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Combined physical-chemical methods of technogenic waste water treatment

Author: Covaliova Olga
Degree:doctor habilitat of chemistry
Speciality: 02.00.20 - Ecological chemistry
Scientific consultant: Gheorghe Duca
doctor habilitat, professor, Moldova State University
Institution: Moldova State University


The thesis was presented on the 18 March, 2016
Approved by NCAA on the 21 April, 2016


Adobe PDF document1.26 Mb / in romanian
Adobe PDF document1.41 Mb / in russian



Adobe PDF document 16.00 Mb / in russian
313 pages


waste waters, d-metals, organic pollutants, flow-through 3D-electrodes, selective regeneration, integrated reactors, photocatalysis, electro- and galvano-coagulation, sediments ferritization, multi-component systems


The work consists of 242 pages including 113 figures and 17 tables, and comprises Abstract in Romanian, Russian and English, Abbreviations, Introduction, 6 Chapters, General Conclusions and Recommendations, 441 References, Annexes, Declaration on Responsibility and Author’s CV. The results obtained are set forth in 86 research publications.

Research area: 145.01 - ecological chemistry.

Objective and Scopes of the work consist in elaboration of new combined methods of technogenic waste waters treatment, including the electrochemical reduction of d-metals from their complex compounds, selective chemicals-free regeneration of solutions to prevent their discharges, photo- and microbiological destruction of persistent organic compounds in water compartments, integrated electroand galvano-chemical processes of multi-component waste waters treatment, study of phase-dispersive transformations’ conditions and ferritization of generated sediments to ensure their utilization, in line with ecological requirements.

Research novelty and originality. For the first time, complex electrochemical studies were performed of d-metal (Zn, Сd, Cu, Ni and Cr) behavior under cathodic and anodic polarization in waste water model solutions, containing ammonia, pyrophosphate, hydroxo- and aqua-complexes, considering their composition and distribution in solutions; the suitability of 3D-electrodes application for diluted waste waters treatment is justified; a new research direction was elaborated on selective chemicals-free reduction of Fe(III) to Fe(II) ions in electrolytes to prevent their discharges; a combined photo- and microbiological destruction of xenobiotics in waster environment was proposed, sequence of intermediates formation and role of Fe-containing photoinductors in active radicals formation was revealed, conditions and kinetic regularities of benzothiasoles destruction were established; catalytic processes conditions and specifics were revealed in formation of ferritized structures and properties of ferromagnetic sediments during the electro- and galvanochemical treatment of multi-component waste water.

Fundamentally new results obtained for science and practice made it possible to identify the new research direction in ecological chemistry consisting in elaboration and theoretical justification of combined physical-chemical treatment methods of technogenic waste waters, containing heavy metal ions, their complex compounds as well as the persistent organic substances-xenobiotics. New processes and equipment elaborated are of practical interest for the detoxication of water systems towards reaching the limited admissible norms to ensure the ecological safety, for the extraction and utilization of valuable components and reuse of treated water at the enterprises dealing with the metal surface processin, such as: ”Topaz”, Glass Container Company (Chișinău), „Răut” (Bălți), experimental factory of IAP ASM, etc.

Theoretical significance. New fundamental knowledge is obtained in the field of electrochemical behaviour of d-metal complexes in the dilute solutions; theoretical regularities are established of flowthrough electrodes operation, based on the numeric calculations in accordance with the mathematical model, the kinetic parameters are determined of the Fe-containing technological solutions regeneration; the specifics of benzothiasoles’ molecules destruction in the presence of iron compounds is shown; the autocatalytic mechanism of phase-disperse transformations is revealed during the electrochemical treatment of waste waters, with the formation of magnetic perceptible sediments’ properties.

Practical value of the work. Combined electrochemical technologies of metal-containing waste waters treatment were elaborated and proposed for practical uses; the conditions of selective extraction of coloured metals and regeneration of technological solutions were justified; processes and reactors for the combined destructive treatment of water systems containing the organic toxicants were elaborated; electro- and galvanochemical processes of multi-component waste waters purification were developed, with the obtaining of chemically stable sediments and the improved quality of purified water; a new concept was proposed of ecologically pure technologies in the treatment of technogenic waste waters and used solutions, along with the solid wastes utilization.

Implementation of research results. A series of the proposed methods have passed the practical tests and are recommended for implementation in industry.