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.     

Enhanced adsorption of hexavalent chromium by a biochar derived from ramie biomass (<Emphasis Type="Italic">Boehmeria nivea</Emphasis> (L.) Gaud.) modified with β-cyclodextrin/poly(L-glutamic acid)

This paper explored biochar modification to enhance biochar’s ability to adsorb hexavalent chromium from aqueous solution. The ramie stem biomass was pyrolyzed and then treated by β-cyclodextrin/poly(L-glutamic acid) which contained plentiful functional groups. The pristine and modified biochar were characterized by FTIR, X-ray photoelectron spectroscopy, specific surface area, and zeta potential measurement. Results indicated that the β-cyclodextrin/poly(L-glutamic acid) was successfully bound to the biochar surface. Batch experiments were conducted to investigate the kinetics, isotherm, thermodynamics, and adsorption/desorption of Cr(VI). Adsorption capacities of CGA-biochar were significantly higher than that of the untreated biochar, and its maximum adsorption capacity could reach up to 197.21 mg/g at pH 2.0. Results also illustrated that sorption performance depended on initial solution pH; in addition, acidic condition was beneficial to the Cr(VI) uptake. Furthermore, the Cr(VI) uptake was significantly affected by the ion strength and cation species. This study demonstrated that CGA-biochar could be a potential adsorbent for Cr(VI) pollution control.     

Transformation of phosphorus during drying and roasting of sewage sludge

Sewage sludge (SS), a by-product of wastewater treatment, consists of highly concentrated organic and inorganic pollutants, including phosphorus (P). In this study, P with different chemical fractions in SS under different drying and roasting temperatures was investigated with the use of appropriate standards, measurements, and testing protocol. The drying and roasting treatment of SS was conducted in a laboratory-scale furnace. Two types of SS samples under different treatment temperatures were analyzed by ³¹P NMR spectroscopy. These samples were dried by a vacuum freeze dryer at ?50 °C and a thermoelectric thermostat drying box at 105 °C. Results show that the inorganic P (IP) content increased as the organic P content decreased, and the bio-availability of P increased because IP is a form of phosphorous that can be directly absorbed by plants. ³¹P NMR analysis results indicate the change in P fractions at different temperatures. Non-apatite P was the dominant form of P under low-temperature drying and roasting, whereas apatite P was the major one under high-temperature drying and roasting. Results indicate that temperature affects the transformation of P.     

重庆大气酸沉降对材料腐蚀危害的研究

在重庆对金属、油漆、橡胶等材料大气曝露试验表明,大气酸沉降已对材料产生广泛的危害影响:加速金属腐蚀,促进油漆、橡胶等高分子材料的老化、恶化性能。     

LS—931Al2O3基硫磺回收催化剂的工业应用

LS－931催化剂是新开发的Al2O3基硫磺回收催化剂，经洛阳炼油厂5000t/a装置使用考察结果证实其具有高活性和稳定性运行的特点。在第一转化器使用LS－931Al2O3基催化剂及在第二转化器仍然使用旧的LS－811Al2O3催化剂的情况下，与原来单纯使用LS－811Al2O3催化剂相对比，装置总硫转化率可提高1％左右，有机硫水解率达到96.4%，尾气中的硫化物含量则稳定地降至1％（V）以下。     

轿车车门内板冲压成形计算机仿真

介绍了采用基于动态显式算法的有限元分析软件包eta／DYNAFORM对典型的汽车覆盖件轿车车门内板冲压成形进行计算机仿真的全过程。论述了覆盖件冲压零件计算机仿真必须注意到的问题，并探讨了其中的关键技术。     

剩余污泥处理新工艺

研究了剩余有机污泥处理新工艺，将剩作污泥进行酸化水解后回到废水处理系统一起代谢，基本达到无污泥排放。该工艺适合于染整废水、乳品厂废水处理站等有机污泥处置，特别适用于泥难以脱水的如锦纶厂废水处理站的剩余污泥处理。     

化工生产中的清洁工艺

简述了清洁生产产生的背景及其重要意义，从改进工艺（聚乙烯醇生产工艺改革），改变生产原料（以乙烯取代乙炔作为合成有机中间体的原料），应用生物技术（两步发酵法生产维生素Ｃ）和改变反应设备（离子膜法生产氢氧化钠）等４个方面说明清洁工艺在化工生产领域取得的实际成效。     

便携式净水器净化放射性污染水的研究

用非放射性元素代替放射性同位素进行静态和动态试验。筛选出了对一、二价阳离子有较好处理效果的D1树脂和对阴离子有较好处理效果的D2树脂。该净水器对两个水源中放射性污染物的净化效果表明 ,对试验水样中污染物的放射性强度均能净化( 2 0L)达到 99%以上 ;即使处理水量达到 35L时 ,其净化率仍能达到 97%以上。