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The purpose of this study is to investigate the biological hydrogen production potential of individual organic fraction of municipal solid wastes (OFMSW) by batch experiments. Seven varieties of typical organic solid wastes including rice, cabbage, carrot, egg, lean meat, fat and chicken skin were selected to estimate the hydrogen production potential. Among the OFMSW, carbohydrate produced the most hydrogen through biological hydrogen fermentation compared with proteins or lipids. Subsequently, the biological hydrogen production potentials of some individual carbohydrate were measured: cabbage, 26.3-61.7 mL/g-VS; carrot, 44.9-70.7 mL/g-VS; and rice, 19.3-96.0 mL/g-VS. The hydrogen percentages of the total biogas produced from cabbage, carrot and rice were 33.9-55.1%, 27.7-46.8% and 44.0-45.6%, respectively.

Hydrogen gas is recognized as a promising energy resource in the future. Microbial hydrogen fermentation would be an attractive process for hydrogen recovery. In particular, hydrogen production using fermentative bacteria has some advantages such as a high rate of hydrogen production without light. In this study, the hydrogen production from organic wastes was investigated using batch experiments. Bean curd manufacturing waste, rice bran and wheat bran were used as the organic wastes. The effects of solid concentration on the hydrogen production potential and the characteristics of substrate decomposition were investigated. The percentages of hydrogen in the produced gas were between 54–78%, 43–68% and 42–72% for bean curd manufacturing waste, ricebran and wheat bran, respectively. The hydrogen production potentials of bean curd manufacturing waste, rice bran and wheat bran were 14–21, 31–61 and 10–43 ml.g VS−1, respectively. The hydrogen yields from carbohydrate degradation were 2.54, 1.29 and 1.73 mol of H2 mol−1 of hexose for bean curd manufacturing waste, rice bran and wheat bran, respectively. The carbohydrate was rapidly consumed just after inoculation. On the other hand, soluble protein was hardly degraded for each substrate, indicating that carbohydrate was the main source of the hydrogen production.

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Abstract:We present a study of using game theory for protecting wireless sensor networks (WSNs) from selfish behavior or malicious nodes. Due to scalability, low complexity and disseminated nature of WSNs, malicious attacks can be modeled effectively using game theory. In this study, we survey the different game-theoretic defense strategies for WSNs. We present a taxonomy of the game theory approaches based on the nature of the attack, whether it is caused by an external attacker or it is the result of an internal node acting selfishly or maliciously. We also present a general trust model using game theory for decision making. We, finally, identify the significant role of evolutionary games for WSNs security against intelligent attacks; then, we list several prospect applications of game theory to enhance the data trustworthiness and node cooperation in different WSNs.

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The effects of sulfate concentration and COD/S ratio on the anaerobic degradation of butyrate were investigated by using 2.0 L anaerobic chemostat-type reactor at 35°C. The study was conducted over a wide range of the COD/S ratio (1.5 to 148) by varying COD concentrations (2500–10000 mg/L) and sulfate concentrations (68–1667 mg-S/L) in the substrate. The sludge retention time at each COD/S ratio was changed from 5 to 20 days. The interaction between methane producing bacteria (MPB) and sulfate-reducing bacteria (SRB) was evidently influenced by COD/S ratio in the substrate. When COD/S ratio was 6.0 or more, methane production was the predominate reaction and over 80% of the total electron flow was used by MPB. At the COD/S ratio of 1.5, SRB utilzed over 50% of the total electron flow. A large amount of sulfate reduction resulted in not only the decrease of methane production, but also the rapid increase of the bacterial growth. The degradation pathway of butyrate and the composition of bacterial populations in the reactor were also dominated by COD/S ratio. In sulfate depleted condition, butyrate was degraded to methane via acetate and hydrogen by MPB. On the other hand, butyrate was firstly degraded into sulfide and acetate in sulfate rich conditions by SRB, and the produced acetate was then degraded by acetate consuming MPB and SRB. The methanogenesis from acetate was inhibited by the high concentration of sulfide.