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Preparation and Performance of the Crystal Seed for Phosphate Removal by Crystallization Based on Hydrothermal Modification

Author: WangGuangWei
Tutor: QiuLiPing
School: Jinan University
Course: Municipal Engineering
Keywords: Crystallization Seed matrix material Hydrothermal Modification Phosphorus Removal seed Hydroxyapatite
CLC: X703
Type: Master's thesis
Year: 2011
Downloads: 64
Quote: 0
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Abstract

Phosphorus is one of the main elements that cause eutrophication, is non-renewable and facing the depletion of important natural resources and, therefore, the study of efficient phosphorus removal technology, the development of new phosphorus resources is imminent. Mold removal and recovery of phosphorus in the wastewater is widely recognized both effective prevention and control of eutrophication, but also an effective way to achieve the sustainable use of phosphorus resources, has important research value. In this paper, the the analog low concentration of phosphorus wastewater processing object contrast investigated the role of quartz sand, ceramic, steel slag and slag material of phosphorus removal from wastewater characteristics dosing screened material can effectively promote the reaction of the phosphate crystals; explored different activation modification methods studied filtered material induced crystallization phosphorus removal, on this basis, the use of mechanical activation of the powder after the slag and slag were prepared dephosphorization seed crystal substrate material, and thus obtained by hydrothermal modified efficient adsorption of phosphorus removal performance and alkalinity and ion sustained release seed Summary Phosphorus Removal seed preparation based on a new type of hydrothermal modification method; investigated phosphorus removal seed processing crystalline addition to low concentrations of phosphorus-containing wastewater phosphorus characteristics of phosphorus removal reaction products were characterized using XRD and SEM-EDS and other means, analysis, preliminary study of the crystallization of phosphorus removal seed phosphorus removal mechanism. The research results show that not adjusted to the conditions of the original wastewater quality, dosing quartz sand, ceramic, steel slag and slag has a different effect of simulated wastewater phosphorus removal. Which steel slag phosphorus removal capacity was significantly better than the slag, ceramics and quartz sand basically does not have the phosphorus removal capacity. Improve the simulation of phosphorus-containing wastewater initial Ca / P, pH value, concentration of phosphorus and prolonging the reaction time, which can effectively improve the efficiency of phosphorus removal of the seed material dosing. When Ca / P gt; 2.0, phosphorus removal efficiency increased slowly; When the pH of the solution gt; 9, the phosphorus removal efficiency significantly improve; When the initial concentration of phosphorus gt; 10mg / L, significantly higher than the low concentration phosphorus removal efficiency phosphorus removal efficiency (lt; 10mg / L); When the crystallization reaction gt; 24 hours, and then extend the reaction time had no significant effect on the crystallization of phosphorus removal efficiency. Ceramics and quartz sand no significant improvement in simulated wastewater phosphorus removal performance under our experimental conditions, dosing, dosing slag can effectively remove phosphorus in the simulated wastewater, the material can promote the release of alkalinity and calcium capacity crystalline phosphorus removal process is a good host material for the preparation of high phosphorus removal seed. Contrastive mechanical, hydrothermal and mechanical - water heat combined method of phosphorus removal effect of activation of slag and slag, modification treatment can effectively improve the phosphorus removal of slag and slag Machinery - hydrothermal method activation effect Jia. First, therefore, the use of mechanical activation method for crushing the slag and slag, coarse processing and sieved after obtain particle diameter of 3-5mm particulate slag and particulate slag; further grinding the resulting slag and slag powder by granulation, molding matrix composite filter media and conservation aspects of the preparation of slag and slag-based composite filter media, and particles of slag and particles of slag as phosphorus removal seed matrix material, the hydrothermal further modified activation treatment. The test results showed that the activation of hydrothermal modification treatment can significantly improve the phosphorus removal capacity of the four matrix material modification temperature, modification time, NaOH concentration and liquid to solid ratio has an important influence on the activation of the effect. Improve the modification temperature, NaOH concentration and liquid to solid ratio, extended modified time, of crystalline phosphorus removal performance of slag, slag and slag-based composite filter media have a significant role in promoting the best modified temperature, modified time, NaOH concentration and liquid-solid ratio, 200 ° C, 24 h, 6M and 1; slag-based composite material with modified activation conditions vary with the other three preferred modification temperature, modification time, NaOH concentration, and the liquid-solid ratio respectively 105 ° C, 6H, 6M and 1. Considering the mechanical activation and hydrothermal modification treatment costs and the matrix material crystallized phosphorus removal performance, summed derived phosphorus removal seed preparation methods based on different matrix materials, four phosphorus removal of the seed material, hydrothermal change phosphorus removal capacity: particles of slag 6.88 mg / cm ^{3 , particles of slag 4.67 mg / cm ^{3 , slag-based composite filter 5.63 mg / cm ^{3 , slag matrix composite filter 4.19 mg / cm ^{3 , respectively, 60.8% higher than before the modification, 45.2%, 54.8%, 39.9%. Study found that phosphorus removal of the seed crystal crystallized dephosphorization characteristic is closely related to its alkalinity and calcium ion sustained release capabilities, when the initial solution, Ca / P = 2, pH = 8.0, the modified particulate slag, particulate slag and slag-based composite fast filter alkalinity and calcium ion release, its crystalline phosphorus removal performance decay faster in the the modified slag matrix composite filter media, which has the more lasting continuous phosphorus removal capacity. XRD and SEM-EDS characterization results indicate that the product as a crystalline phosphorus removal of the seed material in the different reaction conditions for the various forms of calcium phosphate; as prolonged reaction time, the degree of crystallization of calcium phosphate precipitation is gradual strengthening of the nuclei gradually increased in the number of simultaneously crystals gradually increasing, the high crystallinity globular hydroxy calcium phosphate (Ca ₅ (PO ₄) ₃ OH) crystals, the Ca / P = 1.66, and the theoretical value (1.67) are basically the same. Based the slag matrix composites prepared by hydrothermal modification filter contains a lot of calcium silicate hydrate CSH and Ca (OH) ₂ to release alkalinity and calcium ions required for the crystallization process, promote the precipitation of phosphate in the form of calcium phosphate, and further converted into the hydroxyapatite crystal.}}}}

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