Browsing by Author "Covaliov, Victor"

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AUTOCATALYTIC REDUCTION AND CHARACTERISTICS OF BORON-CONTAINING COATINGS
(Academia de Știinițe a Moldovei, 2013) Covaliov, Victor; Covaliova, Olga; Ivanov, Mikhail; Drovosekov, Andrey
The research results of the plating conditions, chemical composition and properties of Ni-B coatings and Ni-Re-B, Ni-Mo-B and Ni-W-B alloys are given. It was shown that introduction of alloying elements (Re, Моand W) in the composition of Ni-containing coatings modifi es the catalytic activity of the alloys’ surface, with regard to the parallel reactions of dimethylamino-borane(DMAB) heterogeneous hydrolysis, Ni reduction and evolving of the molecular hydrogen. It was found that with the increase in concentration of alloying element, boron contents in the coatings is decreased to the trace amounts. The effect of alloys composition on hydrogen evolving overvoltage was studied. Due to the low overvoltage of hydrogen evolving (HE) on the alloy Ni-Re-B surface (11 at.% Re), it can be used as electrode for hydrogen generation from water in the electrolytic cell with novel design and improved technical-economical indicators.
AUTOCATALYTIC REDUCTION AND CHARACTERISTICS OF BORON-CONTAINING COATINGS
(2013) Covaliov, Victor; Covaliova, Olga; Ivanov, Mihail; Drovosecov, Andrei
The research results of the plating conditions, chemical composition and properties of Ni-B coatings and Ni-Re-B, Ni-Mo-B and Ni-W-B alloys are given. It was shown that introduction of alloying elements (Re, Моand W) in the composition of Ni-containing coatings modifi es the catalytic activity of the alloys’ surface, with regard to the parallel reactions of dimethylamino-borane(DMAB) heterogeneous hydrolysis, Ni reduction and evolving of the molecular hydrogen. It was found that with the increase in concentration of alloying element, boron contents in the coatings is decreased to the trace amounts. The effect of alloys composition on hydrogen evolving overvoltage was studied. Due to the low overvoltage of hydrogen evolving (HE) on the alloy Ni-Re-B surface (11 at.% Re), it can be used as electrode for hydrogen generation from water in the electrolytic cell with novel design and improved technical-economical indicators.
BIOREACTOR PENTRU PRODUCEREA FITOCATALITICĂ A BIOHIDROGENULUI ÎN PROCESUL EPURĂRII ANAEROBE A APELOR REZIDUALE AGROINDUSTRIALE
(CEP USM, 2014) Covaliov, Victor; Covaliova, Olga; Nenno, Vladimir; Bobeică, Valentin
CLOSED-CYCLE INTENSIFIED TECHNOLOGY FOR SUSTAINABLE BIOCHEMICAL PRODUCTION OF ALTERNATIVE FUELS FROM AGRICULTURAL WASTES
(Academia de Ştiinţe a Moldovei, 2017) Covaliova, Olga; Covaliov, Victor; Bobeica, Valentin; Nenno, Vladimir; Duca, Gheorghe
CONDITIONING AND UTILIZATION OF ɋО2 FROM FERMENTATION INDUSTRIES FOR THE CULTIVATION OF MICROALGAE
(Academia de Ştiinţe a Moldovei, 2017) Covaliov, Victor; Covaliova, Olga
DEGRADAREA FERMENTATIVĂ A BIOMASEI LIGNOCELULOZICE PENTRU PRODUCEREA BIOGAZULUI: 1. Metode de preprocesare
(CEP USM, 2014) Covaliov, Victor; Ungureanu, Dumitru; Covaliova, Olga; Ioneţ, Ion
Biomasa lignocelulozică sub formă de plante energetice şi resturi/deşeuri vegetale atrage în ultimul timp atenţia specialiştilor în calitate de materie primă/sursă pentru fermentarea anaerobă şi obţinerea biogazului – combustibil netradi- ţional provenit din deşeuri regenerabile. Procesul de fermentare a biomasei lignocelulozice include dezintegrarea/ mărunţirea materiei prime, fermentarea propriu-zisă şi utilizarea produselor fermentării – a masei fermentate şi a biogazului. Datorită faptului că această biomasă este compusă din lignină, polizăharuri ale celulozei şi hemiceluloză – compuşi stabili şi rezistenţi la fermentare, această materie primă trebuie procesată în prealabil prin hidroliză, fiind transformată în zaharuri simple. În lucrare sunt analizate procesele de preprocesare a biomasei lignocelulozice în scopul intensificării fermentării anaerobe şi majorării producţiei de biogaz. Concomitent sunt prezentate rezultatele proceselor de obţinere a biogazului din fermentarea anaerobă a deşeurilor vegetale.
EFFECTS OF AMARANTHS’ SEEDS ON DEHYDROGENASE ACTIVITY AND GASES EMISSION IN METHANOGENIC BIOREACTORS
(CEP USM, 2015) Covaliov, Victor; Senicovscaia, Irina; Nenno, Vladimir; Bobeica, Valentin; Covaliova, Olga
The influence of amaranths‘ seeds as the source of squalene on the dehydrogenase activity and efficiency of methane production were investigated in methanogenic bench-scale (5000 ml) bioreactors used to treat the mixture of distillery wastes and farmyard manure. The adding of amaranth seeds to the methanogenic bioreactor has an inhibitory effect on the dehydrogenase activity and stimulates the process of methanogenesis. Dehydrogenase activity decreased with the increase of doses of squalene and its trend had a close connection with doses (R2 =0.77-0.78). The methane content in the total amount of gases is 65.3-71.3% in a bioreactor with the additive of amaranth seeds in a dose of 50 mg l-1, which is 22.1% higher than in the the control bioreactor without additives. The increase in squalene concentration higher than 0.0005% is not rational because its stimulating effect on the methanogenic process decreases. Anaerobic digestion of alcohol distillery industry wastes with manure is a complex nonlinear time-varying microbiological process. Dehydrogenase activity trends in the experiment are described by the power function for 5 hours observations and by the logarithmic function for 120 hours of observations. Trends of CH4 are described by the polynomial function in all periods of testing. Correlation coefficients are 0.37 and 0.70 for CH4 after 5 and 120 hours of the anaerobic digestion. Dehydrogenase activity is in the close negative connection with the amount of gases, including methane. Correlation analysis between dehydrogenase activity and the release of gases has revealed the moderate and strongly negative link during 24 hours after the start of the experiment.
EFICIENTIZAREA OBŢINERII SEDIMENTELOR FURAJERE B12-VITAMINIZATE DIN APE REZIDUALE AGROINDUSTRIALE: 2. MODIFICĂRI ALE UTILAJULUI
(CEP USM, 2016) Covaliov, Victor; Bobeică, Valentin; Covaleva, Olga; Nenno, Vladimir
Prin modificări constructive ale dispozitivelor bioreactorului şi soluţii noi: separarea zonelor acetogenă şi metanogenă în interiorul bioreactorului, recircularea CO2 şi suplimentarea acestuia cu H2 exogen, adsorbţia vitaminei B12 din lichidul postfermentare cu diatomităs-a obţinut ridicarea conţinutului de vitamina B12 în sedimentele epurării fermentativ–metanogene (anaerobe) a borhotului postalcoolic până la calitatea de concentrat furajer B12-vitaminizat, concomitent cu intensificarea producerii biometanului, ca elemente ale ridicării eficienţei ecologo-economice a epurării anaerobe a borhotului.
INTENSIFICAREA FITOCHIMICĂ A EMISIEI BIOHIDROGENULUI ÎN PROCESELE DE FERMENTARE ANAEROBĂ A BIOMASEI
(2013) Covaliov, Victor; Duca, Gheorghe; Bobeică, Valentin; Covaliova, Olga
Se examinează problemele producerii şi utilizării hidrogenului ca agent energetic ecologic. Se analizează, în special, realizările înregistrate în ceea ce priveşte intensifi carea şi reducerea consumurilor materiale şi energetice pentru obţinerea biohidrogenului în procesul purificării deşeurilor agroindustriale lichide prin metoda fermentării anaerobe, utilizându-se procedeul original de redirecţionare cu ajutorul unor microstimulenţi fi tochimici a metanogenezei în vederea formării hidrogenului, optimizării funcţionale şi energetice a bioreactorului şi utilizării unor procedee ecologo-economice de purifi care a biohidrogenului.
MODIFICATION OF TiO2 PARTICLES NANOSTRUCTURE FOR PHOTOCATALYTIC APPLICATIONS
(Academia de Ştiinţe a Moldovei, 2015) Covaliova, Olga; Covaliov, Victor; Duca, Gheorghe
MODIFIED PROCESS AND BIOREACTOR FOR CYANOCOBALAMINE (VITAMIN В12) AND BIOMETHANE PRODUCTION
(Academia de Ştiinţe a Moldovei, 2017) Covaliov, Victor; Covaliova, Olga
A NEW CONCEPT REGARDING THE SELECTION OF SEWERAGE SYSTEMS AND NATURAL TREATMENT OF MUNICIPAL WASTEWATERS
(2023) Covaliov, Victor; Ungureanu, Dumitru; Duca, Gheorghe; Covaliova, Olga; Romanciuc, Lidia
The article contains a review of methods and procedures of the municipal wastewater treatment, with the discussion of their specifics. A new concept is proposed related to the selection of municipal sewerage and wastewater treatment systems, considering the local/decentralized, semicentralized or centralized systems, especially those suitable to rural and suburban localities, in dependence on the advantages and disadvantages of these systems and local specifics. The concept of phytofilters is proposed for the biological treatment of wastewater in small towns. This technology is simple, inexpensive and requires relatively little maintenance. Biological ponds in the Republic of Moldova have proven to be very suitable for advanced wastewater treatment, being a cheap and natural purification system with a good potential for implementation. When choosing a sewer system, priority must be given to its functionality and practical considerations.
A NEW METHOD OF CYANCOBALAMIN (VITAMIN B12) PRODUCTION AND ITS PRACTICAL USES
(Academia de Ştiinţe a Moldovei, 2015) Covaliova, Olga; Covaliov, Victor; Duca, Gheorghe; Nenno, Vladimir; Bobeica, Valentin
NEW USES OF BIOACTIVE PHYTOCOMPOUNDS DEPENDING ON MOLECULAR STRUCTURE
(Academia de Ştiinţe a Moldovei, 2015) Bobeica, Valentin; Covaliov, Victor; Ivancic, Albert; Nenno, Vladimir; Covaliova, Olga
PERFECȚIONAREA SISTEMELOR DE OBŢINERE A BIOGAZULUI
(Academy of Sciences of Moldova, 2015) Covaliov, Victor
A new-generation intensive ecological technology and integrated bioreactor for biogas production were developed, based on the valorisation of agro-industrial wastes, hazardous for the natural environment. The efficient technology independent from centralized power supply was elaborated, which makes it possible to enhance the reliability and cost efficiency of energy supply in rural areas. An easily manageable technology proposed is environmentally friendly and an acceptable method beneficial for the population. This technology bears a breakthrough character and is based on the use of natural phyto-catalysts introduced into the digested biomass in micro-concentrations. They are obtained by extraction from natural vegetable feedstock and wastes. Biomethane contents in biogas is thus increased from 62% with a caloric value of 5 232 kcal/m3 to 85-92% with a caloric value of 8 010 kcal/m3. Inaddition, the stabilized biomass residues can be used as organic fertilizers, whereas the treated water meets the requirements for irrigation scopes. The technology ensures the generation of a renewable “green” heat and electric energy, and contributes to the improvement of energy and environmental security in accordance with the existing national and international standards.
PERFECŢIONAREA SISTEMELOR DE OBŢINERE A BIOGAZULUI
(2015) Covaliov, Victor
Au fost elaborate o tehnologie ecologic pură şi un bioreactor integrat intensiv de nouă generaţie pentru producerea biogazului prin valorificarea deşeurilor agroindustriale periculoase pentru mediul natural. S-a dezvoltat o tehnologie eficientă, independentă de sursa de alimentare centralizată, sporind astfel fiabilitatea şi eficienţa costurilor aprovizionării cu energie în zonele rurale. Procesul propus este uşor de gestionat, ecologic şi acceptabil pentru populaţie. Această tehnologie este unică în lume şi se bazează pe utilizarea fito-catalizatorilor naturali introduşi în biomasa fermentată în micro-concentraţii. Ei sunt obţinuţi prin extracţie din materii prime vegetale naturale şi deşeuri. Conţinutul biometanului în biogaz a crescut de la 62%, cu o valoare calorica de 5 232 kcal/m3, până la 85-92%, cu o valoare calorica de 8 010 kcal/m3. În plus, reziduurile de biomasă stabilizate pot fi utilizate ca îngrăşăminte organice, în timp ce apa tratată este conformă cerinţelor pentru irigare. Tehnologia asigură generarea energiei regenerabile „verzi”, atât electrice, cât şi termice, şi contribuie la îmbunătăţirea securităţii energetice şi ecologice în conformitate cu standardele naţionale şi internaţionale existente.
PROCEDEUL MODIFICAT DE PRODUCERE BIOCHIMICĂ A CIANCOBALAMINEI (VITAMINA B12) DIN DEŞEURI AGROINDUSTRIALE 1. MODIFICĂRI TEHNOLOGICE PRIVIND INTENSIFICAREA PROCESULUI DE OBŢINERE A ADAOSULUI FURAJER
(CEP USM, 2015) Covaliov, Victor; Bobeică, Valentin; Covaliova, Olga
Aplicarea combinată a unor soluţii tehnologice noi, precum: stimularea chimică a metanogenezei, adaosul de compuşi predecesori ai biosintezei vitaminei B12, recircularea CO2 şi suplimentarea acestuia cu H2, a condus la îmbogăţirea sedimentelor epurării fermentativ-anaerobe a borhotului postdistilare alcoolică cu vitamina B12 de 1,5-2 ori. Drept rezultat, a fost ridicată calitatea concentratului furajer vitaminizat, concomitent cu intensificarea producerii biometanului, astfel mărind eficienţa ecologo-economică a epurării anaerobe a borhotului. O parte a cobalaminei se adsorbă pe particulele sedimentului în procesul de formare a lui, iar o parte rămasă în soluţie se supune epurării avansate prin sorbţie pe sorbentul mineral – diatomită. Produsul format poate fi utilizat în calitate de adaos furajer pentru animale şi păsări din agricultură.
PROCESE TEHNOLOGICE DE OBŢINERE A BIOGAZULUI ÎN SISTEMELE DE EPURARE ANAEROBĂ A APELOR REZIDUALE
(2007) Ungureanu, Dumitru; Covaliov, Victor
The continuous development of the civilization stipulates for the increased consumption of the power resources, which determines the search of the new alternative sources of energy. Among the alternative sources of energy a great importance is accorded to the technology of obtaining the biogas. This problem is very actual, especially in the Republic of Moldova, while the natural energetic resources in this country are absent. However our republic possesses the important recovering organic resources which in most cases are not used but are thrown out in the environment together with the sewage.
PRODUCTION, STRUCTURE AND PHOTOCATALYTIC PROPERTIES OF NANOTUBULAR TiO2
(2020) Duca, Gheorghe; Covaliov, Victor; Covaliova, Olga
Photocatalytic processes are among the most efficient treatment methods of waters polluted with recalcitrant organic substances. Nanotubular TiO2 arrays with photocatalytic properties were obtained in the process of titanium anodic oxidation in the fluoridecontaining electrolyte. Under the proposed conditions of electrolysis, a coherent system of tightly adjoining nanotubes was formed with the internal diameter of 60-80 nm and walls thickness up to 60-65 nm, the tubes height being dependent on process duration, reaching over 200 mkm. It was shown that it is the specifics of the formation, destruction and renewal of the barrier layer that determines the tubular structure of anodic titanium coatings formed. Various anodizing regimes were proposed to obtain the different TiO2-containing structures-nanotubular and fine dispersed ones. Subsequent annealing of nanotubular titanium dioxide provokes the series of structural-phase transformations, modifying its photocatalytic properties. The nanotubular systems thus obtained were tested as photo-catalysts, both as compact coatings and as fine dispersed particles, in the especially developed integrated photoreactor. It was shown that using the proposed equipment and photocatalysts produced, the efficient photodestruction of the persistent organic pollutants such as benozhiazol (BT) can be reached due to the combination of chemical and physical effects.
SAVANT PE LINIA DE AVANGARDĂ A OENOLOGIEI ŞI BIOTEHNOLOGIEI: BORIS GĂINĂ
(2007) Covaliov, Victor