Study On The Pore Structure Regulation And Biological Effect Of High Silicon Iron Tail-based Porous Ceramsite As Microbial Carriers

The development of the steel industry has led to an increase in iron ore mining,resulting in the accumulation of a large number of iron tailings.This object selects high-silicon iron tailings as the main raw material,supplemented by binder,co-solvent and combined pore-forming agent to prepare high-silicon iron tailings-based porous ceramsite used as microbial carrier in biofilm water treatment technology.SEM and XRD were used to analyze the microstructure and mineral composition of high silicon iron tailings;Analysis of thermal properties of porous ceramsite raw materials by synchronous thermal analysis.The microscopic pore structure of the sample was analyzed by image-pro Plus Image analysis software combined with microscopy.SPSS and Minitab data analysis software were used to explore the regulation method of porous ceramsite structure.Based on the requirements of the pore size of the water treatment microorganisms,the ideal pore structure model of the carrier is constructed.In this paper,the macroscopic and microscopic properties of biofilms on the surface of ceramsite with abundant pore structure were observed by optical microscopy,combined with the evaluation of degradation efficiency of organic matter,the biological effects of porous ceramsite were studied.The main findings are:(1)Through the selection of raw material components,optimization of ratio,and reasonable adjustment of thermal system,the best preparation process of high silicon iron tailings-based biological carrier is:Mass ratio of non-porous raw materials is:high silicon iron tailings:attapulgite:sodium bicarbonate=13:4:1,both of the mass percentage of corn flour and activated carbon powder in the combined pore forming agent are 3?15%,sintering temperature is 900?980?.(2)Porous ceramsite pore structure is described by the total porosity of porous ceramsite,the porosity of the fist type of pore(pore size 0.5?25?m),the porosity of the second type of pore(pore size 25?100?m),and the porosity of three types of pores(pore diameter greater than 100?m).Through image and data processing software to analyze the mapping relationship between raw material ratio and ceramsite pore structure,realize microscopic regulation of ceramsite pore structure.The pore model structure of the ideal porous ceramsite is constructed as follows:the three kinds of pores in the ceramsite are evenly distributed,and at the same time,the proportion of the first type of pore is as large as possible.Porous ceramsite with ideal pore structure was obtained with a total porosity of49.27%and a water absorption ratio of 37.02%.Porosity ratio:the first type of pore porosity:the second type of pore porosity:the third type of pore porosity?2:2:1,the crushing force is 176.23 N,and the bulk density is 1.33 g/cm~3;(3)Using the ideal pore structure of the ceramsite-loaded microbial community,using simulated biofilm water treatment technology,the bio-efficiency evaluation results of the ceramsite surface biofilm showed:When the gas-water ratio was adjusted to 10:1 and the hydraulic retention time was 6 h,the continuous reticular cavity is formed in the biofilm contained in the porous ceramsite,which contains a large number of filamentous bacteria and actinomycetes.The removal rates of COD,NH3-N and TP were 73.3%,62.6%and55.3%,respectively.The biofilm thickness of the test control was less than the critical thickness of 285?301?m,which was beneficial to membrane activity and efficient treatment.