Tropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticides

Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21–1.51 ppm), nitrates (2.28–4.89 ppm) and phosphates (0.01–0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8–10 ppm), ammonia (0.02–0.22 ppm) and phenols (0.19–0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08–7.70) with a temperature of 17.8–21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.     

微波诱导水解法制备纳米TiO_2及光催化降解盐酸四环素

采用微波诱导水解法快速制备了纳米TiO_2光催化剂,通过XRD、TEM、SEM、BET和EDS技术对其进行了表征。该方法可在10 min内制备出平均粒径约7.5 nm的锐钛矿相纳米TiO_2。采用该催化剂(加入量0.5 g/L)对盐酸四环素(TC,100 mg/L)进行紫外光催化降解,40 min时降解率高达92.9%,60 min时TOC去除率为81.7%,明显优于市售P25纳米TiO_2。这主要归功于所制备纳米TiO_2表面残留的有机物提高了光生电子-空穴对的分离能力,以及纳米粒子的小尺寸效应和较大的比表面积。溶液p H为9时TC的降解率更高。该催化剂具有较好的光催化稳定性。活性基团捕获实验表明,纳米TiO_2光催化降解TC过程中空穴起主要作用。     

Resource utilization of wasted black pulping liquor for biodiesel production by Scenedesmus obliquus

The possibility of application of black liquor for oil-riched algae cultivation is inspected. The results show that after ligin removal and enzymatic hydrolysis, the hydrolysate of black liquor contained 9.18 g L^?1 of reducing sugar. When the hydrolysate was used for Scenedesmus obliquus (S. obliquus) cultivation, a 1.23 g L^?1, 24.52%, and 23.20 mg L^?1d^?1 was obtained for growth yield, oil content, and the lipid productivity, seperately. The hemicellulose was extracted from black liquor and hydrolyzed. With addition of 3 g L^?1 yeast extract, the growth yield of S. obliquus in hemicellulose hydrolysate increased to 2.7 g L^?1, an increase of 26.8% than that of in glucose medium, oil content was 25.7% and the final lipid productivity reached 53.37 mg L^?1d^?1. The results indicate that black liquor can not be directly used by microalgae, but with approprate treatment, the carbohydrate of it could be recovered and uitilized for the oil production from microalgae.     

甲萘威在水环境中的水解及其影响因素

选择pH值、温度、水质和浓度四个因素对甲萘威在水中水解的影响进行了研究.结果表明,pH值和温度是两个主要的影响因素,碱性和高温都会促使甲萘威的水解反应加快.甲萘威在去离子水中的水解速率和在河水中的水解速率相差不多,但这种差别随pH值的增大而有所增加,说明河水中的一些无机离子和腐殖酸等对甲萘威的水解有一定的影响.而不同浓度的甲萘威也对水解速率有所影响.在pH值为7,温度30℃下,甲萘威很容易水解,其半衰期大约只有120h.     

应用水解+A/O工艺治理化工废水的工程实践

兰州石化公司应用水解(酸化)+AO工艺组合治理化工废水。化工废水经水解(酸化)处理后,BOD5CODCr比值从<0.2提高到0.37,提高了化工废水的可生化性。该工艺利用兼氧和好氧微生物对高浓度化工废水处理后,CODCr的去除率达85%以上,NH3N的去除率达95%以上。     

正交优化制备污泥水解蛋白质的实验研究

以武汉市污水处理厂剩余活性污泥为原料,在不同加水量、温度和催化条件下水解制备水解蛋白质,并通过正交试验优化了剩余污泥水解的反应条件。结果表明,当时间固定在6h时,以固液比(此为鲜泥与加水量的质量之比)为1∶2,温度1200℃,盐酸催化(pH为1.5)为水解反应的最佳条件。本研究为污泥水解蛋白液的制备及污泥处理的减量化、无害化和资源化提供了理论支持和数值依据。     

糠醛渣纤维素酶解研究

以糠醛渣为原料进行纤维素酶解研究,考察了预处理方式、酶用量、底物浓度和酶解时间对糠醛渣酶解的影响,并将其与稀酸预处理的玉米芯进行对比.结果表明,未经处理的糠醛渣由于酸性较强并含有糠醛等抑制性的物质,不能直接用于酶解,水洗和Ca(OH)₂脱毒法都可以显著提高糠醛渣的酶解效果;水洗糠醛渣的酶解最佳条件为：1∶9（g∶mL）的底物浓度、20 FPU/g（酶活/底物）,酶解时间为48 h,在此条件下,还原糖浓度为35 g/L,糠醛渣的转化率为30%,糠醛渣中纤维素的转化率为61%.     

PN/A-颗粒污泥工艺处理热水解污泥消化液

本研究构建了基于一体式厌氧氨氧化颗粒污泥及絮体污泥的部分硝化-厌氧氨氧化(PN/A)脱氮处理系统,通过运行参数优化调控实现了热水解污泥消化液的高效脱氮.试验结果表明,通过接种厌氧氨氧化菌(AnAOB)生物膜污泥与普通活性污泥、控制高游离氨(FA)(>20mg/L)和限制曝气(DO≤0.2mg/L)等运行条件,能够快速构建短程硝化-厌氧氨氧化反应,亚硝酸盐积累率可达85%以上,脱氮负荷达到0.60kgN/(m³·d).稀释后的热水解污泥消化液仍对AnAOB活性具有一定的抑制作用,导致反应器总氮负荷降至0.20kgN/(m³·d)以下;但系统内AnAOB丰度总体呈增加趋势,说明AnAOB的增殖未受到完全抑制.系统内混合污泥的平均中位径由53μm缓慢增长至109μm.定量PCR数据及高通量分析显示,该处理系统富集了较高纯度的An AOB,最大丰度占比可达8.06%,其优势菌属为Kuenenia菌属.此外,在第93运行周期下Kuenenia菌属在颗粒污泥的丰度占比大于AOB,为5.26%;絮体污泥中具有亚硝化效果的单胞菌属Nitrosomona...     

热碱水解提取污泥蛋白质的实验研究

为了确定污泥热碱提取微生物蛋白质的操作工艺条件,首先选用1#原泥为原料进行了以pH值、温度T为变量的全面实验,考察了pH值、T随反应时间的延长对蛋白质提取的影响。在1#原泥实验结果的基础上确定了以2#原泥为原料的正交实验因素水平,考察了体系pH值、T、原料含水率W以及水解时间t对污泥蛋白质回收率的影响,结果表明,热碱水解是一种有效的污泥蛋白提取方法,在热碱条件下蛋白质的回收率高达61.37%。水解过程中各因素对蛋白质回收的影响程度为pH>T>W>t,较优的提取工艺条件为：pH=13,T=140,W=91%,t=3 h。     

剩余污泥超声预处理后水解酸化特性

为探讨剩余污泥超声预处理后的水解酸化特性,考察了0.6 W/mL、5 min和1 W/mL、5 min 2种超声预处理条件下污泥水解酸化过程有机质、氮、磷的释放情况。实验结果表明,2种超声预处理均可促进污泥水解酸化,并且0.6 W/mL比1 W/mL的超声预处理更有利于SCOD的释放、VFAs的产生以及氮和磷的释放;水解酸化初期,超声预处理比未经超声预处理的污泥在有机质、氮、磷释放率上差异非常明显,随着水解酸化的进行,有机质和氮释放率差异仍很明显,而磷释放程度逐渐接近;经0.6 W/mL超声预处理,污泥水解酸化3 d后,SCOD释放率、VFAs浓度、TN释放率和NH4+-N释放率分别是未经处理污泥的1.85、2.63、1.85和1.41倍,而TP和PO43--P释放率较未经处理污泥仅分别多2.44和1.23个百分点。研究表明,控制适宜的声能密度、超声时间和水解酸化进程是超声预处理强化剩余污泥水解酸化效果的关键。