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Composting and Fermentation of Biowaste - Advantages and Disadvantages of Processes

Abstract

In 2016, in EU Member States (EU), only less than half of the biowaste produced, i.e. around 40 million tonnes, was used to produce compost and, to some extent, biogas. Most of it was still incinerated or stored together with other waste. On 14 June 2018, amendments to 6 directives on waste management were published. One of the most important changes introduced in the Waste Framework Directive is the obligation for Member States to recycle biowaste at source or selectively collect it for composting or fermentation by 31 December 2023 at the latest. The article presents the potential of biowaste and its use for the production of compost and changes in directives concerning the handling of biowaste, which will shape the directions of development of this waste management in the EU after 2020. The composting and fermentation processes of biowaste were also compared, defining their advantages and disadvantages. This information can be helpful in the selection of technologies for its processing, making decisions on the construction of new or modernization of existing installations.

Open access
Dynamic Behavior of A High-Rise Building Under Seismic Loads for Different Bearing Frame Types

Abstract

Paper presents the results of dynamic behavior analysis of a high-rise building under seismic loads as part of the “base-foundation-building” system. Analysis covers different types of reinforced concrete construction with girder frame and non-girder frame. Using modal analysis, paper presents differences in mode shapes and frequencies caused by the presence or absence of girders. Paper also demonstrates variations in the stress-strain state for the vertical bearing structures under the seismic load for different frame types.

Open access
Exergetic Analysis of Hybrid Photovoltaic - Thermal Solar Collectors Coupled to Organic Rankine Cycles

Abstract

In this work, the application of hybrid solar modules that combine photovoltaic panels and solar thermal collectors coupled with a low-temperature thermal cycle such as the Organic Rankine Cycle is discussed, their main purpose being an increase in the total electric power production per available area. This work will study the thermal and electrical power production efficiency of the hybrid system, the increase in the PV module electric conversion efficiency due to their cooling through heat transfer to the thermal cycle and the total exergetic efficiency of the system. A simplified simulation of the system in steady state conditions based on a thermal efficiency model will be performed with the aid of the EES (Engineering Equation Solver) software using climate data from Campinas, São Paulo, Brazil. The study shows that while the PV/T+ORC system does fulfill the purpose of increasing the electrical power generation both from the generator coupled to the thermal cycle and from the increase in the PV module efficiency due to its cooling. Thus, there is an increase the overall exergy efficiency of the system compared to uncoupled PV/T collectors.

Open access
Experimental and Numerical Analysis of Photovoltaics System Improvements in Urban Area

Abstract

Nowadays, photovoltaic systems installed in urban areas have to be an essential part of distributed generation systems, and lead to improve energy efficiency of buildings. The paper describes the operation aspects of the 7,5 kWp photovoltaic installation located on the roof of the didactic building of AGH University of Science and Technology. The significant part of the roof Is occupied by HVAC installation, so the periodic shading is occurring. It makes, that a level of energy generated in the PV system is lower than expected. The first part of the test was focused on the validating model of the installation and determine its impact on the CO2 emissions. Then, modifications in the arrangement of the panels were considered (redirecting of additional light stream). Moreover, an economic and environmental analysis of proposed improvements were conducted.

Open access
Experimental Verification of Method to Synthesize the Track Vertical Irregularities

Abstract

The paper focuses on the experimental verification of the results derived from numerical simulations, based on a model of the bogie-track system, where the vertical track irregularities are introduced in the form of a pseudorandom function. This function comes from an original method of synthesizing the vertical track irregularities, depending on the geometric quality of the track and on the velocity. To verify the method, the root mean square (RMS) of the simulated accelerations in the axles and the bogie frame against each axle is compared to the experimental accelerations within the frequency range of wavelengths of the track vertical irregularities from 3 to 120 m. The results have shown a good correlation between the simulated RMS accelerations for a low quality track and the measured RMS accelerations.

Open access
Influence of Steel and Polypropylene Fibers Addition on Selected Properties of Fine-Grained Concrete

Abstract

The article presents results of laboratory tests of selected mechanical and physical properties of fine-grained fiber concrete. Tests were conducted on samples with a different degree of reinforcement made on the basis of steel and polypropylene fibers. For the designed concrete mixtures and prepared samples, slump class, shrinkage, compressive and bending strength and water tightness were determined.

Open access
The Influence of Trace Elements on Anaerobic Digestion Process

Abstract

The article is the literature review on the importance of trace elements supplementation in the methane fermentation process. The production of biogas, including methane, as well as the efficiency of the process depend on the substrates to be fermented. Substances supplied with the substrate as well as products generated in the decomposition phases can inhibit the process. The factor limiting fermentation is the rate of enzymatic hydrolysis of substrates. Certain compounds, such as alkanes, alkenes, biphenol, aromatic hydrocarbons, alcohols and ketones, are not directly susceptible to hydrolysis. They undergo this process in the presence of extracellular enzymes.

The instability of the methane fermentation process described in the literature may be related to the lack of trace elements or micronutrients. Trace elements (Co, Ni, Cu, Mn, Fe, Zn, Se and Mo) are components of enzymes, some bacterial nucleic acids and essential for the synthesis of vitamins. The role of some trace elements, eg. Fe or Mo, has been well understood, while the importance of others still needs to be clarified. Literature data indicate that supplementing trace elements not only prevents process inhibition, but can also improve its performance by providing higher methane production.

Open access
Innovative Calculation Method of the Productivity of Vibrating Screens Used in Mineral Aggregates Sorting

Abstract

In the process of preparing cement or asphalt concrete – frequently used in ways, roads and access road construction, it is necessary to sort out poly-dispersed granular mixtures from bilge deposits or quarries. The mechanical sieving performs the separation of the granules on dimensional sorts (the size of graded grains can be 1... 70 mm) by means of machines called screeners. In the case of vibrating screeners, the working body (the sieve) presents a vibratory movement that ensures a high productivity of the screening machine and a very good quality of the final products obtained. The article studies the productivity of the vibrating screen used in mineral aggregates sorting process obtained by different methods. In this regard, a pragmatic simplified formula called Pragma is proposed, a formula which was tested with good results in situ experiments done on a bi-mass vibrating screen in a pilot station.

Open access
Modal Competition and Complementarity: Cost Optimization at End-User Level

Abstract

The paper aims to identify possible methods for balancing the allocation of transport flow on modal subsystems in order to efficiently use the infrastructures and reduce the negative effects of today’s unbalance. The aspects of intermodal competition are reviewed, considering the economic concepts regarding the substitutability of transportation services, conformation degree to the perfect competition model and the nature of cross elasticity demand.

A top-down analysis over the whole infrastructure assembly is performed. The results, under the presumption of valid work hypothesis, indicated that for further analysis the set of networks transferring material flows can be assumed as disconnected from the other networks sets transferring energy, informational and values flows.

The second part of the paper develops, for that disconnected networks, a generalized cost optimization model for multimodal transportation, where the comfort and safety are accounted. Thus, the performance of the existing algorithms based only on trip length, trip duration and energy consumption can be significantly improved. Additionally, the author proposes three new independent types of modal analysis that allow end-users and companies involved in transport organization to optimize their modal choice and the whole transport process organization.

Open access
The Possibility to Use Modified Flight Ash as a Neutralizer in the Acid Soils Reclamation Processes

Abstract

Using the alkaline fly ash after combustion of lignite as the acid soils neutralizer is a technique known for decades. Due to many disadvantages of the direct fly ash application it is sought to modify this material prior to its use. The process of fly ash modification in the magnetic activator involved breaking up fly ash to small grain sizes in order to obtain a material with a very large specific surface and modified properties. The purpose of the research was to compare the properties of unmodified fly ash with those of ash modified in the magnetic activator in terms of its usefulness in the neutralization of acidic soils. Unmodified fly ash was classified as a medium-grained calciferous material. The basic components of ash were silicates (33.28% of SiO2) and calcium compounds (31.26% of CaO). It has a low heavy metal content falling within a range characteristic of coal ash and meeting soil quality standard requirements. As a result of activation, the following changes were obtained in the properties of modified ash compared with unmodified ash: sand fraction content – reduced to 0.40, silt fraction content – increased by 1.40, silt fraction content – increased by 1.68, content of the sum of the dust and silt fractions – increased by 1.49, specific surface – increased by 1.65, fineness – reduced by 0.48. Modification of fly ash in the magnetic activator was found to have improved the physical properties of ash as acidic soil neutralizer, and its chemical properties make such an application possible.

Open access