1,721,270 research outputs found
Procedures for the production of biofules from organic wastes
No full textThe present invention concerns a procedure to produce bio-fuels of natural origin from organic wastes. In particular the present invention concerns a procedure to obtain bio-fuels starting from the organic fraction of waste comprising a phase of extraction with a solvent of said organic fraction and a separation of said bio-fuel from said solvent
An interlaboratory study of heavy metal content in compost
No full textHeavy metals in 15 composts were determined by four Italian laboratories participating in a study involving interlaboratory work. The data obtained were processed using a statistical approach focused on measuring precision, that is to say, on repeatability (r) and reproducibility (R) limit determination. The results indicate how precision is substantially in agreement with what is reported in the literature, and that repeatability and reproducibility affect the statistical validity of data. It has been shown that only for data with R ≤ 1.25 r can the means of four laboratories be considered as being of the same population (the same compost), revealed by ANOVA as such. For each heavy metal, consideration was given only to those results where R ≤ 1.25 r in order to determine the interval of confidence. Upper variation limits (expressed as relative variation with respect to the mean) were then used to calculate the upper value to be detected to respect heavy metal limits according to Italian law
L’importanza della stabilità biologica nel controllo di processo e nella qualità dei prodotti
No full textThe contribution of water soluble and water insoluble organic fractions to oxygen uptake rate during high rate composting
No full textThis study aims to establish the contribution of the water soluble and water insoluble organic fractions to total oxygen uptake rate during high rate composting process of a mixture of organic fraction of municipal solid waste and lignocellulosic material. This mixture was composted using a 20 l self-heating pilot scale composter for 250 h. The composter was fully equipped to record both the biomass-temperature and oxygen uptake rate. Representative compost samples were taken at 0, 70, 100, 110, 160, and 250 h from starting time. Compost samples were fractionated in water soluble and water insoluble fractions. The water soluble fraction was then fractionated in hydrophilic, hydrophobic, and neutral hydrophobic fractions. Each fraction was then studied using quantitative (total organic carbon) and qualitative analysis (diffuse reflectance infrared spectroscopy and biodegradability test). Oxygen uptake rates were high during the initial stages of the process due to rapid degradation of the soluble degradable organic fraction (hydrophilic plus hydrophobic fractions). Once this fraction was depleted, polymer hydrolysis accounted for most of the oxygen uptake rate. Finally, oxygen uptake rate could be modeled using a two term kinetic. The first term provides the oxygen uptake rate resulting from the microbial growth kinetic type on easily available, no-limiting substrate (soluble fraction), while the second term considers the oxygen uptake rate caused by the degradation of substrate produced by polymer hydrolysis
An index for quantifying the aerobic reactivity of municipal solid wastes and derived waste products
No full textThe organic matter contained in municipal solid waste (MSW) and in the MSW fractions obtained by mechanical separation has strong environmental impact when the waste is used as landfill. This is partly due to the biological activity that occurs under anaerobic conditions. Negative effects on the environment include unpleasant odors, biogas, leachate and biomass self-heating. Measuring the biological reactivity of waste with the help of indicators is an important tool to prevent waste impact. The aim of this study was to develop an index capable of describing the aerobic reactivity of waste, using both biological and chemical indicators. To develop this index, 71 MSW and MSW-product samples, including biologically treated MSW and mechanically separated MSW fractions, were analyzed. Fifty of the 71 samples analyzed represented MSWs and their derived products collected from a number of Italian waste plants and sites. The remaining 21 were MSW samples collected at different times during 8 different full-scale aerobic biological processes in four treatment plants used to reduce the biological reactivity of wastes. Five of these processes used the entire (unsorted) MSW, while the remaining three used the organic fraction of the MSW obtained by mechanical pre-treatment (waste sieving). Respirometric activity (Dynamic Respiration Index, DRI) and eluates characterization (chemical oxygen demand - COD, and 5 days biological oxygen demand - BOD5) were used as indicators of waste strength, as they had previously been reported to be indirect measures of waste impact on landfill. Summarizing all studied indicators, Principal Component Analysis (PCA) was used to develop the Putrescibility Index (Ip). The results revealed Ip index of 204 ± 33 (mean ± standard deviation) and 159 ± 14 for the organic fraction of MSW and MSW untreated waste respectively, and of 106 ± 16 and 101 ± 22 for the corresponding biologically treated waste
Qualità del compost : influenza del grado di stabilità biologica sul contenuto di enterobatteriacee totali
No full textBiodegradability of soil water soluble organic carbon entracted from seven different soils
No full textWater soluble organic carbon (WSOC) is considered the most mobile and reactive soil carbon source and its characterization is an important issue for soil ecology study. A biodegradability test was set up to study WSOC extracted from 7 soils differently managed. WSOC was extracted from soil with water (soil/water ratio of 1:2, W/V) for 30 min, and then tested for biodegradability by a liquid state respirometric test. Result obtained confirmed the finding that WSOC biodegradability depended on the both land use and management practice. These results suggested the biodegradability test as suitable method to characterize WSOC, and provided useful information to soil fertility
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