scholarly journals Sequential pretreatment to recover carbohydrates and phosphorus from Desmodesmus sp. cultivated in municipal wastewater

2020 ◽  
Vol 82 (6) ◽  
pp. 1237-1246
Author(s):  
R. M. González-Balderas ◽  
S. B. Velásquez-Orta ◽  
I. Valdez-Vazquez ◽  
M. T. Orta Ledesma
Keyword(s):  
Ozone Concentration ◽  
Contact Time ◽  
Energy Demand ◽  
Large Scale ◽  
Municipal Wastewater ◽  
Atmospheric Conditions ◽  
Alkaline Ph ◽  
Experimental Parameters ◽  
Ozone Pretreatment ◽  
Sequential Pretreatment

Abstract This study focused on the simultaneous recovery of carbohydrates (CHO) and phosphorus (P) from Desmodesmus sp. biomass cultivated in municipal wastewater, through a sequential pretreatment. The pretreatment consisted first of ultrasound to trigger cell disruption followed by ozonation to recover CHO and P. For ozone pretreatment, three different parameters were considered: ozone concentration (9, 15, 21, 27, 36, and 45 mg O3/L), contact time (15, 25 and 35 min), and pH (8 and 11). The maximum simultaneous release of 84% of CHO and 58% of P was achieved at the experimental parameters of ozone concentration of 45 mg O3/L, contact time of 35 min, and pH of 11. Also, P was concentrated in solution by 8- to 14-fold with respect to municipal wastewater. The sequential pretreatment was conducted at alkaline pH of 11 and atmospheric conditions, which may considerably reduce energy demand and reagents, in comparison to a traditional hydrolysis pretreatment. The results found suggest that the sequential pretreatment could be feasible on a large scale.

scholarly journals The Separation of Emulsified Water/Oil Mixtures through Adsorption on Plasma-Treated Polyethylene Powder

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1086
Author(s):  
Asma Abdulkareem ◽  
Anton Popelka ◽  
Patrik Sobolčiak ◽  
Aisha Tanvir ◽  
Mabrouk Ouederni ◽  
...  
Keyword(s):  
Droplet Size ◽  
Contact Time ◽  
Diesel Oil ◽  
Polluted Water ◽  
Order Kinetic ◽  
Atmospheric Conditions ◽  
Sonication Time ◽  
Oil Concentration ◽  
Oil Water ◽  
Emulsified Water

This paper addresses the preparation and characterization of efficient adsorbents for tertiary treatment (oil content below 100 ppm) of oil/water emulsions. Powdered low-density polyethylene (LDPE) was modified by radio-frequency plasma discharge and then used as a medium for the treatment of emulsified diesel oil/water mixtures in the concentration range from 75 ppm to 200 ppm. Plasma treatment significantly increased the wettability of the LDPE powder, which resulted in enhanced sorption capability of the oil component from emulsions in comparison to untreated powder. Emulsions formed from distilled water and commercial diesel oil (DO) with concentrations below 200 ppm were used as a model of oily polluted water. The emulsions were prepared using ultrasonication without surfactant. The droplet size was directly proportional to sonication time and ranged from 135 nm to 185 nm. A sonication time of 20 min was found to be sufficient to prepare stable emulsions with an average droplet size of approximately 150 nm. The sorption tests were realized in a batch system. The effect of contact time and initial oil concentrations were studied under standard atmospheric conditions at a stirring speed of 340 rpm with an adsorbent particle size of 500 microns. The efficiency of the plasma-treated LDPE powder in oil removal was found to be dependent on the initial oil concentration. It decreased from 96.7% to 79.5% as the initial oil concentration increased from 75 ppm to 200 ppm. The amount of adsorbed oil increased with increasing contact time. The fastest adsorption was observed during the first 30 min of treatment. The adsorption kinetics for emulsified oils onto sorbent followed a pseudo-second-order kinetic model.

scholarly journals Bio-Flocculation Property Analyses of Oleaginous Microalgae Auxenochlorella protothecoides UTEX 2341

2021 ◽  
Vol 13 (5) ◽  
pp. 2885
Author(s):  
Jinyu Li ◽  
Baozhen Li ◽  
Jinshui Yang
Keyword(s):  
Large Scale ◽  
Municipal Wastewater ◽  
Biofuel Production ◽  
Microalgae Harvesting ◽  
Flocculation Efficiency ◽  
Oleaginous Microalgae ◽  
Freeze Dried ◽  
Flocculation Ability ◽  
Powder Samples ◽  
Auxenochlorella Protothecoides

The bio-flocculation ability of UTEX 2341 was studied for the purpose of improving microalgae harvesting efficiency to cut the high cost of biofuel production. The algae cells of UTEX 2341 cultured under heterotrophic and municipal wastewater conditions were found to have better self-flocculation ability, with flocculation rates of 92% and 85% at 2 h, respectively. Moreover, the flocculation rates of 16 freeze-dried microalgae powder samples cultured under different stress conditions were 0~72% with an algae powder dosage of 35 mg L−1. The flocculation efficiency of DIM, DCd1, DT28, and L6S was stable under different pH of 3~9 and temperatures of 15~50 °C. For samples of IM, LCd0.6, LMn2, and LZn2, the flocculation efficiency decreased or increased respectively with increased pH or temperatures. Though the flocculation properties of the eight samples showed wide differences, their flocculant compositions were almost the same with unknown components occupying large proportions. More studies needed to be further carried out to reveal the flocculation mechanisms and analyze the flocculation abilities in practical application, which would be conducive to future large-scale application of the bio-flocculation method and also cost reduction.

scholarly journals Enhancing removal efficiency of anionic dye (Cibacron blue) using waste potato peels powder

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kahina Bouhadjra ◽  
Wahiba Lemlikchi ◽  
Azedine Ferhati ◽  
Samuel Mignard
Keyword(s):  
Experimental Data ◽  
Contact Time ◽  
Potato Peel ◽  
X Ray ◽  
Cibacron Blue ◽  
Anionic Dye ◽  
Experimental Parameters ◽  
Optimum Ph ◽  
Potato Peels ◽  
Scanning Electron

AbstractIn the present study, the potato peel waste (PP) was used for the removal of the anionic dye Cibacron Blue P3R from an aqueous solution, activated with phosphoric acid (PPa) and calcined at 800 °C (PPc). The materials were characterized by Scanning Electron Microscope, Energy dispersive X-ray analysis and Fourier Transform Infrared Spectroscopy. The effects of various experimental parameters (pH, dye concentration, contact time) were also studied. The experimental results have shown that PPc has a greater capacity compared to pp and ppa. The capacity of PP bio-char (PPc) is 270.3 mg g−1 compared to PP (100 mg g−1) and PPa (125 mg g−1). Equilibrium experiments at 180 min for all materials were carried out at optimum pH (2.2): 76.41, 88.6 and 94% for PP, PPa and PPc respectively; and the Langmuir models agreed very well with experimental data. The ability of sorbent for the sorption of CB dye follows this order: calcined > activated > native materials. Potato peel biochar (PPc) can be considered a promising adsorbent for removing persistent dyes from water.

scholarly journals Atmospheric Conditions Associated with Labrador Sea Deep Convection: New Insights from a Case Study of the 2006/07 and 2007/08 Winters

2016 ◽  
Vol 29 (14) ◽  
pp. 5281-5297 ◽  
Author(s):  
Who M. Kim ◽  
Stephen Yeager ◽  
Ping Chang ◽  
Gokhan Danabasoglu
Keyword(s):  
North America ◽  
North Atlantic ◽  
Large Scale ◽  
Initial Conditions ◽  
Deep Convection ◽  
La Niña ◽  
Labrador Sea ◽  
Atmospheric Conditions ◽  
Circulation Anomaly ◽  
La Nina

Abstract Deep convection in the Labrador Sea (LS) resumed in the winter of 2007/08 under a moderately positive North Atlantic Oscillation (NAO) state. This is in sharp contrast with the previous winter with weak convection, despite a similar positive NAO state. This disparity is explored here by analyzing reanalysis data and forced-ocean simulations. It is found that the difference in deep convection is primarily due to differences in large-scale atmospheric conditions that are not accounted for by the conventional NAO definition. Specifically, the 2007/08 winter was characterized by an atmospheric circulation anomaly centered in the western North Atlantic, rather than the eastern North Atlantic that the conventional NAO emphasizes. This anomalous circulation was also accompanied by anomalously cold conditions over northern North America. The controlling influence of these atmospheric conditions on LS deep convection in the 2008 winter is confirmed by sensitivity experiments where surface forcing and/or initial conditions are modified. An extended analysis for the 1949–2009 period shows that about half of the winters with strong heat losses in the LS are associated with such a west-centered circulation anomaly and cold conditions over northern North America. These are found to be accompanied by La Niña–like conditions in the tropical Pacific, suggesting that the atmospheric response to La Niña may have a strong influence on LS deep convection.

scholarly journals Domain-Adversarial Training of Self-Attention-Based Networks for Land Cover Classification Using Multi-Temporal Sentinel-2 Satellite Imagery

2021 ◽  
Vol 13 (13) ◽  
pp. 2564
Author(s):  
Mauro Martini ◽  
Vittorio Mazzia ◽  
Aleem Khaliq ◽  
Marcello Chiaberge
Keyword(s):  
Land Cover ◽  
Large Scale ◽  
Domain Adaptation ◽  
Learning Approaches ◽  
Atmospheric Conditions ◽  
Practical Applications ◽  
Area Of Interest ◽  
Multi Temporal ◽  
Significant Performance ◽  
Adversarial Training

The increasing availability of large-scale remote sensing labeled data has prompted researchers to develop increasingly precise and accurate data-driven models for land cover and crop classification (LC&CC). Moreover, with the introduction of self-attention and introspection mechanisms, deep learning approaches have shown promising results in processing long temporal sequences in the multi-spectral domain with a contained computational request. Nevertheless, most practical applications cannot rely on labeled data, and in the field, surveys are a time-consuming solution that pose strict limitations to the number of collected samples. Moreover, atmospheric conditions and specific geographical region characteristics constitute a relevant domain gap that does not allow direct applicability of a trained model on the available dataset to the area of interest. In this paper, we investigate adversarial training of deep neural networks to bridge the domain discrepancy between distinct geographical zones. In particular, we perform a thorough analysis of domain adaptation applied to challenging multi-spectral, multi-temporal data, accurately highlighting the advantages of adapting state-of-the-art self-attention-based models for LC&CC to different target zones where labeled data are not available. Extensive experimentation demonstrated significant performance and generalization gain in applying domain-adversarial training to source and target regions with marked dissimilarities between the distribution of extracted features.

scholarly journals Cloud-to-ground lightning in Portugal: patterns and dynamical forcing

2012 ◽  
Vol 12 (3) ◽  
pp. 639-649 ◽  
Author(s):  
J. A. Santos ◽  
M. A. Reis ◽  
J. Sousa ◽  
S. M. Leite ◽  
S. Correia ◽  
...  
Keyword(s):  
Large Scale ◽  
Bimodal Distribution ◽  
Lightning Activity ◽  
Atmospheric Conditions ◽  
Remote Forcing ◽  
Cloud To Ground Lightning ◽  
Using Data ◽  
Number Of Discharges ◽  
Low Pressures ◽  
Large Scale Atmospheric Circulation

Abstract. An analysis of the cloud-to-ground discharges (CGD) over Portugal is carried out using data collected by a network of sensors maintained by the Portuguese Meteorological Institute for 2003–2009 (7 yr). Only cloud-to-ground flashes are considered and negative polarity CGD are largely dominant. The total number of discharges reveals a considerable interannual variability and a large irregularity in their distribution throughout the year. However, it is shown that a large number of discharges occur in the May–September period (71%), with a bimodal distribution that peaks in May and September, with most of the lightning activity recorded in the afternoon (from 16:00 to 18:00 UTC). In spring and autumn the lightning activity tends to be scattered throughout the country, whereas in summer it tends to be more concentrated over northeastern Portugal. Winter generally presents low lightning activity. Furthermore, two significant couplings between the monthly number of days with discharges and the large-scale atmospheric circulation are isolated: a regional forcing, predominantly in summer, and a remote forcing. In fact, the identification of daily lightning regimes revealed three important atmospheric conditions for triggering lightning activity: regional cut-off lows, cold troughs induced by remote low pressure systems and summertime regional low pressures at low-tropospheric levels combined with a mid-tropospheric cold trough.

Benchmarks for the energy demand of nutrient removal plants

2003 ◽  
Vol 47 (12) ◽  
pp. 125-132 ◽  
Author(s):  
O. Nowak
Keyword(s):  
Nutrient Removal ◽  
Energy Demand ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Electrical Energy ◽  
Anaerobic Sludge ◽  
Operational Experience ◽  
Municipal Wastewater Treatment ◽  
Sludge Digestion ◽  
Municipal Wastewater Treatment Plants

The energy demand of municipal wastewater treatment plants for nutrient removal equipped with primary clarifiers, activated sludge system, anaerobic sludge digestion, and CHP is evaluated theoretically, on the basis of COD balances. Operational experience from energy-efficient Austrian treatment plants confirms that the demand on external electrical energy can be kept as low as 5 to 10 kWh/(pe.a) depending on the N:COD ratio in the raw wastewater. A low N:COD ratio helps to keep not only the effluent nitrogen load low, but also the energy demand. Measures to minimise the energy demand at treatment plants and to reduce the nitrogen load are discussed.

scholarly journals Comparison of Different Electricity-Based Thermal Pretreatment Methods for Enhanced Bioenergy Production from Municipal Sludge

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 2006 ◽  
Author(s):  
E. Hosseini Koupaie ◽  
T. Johnson ◽  
C. Eskicioglu
Keyword(s):  
Energy Production ◽  
Municipal Wastewater ◽  
Wastewater Sludge ◽  
Conventional Heating ◽  
P Value ◽  
Net Energy ◽  
Rf Heating ◽  
Thermal Pretreatment ◽  
Bioenergy Production ◽  
Sequential Pretreatment

This paper presents results for a comprehensive study that compares the performance of three electricity-based thermal pretreatment methods for improving the effectiveness of anaerobic digestion (AD) to process municipal wastewater sludge. The study compares thermal pretreatment using conventional heating (CH), microwave (MW), and radio frequency (RF) heating techniques. The effectiveness of the pretreatment methods was assessed in terms of chemical oxygen demand (COD) and biopolymers solubilization, AD bioenergy production, input electrical energy, and overall net energy production of the sequential pretreatment/AD process. The heating applicators for the bench-scale testing consisted of a custom-built pressure-sealed heating vessel for CH experiments, an off-the-shelf programmable MW oven operating at a frequency of 2.45 GHz for MW heating experiments, and a newly developed 1 kW RF heating system operating at a frequency of 13.56 MHz for RF heating experiments. Under identical thermal profiles, all three thermal pretreatment methods achieved similar sludge disintegration in terms of COD and biopolymer solubilization as well as AD bioenergy production (p-value > 0.05). According to the energy assessment results, the application of CH and MW pretreatments resulted in overall negative energy production, while positive net energy production was obtained through the sequential pretreatment/AD process utilizing RF pretreatment.

Innovative Volumetric Solar Receiver Micro-Design Based on Numerical Predictions

2015 ◽  
Author(s):  
Raffaele Capuano ◽  
Thomas Fend ◽  
Bernhard Hoffschmidt ◽  
Robert Pitz-Paal
Keyword(s):  
Solar Radiation ◽  
Energy Demand ◽  
Large Scale ◽  
Solar Power ◽  
Numerical Models ◽  
Numerical Predictions ◽  
Proper Design ◽  
Global Increase ◽  
Solar Power Tower ◽  
Solar Receiver

Due to the continuous global increase in energy demand, Concentrated Solar Power (CSP) represents an excellent alternative, or add-on to existing systems for the production of energy on a large scale. In some of these systems, the Solar Power Tower plants (SPT), the conversion of solar radiation into heat occurs in certain components defined as solar receivers, placed in correspondence of the focus of the reflected sunlight. In a particular type of solar receivers, defined as volumetric, the use of porous materials is foreseen. These receivers are characterized by a porous structure called absorber. The latter, hit by the reflected solar radiation, transfers the heat to the evolving fluid, generally air subject to natural convection. The proper design of these elements is essential in order to achieve high efficiencies, making such structures extremely beneficial for the overall performances of the energy production process. In the following study, a parametric analysis and an optimized characterization of the structure have been performed with the use of self-developed numerical models. The knowledge and results gained through this study have been used to define an optimization path in order to improve the absorber microstructure, starting from the current in-house state-of-the-art technology until obtaining a new advanced geometry.

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