141 research outputs found
Two-reactor system with partial phase separation for anaerobic treatment of olive oil mill effluents
No full textPrevious works on the anaerobic treatment of olive oil mill effluents (OME) have shown that the inhibition of methane production is mainly caused by the presence of lipids. Saturation of unsaturated long-chain fatty acids (LCFAs) is the key factor to prevent inhibition of methanogenesis. This paper reports the experimentation carried out in a semi-continuous lab scale two-reactor system fed with diluted OME. Phase separation (acidogenesis and methanogenesis) was not complete in the two reactors. Indeed, a moderate methanogenic activity was allowed to be established in the first reactor. This scheme proved to be suitable to obtain an almost quantitative biotransformation of unsaturated LCFAs to palmitic acid in the first reactor, thus drastically lowering lipid inhibition on methanogenesis in the second reactor. The addition of an easily biodegradable substrate such as glucose did not improve biodegradation of pol!,phenols. A continuous flushing of N-2/CO2 through the 'acidogenic' reactor did not promote the P-oxidation of palmitic acid. The two-reactor system with partial phase separation could find useful application for the anaerobic treatment of any lipid-containing wastewater. (C) 1998 Published by Elsevier Science Ltd. All rights reserved
Measurement of thermal conductivity and thermal resistance in composite materials for space applications
No full textIntegrated treatment of olive oil mill effluents: effect of chemical and physical pretreatments on anaerobic treatability
No full textDifficulties met in the anaerobic treatment of olive oil mill effluents (OME) suggest the use of a chemicophysical pretreatment for the removal of biorecalcitrant and/or inhibiting substances (essentially lipids and polyphenols) as selectively as possible before anaerobic digestion. Laboratory scale experiments were carried out in order to identify pretreatment type and conditions capable of optimizing OME anaerobic digestion in terms both of kinetics and methane yield. Ultrafiltration, even if it allowed very high removals of lipids and polyphenols, was affected by poor selectivity (indeed, large amounts of biodegradable COD were also removed). Centrifugation turned out to be preferable to sedimentation owing to smaller volumes of separated phase. Results of great significance were obtained by adding Ca(OH)(2) (up to pH 6.5) and 15 g/l of bentonite, and then feeding the mixture to the biological treatment without providing an intermediate phase separation. Indeed, the biodegradable matter adsorbed on the surface of bentonite was gradually released during the biotreatability test, thus allowing the same methane yield (referred to the total COD contained in untreated OME) both in scarsely diluted (1 : 1.5) pretreated OME and in very diluted (1 : 12) untreated OME. Application of a continuous process combining pretreatment (with Ca(OH)(2) and bentonite) and anaerobic digestion without intermediate phase separation is suggested
The European Water Framework Directive 2000/60/EC in the evaluation of the ecological status of watercourses. Case study : the river Chienti (central Apennines, Italy)
No full textThe quality of the river Chienti (eastern-central Apennines, Italy) has been evaluated according to the Water Framework Directive 2000/60/EC, taking into consideration both biotic (animal and vegetable) and chemical parameters. In studying the biotic component, two indices were used: the E.B.I, Extended Biotic Index (version adapted to the Italian rivers), based on macroinvertebrates, and the EPI-D, the Eutrophication and/or Pollution Index, based on diatoms. For both macroinvertebrates and diatoms, two samplings were conducted, one in June and the other in October 2003. Instead, according to the Italian Law 152/99 the chemical and bacteriological analyses were conducted monthly for the entire year. The results of biomonitoring and chemical-bacteriological analyses unanimously demonstrated a good ecological situation for the upper section of the Chienti, though the situation tends to worsen as the river continues its descent and undergoes increased anthropogenic pressure. Data obtained were correlated with Spearman's coefficients and principal component analysis. Both statistical calculations showed clear, direct correlation between the two biotic indices and an inverse correlation between these and the chemical and bacteriological parameters. However, a few differences of judgement that emerged among the various indices highlight the importance of using them simultaneously in order to obtain a more accurate diagnosis of the ecological status of the watercourses
Role of lipids and phenolic compounds in the anaerobic treatment of olive oil mill effluents
No full textThe inhibitory effects of olive oil mill effluents (OME) on methanogenesis were studied by using p-hydroxybenzoic acid (HBA) and oleic acid (OA) as model compounds for phenolic compounds and Lipids respectively. The addition of HBA (0.3 g 1(-1)') to diluted OME (5.7 g COD 1(-1)) had a negligible effect on methanogenesis in terms of kinetics and final methane yield. Strong inhibition was observed only at high HBA concentrations (6 g 1(-1)). The OA inhibited methane production much more strongly Indeed, 0.35 g 1(-1) of OA were able to double the lag phase for methanogenesis fi om diluted OME. With both compounds, the presence of an easily biodegradable co-substrate (glucose) did not increase the rate of substrate degradation nor methane formation. OME acidogenesis was significantly less sensitive than methanogenesis to the inhibitory effects exerted by OA and HBA, even at relatively high concentrations of the model compounds
Enhancement of anaerobic treatability of olive oil mill efflents by addition of Ca(OH)2 and bentonite without intermediate soild/liquid separation
No full textPrevious work on the anaerobic treatment of olive oil mill effluents (OME) have shown: (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH), and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bloconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH), and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment: the best results in terms of methane production were obtained by addition of Ca(OH)(2) UP to pH 6.5 and of 10 g L-1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous mathanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m(-3) d(-1) and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor)
Comparative monitoring by means of diatoms, macroinvertebrates and chemical parameters of an Apennine watercourse of central Italy: The river Tenna.
No full textTheWFD/60/2000/EC establishes the use of different biological indicators to assess the ecological status of
rivers, in addition to chemical, physical and bacteriological parameters. At this purpose, the present study
concerning the river Tenna, a central Apennine watercourse (Italy), aimed to analyse and discuss the
information given by two biological indices: the Extended Biotic Index or E.B.I. that uses benthic
macroinvertebrates, in the version adapted to the Italian rivers (I.B.E.), and the diatom-based
Eutrophication and/or Pollution Index (EPI-D). Sampling has been carried out twice, in May (deep water
conditions) and October 2006 (low water conditions), in ten stations along the hydrographic basin of the
river. Chemical parameters have been determined monthly during a year because they present a higher
variability than biotic indicators. The correlations between the biological and abiotic data obtained have
been statistically analysed by means of the Spearman’s test. The statistical data, in general, showed a direct
correlation between the two biotic indices, and an inverse correlation between these and the chemicalphysical
and bacteriological parameters. Some of the differences of judgement emerging from the
application of the two biotic indices showed a complementary response of the diatoms and
macroinvertebrates to various environmental stresses. These results suggest the usefulness of an
integrated multidisciplinary approach, in order to obtain a more accurate diagnosis of the health status of
the watercourses
PROCESSO INTEGRATO CHIMICO-FISICO E BIOLOGICO PER IL TRATTAMENTO DI REFLUI DI FRANTOI OLEARI (ACQUE DI VEGETAZIONE, AV)
No full textThe process makes it possible to biologically treat olive oil mill wastewaters (OMW) at low dilution and high organic load rate in spite of their high content of inhibitory compounds, namely lipidic and phenolic ones. The process is based on combination of physical-chemical and biological (anaerobic) treatment in a single and simultaneous step. The physical-chemical part of the process is based on the addition of natural sorbents and chemicals which regulate the inhibitory compounds at non inhibitory concentration while still leaving them available for biodegradation. Thus OMW conversion to methane can be obtained at high organic load rate (up to 8.2 kg COD m-3 d-1) even though the feed is very little diluted (1:1.5). Very good performance is obtained (total COD removal : 91 %; methane yield : 0.80 g CH4 (as COD) / g removed COD; lipids removal: 98%; phenols removal: 63%). Moreover, the addition of natural sorbents and chemicals introduce neither any sophisticated reactor engineering nor treatment or disposal of concentrated or toxic side streams
Qualità biologica dei corsi d'acqua dell'Appennino centrale monitorati tramite l'indice diatomico integrato di eutrofizzazione/polluzione (EPI-D) e l'indice biotico esteso (IBE).
No full textUltrasound and color Doppler applications in chronic kidney disease
No full textChronic kidney disease (CKD) includes all clinical features and complications during the progression of various kidney conditions towards end-stage renal disease (ESRD). These conditions include immune and inflammatory disease such as: primary and hepatitis C virus (HCV)-related glomerulonephritis; infectious disease such as pyelonephritis with or without reflux and tuberculosis; vascular disease such as chronic ischemic nephropathy; hereditary and congenital disease such as polycystic disease and congenital cystic dysplasia; metabolic disease including diabetes and hyperuricemia; and systemic disease (collagen disease, vasculitis, myeloma). During the progression of CKD, ultrasound imaging and color Doppler imaging (US-CDI) can differentiate the etiology of the renal damage in only 50-70% of cases. Indeed, the end-stage kidney appears shrunken, reduced in volume (Ø < 9 cm), unstructured, amorphous, and with acquired cystic degeneration (small and multiple cysts involving the cortex and medulla) or nephrocalcinosis, but there are rare exceptions, such as polycystic kidney disease, diabetic nephropathy, and secondary inflammatory nephropathies. The main difficulties in the differential diagnosis are encountered in multifactorial CKD, which is commonly presented to the nephrologist at stage 4-5, when the kidney is shrunken, unstructured and amorphous. As in acute renal injury and despite the lack of sensitivity, US-CDI is essential for assessing the progression of renal damage and related complications, and for evaluating all conditions that increase the risk of CKD, such as lithiasis, recurrent urinary tract infections, vesicoureteral reflux, polycystic kidney disease and obstructive nephropathy. The timing and frequency of ultrasound scans in CKD patients should be evaluated case by case. In this review, we will consider the morpho-functional features of the kidney in all nephropathies that may lead to progressive CKD
- …
