Enhancing sensitivity of microbial fuel cell sensors for low concentration biodegradable organic matter detection: Regulation of substrate concentration, anode area and external resistance

The relatively low sensitivity is an important reason for restricting the microbial fuel cell (MFC) sensors’ application in low concentration biodegradable organic matter (BOM) detection. The startup parameters, including substrate concentration, anode area and external resistance, were regulated to enhance the sensitivity of MFC sensors. The results demonstrated that both the substrate concentration and anode area were positively correlated with the sensitivity of MFC sensors, and an external resistance of 210 Ω was found to be optimal in terms of sensitivity of MFC sensors. Optimized MFC sensors had lower detection limit (1 mg/L) and higher sensitivity (Slope value of the linear regression curve was 1.02), which effectively overcome the limitation of low concentration BOM detection. The essential reason is that optimized MFC sensors had higher coulombic efficiency, which was beneficial to improve the sensitivity of MFC sensors. The main impact of the substrate concentration and anode area was to regulate the proportion between electrogens and nonelectrogens, biomass and living cells of the anode biofilm. The external resistance mainly affected the morphology structure and the proportion of living cells of the anode. This study demonstrated an effective way to improve the sensitivity of MFC sensors for low concentration BOM detection.     

Natural radioactivity in groundwater from the south-eastern Arabian Peninsula and environmental implications

Groundwater is the most valuable resource in arid regions, and recognizing radiological criteria among other water quality parameters is essential for sustainable use. In the investigation presented here, gross-α and gross-β were measured in groundwater samples collected in the south-eastern Arabian Peninsula, 67 wells in Unite Arab Emirates (UAE), as well as two wells and one spring in Oman. The results show a wide gross-α and gross-β activities range in the groundwater samples that vary at 0.01～19.5 Bq/l and 0.13～6.6 Bq/l, respectively. The data show gross-β and gross-α values below the WHO permissible limits for drinking water in the majority of the investigated samples except those in region 4 (Jabel Hafit and surroundings). No correlation between groundwater pH and the gross-α and gross-β, while high temperatures probably enhance leaching of radionuclides from the aquifer body and thereby increase the radioactivity in the groundwater. This conclusion is also supported by the positive correlation between radioactivity and amount of total dissolved solid. Particular water purification technology and environmental impact assessments are essential for sustainable and secure use of the groundwater in regions that show radioactivity values far above the WHO permissible limit for drinking water.     

大学语文教学艺术初探

大学语文教学是传播文化观念、提高大学生人文素质的主渠道,本文从大学语文教学的内容、模式、原则以及方法等不同角度来探讨如何加强大学语文教学效果,如何在提高大学生母语运用能力的同时,培养其高尚的道德情操和健康的审美情趣.     

多级生物系统工程处理沈阳西部污水的研究(示范工程)

建立以污水驱动水轮机,再带动转盘和低坝的落水曝气充氧,和大气复氧,菌藻吐氧,达到多次充氧的多级生物系统工程,以逐级沉淀和多次降解,以及沙滤等设施代替工厂处理的复杂工程。在沈阳西部中试结果证明该工程结构简单、管理方便、处理效果高、节能节资.同时,建立了快速监测生物活性和水质毒性的方法.     

激光的特性与职业危害

对激光的特性及对人体组织的损伤进行了描述,特别是对眼睛、皮肤、皮下组织及内部器官的危害及防护办法作了介绍。     

中低水平放射性废水处理技术研究进展

伴随着核能作为能源技术的利用和发展,放射性废水的处理一直是各国研究的热点.本文主要介绍了放射性废水浓缩处理的几种主要方法的原理及存在的不足,概述了膜分离技术处理低中水平放射性废水的基本原理及研究进展,讨论了废水处理技术今后研究方向.     

Tracking the reactivity of ozonation towards effluent organic matters from WWTP using two-dimensional correlation spectra

The characteristics of effluent organic matter (EfOM) from a wastewater treatment plant (WWTP) during ozonation were investigated using excitation and emission matrix (EEM) spectra, Fourier transform infrared spectroscopy (FT-IR) and high-performance size exclusion chromatography (HPSEC) at different ozone dosages. The selectivity of ozonation towards different constituents and functional groups was analysed using two-dimensional correlation spectra (2D-COS) probed by FT-IR, synchronous fluorescence spectra and HPSEC. The results indicated that ozonation can destroy aromatic structures of EfOM and change its molecular weight distribution (MWD). According to 2D-COS analysis, microbial humic-like substances were preferentially removed, and then the protein-like fractions. Terrestrial humic-like components exhibited inactivity towards ozonation compared with the above two fractions. Protein-like substances with small molecular weight were preferentially reacted during ozonation based on 2D-COS probed by HPSEC. In addition, the selectivity of ozone towards different functional groups of EfOM exhibited the following sequence: phenolic and alcoholic CO groups?>?aromatic structures containing CC double bonds?>?aliphatic CH. X-ray photoelectron spectroscopy (XPS) further elucidated the preferential reaction of aromatic structures in EfOM during ozonation.     

可调辊轧式弯曲模控制U型零件的回弹

叙述了薄板弯曲成“U”型所采用可调辊轧式模具的实际情况,介绍了应用各种不同材料后如何控制回弹的方法.     

污染水体底泥治理技术研究进展

水体底泥污染,是世界范围内的一个环境问题,污染物通过大气沉降、废水排放、雨水淋溶与冲刷进入水体,最后沉积到底泥中并逐渐富集,底泥中主要的污染物有重金属、营养元素、难降解有机物.目前底泥的治理方法有原位修复和异位处置,原位修复主要有掩蔽技术、淋洗技术;异位处置主要有卫生填埋、堆肥法、干式热处理;生物修复技术是既可用于原位修复又可用于异位处置的一种方法,具有投资少、见效快且没有二次污染的优点,是一种具有广阔应用前景的技术.