Search results for "Gradation"
showing 10 items of 1275 documents
Behaviour of EDTA in marine microcosms
2000
Laboratory-scale microcosm tests were carried out in sea water with and without sediment to investigate the importance of ultraviolet (UV) light and microbes in the temperature-dependent degradation of metal complexes of ethylenediaminetetraacetic acid (EDTA). After 17 weeks, 44% and 48% of the original EDTA (initial concentration 385 microg/L) were converted at 10 degrees C and 22 degrees C, respectively. The degradation was more influenced by UV light than by sediment microbes, although the latter were very important. At both temperatures, absorption of EDTA to the sediment phase reached a maximum in the initial stage of the experiments (4 weeks): at 10 degrees C about 4% and at 22 degree…
A new foam-based method for the (bio)degradation of hydrocarbons in contaminated vadose zone
2020
International audience; An innovative foam-based method for Fenton reagents (FR) and bacteria delivery was assessed for the in situ remediation of a petroleum hydrocarbon-contaminated unsaturated zone. The surfactant foam was first injected, then reagent solutions were delivered and propagated through the network of foam lamellae with a piston-like effect. Bench-scale experiments demonstrated the feasibility of the various treatments with hydrocarbon (HC) removal efficiencies as high as 96 %. Compared to the direct injection of FR solutions, the foam-based method led to larger radii of influence and more isotropic reagents delivery, whereas it did not show any detrimental effect regarding H…
Concentrations of monosaccharides in humic substances in the early stages of humification.
2001
Deteriorated liquid packaging board (LPB) and biowaste compost are matrices, mainly consisting of cellulose, in the early stages of humification. Degradative studies on these matrices allow an examination of the role of carbohydrates in the synthesis of humic substances. Samples of different age were collected and divided by extraction into hot water extract (HWE), bitumen, humic acid (HA), fulvic acid (FA) and humin or residual fibre fractions. The following monosaccharides were identified in these fractions: L-arabinose, D-ribose, D-xylose, L-fucose, D-mannose, D-fructose, D-galactose, D-glucose, L-rhamnose and xylitol. The main component in all fractions was glucose. The concentrations o…
Effect of additives on process stability of mesophilic anaerobic monodigestion of pig slaughterhouse waste
2012
The effect of two additives on anaerobic monodigestion of pig slaughterhouse waste was studied in three laboratory scale continuously stirred tank reactors (CSTRs) operated for 242-284 days at 35°C. A higher organic loading rate (OLR), namely 2.25 kg volatile solids (VS)/m(3)d with a hydraulic retention time (HRT) of 30 d was feasible with an additive containing Fe, HCl and trace elements while an OLR of 1.5 kg VS/m(3)d (HRT 30 d) led to instabilities in CSTR with an additive consisting of Fe and HCl and in CSTR without additives. Methane yields of ca. 700 dm(3) CH(4)/kg VS(fed) were obtained in all reactors under stable conditions. Both additives decreased H(2)S concentration of the biogas…
Hydrogen sulfide and odor removal by field-scale biotrickling filters: Influence of seasonal variations of load and temperature
2012
Two biotrickling filters were set up at two wastewater treatment plants (WWTP) in The Netherlands to investigate their effectiveness for treatment of odorous waste gases from different sources. One biotrickling filter was installed at Nieuwe Waterweg WWTP in Hook of Holland to study the hydrogen sulfide removal from headworks waste air. The other reactor was installed at Harnaschpolder WWTP (treating wastewater of the city of The Hague) to remove mercaptans and other organic compounds (odor) coming from the emissions of the anaerobic tanks of the biological nutrient removal (BNR) activated sludge. The performance of both units showed a stable and highly efficient operation under seasonal va…
Bifunctional Z-Scheme Ag/AgVO3/g-C3N4 photocatalysts for expired ciprofloxacin degradation and hydrogen production from natural rainwater without usi…
2020
Abstract To maximize the employment of sustainable solar energy in treating the recalcitrant pollutant and hydrogen energy production, the development of a highly efficient photocatalyst is desirable. Herein, a Z-scheme Ag/AgVO3/g-C3N4 photocatalyst was synthesized via a wet-impregnation method. The amount of Ag/AgVO3 deposited onto g-C3N4 has a significant effect on the photocharge carrier separation and migration of the as-developed Z-scheme photocatalyst. It was found that 0.5 wt % Ag/AgVO3/g-C3N4 photocatalyst exhibited a profound photocatalytic degradation performance with 82.6% ciprofloxacin removal and 3.57 mmol/h of hydrogen produced from natural rainwater under visible-light irradi…
Effect of intracellular P content on phosphate removal in Scenedesmus sp. Experimental study and kinetic expression
2014
The present work determines the effect of phosphorus content on phosphate uptake rate in a mixed culture of Chlorophyceae in which the genus Scenedesmus dominates. Phosphate uptake rate was determined in eighteen laboratory batch experiments, with samples taken from a progressively more P-starved culture in which a minimum P content of 0.11% (w/w) was achieved. The results obtained showed that the higher the internal biomass P content, the lower the phosphate removal rate. The highest specific phosphate removal rate was 6.5 mgPO4 P gTSS -1 h -1 . Microalgae with a P content around 1% (w/w) attained 10% of this highest removal rate, whereas those with a P content of 0.6% (w/w) presented 50% …
Photoinductive efficiency of soil extracted humic and fulvic acids
2002
Humic and fulvic acids extracted from soils of different genesis were investigated for their ability to photoinduce the transformation of fenuron (2 x 10(-4) mol(-1)) at 365 nm. The ratio of the initial rate of fenuron consumption over the rate of light absorption by humic substances was found to be higher for fulvic acids (range 2.0 x 10(-3) to 9.0 x 10(-5)) than for humic acids (range 1.7 x 10(-4) to - 3.6 x 10(-5)). Within the FAs population, this ratio decreased as the specific absorption coefficient at 365 nm increased. It seems therefore that most of 365-nm absorbing components have no photoinductive activity and even reduce that of photoinductive chromophores.
The overproduction of 2,4-DTBP accompanying to the lack of available form of phosphorus during the biodegradative utilization of aminophosphonates by…
2014
Although information about the ability of some filamentous fungi to biodegrade organophosphonates is available, the knowledge about accompanying changes in fungal metabolism is very limited. The aim of our study was to determine the utilization of the chosen, structurally diverse aminophosphonates by Aspergillus terreus (Thom), in the context of the behaviour of this fungus while growing in unfavourable conditions, namely the lack of easily available phosphates. We found that all the studied compounds were utilized by fungus as nutritive sources of phosphorus, however, their effect on the production of fungal biomass depended on their structure. We also observed an interesting change in the…
Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.
2017
Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …