Agricultural Engineering International (E-Journal, CIGR - International Commission of Agricultural Engineering)
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Disposal of Sea Bottom Sediments by Use as Raw Material for Concrete Elements
Full text linkThe possibility of using sea bottom sediments as a substitute for fine sand aggregate was investigated for the fabrication of concrete solids and marine reefs. The proportions of raw materials in the concrete mixture were optimized, and the materials were evaluated with by testing their slump, air content, mass change, total shrinkage and compressive strength. In the short term, i.e. a curing age of 3 to 28 days, the compressive strengths of the concrete materials made with the sediments were better than those of the normal concrete blocks. Furthermore, after 187 days of curing, the compressive strengths were 44, 31 and 12 MPa respectively for the concrete products with a water-cement ratio (w/c) by weight of 0.47, 0.69 and 1.15 using the sediments. When the concrete materials were field-tested in the sea for approximately one year, the blocks were not damaged by the sea environment because the compressive strengths were 48, 33 and 14 MPa with w/c = 0.47, 0.69 and 1.15, respectively. Since the concrete blocks constructed with the optimal mix of raw materials had enough solid strength to be used in the sea, it may be unnecessary to add steel reinforcement to this concrete for the specific purpose of constructing marine reefs
Carbon Dioxide Production in Animal Houses: A Literature Review
Full text linkThis article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers.Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20 oC) has often been used. The article shows that the carbon dioxide production per hpu increases with increasing respiration quotient. As the respiration quotient increases with body mass for growing animals, the carbon dioxide production per heat production unit also increases with increased body mass. The carbon dioxide production is e.g. less than 185 litres per hour per hpu for weaners and broilers and higher for growing finishing pigs and cows.The analyses show that the measured carbon dioxide production is higher in full scale animal houses than measured in respiration chambers, due to differences in manure handling. In respiration chambers there is none or very limited carbon dioxide contribution from manure; unlike in animal houses, where a certain carbon dioxide contribution from manure handling may be foreseen. Therefore, it is necessary to make a correction of data from respiration chambers, when used in full scale animal buildings as basis for estimation of ventilation flow. Based on the data reviewed in this study, we recommend adding 10% carbon dioxide production to the laboratory based carbon dioxide production for animal houses with slatted or solid floors, provided that indoor manure cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration for these houses
Production and Characterization of Polyhydroxybutyrate from Molasses and Corn Steep Liquor produced by Bacillus megaterium ATCC 6748
Full text linkThe accumulation of polyhydroxybutyrate (PHB) granule in cells of Bacillus megaterium ATCC 6748 was significantly depended on the ratio of C-source and N-source in the medium culture. Sugarcane molasses (MOL) and corn steep liquor (CSL) were used as renewable raw materials, since they were rich in carbon and nitrogen respectively, leading to develop a low cost process of PHB production. The highest PHB production was observed after 45h of growth (43% w/w, dry matter) when 4% molasses and 4% CSL were used, whereas the highest biomass (7.2 g l-1) was obtained at 4% molasses and 6% CSL. This indicated that bacterial growth increased as CSL concentration increased, whereas the PHB accumulation decreased. The formation rate of PHB up to 0.016 h-1 and specific growth rate up to 0.25 h-1 were observed during growth. The chemical structure and thermal properties of PHB produced from molasses and CSL were obtained the same properties as commercial PHB, except for the higher molecular mass (approx. 3.9 x 106 Da) and the lower degree of crystallinity (60% XC). Thus, the present data indicate that molasses and CSL could be alternatively used for PHB production by this bacterium with high PHB content and adequate properties of biopolymer from a low cost process
Evaluation of Box Type Paddy Dryers in South Sumatra, Indonesia
Full text linkIndonesia is the third biggest paddy producing country worldwide with its annual production of around 54 million ton. South Sumatra Province has an annual paddy production of around 2.32 million ton. Paddy has high moisture content, up to 24%, when it is harvested. Moist paddy needs immediate drying after it is harvested to reduce its moisture content to 14% or less for milling or for safe storage, respectively. Sun drying of paddy has been practiced for years despite many problems associated with it. Different studies show that the post harvest loss of the paddy lies in between 10% and 37%, in which drying related losses might be from 1% up to 10%. Like in any other parts of the country, South Sumatra Province also has no commercial paddy drying systems in practice. In 2004, as a first prototype of such type, a box type paddy dryer with a rice husk burning oven was introduced in Upang village. Now there are already more than 30 box dryers installed in three neighbouring villages – Muliasari, Upang and Upangceria - where this study was carried out. The drying capacity of each dryer varies between 3.5 ton and 10 ton of harvested paddy. Although the widespread of dryers is rapid in these villages, none of the field experiments were carried out so far to evaluate their technical, economical and social performances. This study aimed to conduct the experiments on the selected dryers and to assess their technical performances at first. Three dryers were chosen for the experiments and altogether eight experiments were carried out. Parallel sun drying experiments were carried out for quality test of rice yielded from milling the paddy dried in box dryer and dried in sun drying. Based on the observed data, economic analysis of paddy drying considering two important stakeholders – investors and farmers is presented in this paper