Papers by Keyword: Anaerobic

Abstract: This document it is established that 2 types of biogas anaerobic digester that usually found in developing country. First type is fixed dome type of anaerobic digester and secondly is floating drum biogas anaerobic digester. Both of this type have draw back that the anaerobic process is not completed with agitation process that yield low rate of biogas production. Other serious problem is the release of slurry cannot optimal. Some of the slurry will still remain stay in the anaerobic digester especially scum. To drain and cleaning the fixed dome or floating drum biogas anaerobic digester is mandatory to be done regularly that consume time and cost. The fixed dome types as well as floating drum type are usually not portable which cause no possibility to relocate in the new site. It is the purpose of this work to introduce portable biogas anaerobic digester that suitable for developing country with volume of digester around 500 liter of slurry. The requirement of agitator is facilitated, and the anaerobic digester is possible to be operated in batch system or continuous system. The material that is used for anaerobic digester is stainless steel 304 with tungsten inert gas welding technology that is used for the manufacturing. With this design the anaerobic digester are easy to be maintenance. The batch system can keep producing biogas until 52 day with total production of biogas around 3320 liters. The continuous system was conducted by releasing for about 5 liters slurry from the outlet and after that filled with new slurry with stirring with agitator was conducted for about 10 minutes for 3 times in a day (morning, noon, and evening). The result for continuous system is a linear biogas production with rate biogas production is around 51.7 liter/day (1550 liter/30days).

Abstract: Bioleaching is applied mainly for copper recovery from low-grade sulfide ores via heap leaching. The main copper processing route includes pyrometallurgy and the remaining copper slag from smelting may still contain copper in amounts found in the ore. Here bioleaching of copper slag material with a copper content of about 1 % (grain size < 63 µm) and fayalite (Fe₂SiO₄) und magnetite (Fe₃O₄) as main mineral phases was tested in aerobic shake flask experiments with a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidiphilium spp..To additionally test for reductive bioleaching, experiments under anaerobic conditions (80% N₂, 20% CO₂, v/v) with or without addition of elemental sulfur were run. The pH was adjusted to < 3 by addition of sulfuric acid. After the incubation period of more than 50 days at 30°C cell growth was observed in all biological assays. The redox potential was above 800 mV SHE in the aerobic biological assays and dropped to around 500 mV in the chemical control assays as well as in the anaerobic biological and chemical assays. A significant copper bioleaching was observed in the aerobic experiments with 91 % copper release (max. 35 % in the chemical controls). Anaerobic bioleaching experiments did not show a significant copper release, however the release of iron (as iron(II)) and sulfate was much higher than in the abiotic assays and several fold higher than in the classical aerobic bioleaching experiments. Overall the results show that copper bioleaching from slag material is possible, however the economic feasibility needs to be demonstrated.

Abstract: Ferric iron may act as a thermodynamically favourable electron acceptor during elemental sulfur oxidation by Acidithiobacillus ferrooxidans in extremely acidic anoxic environments. A loss of anaerobic ferric iron reduction ability has been observed in ferrous iron-grown A. ferrooxidans CCM 4253 after aerobic passaging on elemental sulfur. In this study, iron-oxidising cells aerobically adapted from ferrous iron to elemental sulfur were still able to anaerobically reduce ferric iron, however, following aerobic passage on elemental sulfur it could not. Preliminary quantitative proteomic analysis of whole cell lysates of the passage that lost anaerobic ferric iron-reducing activity resulted in 150 repressed protein spots in comparison with the antecedent culture, which retained the activity. Identification of selected protein spots by tandem mass spectrometry revealed physiologically important proteins including rusticyanin and outer-membrane cytochrome Cyc2, which are involved in iron oxidation. Other proteins were associated with sulfur metabolism such as sulfide-quinone reductase and proteins encoded by the thiosulfate dehydrogenase and heterodisulfide reductase complex operons. Furthermore, proteomic analysis identified proteins directly related to anaerobiosis. The results indicate the importance of iron-oxidising system components for anaerobic sulfur oxidation in the studied microbial strain.

Abstract: This paper compares the inhibitory effect of high CaCl₂ and MgCl₂ content on anaerobic microorganism based on kinetics model. Salt inhibition kinetics experiments were performed at granular sludge and activated sludge in order to investigate salt inhibition effects on kinetic constants. Half-velocity constant values considerably increased when CaCl₂ or MgCl₂ concentration increased from 0 to 35g/L for granular sludge and activated sludge. Salt inhibition biokinetic coefficients (K_ρ) were obtained by using Ghose and Tyagi model. For granular sludge, K_ρ of CaCl₂ was found to be 130.3 g/L, and K_ρ of MgCl₂ was found to be 86 g/L. For activated sludge, K_ρ of CaCl₂ was found to be 92.8 g/L, and K_ρ of MgCl₂ was found to be 77.6 g/L. Results showed that the inhibitory CaCl₂ limit was higher than the inhibitory MgCl₂ limit for anaerobic microorganisms.

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Abstract: This research aims to give an overview on how to improve the biogas yeild in Balinese digester plants using various co-substrates which are available in Bali. A series testing on the digestibility of substrates were set up either in the field or in the biogas laboratory. In-field analyses like testing the CO₂-content and taking samples from digested manure were undertaken. Analyses such as dry matter (DM) and organic dry matter (oDM) determination, pH measurement and FOS/TAC were handled in the biogas laboratory. The huge number of different fruits in Bali gives a good opportunity to use their wastes like Durian hulls and Banana peelings, which can not be used anymore, as co-substrates in biogas plants. The results of these investigations allow to estimate the additional biogas yield, when adding co-substrates to a cow manure biogas plant.

Abstract: Aiming at the fact that the low concentration sewage in small cities, this paper presents Two-phase Anaerobic Baffled Reactor (TAABR) for living wastewater treatment, importantly, it designs and researches Two-phase Anaerobic Baffled Reactor and its advantages, designs a trial project according to the characteristics of the reactor equip. The experiment uses the method that by shortening HRT to raise the load to start and analyses the operating results during startup as follows: 1. 53 days later anaerobic reactor start-up successes.2. When the load is 0.5kgCOD/m³.d, the removal rate of COD is more than 80%. 3. PH value is not the main limiting factors during start up in the reactor and there is basically no danger of excessive acidification.

Abstract: A pilot-scale combined system composed of anaerobic digenstion, membrane bioreactor (MBR) and Electro-Catalyzed oxidation processes has been set up to treat the leachate from municipal solid waste (MSW) transfer station. System performance was evaluated by ammonia and chemical oxidation demand (COD) removal . Results showed that 97% of ammonia was removed by MBR, and the elimination of COD was mainly completed in anaerobic process and MBR with a total removal of 99%. In addition, the analysis of microbial communities in the MBR, carried out by clone library and denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA genes, indicated a highly diverse bacterial community and the enrichment of N-cycling bacteria.

Abstract: Aeromonas hydrophila is a facultative anaerobe which, under conditions of oxygen depletion, is able to respire iron (III). Scanning electron microscopy (SEM) and conducting-probe atomic force microscopy (AFM) revealed the presence of filaments between cells and cell-substrate and their conductive nature. These results indicate that the pili of A. hydrophila might serve as biological nanowires, transferring electrons from the cell to the surface of Fe (III) oxides. Conductive pili could also play a role in bacterial interactions and in inter/intra species signalling, and could lead to biotechnological approaches for novel materials.

Abstract: This paper presented Low investment and low running cost Two-phase Anaerobic Baffle Treatment Craft for living wastewater treatment, it designed Two-phase anaerobic reactor and carried out a successful launch and Experiment research. The results are as follows: 1. The experiment uses the start method that by shortening HRT to raise the load, after 53 days completes experiment start.2. By the analysis of HRT to the system effect, suggest that the best HRT is 6 h when the craft processes sewage. 3. The system clean rates of the total nitrogen and total phosphoric are respectively 21.05% and 20.1%.4. The temperature has an influence on clean effect of the system, when the temperature descends from 20 °C to 10 °C, system clean rate of average COD descends from 87.1% to 52.4%. 5. Reactor VFA and PH measurement results express that the craft could circulate stably and efficiently.