Search results for "801"
showing 10 items of 1684 documents
Are calanco landforms similar to river basins?
2017
In the past badlands have been often considered as ideal field laboratories for studying landscape evolution because of their geometrical similarity to larger fluvial systems. For a given hydrological process, no scientific proof exists that badlands can be considered a model of river basin prototypes. In this paper the measurements carried out on 45 Sicilian calanchi, a type of badlands that appears as a small-scale hydrographic unit, are used to establish their morphological similarity with river systems whose data are available in the literature. At first the geomorphological similarity is studied by identifying the dimensionless groups, which can assume the same value or a scaled one in…
Insight into the role of the zeolitization process in enhancing the adsorption performance of kaolinite/diatomite geopolymer for effective retention …
2021
Abstract Diatomite/kaolinite-based geopolymer (GP) was synthesized and incorporated in zeolitization process (Z/GP) to investigate the role of the zeolite phases in inducing its retention capacity of the dissolved Sr (II) ions in water. The retention of Sr (II) ions using Z/GP in comparison with GP was evaluated based on both batch and fixed-bed column studies. In the batch study, the zeolitized geopolymer (Z/GP) shows enhancement in the Sr (II) retention capacity (193.7 mg/g) as compared to the normal geopolymer (102 mg/g). Moreover, the recyclability studies demonstrate higher stability for Z/GP than GP with a retention percentage higher than 90% for five reusing runs. The kinetic and the…
Dewaterability of CAS and MBR Sludge: Effect of Biological Stability and EPS Composition
2018
The dewaterability of sludge from two conventional activated sludge (CAS) and three membrane bioreactor (MBR)-based wastewater treatment plants is investigated prior to and after anaerobic digestion. The concentration and composition of extracellular polymeric substances (EPS) mostly affect the dewaterability of all raw sludge samples. Better sludge dewaterability is observed when the concentration of proteins, carbohydrates, uronic acids, and humic acids is below approximately 400, 250, 200, and 40 mg/L, respectively. In contrast, the specific resistance to filtration (SRF) increases in the sludge samples with a higher EPS concentration. The MBR results in a lower EPS production and a uron…
Life cycle assessment of olive oil: A case study in southern Italy
2018
Abstract The paper describes the results of a specific LCA based analysis of the production of olive oil in the region of Calabria, in southern Italy. The goal of the study is to assess the energy and environmental impacts of different scenarios involving conventional and organic cultivations, plains and hills cultivations and involving different operating techniques. The study also aims at assessing the share of each life cycle step on the total of energy and environmental impacts. The functional unit chosen for the comparative analysis is a glass bottle of 0.75 L of extra virgin olive oil. A “from cradle to gate” perspective was chosen. The analysis was developed according to the LCA stan…
Greenhouse Gas Emissions from Wastewater Treatment Plants on a Plantwide Scale: Sensitivity and Uncertainty Analysis
2016
This paper presents the sensitivity and uncertainty analysis of a mathematical model for greenhouse gas emission (GHG) and energy consumption assessment in wastewater treatment plants. A sensitivity analysis was carried out (using two different methods) to determine which model factors have the greatest effect on the predicted values of the GHG production. Further, an uncertainty analysis was carried out to quantify the uncertainty of the key model outputs, such as carbon dioxide production from activated sludge treatment. The results show that influent fractionation factors, which characterize influent composition, have an important role on direct and indirect GHGs production and emission.…
Strontium isotopes as tracers of water-rocks interactions, mixing processes and residence time indicator of groundwater within the granite-carbonate …
2016
This study aims at identifying the water-rock interactions and mixing rates within a complex granite-carbonate coastal aquifer under high touristic pressure. Investigations have been carried out within the coastal aquifer of Bonifacio (southern Corsica, France) mainly composed of continental granitic weathering products and marine calcarenite sediments filling a granitic depression. A multi-tracer approach combining physico-chemical parameters, major ions, selected trace elements, stable isotopes of the water molecule and 87Sr/86Sr ratios measurements is undertaken for 20 groundwater samples during the low water period in November 2014. 5 rock samples of the sedimentary deposits and surroun…
Assessing the conservation values and tourism threats in Barrientos Island, Antarctic Peninsula
2019
Antarctica has been witnessing continued growth of tourism, both in the overall visitation and in the diversity of itineraries and visitor activities. Expanding tourism presents unique business and educational opportunities, but it is also putting immense pressure on Antarctica's natural, and for the most parts, pristine environment. Understanding the effectiveness of different tourism management strategies and instruments, like the Visitor Site Guidelines adopted by the Antarctic Treaty, is fundamental to the sustainable management of Antarctic tourism. The purpose of this study was to assess the effectiveness of Visitor Site Guidelines and other tourism management actions in reducing impa…
Greenhouse gas emissions and the links to plant performance in a fixed-film activated sludge membrane bioreactor - Pilot plant experimental evidence
2017
The present study explores the interlinkages among the operational variables of a University of Cape Town (UCT) Integrated Fixed Film Activated Sludge (IFAS) membrane bioreactor (MBR) pilot plant. Specifically, dedicated experimental tests were carried out with the final aim to find-out a constitutive relationship among operational costs (OCs), effluent quality index (EQI), effluent fines (EF). Greenhouse gas (GHG) emissions were also included in the study. Results showed that the EQI increases at low flow rate likely due to the dissolved oxygen (DO) limitation in the biological processes. Direct GHGs increase with the increasing of the air flow due to the anoxic N2O contribution. Irreversi…
Effect of extended famine conditions on aerobic granular sludge stability in the treatment of brewery wastewater
2017
Results obtained from three aerobic granular sludge reactors treating brewery wastewater are presented. Reactors were operated for 60 d days in each of the two periods under different cycle duration: (Period I) short 6 h cycle, and (Period II) long 12 h cycle. Organic loading rates (OLR) varying from 0.7 kg COD m-3 d-1 to 4.1 kg COD m-3 d-1 were tested. During Period I, granules successfully developed in all reactors, however, results revealed that the feast and famine periods were not balanced and the granular structure deteriorated and became irregular. During Period II at decreased 12 h cycle time, granules were observed to develop again with superior structural stability compared to the…
A review on anaerobic membrane bioreactors (AnMBRs) focused on modelling and control aspects
2018
[EN] The use of anaerobic membrane bioreactor technology (AnMBR) is rapidly expanding. However, depending on the application, AnMBR design and operation is not fully mature, and needs further research to optimize process efficiency and enhance applicability. This paper reviews state-of-the-art of AnMBR focusing on modelling and control aspects. Quantitative environmental and economic evaluation has demonstrated substantial advantages in application of AnMBR to domestic wastewater treatment, but detailed modelling is less mature. While anaerobic process modelling is generally mature, more work is needed on integrated models which include coupling between membrane performance (including fouli…