Ozonation of N-Nitrosamines in the Reverse Osmosis Concentrate from Water Recycling Applications

This study aims to evaluate the performance of ozone treatment for removing N-nitrosamines from reverse osmosis (RO) concentrate in water recycling applications. In the absence of any N-nitrosamine precursors, the destruction efficiency of N-nitrosamines was dependent on their molecular weight or the length of the alkyl chain in their molecular structure. Experiments conducted with RO concentrate showed that ozonation could lead to the formation of N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), resulting in an increase in concentrations of these N-nitrosamines. Nevertheless, ozonation was effective for destruction of N-nitrosamines with molecular weight greater than that of NDEA (102 g/mol).     

腊肉加工过程中N-亚硝胺的分析

为了解腊肉中N-亚硝胺的形成及水平状况,利用气相色谱法(FID氢火焰检测器)对腊肉中的N-二甲基亚硝胺(NDMA)和N-二乙基亚硝胺(NDEA)的含量进行跟踪分析。结果表明:烤制阶段N-亚硝胺急速增加,且NDEA最大含量几乎是NDMA的2倍。经过腌制后NDMA含量为4.06μg/kg,烤制结束增加到9.23μg/kg,NDEA含量腌制结束时为4.26μg/kg,烤制第1天就增加到7.90μg/kg,烤制结束时达到16.20μg/kg,烘烤是影响腊肉中N-亚硝胺形成的重要环节。成熟阶段增加速度相对平缓,成熟12 d,NDMA和NDEA含量分别为10.52μg/kg和20.25μg/kg。     

化妆品中N-亚硝基二甲胺和N-亚硝基二乙胺的顶空气相色谱-质谱测定法

建立了快速检测化妆品中N-亚硝基二甲胺(NDMA)和N-亚硝基二乙胺(NDEA)的顶空气相色谱-质谱联用分析方法.选用安捷伦DB-1701(14％-氰丙基-苯基)-甲基聚硅氧烷毛细管柱色谱柱,以N-甲基吡咯烷酮为溶剂,流速为1.5 mL/min,分流比为5:1.结果表明:N-亚硝基二甲胺和N-亚硝基二乙胺分别在0.1～...     

饮用水含氮消毒副产物NDMA分析技术研究进展

N-亚硝基二甲胺(NDMA)是强烈致癌物质--N-亚硝胺家族中的一员.近年来,研究发现饮用水氯化消毒之后会产生NDMA,引起了人们的广泛关注.本文简要介绍了消毒副产物NDMA的形成机理,阐述了NDMA样品预处理技术,包括:液液萃取(LLE)、固相萃取(SPE)和固相微萃取(SPME),并详述了气相色谱、气质联用、高效液相色谱和液质联用等分析方法,展望了今后的研究方向.     

AN INVESTIGATION INTO THE APPARENT TOTAL N-NITROSO COMPOUNDS IN MALTS

The levels of apparent total N-nitroso compounds in a range of UK malts have been investigated, and the effects of various kilning procedures are reported. Concentrations of N-nitrosodimethylamine and N-nitrosoproline have been determined for selected malts kilned with and without sulphuring. Low or non-detectable levels of apparent total N-nitroso compounds are consistently found only in malts kilned under low NOX conditions. Sulphuring appreciably reduces N-nitrosodimethylamine but has little effect on production of the majority of non-volatile N-nitroso compounds.     

在钴/氧化铝(Co/Al_2O_3)上臭氧催化降解水体中痕量N-亚硝基二甲胺(NDMA)

在实验室的间歇反应器中研究了在Al_2O_2和Co/Al_2O_3催化剂上臭氧催化降解水体中N-亚硝基二甲胺(NDMA)的效果,结果表明两种催化剂的添加显著地提高了NDMA的降解效率。主要试验参数的研究表明:Co/Al_2O_3的投加量、臭氧的投加量、温度等试验参数对于降解率有很大影响;当单位体积溶液中催化剂Co/Al_2O_3的投加量为167 mg/L、臭氧的投加量为3 mg/L时可以获得最佳的降解效果。随着温度的升高,NDMA降解去除率逐渐升高,当反应温度由283 K升高到323 K时,在Al_2O_3和Co/Al_2O_3上NDMA的降解效率分别由17.4%、55.4%提高到69.4%、82.5%。另外,在催化剂上添加K元素可明显提高Co/Al_2O_3臭氧催化降解NDMA的效率。     

Applicability of Ozone and Biological Activated Carbon for Potable Reuse

The Upper San Gabriel Valley Municipal Water District in California is considering groundwater replenishment as a potential strategy to augment its potable water supply. This case study demonstrates the broad applicability of ozone and biological activated carbon (BAC) for such potable reuse systems based on recently developed criteria and models for bulk organics, trace organic contaminants, disinfection byproducts, and cost. Using an advanced treatment train composed of ozone (ozone to total organic carbon ratio of 1.0) and BAC (empty bed contact time of 20 min), a 10 million gallon per day potable reuse facility can achieve savings of $25–$51 million in capital costs, $2–$4 million per year in operations and maintenance costs, and 4–8 GWh per year in energy consumption in comparison to alternative treatment trains with reverse osmosis. This ozone-based treatment train is also capable of achieving public health criteria recently developed by the California Department of Public Health and the National Water Research Institute for potable reuse applications.     

Measurement of dissolved organic nitrogen in a drinking water treatment plant: size fraction, fate, and relation to water quality parameters

This paper investigates the characteristics of dissolved organic nitrogen (DON) in raw water from the Huangpu River and also in water undergoing treatment in the full-scale Yangshupu drinking water treatment plant (YDWTP) in Shanghai, China. The average DON concentration of the raw water was 0.34 mg/L, which comprised a relatively small portion (~ 5%) of the mass of total dissolved nitrogen (TDN). The molecular weight (MW) distribution of dissolved organic matter (DOM) was divided into five groups: > 30, 10-30, 3-10, 1-3 and < 1 kDa using a series of ultrafiltration membranes. Dissolved organic carbon (DOC), UV absorbance at wavelength of 254 nm (UV254) and DON of each MW fraction were analyzed. DON showed a similar fraction distribution as DOC and UV254. The < 1 kDa fraction dominated the composition of DON, DOC and UV254 as well as the major N-nitrosodimethylamine formation potential (NDMAFP) in the raw water. However, this DON fraction cannot be effectively removed in the treatment line at the YDWTP including pre-ozonation, clarification and sand filtration processes. The results from linear regression analysis showed that DON is moderately correlated to DOC, UV254 and trihalomethane formation potential (FP), and strongly correlated to haloacetic acids FP and NDMAFP. Therefore, DON could serve as a surrogate parameter to evaluate the reactivity of DOM and disinfection by-products FP.