Petrychenko A. Protection of water bodies from pollution by nitrogen compounds and phosphorus

Українська версія

Thesis for the degree of Candidate of Sciences (CSc)

State registration number

0419U002021

Applicant for

Specialization

  • 21.06.01 - Екологічна безпека

02-04-2019

Specialized Academic Board

Д 26.002.05

Publishing and Printing Institute of Igor Sikorsky Kyiv Polytechnic Institute

Essay

The dissertation is devoted to the creation of low-waste methods for extracting nutrients from water. The first section describes the various cleaning methods that have been up-to-date. Each of these methods has its own advantages and disadvantages. It has been shown that sorption and biological degradation are still the most common methods of water purification from nitrogen and phosphorus. It was found that sorption on synthetic materials creates a problem of utilization of concentrated solutions. Natural sorbents are very limited in capacity and need to be refined. The second section of the article presents the objects and methodology of research, description, characteristics and physical and chemical properties of materials and downloads that were used in researches. The third section presents the results of researches on the removal of ammonia by biological, sorption and electrochemical methods. It has been established that the most suitable medium for the efficient removal of ammonium ions in a bioreactor is the hypolymniotic zone of reservoirs. It is shown that the best loading is polystyrene blocks with the addition of clay. It has been established that cationite КУ-2-8 has a higher selectivity for ammonium ions in the Н+-form, in comparison with the Na+-form. The influence of rigidity ions on the efficiency of removal of ammonium has been investigated and it has been established that without the prior mitigation of water use of cation exchangers is inappropriate. It was shown that regeneration was more effective when using acid solutions. It has been established that rigidity ions do not significantly affect the removal of ammonium from zeolite, as compared with ion exchange. The boundary capacity of zeolite by ammonium ions is 40 mg/g. The processes of ammonium oxidation in a two-chamber and one-chamber electrolyzer, depending on the composition of the solution, have been studied. It was found that the presence of chlorides in anolyte catalyzes the process of oxidation of ammonia, and the growth of sulfate concentration slows the destruction of ammonia, which increases the consumption of electricity. In the fourth section, results are given for removal of nitrates and phosphates from water by means of sorption, reagent and electrochemical methods. The efficiency of extracting nitrates from water on anion exchangers is studied, depending on the strength of ion exchangers. It was found that both anion exchangers in sulfate and chloride form ensured the degree of nitrate extraction at 90 % level. It has been established that regeneration of anion is 94 – 97 % with the use of solutions of ammonium chloride, potassium carbonate and ammonia. It was shown that high-base anion exchange agent AB-17-8 in chloride and basic form provided effective removal of phosphates from model solutions. In tap water, the capacity of anion exchangers in phosphates practically does not depend on the shape of ion exchangers and significantly depends on the concentration of sulfates. High levels of desorption of phosphates can be achieved using solutions of sodium chloride or ammonium at a concentration of 10 − 15%. It is shown that phosphates are effectively removed from a solution of ammonium chloride, if you add stoichiometric amount of magnesium chloride at pH ≥ 9. The regeneration solution reconditioned for this purpose is suitable for reuse. The efficiency of precipitation of phosphates from solutions with the use of electrocoagulation methods is investigated. This method provides 99 % removal of phosphates using steel and aluminum anodes. It is shown that in a weakly acidic medium or in the presence of chlorides in the solution, the electrodes are not absorbed, which accelerates the electrocautery process. The mathematical description of the processes was made on the basis of a complete factor-making experiment of the second order. The basic regression equations are shown, which show the interdependence of the main factors of the purification processes. Based on the results obtained, technological schemes for the removal of biogenic elements from water have been developed and described. The technological schemes of water purification from biogenic elements are proposed, which allow solving the problem of sewage treatment without the formation of dangerous concentrates.

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