改性纳米黄铁矿为电子供体的生物反硝化脱氮性能

Biological denitrification performance of modified nano pyrite as electron donor

摘要:

为解决实际污水处理中碳源不足的问题，探究改性纳米黄铁矿为电子供体的生物脱氮性能。将天然黄铁矿球磨至纳米尺度，与二甲基亚砜溶液混合后经过600℃无氧煅烧2 h得到改性纳米黄铁矿。XRD和SEM以及BET分析结果表明，结晶度高的黄铁矿通过改性转变成了结晶度低的磁黄铁矿(Fe0.95S1.05)且呈多孔蜂窝状结构，比表面积从0.82 m2/g增加到10.54m2/g，孔径从7.70 nm增加到22.41 nm，同时VSM结果显示改性纳米黄铁矿的磁化强度为12 emu/g。探究了不同理化因素对改性纳米黄铁矿生物脱氮性能的影响。结果表明，在改性纳米黄铁矿投加量500 mg/L、温度30~35℃、pH 6.5~7.5的实验条件下，模拟污水中NO3--N浓度从18.5 mg/L降到0.362 mg/L，反应时间从4.5 h缩短至1 h，NO3--N去除率较改性前的42.8%提高至98.2%，显示了改性纳米黄铁矿能够作为电子供体被反硝化微生物高效利用。脱氮动力学分析表明，改性纳米黄铁矿为电子供体的自养反硝化(MNPAD)反应动力学符合零级反应特征(R2>0.97)。

Abstract:

In order to solve the problem of insufficient carbon source in actual sewage treatment, the biological nitrogen removal performance of modified nano-pyrite as electronic donor was explored. Natural pyrite was milled to nanometer scale, mixed with dimethyl sulfoxide solution, and then calcined at 600℃ for 2 hours without oxygen to obtain modified nanometer pyrite. XRD, SEM and BET analysis results showed that the pyrite with high crystallinity was transformed into pyrrhotite with low crystallinity (Fe0.95S1.05) through modification and showed a porous honeycomb structure. The specific surface area increased from 0.82 m2/g to 10.54 m2/g, and the pore size increased from 7.70 nm to 22.41 nm. At the same time, VSM results showed that the magnetic strength of modified nano-pyrite was 12 emu/g. The effects of different physical and chemical factors on the biological nitrogen removal performance of modified nano-pyrite were investigated. The results showed that under the experimental conditions of 500 mg/L of modified nano-pyrite, temperature 30~35℃, pH 6.5~7.5, the concentration of NO3--N in the simulated wastewater decreased from 18.5 mg/L to 0.362 mg/L, the reaction time shortened from 4.5 h to 1 h, and the removal rate of NO3--N increased from 42.8% to 98.2% compared with that before the modification, which showed that the modified nano-pyrite could be used as an electronic donor by denitrifying microorganisms efficiently. The analysis of denitrification kinetics showed that the kinetics of autotrophic denitrification (MNPAD) reaction with modified nano-pyrite as electron donor was in line with zero-order reaction characteristics (R2>0.97).