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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF NATION DEFENSE ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY NGO VAN THANH HUY RESEARCH ON RECOVERY FOR AMMONIUM AND PHOSPHORUS IN RUBBER LATEX PROCESSING WASTEWATER BY STRUVITE PRICIPITATION Specialization: Environmental Engineering Code: 9520320 SUMMARY OF PhD THESIS IN ENVIRONMENTAL ENGINEERING HCMC – 2022 download by : skknchat@gmail.com This thesis has been completed at: ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY Scientific supervisors: Assoc Prof Dr Le Anh Kien Dr Tran Minh Chi Reviewer 1: Prof Dr Nguyen Phuoc Dan Reviewer 2: Prof Dr Nguyen Quoc Hien Reviewer 3: Assoc Prof Dr Phung Chi Sy The thesis is defended in front of the doctoral evaluating Council at Academy of Military Science and Technology at… hour date … month … year 2022 The thesis can be found at: - Library of the Academy of Military Science and Technology - Vietnam National Library download by : skknchat@gmail.com OPENING THE ESSENTIAL OF THE THESIS In recent years, the scarcity of nitrogen and phosphorus is gradually becoming a crisis for the fertilizer industry in particular and the global food system in general According to calculations by the Florida Phosphate Research Institute (2015), it is estimated that in the world today there are about 7,000 million tons of rock phosphate such as P2O5 that exist in nature that can be exploited economically, human consumption consume about 40 million tons of P as P2O5 per year and it is predicted that the world demand for phosphate will increase by 1.5% per year Stemming from the pressure of both controlling eutrophication and meeting the supply of nitrogen and phosphorus for the fertilizer industry, many studies have focused on developing solutions to recover nitrogen and phosphorus from wastewater Among the many alternatives, one based on the recovery and reuse of nutrients present in wastewater by Struvit precipitation technology is very advantageous and feasible because it promotes the development of sustainable technology The recovery and reuse of nutrients in wastewater can both meet the goals of protecting water sources, saving energy and chemicals, and recovering nutrient compounds as fertilizers and reducing resource exploitation resources The thesis "Research on recovery of ammonium (NH4+) , phosphate (PO43-) in rubber latex processing wastewater by struvit precipitation technology" will study the kinetics of the struvit precipitation process as: reaction speed, reaction order, application of experimental planning software (Design of Experiments) to study and identify influencing factors in order to optimize the struvit precipitation process Besides, Ansys fluent simulation modeling software application with agitation balance model to develop a 3D model can download by : skknchat@gmail.com predict the amount of struvit formed and the influence of stirring velocity in the reactor to the struvit precipitation process, thereby evaluating the feasibility of the process and thereby designing a highly efficient process to recover ammonium and phosphorus in wastewater to meet the goal of water protection, saving resources, and combining product recovery with struvit, a slow-release fertilizer used in horticulture, is a new research trend for practical application in the future RESEARCH OBJECTIVE Determining the factors affecting the efficiency of ammonium and phosphate recovery in wastewater by struvite precipitation technology Building standard numerical equations to expand the processing model at industrial scale Building an optimal model for recovery of ammonium and phosphate in wastewater by struvite precipitation technology RESEARCH METHODS AND TECHNIQUES USED The thesis uses physicochemical analysis techniques, tools such as SEM and XRD scanning electron microscopy, to evaluate the struvit precipitate formation of the tested samples, the kinetic parameters SCIENTIFIC AND PRACTICAL SIGNIFICANCE Modeling of (physical) objects operating under ideal stirring and ideal pushing models Derive the kinetic laws of the process through reaction time, stirring speed From there, evaluate the efficiency of ammonium and phosphate recovery in wastewater by Struvit precipitation technology Determining the optimal model for recovery of ammonium and phosphate in wastewater by struvit precipitation technology download by : skknchat@gmail.com CHAPTER OVERVIEW Overview of Sources of wastewater containing a lot of ammonium and phosphorus; Chemical properties of ammonium, phosphate; Methods and technologies to treat ammonium, phosphorus, both ammonium and phosphorus present in wastewater; Summary of struvite (MAP) and Factors affecting the struvite precipitation reaction (MAP); Research models for ammonium and phosphate recovery by struvite precipitation technology in the world; Overview of ammonium and phosphate recovery studies in the world and in Vietnam CHAPTER MATERIALS AND RESEARCH METHODS 2.1 Material 2.1.1 Tools and chemicals The experiment was conducted with simulated wastewater and Wastewater from the treatment system of The rubber latex processing factory 74 The chemicals used such as: Nessler reagent, NaOH, NH4Cl, KH2PO4, MgCl2.6H2O are pure chemicals belonging to Merck company 2.1.2 Experimental model - Batch experiment model: The research model is a reaction model with continuous stirring (Figure 2.1) Figure 2.1 CSTR batch test model - Continuous experimental model: laboratory studies are conducted as shown in Figure 2.2 download by : skknchat@gmail.com Figure 2.2 Diagram of continuous experimental model 2.2 Research Methods experiment 2.2.1 Batch experiment 2.2.2 Continuous experiment 2.2.3 Experimental Method of Design Expert 2.2.4 EM scanning electron microscopy method 2.2.5 Analysis of material surface structure of XRD 2.2.6 Sample analysis method 2.2.7 Systems approach method 2.2.8 Simulation study using software Ansys Fluent CHAPTER RESULTS AND DISCUSSION 3.1 Experimental study 3.1.1 Research to determine the factors affecting the formation of struvite precipitate 3.1.1.1 Effect of pH The experiment was conducted with the molar ratio of Mg2+: NH4+: PO43- is 1:1:1, and the investigated pH value was 8.0÷11; reaction time is 60 minutes, stirring speed is 50 rpm download by : skknchat@gmail.com Research results show that: At pH 8-10.5 the efficiency of NH4+ removal increases as the pH increases, reaching more than 80%, but the efficiency of NH4+ removal tends to decrease to 76% when pH > 10 (Figure 3.1) Phosphate removal efficiency increased from pH 8-10, reaching 93% at pH 9.5 When pH increased to 10 and 11, the phosphate removal efficiency increased but not significantly pH ≥ 8.5 is an important factor to form struvite precipitate, when pH
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