Abstract Presented paper aimed to employ the near infrared spectroscopy (NIRS) as a rapid and simultaneous method for quality assessment of biochar samples made of agricultural waste materials (chatter bamboo; firewood; coconut shell). Spectral data were obtained in the wavelength range of 1000–2500 nm, while actual fixed carbon, volatile matter and ash contents were observed using standard chemical analysis. Moreover, prediction models were established using two different regression approaches: principal component regression and partial least square regression. Prediction performances were evaluated by assessment of several statistical indicators, such as correlation coefficient and ratio of prediction to deviation index. The results showed that PLS generated a better prediction performance with maximum r coefficient and RPD index – 0.89 and 2.26 for fixed carbon; 0.93 and 2.84 for volatile matter; 0.90 and 2.30 for ash content. Based on the results acquired, it can be concluded that NIRS is usable for the purposes of a rapid and simultaneous approach to biochar quality determination.

Abstract The purpose of this study was to determine the possibility of practical use of the Hackathon Platform for ecological protection of the university biosystem to prevent a new outbreak of the COVID-19 pandemic. The COVID-19 pandemic significantly affects companies and population’s behaviour. The most significant change occurred in the attitude of companies to the environment from technical and technological points of view. To increase their production sustainability, these companies are looking at the possibilities of waste recovery through sustainable recycling, or recovery of waste as a source of secondary raw material. One of the simplest ways is to use agricultural waste for energy purposes, bringing bioenergy to the forefront as a new area of Industry 4.0. The ALARA model was used to assess the quality of six biosystem components (atmospheric air, water resources, soil layer, the level of land pollution with chemicals and littering by the unauthorized dumps; sufficient volume of green planting on the territory). This allowed the development of management decisions and environmental protection measures based on the system of calculated indicators of potential environmental damage for each of six biosystem components. The forecast of plan implementation: the quality of four from among six biosystem components (atmospheric air, water resources, soil layer, sufficient volume of green planting on the territory) will increase on average by 30–40%. A minor improvement in the quality of the other biosystem components (approx. by 10%) raises concerns about the high probability of a new outbreak of the COVID-19 pandemic.

Abstract The paper provided describes a mathematical model of calibration process of fruit-stone culture seeds of cherry, sweet cherry, cherry-plum, apricot and almond using flat sieves with impact shock ball cleaners oscillating in the horizontal plane. It has been defined that the mathematical expectation of time of knocking out the fruit-stone from the sieve opening T ⌢ \mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown$}}\over T} is the minimum value of ratio of average time of complete ball motion cycle in space under sieve to the probability of knocking out the stone by a ball with the kinetic energy level of 2 Mj. The dependences of energy distribution density of ball on impact on the sieve have been obtained, based on which the intervals of ball cleaner parameters have been determined, i.e. the ball diameter D belongs to the interval 25–35 mm; the space height H under sorting sieve belongs to the interval 1.2D–1.4D mm; the value range for distance between rods t belongs to the interval 0.5D–0.7D mm. Using the method of golden section, the following parameters of ball cleaner were obtained: D = 33 mm, t = 23 mm, H = 40 mm. The parameters obtained provide mathematical expectation of time of knocking out the fruit-stone from the sieve opening T ⌢ \mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown$}}\over T} = 0.03 s. Consequently, the average ball velocity v ⌢ \mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown$}}\over v} is = 0.4 m∙s-1, and the average ball path is L ⌢ \mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\frown$}}\over L} = 0.006 m.

Abstract Jet aeration loop reactors are widely used in the chemical industry due to their high mixing intensity, possibility of significant saturation of medium with gases, and simplicity of scaling the processes when passing from laboratory equipment to industrial designs. However, to ensure the necessary amount of air in standard jet aeration schemes with ejectors, high pressure of the medium (up to 6 bars) is required in the reactor loop. This paper presents a newly developed scheme of jet aeration, based on mixing the pressure flows of medium and air supplied to the ejector by individual blowers. Experiment results of the new water aeration scheme showed that, for the formation of suspended matter in the ejector with an air content of 2–20 l per 1 l of water, a pressure of 0.3 bar in the reactor loop at an air pressure of 1 bar is sufficient. This allows usage of low-pressure pump and compressor, which form the basis for the energy consumption reduction and creates prerequisites for lowering the shear loads on a crop. The medium aeration rate during experiments was 0.220–0.266 vvm. It was found that, for each mode of joint operation of pump and compressor, it is possible to maintain a constant aeration rate, which is not significantly affected by the flowrate regulation of medium in loop.

Abstract The article presented conducts the research of infrared radiation power effect on the colour and surface changes of peach slices coated with basil seeds gum (BSG) and xanthan gum during drying. The colour indices include redness ( a *), yellowness ( b *), lightness ( L *), and total colour difference (∆ E ), which were used for the purposes of colour change calculation. As the IR radiation power increased from 150 W to 375 W, the average values of L *, a * and b * of uncoated and coated peach slices decreased from 67.45 to 65.41; 7.95 to 5.89; and 49.21 to 38.52, respectively. The lowest ∆ E and surface change values were observed in peach samples coated with BSG. The modelling results showed that the MMF model was the best model to describe the total colour difference of uncoated and coated peach slices (the average correlation coefficient was equal to 0.991 and the average standard error was equal to 1.791). The surface area change (%) of uncoated and coated peach slices increased with the progression of drying time, but the rate of changes was lower for the coated peach slices with BSG. The current research indicated that BSG coating has the potential to improve surface colour and appearance quality of dried peach slices.

Abstract Agriculture as a key industry for human food suply will face various concerns in near future. This research is complementary and aims to present the dynamic modelling and simulation, as well as algorithm development of a 4-DOF SCARA-type robotic arm designed for real agricultural cultivation process, such as seeding, watering, fertilizing, weeding, etc. In terms of a previously designed system, the equations of motion profile were solved (acceleration and deceleration control of joints) to reduce inertia, ensure a smooth motion, and minimize torque requirement. The algorithm is evaluated by PTP motion, TCP linear motion, and spline motion. The results show that the developed algorithm can move the TCP using ST-profile. Furthermore, it can control all joints for an estimated time duration. A novel method was developed to manoeuvre the TCP along the shortest path to reach a goal point. Finally, the algorithm was evaluated in a closed path inside the working space.

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Abstract Anaerobic co-digestion of oil palm empty fruit bunches with cow manure was studied. The research focus was on the evaluation of feeding different solid concentrations of the substrate in the on-going process of anaerobic digestion. The solid concentrations ranged from 0.5 to 12% TS. Results of the study showed that the maximum methane production could be reached with the reactor digesting substrates with 4 to 8% TS, in which the methane produced was from 1300 to 1400 mL per day. A significant drop of pH from 7.02 to 5.97 occurred when the reactor was digesting substrates with 10 and 12% TS. Acidic condition caused by organic matter overloads lowered the efficiency of organic conversion represented in the low removal of COD, which was only 22.4%. This finding is highly significant for the waste management industries in terms of dealing with the digester upset due to the digestion of large amount of organic wastes.

Abstract The aim of this work is to optimize the mixing ratio for production of particleboard (PB) from groundnut shell and rice husk. This research is focused on optimization approach for turning the agricultural waste into quality value-added composite PB for sustainable development. Box-Behnken design was used to optimize the effect of three process variables: groundnut husk (0–100 g); rice husk (0–100 g) and resin (1.5–2.5 g). The best process levels for PB production predicted by the software were validated. The PB samples produced were analysed using scanning electron microscope. The best results were obtained at levels: groundnut husk – 50 g; rice husk –100 g; resin – 3.50 g with rupture modulus of 3.50 N·mm−2 and elasticity modulus of 932.4 N·mm−2, the predicted optimal levels of 65.99 g; 86.34 g and 1.69 g were validated. The validation results gave rupture modulus of 3.49 N·mm−2, and elasticity modulus of 932.10 N·mm−2. It can be concluded that PB produced at the optimized conditions satisfied the American National Standard ANSI/A208.1-999 specification for general purpose particleboards for sustainable development.

Abstract The aim of experiment was to analyse the structural transformations and changes in mechanical properties of K720 steel during heat treatment (quenching). Three types of cooling medium were selected. The heating parameters and subsequent delays at the recrystallisation temperature were the same for all samples and were observed in a laboratory furnace. Water with the highest cooling capacity was selected as the benchmark cooling medium. Subsequently, the hardening oil TK – 46 was used. Sunflower oil was selected as the last quenching medium, which can be considered an ecological replacement of quenching oil with possibility of biological disposal. The microstructure and microhardness of individual samples were subjected to a metallographic evaluation and evaluated according to ČSN EN ISO 6507, respectively. The impact toughness analysis was performed according to the ČSN EN ISO 148-1 and a three-point bending test was performed according to ČSN EN ISO 7438. This test specifies a method for determining the ability of metallic materials to undergo plastic deformation in bending. The bend test includes subjection of round, square, rectangular or polygonal cross-section to plastic deformation by bending, without changing the direction of loading, until the specified angle of bend is reached.