Energy accumulation and storage is one of the most important topics in our times. This paper presents the topic of supercapacitors (SC) as energy storage devices. Supercapacitors represent the alternative to common electrochemical batteries, mainly to widely spread lithium-ion batteries. By physical mechanism and operation principle, supercapacitors are closer to batteries than to capacitors. Their properties are somewhere between batteries and capacitors. They are able to quickly accommodate large amounts of energy (smaller than in the case of batteries-lower energy density from weight and volume point of view) and their charging response is slower than in the case of ceramic capacitors. The most common type of supercapacitors is electrical double layer capacitor (EDLC). Other types of supercapacitors are lithium-ion hybrid supercapacitors and pseudo-supercapacitors. The EDLC type is using a dielectric layer on the electrode-electrolyte interphase to storage of the energy. It uses an electrostatic mechanism of energy storage. The other two types of supercapacitors operate with electrochemical redox reactions and the energy is stored in chemical bonds of chemical materials. This paper provides a brief introduction to the supercapacitor field of knowledge.
Ammonia increases buffer capacity of methanogenic medium in mesophilic anaerobic reactor thus increasing the stability of anaerobic digestion process. Optimal ammonia concentration ensures sufficient buffer capacity while not inhibiting the process. It was found out in this paper that this optimum depends on the quality of anaerobic sludge under investigation. The optimal concentrations for methanogens were 2.1, 2.6 and 3.1 g/L of ammonia nitrogen in dependence on inoculum origin. High ammonia nitrogen concentration (4.0 g/L) inhibited methane production, while low ammonia nitrogen concentration (0.5 g/L) caused low methane yield, loss of biomass (as VSS) and loss of the aceticlastic methanogenic activity. It was found out that negative effect of low ammonia nitrogen concentration on biomass is caused not only by low buffer capacity but also by insufficiency of nitrogen as nutrient. It was also found out that anaerobic sludge with higher ammonia nitrogen concentration (4.2 g/L) tolerates even concentration of volatile fatty acids (160 mmol/L) which causes inhibition of the process with low ammonia nitrogen concentration (0.2 g/L).
The treatment of solid wastes containing slowly biodegradable compounds or high level of sulphur compounds was carried out. In both cases the application of microaerobic conditions (that means controlled dosing of small amount of air or oxygen into digester) was an efficient tool to increase the biodegradability of treated material and/or to increase the activity of methanogenic bacteria by removal of their inhibitor.
In this study a completely stirred tank reactor was used to study the effect of sulfide to nitrate (S/N) ratio on sulfide removal while nitrate was used as electron acceptor. Several S/N ratios were studied for this purpose ranging from 0.3 to 2.4 mol/mol. The complete sulfide removal was achieved when S/N ratio 0.85 mol/mol was used with the autotrophic denitrification efficiency up to 80 %. No nitrite accumulation was observed, and the main product of sulfide oxidation was sulfate. Dissimilatory nitrogen reduction to ammonia occurred and subsequently, elemental sulfur accumulated while S/N ratio was higher than 1.3 mol/mol. The specific autotrophic denitrification rates under S/N ratios 0.8 and 1.2 were 5 and 26 mg g(-1) h(-1) (N-NO3 (-), VSS), respectively. Thiobacillus denitrificans and Thiomicrospira denitrificans were detected in the reactor by fluorescent in situ hybridization, but their overall representation was not more than 5 % of the entire microbial populations.
Abstract:We discuss the experimental verification of changes in the structure of a liquid water sample inserted in a special spiral "gradient" magnetic field. The magnetic flux components are characterized by a high degree of inhomogeneity; thus, a gradient is found in the monitored section of space. The relevant measurement of the modified, rearranged water sample pointed to a specific ion conductivity lower than that of the untreated water. The results of the experiment, where a sample of demineralized water was exposed to a spiral "gradient" magnetic field for the period of 5 min, show decreased ion conductivity in the examined samples.
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