Degradation of polyacrylamide (PAM) and methane production by mesophilic and thermophilic anaerobic digestion: Effect of temperature and concentration

• PAM degradation in thermophilic AD in comparison with mesophilic AD. • PAM degradation and its impact on thermophilic and mesophilic AD. • Enhanced methane yield in presence of PAM during thermophilic and mesophilic AD. • PAM degradation and microbial community analysis in thermophilic and mesophilic AD. Polyacrylamide (PAM) is generally employed in wastewater treatment processes such as sludge dewatering and therefore exists in the sludge. Furthermore, it degrades slowly and can deteriorate methane yield during anaerobic digestion (AD). The impact or fate of PAM in AD under thermophilic conditions is still unclear. This study mainly focuses on PAM degradation and enhanced methane production from PAM-added sludge during 15 days of thermophilic (55°C) AD compared to mesophilic (35°C) AD. Sludge and PAM dose from 10 to 50 g/kg TSS were used. The results showed that PAM degraded by 76% to 78% with acrylamide (AM) content of 0.2 to 3.3 mg/L in thermophilic AD. However, it degraded only 27% to 30% with AM content of 0.5 to 7.2 mg/L in mesophilic AD. The methane yield was almost 230 to 238.4 mL/g VSS on the 8th day in thermophilic AD but was 115.2 to 128.6 mL/g VSS in mesophilic AD. Mechanism investigation revealed that thermophilic AD with continuous stirring not only enhanced PAM degradation but also boosted the organics release from the sludge with added PAM and gave higher methane yield than mesophilic AD.     

水中丙烯酰胺气相色谱测定方法研究

研究建立了大口径毛细管柱气相色谱法测定水中丙烯酰胺的方法。优化了水中丙烯酰胺的衍生化条件,用乙酸乙酯和正己烷混合溶剂萃取衍生产物,萃取后直接进行色谱分离分析,水中丙烯酰胺的最低检测浓度为0.05μg/L,回收率在94.5%～113%之间;进行6次平行精密度试验,相对标准偏差低于11.5%。研究建立的气相色谱法简便、快速、准确、重现性好,定量、定性准确可靠,适合水中丙烯酰胺的分析测定。     

降解丙烯酰胺的活性污泥培养及驯化研究

采用阶梯式驯化法，控制温度在18℃～24℃，pH在6—8，溶解氧在4—8mg／L，在容积为6L的驯化器中对活性污泥进行培养驯化。经过25d的培养之后，得到了稳定降解丙烯酰胺的活性污泥。驯化后的活性污泥SVI为85—132，COD去除率达70％。     

Efficiency of mercapto flavor compounds in removing acrylamide under high temperature and low humidity conditions

Acrylamide (AA) is a potential human carcinogen, genotoxicant, and neurotoxicant. Thus, the aim of this study was to examine the ability of mercapto flavor compounds to remove AA released from consumer packaging into food products. Four mercapto flavor compounds including 1,2-ethanedithiol, 1-butanethiol, 2-methyl-3-furanthiol, and 2-furanmethanethiol were employed to extract AA in model system using high temperature and low humidity. Our study showed that mercaptans were effective in eliminating AA in our model system. In order to remove 0.2 μmol AA, the optimal conditions in the reaction system were mercaptan flavor chemicals at 5 μmol, temperature 180 °C, and reaction time 25 min. In the presence of a higher pH, the greater was the amount of AA eliminated. Evidence indicates that employment of mercapto flavor chemicals under certain temperature and pH conditions is a reliable method to remove any unwanted AA from food products.     

壳聚糖-丙烯酰胺-丙烯酸三元接枝共聚物去除废水中铜离子研究

研究pH值、温度、反应物比率对生成三元接枝共聚物的影响,三元接枝共聚物接枝率与接枝效率的计算,以及三元接枝共聚物对铜离子的吸附效果.实验与计算结果表明：生成三元接枝共聚物的最佳反应条件为引发剂（NH4）2S2O8用量6 mmol/L,反应温度50℃,壳聚糖（CTS）：丙烯酰胺（AM）：丙烯酸（AA）=1∶2.7∶0.3,pH值=7,反应时间5h;在相同条件下,三元接枝共聚物对铜离子去除效果比壳聚糖有了明显的改善,对铜离子去除率最高达到90.06％,比壳聚糖对铜离子的去除率高49.72％.     

木质素磺酸盐接枝改性的条件优化

以粘度和产率为表征,研究不同引发剂、温度、单体丙烯酰胺用量、反应时间对木质素磺酸钠与丙烯酰胺接枝共聚反应的影响,并对木质素磺酸钠接枝共聚条件进行优化。结论:K2S2O8引发的接枝反应产物具有较大粘度和产率,而(NH4)2S2O8、Na2S2O3·5H2O引发体系得到共聚物粘度和产率相对较小,所以该研究采用K2S2O8作为引发剂;通过三因素三水平的正交试验得出对共聚物的产率与粘度的影响顺序为单体丙烯酰胺用量大于反应温度大于反应时间;接枝共聚反应的优化条件是K2S2O8引发剂浓度6×10-3mol/L,反应温度为45℃,反应时间为4 h,单体丙烯酰胺与木钠比为4:1,蒸馏水与木钠比5:1。     

Acrylamide and its metabolite glycidamide can affect antioxidant defenses and steroidogenesis in Leydig and Sertoli cells

Acrylamide, which is commonly used in various industries, may also form in food products cooked in high temperatures. Glycidamide, the ultimate genotoxic metabolite of acrylamide, is generated within cells through CYP4502E1-mediated epoxidation. Recent studies have shown that acrylamide and/or glycidamide may cause infertility by disrupting spermatogenesis, decreasing germ cell production and sperm fertilization ability due to their toxic effects on the male reproductive system. This study aimed to determine some direct effects of acrylamide and glycidamide on antioxidant defenses and on steroidogenic enzymes of Leydig and Sertoli cells. For this purpose, mouse Leydig and Sertoli cells were exposed to acrylamide (0.01 or 1?mmol/L) or to glycidamide (0.001 or 0.5?mmol/L) for 24?h. Following the exposure, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase and γ-glutamyl transpeptidase), cellular antioxidant levels (glutathione) and steroidogenic enzyme activities (3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase) were calculated. It was shown that acrylamide and glycidamide may cause inhibition of antioxidant and steroidogenic enzymes in Leydig and Sertoli cells. In conclusion, acrylamide and glycidamide may alter testicular function, thereby disrupting male reproduction.     

Acrylamide-induced alterations in lungs of mice in relation to oxidative stress indicators

The aim of the experiment was to study the influence of acrylamide (ACR) on major antioxidants in the lungs of Swiss mice. The experiment was conducted on male mice that were 8 weeks old. The mice were exposed to ACR at a single dose of 26 µg per animal, which was administered orally. Mice were anesthetized 3, 24, and 48 h after the ACR gavage. Next, histopathological and biochemical analyses of GSH concentration and the activities of SOD, GPx, and CAT were performed in the lungs. Animals exposed to ACR showed demonstrated symptoms of inflammation in lungs, hypertrophy of bronchiolar epithelium, and hyperplasia of alveolar epithelium. GSH concentration was significantly decreased 3 h after ACR gavage, which was followed by a significant increase 48 h after ACR gavage. Similarly, SOD and GPx demonstrated decreased activities 3 h after exposure to ACR, followed by increased activities 48 h after exposure to ACR. CAT activity was significantly increased 24 and 48 h after exposure to ACR. We conclude that oral exposure of mice to ACR results in alterations of lung microstructure, accompanied by the symptoms of redox imbalance.     

改性淀粉絮凝剂的性能研究

介绍了合成淀粉接枝丙烯酰胺淀粉改性高分子絮凝剂,考察了淀粉单体浓度、引发剂浓度、投料顺序对絮凝效果的影响,并将其处理模拟废水,考察了其絮凝性能。实验结果表明:引发剂浓度为3.0×10-3mol/L,淀粉用量为5g/200(mL.溶液),先加入引发剂后加入单体有利于接枝共聚。