氧化铁改性砂联合生物预处理对氨氮的吸附特性

对含氨氮(NH3-N)的微污染原水,采用自制氧化铁改性石英砂(iron oxide coated sand,IOCS)滤料强化过滤与生物预处理技术联合,进行强化处理与吸附效果研究.结果表明,采用强化挂膜法,生物预处理反应器的生物膜成熟期约为7 d,其对氨氮的去除率为60%~70%,但反应器中存在亚硝酸盐氮积累的现象.IOCS与生物预处理技术联合,对NH3-N的平均去除率为84.67%,出水NH3-N浓度均低于0.5 mg/L,NO2--N含量趋于0;而普通石英砂(RQS)在同等条件下,对氨氮的去除效果不稳定,平均去除率为74.31%,出水NH3-N平均浓度未达标,对NO2--N平均去除率仅有33.29%.在4 m/h滤速工况下,与生物预处理技术联合,IOCS和RQS对NH3-N最高去除率分别为94.3%和82.72%.IOCS与RQS的表面形态结构存在明显差异:前者的表面结构更加复杂多孔,比表面积大,有利于生物牢固附着;后者表面较光滑,比表面积小,挂膜后生物易脱落.

Adsorption property of iron oxide coated sand combined with biological pretreatment to NH3-N

Enhanced filtration technology by using self-made iron oxide coated sands (IOCS) was combined with biological pretreatment technology to micro-polluted raw water containing ammonia nitrogen (NH3-N). Strengthening treatment and adsorption property were studied. The results show that maturation time of biofilm is approximately 7 d by using enhanced biofilm culturing technique. The removal rate of pre-biotreatment to ammonia nitrogen is 60%—70%, but there is a nitrite nitrogen (NO2--N) accumulation in the reactor. The average removal rate of NH3-N is 84.67% when combined with the biological pretreatment process.The residual concentration of NH3-N is below 0.5 mg/L and that of NO2--N tends to zero. For RQS, under the same condition, it has unstable removal efficiency to NH3-N and the average removal rate is roughly 74.31%. The average remainder concentration of NH3-N can not reach the required standard and the removal rate of NO2--N is only 33.29%. When filtration velocity is 4 m/h, the removal rates of NH3-N by IOCS and RQS are up to 94.3% and 82.72%, respectively in conjunction with the biological pretreatment process. The morphological structures on the surface of IOCS and RQS are significantly different. The former has a more complex and porous surface structure, larger specific surface area, which is beneficial for the firm adhesion of microorganisms, while the later has a smoother surface, smaller specific surface area.