scholarly journals Microwave Radiation as a Pre-Treatment for Standard and Innovative Fragmentation Techniques in Concrete Recycling

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 488 ◽  
Author(s):  
Maarten Everaert ◽  
Raphael Stein ◽  
Simon Michaux ◽  
Vincent Goovaerts ◽  
Carlo Groffils ◽  
...  
Keyword(s):  
Innovative Technology ◽  
Cement Matrix ◽  
Treatment Technique ◽  
Treatment Processes ◽  
Aggregate Fractions ◽  
Matrix Removal ◽  
Fragmentation Techniques ◽  
Pre Treatment ◽  
Natural Aggregates ◽  
Concrete Recycling

Recent advances in concrete recycling technology focus on novel fragmentation techniques to obtain aggregate fractions with low cement matrix content. This study assesses the aggregate liberation effectiveness of four different treatment processes including standard and innovative concrete fragmentation techniques. Lab-made concrete samples were subjected to either standard mechanical crushing technique (SMT) or electrodynamic fragmentation (EDF). For both fragmentation processes, the influence of a microwave weakening pre-treatment technique (MWT) was investigated. A detailed analysis of the particle size distribution was carried out on samples after fragmentation. The >5.6 mm fraction was more deeply characterized for aggregate selective liberation (manual classification to separate liberated aggregates) and for cement matrix content (thermogravimetric measurements). Results highlight that EDF treatment is more effective than SMT treatment to selectively liberate aggregates and to decrease the cement matrix content of the >5.6 mm fraction. EDF fully liberates up to 37 wt.% of the >5.6 mm natural aggregates, while SMT only liberates 14–16 wt.%. MWT pre-treatment positively affects aggregate liberation and cement matrix removal only if used in combination with SMT; no significant effect in combination with EDF was recorded. These results of this study can provide insights to successfully implement innovative technology in concrete recycling plants.

scholarly journals Membrane condenser as emerging technology for water recovery and gas pre-treatment: current status and perspectives

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Adele Brunetti ◽  
Francesca Macedonio ◽  
Giuseppe Barbieri ◽  
Enrico Drioli
Keyword(s):  
Current Status ◽  
Innovative Technology ◽  
Water Recovery ◽  
Treatment Unit ◽  
Treatment Stage ◽  
Treatment Technologies ◽  
Pre Treatment ◽  
And Control

Abstract The recent roadmap of SPIRE initiative includes the development of “new separation, extraction and pre-treatment technologies” as one of the “key actions” for boosting sustainability, enhancing the availability and quality of existing resources. Membrane condenser is an innovative technology that was recently investigated for the recovery of water vapor for waste gaseous streams, such as flue gas, biogas, cooling tower plumes, etc. Recently, it has been also proposed as pre-treatment unit for the reduction and control of contaminants in waste gaseous streams (SOx and NOx, VOCs, H2S, NH3, siloxanes, halides, particulates, organic pollutants). This perspective article reports recent progresses in the applications of the membrane condenser in the treatment of various gaseous streams for water recovery and contaminant control. After an overview of the operating principle, the membranes used, and the main results achieved, the work also proposes the role of this technology as pre-treatment stage to other separation technologies. The potentialities of the technology are also discussed aspiring to pave the way towards the development of an innovative technology where membrane condenser can cover a key role in redesigning the whole upgrading process.

Prospects and problems of sludge pre-treatment processes

2001 ◽  
Vol 44 (10) ◽  
pp. 121-128 ◽  
Author(s):  
J.A. Müller
Keyword(s):  
Wastewater Treatment ◽  
Phase Changes ◽  
Ozone Treatment ◽  
Thermal Methods ◽  
Sludge Treatment ◽  
Freeze Thaw ◽  
Positive Effects ◽  
Treatment Processes ◽  
Stage Of Development ◽  
Pre Treatment

Pre-treatment processes have been developed in order to improve subsequent sludge treatment and disposal. Disintegration of sludge solids in the aqueous phase changes the sludge structure and solubilizes organic matter. This paper provides an overview of the applications of wet disintegration in wastewater and sludge treatment. Applied disintegration techniques such as mechanical, thermal, chemical and biological methods are briefly described. The methods are compared regarding energy consumption, operational reliability and stage of development for application on wastewater treatment plants. Mechanical and thermal methods appear to be most suitable at this stage. The effects of pre-treatment on subsequent sludge treatment processes and the wastewater treatment are described. The performance of various methods is assessed. For the improvement of stabilization, mechanical and ozone treatment as well as thermal treatment perform best. Dewatering can be enhanced by thermal and freeze/thaw treatment. All methods show positive effects in the reduction of the number of pathogens. Pre-treatment leads to secondary effects like the generation of recalcitrant compounds and odor, which is mainly a problem of thermal and ozone treatment. The evaluation of capital and operational costs is difficult, because of the lack of full-scale experience. Especially thermal, freeze/thaw and biological treatments can be realized at low costs if the conditions are appropriate. Nevertheless, the economic efficiency has to be investigated critically for each individual application.

Investigation and assessment of sludge pre-treatment processes

2004 ◽  
Vol 49 (10) ◽  
pp. 97-104 ◽  
Author(s):  
J.A. Müller ◽  
A. Winter ◽  
G. Strünkmann
Keyword(s):  
Fine Particles ◽  
Degradation Process ◽  
Solid Content ◽  
Ozone Treatment ◽  
Treatment Processes ◽  
Sludge Properties ◽  
Pre Treatment ◽  
The Cost ◽  
Degree Of Degradation ◽  
Cell Disintegration

The pre-treatment of sludges by disintegration will result in a number of changes in sludge properties. Floc destruction as well as cell disintegration will occur. This leads to an increase of soluble substances and fine particles. Furthermore, biochemical reactions may appear during or immediately after disintegration. The influence of disintegration of excess sludge on anaerobic digestion was studied in full scale. A stirred ball mill, an ultrasound disintegrator, a lysate centrifuge and ozone treatment were used. The results of the degradation process were compared to a reference system without pre-treatment. An enhancement of the degree of degradation of 7.4% to 20% was observed. The pollution of sludge water as well as the dewatering properties of the digested sludge were investigated. COD and ammonia in the sludge water were increased and a higher polymer demand was observed while the solid content after dewatering stayed almost unchanged. Based on these results the cost effectiveness has been assessed taking into account different conditions (size of WWTP, cost for disposal, etc.). Capital and energy costs are the main factors while the decrease in disposal costs due to the reduced amount of sludge is the main profit factor.

scholarly journals Changes in thermal stability of lignocelluloses waste aggregates long-term incorporated in composite

2021 ◽  
Vol 900 (1) ◽  
pp. 012042
Author(s):  
N Stevulova ◽  
A Estokova
Keyword(s):  
Thermal Stability ◽  
Alkaline Treatment ◽  
Cement Matrix ◽  
Scanning Calorimetry ◽  
Alkali Ions ◽  
Thermal Gravimetry ◽  
Pre Treatment ◽  
Surface Modified ◽  
Thermal Stability Of

Abstract This paper is addressed to comparative study of changes in thermal stability of surface-modified hemp-hurds aggregates long-term incorporated in bio-aggregate-based composites with the original ones before their integration into alternative binder matrix. In this study, the effectiveness of alkaline treatment of hemp hurds compared to the raw bio-aggregates as well as in relation to their behaviour when they are long-term incorporated in the MgO-cement environment is investigated. The differences in the thermal behaviour of the samples are explained by the changed structure of hemp hurds constituents due to the pre-treatment and long-term action of the alternative binder components on the bio-aggregates. Alkaline treatment increases thermal stability of hemp hurds compared to raw sample. Also long-term incorporation of hemp hurds in MgO-cement matrix had a similar effect in case of alkaline modified bio-aggregates. The more alkali ions present in the structure of hemp hurdssamples, the more ash is formed during their thermal decomposition studied by thermal gravimetry (TG) and differential scanning calorimetry (DSC).

scholarly journals Enhancement of flaky graphite cleaning by ultrasonic treatment

2019 ◽  
Vol 6 (12) ◽  
pp. 191160 ◽  
Author(s):  
Wenze Kang ◽  
Huijian Li
Keyword(s):  
Carbon Content ◽  
Ultrasonic Treatment ◽  
Treatment Time ◽  
Treatment Technique ◽  
Particle Sizes ◽  
Cleaning Process ◽  
Flotation Concentrate ◽  
Metal Impurities ◽  
Pre Treatment ◽  
Ultrasound Power

In this study, the aim is to simplify the graphite cleaning process. In order to achieve flotation for graphite effectively, ultrasonic treatment was used as a pre-treatment technique. Flotation tests were conducted using different ultrasound power and ultrasonic treatment time. The influences of ultrasonic treatment on particle sizes, morphologies, wettability, the content of surface elements and on the flotation effect of flaky graphite were investigated. The results of ultrasonic treatment for graphite flotation were compared with the results of conventional flotation. The results showed that ultrasonic treatment not only changed the size of flaky graphite, but also eliminated impurities on the graphite surface. Additionally, the ultrasonic treatment improved the hydrophobicity of graphite. It was observed that ultrasound can remove not only silicate impurities but also most other metal impurities. The yield, carbon content and recovery of flotation concentrate were 91.46%, 95.17% and 96.12% after ultrasonic treatment for 4 min with ultrasound power 1600 W, which were 5.83%, 2.86% and 8.84% higher than that of conventional flotation, respectively. The graphite after ultrasonic treatment was conducted only one times flotation, the carbon content in concentrate products had reached 95%. This study indicates that intensifying graphite flotation by ultrasonic treatment can shorten the graphite cleaning process.

scholarly journals Is Recycling Always the Best Option? Environmental Assessment of Recycling of Seashell as Aggregates in Noise Barriers

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 776
Author(s):  
Begoña Peceño ◽  
Carlos Leiva ◽  
Bernabé Alonso-Fariñas ◽  
Alejandro Gallego-Schmid
Keyword(s):  
Life Cycle ◽  
Environmental Impacts ◽  
Waste Recycling ◽  
Point Of View ◽  
Raw Material ◽  
Recycling Process ◽  
Noise Barriers ◽  
Noise Barrier ◽  
Pre Treatment ◽  
Natural Aggregates

Waste recycling is an essential part of waste management. The concrete industry allows the use of large quantities of waste as a substitute for a conventional raw material without sacrificing the technical properties of the product. From a circular economy point of view, this is an excellent opportunity for waste recycling. Nevertheless, in some cases, the recycling process can be undesirable because it does not involve a net saving in resource consumption or other environmental impacts when compared to the conventional production process. In this study, the environmental performance of conventional absorption porous barriers, composed of 86 wt % of natural aggregates and 14 wt % cement, was compared with barriers composed of 80 wt % seashell waste and 20 wt % cement through an attributional cradle-to-grave life cycle assessment. The results show that, for the 11 environmental impact categories considered, the substitution of the natural aggregates with seashell waste involves higher environmental impacts, between 32% and 267%. These results are justified by the high contribution to these impacts of the seashell waste pre-treatment and the higher cement consumption. Therefore, the recycling of seashells in noise barrier manufacturing is not justified from an environmental standpoint with the current conditions. In this sense, it could be concluded that life cycle assessments should be carried out simultaneously with the technical development of the recycling process to ensure a sustainable solution.

Effects of chemical–physical pre-treatment processes on hemp fibres for reinforcement of composites and for textiles

2006 ◽  
Vol 24 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Anne Belinda Thomsen ◽  
Anders Thygesen ◽  
Vibeke Bohn ◽  
Kristina Vad Nielsen ◽  
Bodil Pallesen ◽  
...  
Keyword(s):  
Treatment Processes ◽  
Hemp Fibres ◽  
Pre Treatment

Optimization of Synthesis Condition for LiFePO4/C Cathode Material

2011 ◽  
Vol 236-238 ◽  
pp. 698-702
Author(s):  
Ling Zhi Zhu ◽  
En Shan Han ◽  
Ji Lin Cao
Keyword(s):  
Citric Acid ◽  
Room Temperature ◽  
Specific Capacity ◽  
Carbon Coatings ◽  
Treatment Processes ◽  
Initial Discharge ◽  
Structure Morphology ◽  
Tap Density ◽  
Pre Treatment ◽  
Acid Coating

This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. Common and cheap organic matters (Glucose anhydrous, Citric acid, Vitamin C, Sucrose) were selected for carbon coatings on LiFePO4. The four pre-treatment processes were employed to optimize the carbon coating process, and through solid state-carbothermal reduction synthesis of LiFePO4/C composites. The structure, morphology and electrochemical performance of the material were studied by XRD, SEM and galvanostatic charge-discharge methods. It is observed that the tap density of citric acid coating material can reach 1.44 g/ml. Conductivity increased four orders of magnitude. At room temperature, the initial discharge specific capacity of the materials is as high as 89.6 mAh/g at 5.0 C (corresponding to 850 mA/g). After 30 cycles, the capacity is 83.9 mAh/g and decay only 2.0 %.

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