. The volumetric rate of nitrogen during the torrefaction process is 42 L · min−1, while the purge flow rate of nitrogen gas is 0.2 L · min−1 for the thermogravimetric analysis. The temperature range for the thermal degradation of the torrefied pine needles is 308 K‐873 K. The activation energies determined by the FWO and the KAS methods are 157.08 kJ · mol−1 and 160.54 kJ · mol−1, respectively, whereas it is 137 kJ · mol−1 by the Kissinger method. The activation energy computed by the FWO and the KAS schemes for the raw material is found to be 1.3% less than that of the processed pine needles. The aromaticity of the thermally processed pine needles is increased by 13.61%. Thermal immunity or stability due to the increasing fraction of lignin causes the activation energy and frequency factor of the pre‐treated pine needles to slightly elevate. The redistribution of the pyrolysis stages has been observed for the torrefied pine needle sample, the temperature scale at a constant heating rate increases slightly by 0.34% during the char formation.

Biogas potential of swine manure of different animal classes

ABSTRACT In regions with developed animal husbandry, there is a problem of utilization of animal waste, which could be used as raw material for biogas production. In Russia most of the stations are designed and built by foreign companies taking into account generalized data on the properties of substrate. The particular characteristics of the local raw materials and substrates are not considered in the design process. Subsequently, this factor negatively affects the efficiency of biogas plants. In order to solve the problem, it is necessary to study the biogas potential of local substrates. The novelty of this work is to identify the peculiarities of pig manure as a substrate for biogas production depending on the classes of animals and the place of origin of raw materials. The goal of the present study of biogas potential of swine manure of different classes of animals (pregnant sows, lactating sows, piglets, fattening pigs) in Belgorod region of Russia. The experiment was carried out in small-scale batch reactors with the volume of 0.3 L each. Specific biogas yield from pig manure of different classes of animals ranged from 76.73 ± 11.77 to 151.42 ± 20.18 mn 3/t оDM, methane content – from 29.79 to 66.88%. In general, pig manure showed low biogas productivity. The highest rates were achieved at manure of sows. Taking into account the developed industry of pig breeding, biogas technologies, however, are the most optimal option of liquid manure utilization for the Belgorod region of Russia and are promising for many regions of the world with intensive animal breeding. When designing biogas plants, the specifics of local substrates should be taken into account.

Prerequisites for the action of mixed infections of basidiomycetes closed agrobiocenoses

Goal. The study of functional features of pathogens isolated from Agaricus bisporus depending on taxonomic groups.
 Methods. The subject of the study is isolates of pathogenic bacteria and isolated total RNA from Agaricus bisporus, which manifested themselves as primary infections at the stage of active growth of the fungus and are typical only for mushrooms. Research methods are biotechnological. Biotechnological research methods were used in the work. To identify the isolated cultures of microorganisms, sowing was performed to split carbon sources on synthetic media with the introduction of appropriate sugars. We used biochemical methods to determine the trophic characteristics of pathogenic bacteria in order to develop biotechnologies to control their spread.
 Results. Isolates 1.5 and 1.6 must have a positive reaction to oxidase. Isolates 1.2 and 13.2 had a weak reaction. Sources of monosaccharides (xylose, dextrose, galactose), polysaccharides and amino acids have been identified as sources of carbon nutrition. The reaction to the breakdown of carbohydrates showed that all isolates had an oxidative type of metabolism. We have proved that chemical contamination of raw materials, substrates, casing layer and monoculture causes mutational processes in bacteria, viruses and microscopic fungi.
 Conclusions. Champignon double-pore in closed agrobiocenoses (mushroom growing chambers) is affected by microorganisms, forming a complex of infections that cause significant pathologies of fungi. We found that the double-pore champignon inartificial agro biocenoses (tunnels) is affected by microorganisms, forming a complex of infections that cause significant pathologies of mushroom in the course of the experiment. To obtain high-quality mycelium is necessary to introduce technologies of modern methods of diagnostic and identification of bacteria, viruses, and other pathogens of different taxonomic groups.

Investigating the properties of nano core-shell CeO2@C as haloperoxidase mimicry catalyst for antifouling applications

Developing environmental and cost-effective antifouling technologies is essential to solve serious biofouling problems. Recently, enzyme mimics and halogenating enzymes have caught progressively attention as valuable tools to combat biofilm formation. In this work, the core-shell structure of CeO2@C, as one effective haloperoxidase-like enzyme mimics, was successfully synthesized using the carbon sphere as template through a simple coprecipitation method. Through the UV–vis absorption spectra and kinetic measurements, the CeO2@C displays intrinsic haloperoxidase-like activity via catalyzing the bromination of organic signaling compounds. Meanwhile, the prepared CeO2@C catalyst process high catalytic stability and recyclability, corresponding to a well catalytic performance repeatability after refresh of raw substrates (at least 10 times). The antibactrial property of CeO2@C as haloperoxidase mimicry is evaluated by immersing titanium plate/CeO2@C modified titanium plates into bacterial suspensions with different conditions for 4 h at 37 °C. It can catalyze the oxidation of Br− with H2O2 to the corresponding hypobromous acid (HBrO), which exhibits strong antibacterial activity against Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus) bacteria and typical marine (Pseudomonas aeruginosa) bacteria. This study introduces a stable, non-poisonous and inexpensive biomimetic material for antibacterial, antifouling and disinfection applications based on novel sustainable and conservation methods.

Growth, total lipid, and omega-3 fatty acid production by Nannochloropsis spp. cultivated with raw plant substrate

Improving productivity and lipid concentration in microalgae is important for the economic success of both biofuel and microalgae coproducts production. Nannochloropsis spp. are marine microalgae currently being grown at large-scale for the production of biofuel and lipid coproducts. Here we demonstrate improvements of growth and omega-3 production in Nannochloropsis gaditana CCMP526 and Nannochloropsis oceanica CCAP849/10 with plant substrate addition, a potentially economical option for increasing microalgal productivity. We examine growth in the presence of corn stover, switchgrass, sugarcane bagasse, and yard waste. By examining the microbial ecology of N. gaditana cultures with and without plant substrate and with and without antibiotics, we discovered a potential bacterial interaction in these cultures, but its presence is not necessary for algal growth improvements in the presence of plant substrate. Analysis of plant substrate morphology by scanning electron microscopy (SEM) after cultivation in media with and without N. gaditana shows a degradation of specific plant structural features and a colonization of the plant phloem by N. gaditana. An examination of N. gaditana in a Congo red plate assay indicates potential cellulolytic activity, but a preliminary examination of the potential cellulase transcripts does not reveal differential expression of a candidate in the presence of plant. This evidence demonstrates potential raw plant utilization by a marine microalga for increased productivity and provides a potentially economical option for increasing coproduct concentration at industrial scale without genetic engineering.

A Holistic Review on Euro-Asian Lactic Acid Bacteria Fermented Cereals and Vegetables.

Lactic acid fermentation is one of the oldest methods used worldwide to preserve cereals and vegetables. Europe and Asia have long and huge traditions in the manufacturing of lactic acid bacteria (LAB)-fermented foods. They have different cultures, religions and ethnicities with the available resources that strongly influence their food habits. Many differences and similarities exist with respect to raw substrates, products and microbes involved in the manufacture of fermented products. Many of them are produced on industrial scale with starter cultures, while others rely on spontaneous fermentation, produced homemade or in traditional events. In Europe, common LAB-fermented products made from cereals include traditional breads, leavened sweet doughs, and low and non-alcoholic cereal-based beverages, whereas among vegetable ones prevail sauerkraut, cucumber pickles and olives. In Asia, the prevailing LAB-fermented cereals include acid-leavened steamed breads or pancakes from rice and wheat, whereas LAB-fermented vegetables are more multifarious, such as kimchi, sinki, khalpi, dakguadong, jiang-gua, soidon and sauerkraut. Here, an overview of the main Euro-Asiatic LAB-fermented cereals and vegetables was proposed, underlining the relevance of fermentation as a tool for improving cereals and vegetables, and highlighting some differences and similarities among the Euro-Asiatic products. The study culminated in “omics”-based and future-oriented studies of the fermented products.

Characteristics of Raw-Starch Degrading Amylase Bacteria from Natar Hot Spring Lampung

Indonesia has a diversity of hot spring as a habitat of bacteria. One of the hot springs is Natar hot spring, Lampung. This study is to report the characteristics of a bacterium called Nat1 isolate that produces amylase to degrade raw starch from Natar hot spring. Water samples were taken from hot springs with a temperature of 45°C and a pH of 7.0. Nat1 was isolated by screening on the medium of Starch-Luria Bertani at 37°C. Its amylase-producing bacteria showed an optimum amylolytic activity of a crude enzyme of Nat1 isolate in soluble starch was 267.2774 U/mL at 60°C. Genotypic identification results using the 16S rRNA gene showed that the Nat1 isolate is identified as Panninobacter phragmatetus. A crude enzyme of Nat1 isolate showed a novel amylase ability and could degrade the raw starch substrates, such as corn and sago, with the amount of reducing sugar for each raw starch, 37.0688 µmol/mg, and 24.2697 µmol/mg. In conclusion, Nat1 amylase is potentially used in industry for its ability to degrade raw starch directly.

One-pot process for lactic acid production from wheat straw by an adapted Bacillus coagulans and identification of genes related to hydrolysate-tolerance

In this study, Bacillus coagulans CC17A with highly tolerant to hydrolysate was obtained through adaptive evolution. After 63 generations, the strain CC17A was stably in 45% (v/v) hydrolysate media and could digest multiple inhibitors in the hydrolysate. Based on its promising features, a one-pot process was developed to produce lactic acid (LA) from wheat straw. After dilute acid pretreatment of wheat straw, simultaneous saccharification and co-fermentation was conducted using CC17A without any solid-liquid separation and pre-detoxification. Total 35.50 g LA was produced from 80 g raw substrate and the production yield was as high as 70.9% of theoretical. To elucidate the tolerance mechanism, transcriptomic profiling of CC17A was studied. The highly up-regulated oxidoreductases and phenolic acid decarboxylase are considered to be involved with the inhibitors-tolerance of B. coagulans CC17A.

Cellobiose-dehydrogenase production by some fungal species isolated in rain forests of Northern Vietnam

Fungal enzymes are well-known as effective in hydrolyze lignocellulose-rich materials. This decomposition process requires many enzymes to participate in a coordinated factor to hydrolyze the polymer structure. Among them, there are some of popular oxidized enzymes such as lignin peroxidase, mangan peroxidase and laccase. Cellobiose dehydrogenase (CDH) is an extracellular enzyme found in various fungi, it was first discovered in 1974 by Westermark in white rot fungus Trametes verscolor and Phanerochaete chrysosporium. The biological role of CDH has been proven to participate in the decomposition of natural polymers such as cellulose, hemicellulose and lignin by generating hydroxyl radical through Fenton reaction. CDH has unique biochemical and catalytic properties that have been used in biosensors to detect cellodextrin, maltose, lactose and diphenol compounds or in biomedical applications such as lactobionic acid production. Therefore, CDH is an important component of the extracellular enzyme system for lignocellulose decomposition. In this study, 47 fungal strains isolated from rainforests of Cuc Phuong and Muong Phang National Parks and screened for CDH activity. Of which, 33 active fungi exhibited CDH activity from 8.89 to 74.4 U/L during growth on solid medium with rice straw as raw substrate. The highest enzyme production was identified for Coprinellus aureogranulatus (MPG14) reach 77.4 U/L on basic medium and its CDH activity of up to 237.4 U/L under optimal condition: supplemented with carbon source of α- cellulose (20 g/L), nitrogen source (5 g/L peptone) incubated for 12 days at 30℃, pH 5.5 and 200 rpm after inoculation. Thus, the fungus has the potential to exploit the CDH enzyme applied in the pretreatment of lignocellulose-rich materials.

Effect of coupling alkaline pretreatment and sewage sludge co-digestion on methane production and fertilizer potential of digestate

This study aims at investigating how organic waste co-digestion coupled with alkaline pretreatment can impact the methane production and agronomic value of produced digestates. For this purpose, sludge alone and mixed with olive pomace or macroalgal residues were subjected to anaerobic digestion with and without alkaline pretreatment. In addition, co-digestion of pretreated sludge with raw substrates was also carried out and compared to the whole mixture pretreatment. KOH pretreatment enhanced methane production by 39%, 15% and 49% from sludge, sludge mixed with olive pomace and sludge mixed with macroalgal residues, respectively. The digestates were characterised according to their physico-chemical and agronomic properties. They were then applied as biofertilizers for tomato growth during the first vegetative stage (28 days of culture). Concentrations in chlorophyll a and carotenoids in tomato plants, following sludge digestate addition, rose by 46% and 41% respectively. Sludge digestate enhanced tomato plant dry weight by 87%, while its nitrogen content increased by 90%. The impact of nitrogen and phosphorus contents in the digestate was strongest on tomato plant dry weight, thus explaining the efficiency of sludge digestate relative to other types of digestate. However, when methane production is considered, the combination of pre-treatment with co-digestion of macroalgal residues and sludge appears most beneficial for maximizing energy recovery and for biofertilizer generation.

Surface Properties Enhancement of Light Alloys by Appliance of Laser Treatment

Laser surface treatment is at present one of up-to-date methods for surface layer engineering, in this technique into the matrix material are introduced some amount of alloying additives. So the surface layer is obtained in form of composite material consisting of ceramic particle powders with different properties influencing the surface layer appliance possibilities. Using the technology it is possible to obtain a layer revealing a structured structure consisting of the heat affected zone (HAZ), transition zone (TZ) and remelted zone (RZ), as well as the substrate material. The laser is without cracks and defects as well as has with a slightly higher hardness value compared to the raw substrate material. The used laser power range is set in the range between 1.0 to 2.5 Kw, with the laser scan rate of the beam head in a range between 0.25-0.75 m/min, depending of the applied laser power and material used for alloying.This study was conducted to determine the effect of carbide on oxide ceramic powders addition on the microstructure and mechanical properties their changes and enhancement possibilities during a rapid solidification process of the remelted surface layer. The investigation should help to use this laser treatment technology for alloying of ceramic powder particles into the surface of light alloys, especially magnesium and aluminium. The scientific reason of this work is the usage of High Power Diode Laser (HPDL) for improvement of aluminium`s mechanical properties, especially the surface hardness and war resistance.There was found during the investigations and analysis of the results that, the obtained surface layer is without cracks and defects as well as with a relatively higher hardness compared to the raw material, after standard heat treatment. The hardness value increases according to the laser power used so that the highest power applied gives the highest hardness value in the remelted layer, similar relation can be found in the wear resistance parameters, which increases also with increasing laser power.The findings of the investigations allows to state, that the distribution of the used ceramic particles is generally satisfied, especially the carbide powder was confirmed in the alloys matrix, the particles are mainly present in the upper part of the surface layer or in the bottom zone of the remelted area. The hardness value increases in general according to the laser power used and the highest power results with the highest hardness value in the surface layer. The main aim of this work is to investigate and determine the effect of HPDL remelting and alloying on the cast Al-Si-Cu and Mg-Al-Cu cast aluminium and cast magnesium alloys micro structure for possible application in real working conditions mainly for light metal constructions as well as in many branches of the industry like automotive and rail transportation.