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1.
Environ Sci Pollut Res Int ; 27(8): 8507-8525, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907809

RESUMO

The extensive waste produced in construction and demolition activities affects the ecological environment, impeding green development in countries worldwide, including China. China has paid increasing attention to managing construction and demolition waste (CDW). However, most of the existing research only qualitatively studies the factors affecting the recycling of CDW and does not reveal the critical factors. Therefore, based on stakeholder theory and the grey-DEMATEL method, this paper aims to identify and quantitatively analyze the critical factors in CDW recycling from the perspective of China. This paper drew the following conclusions: (1) Stakeholders in China's CDW recycling mainly include the government, CDW production units, and CDW recycling units. (2) Public policy, government subsidies, media promotion, human resources, cost, environmental awareness, technological innovation, and supply chain management are the eight dimensions with 13 factors that constitute CDW recycling in China. (3) For the total relations between factors affecting the recycling of CDW in China, the most influential factor is specific legislation and regulations. The factor with the highest degree of prominence is environmental awareness. The factor with the largest net cause value is the rationality of disposal and landfill charges. The factor with the largest net effect value is experienced construction workers. (4) The critical factors in China's CDW recycling include specific legislation and regulations, mandatory degree of normative standards, environmental awareness, the supply of raw materials for CDW recycling units, and the sale of remanufactured products. Finally, this paper identifies the following management implications: (1) the government should prioritize the task of improving specific legislation and regulations, with a focus on a mandatory degree of normative standards. (2) CDW production units should put the task of improving environmental awareness high on their agenda, with a focus on the supply of raw materials for recycling units. (3) CDW recycling units should prioritize the issue of the sale of remanufactured products. This paper also provides a theoretical basis for revealing the critical factors of CDW recycling in other countries or regions.


Assuntos
Indústria da Construção , Materiais de Construção/análise , Reciclagem/métodos , Gerenciamento de Resíduos , China , Indústria da Construção/economia , Materiais de Construção/economia , Humanos , Resíduos Industriais , Gerenciamento de Resíduos/métodos
2.
Chemosphere ; 246: 125725, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927362

RESUMO

Contaminated air in battery recycling halls threatens the health of factory workers. In this work, a new 3D hydrogel was designed in a simulated salon with an innovative rotary module. The Pb(II), Fe(III) and SO42- was adsorbed from air. Solar energy was transferred by wind to the factory hall and absorbed moisture was evaporated. The hydrophilicity, stability in water and storage of Pb(II) and Fe(III) in the hydrogel were optimized. Brunauer-Emmett-Teller (BET) theory, Field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize and analyze the 3D hydrogel. The collector was able to quickly raise the wind temperature to 44 °C. In each cycle, in average 60% of air moisture was absorbed on the 3D hydrogel. The evaporation rate was more than 1.4 kg m-2 h-1. The efficiency of ions removal in each cycle was 82%. In the 0.68 m3 min-1 of wind flow the temperature was 43.3 °C and evaporation was done in a shorter time.


Assuntos
Fontes de Energia Elétrica , Hidrogéis , Reciclagem/métodos , Energia Solar , Vento , Adsorção , Compostos Férricos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
3.
Chemosphere ; 242: 125291, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896181

RESUMO

The huge usage of rechargeable batteries in electronics has added to a recurrent problem worldwide in generating tonnage of spent lithium-ion batteries (LIBs). The inadequacy of the resources of the depleting critical metals has also been described in vogue. The environmental assessment of the life cycle of the LIBs has been elucidated vis-a-vis the effects of raw material supply, transportation, and recycling. Based on the available work for recycling technologies, this review also attempts to elicit the various methods practiced in discharging/dismantling, classification, and separation of components followed by metal recovery. The authors have reviewed the major developments in the area of recycling of cathode material by using various acids for extraction of metals from spent LIBs, compared the merits and demerits of acids used and presented a comprehensive outlook to the processes formulated vis-à-vis imperative need for using green techniques. The necessity for benign recycling methods is stressed upon to alleviate the need for high temperature and oxidative acid leaching conditions. The various green lixiviants (organic acids) attempted to extract metals from spent LIBs have been discussed in detail with respect to the mechanism, efficacies as well as the various factors (selectivity, cost, etc.) that govern the use of organic acids in battery recycling. It was ascertained that the GHG emissions to extract Co using organic acids stand 1/8 of that using an inorganic acid leaching process. Efforts need to be envisaged in separating the leached metals from these lixiviants ensuring economics and environmental benefits.


Assuntos
Ácidos Carboxílicos/química , Fontes de Energia Elétrica , Resíduo Eletrônico/análise , Poluentes Ambientais/análise , Lítio/análise , Reciclagem/métodos , Eletrodos , Íons
4.
Chemosphere ; 241: 124975, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610460

RESUMO

A decline in the availability of fossil fuel resources coupled with deleterious environmental concerns has prompted further research into biofuels. Conventional bioethanol production via a first-generation approach may soon become superseded through integration with lignocellulosic feedstocks. However, the underlying concerns pertaining to the disposal of high-strength liquid waste (i.e. spentwash) remain both unchanged and constitute a substantial cost to bioethanol manufacturers. Therefore this review details current efforts in the literature to elucidate various approaches for spentwash treatment and investigate the potential for resource recovery. Insight into the composition of distillery wastewater is given in the lead-up to a thorough discussion encompassing the origin, transformation and characterisation of the highly problematic melanoidin compounds entrained within this effluent. Close examination of advanced organic characterisation methods used by researches yields further insight into the nature of spentwash dissolved organic matter (DOM). Employment of both biological and physio-chemical treatment schemes to alleviate the environmental footprint of such high-strength wastewater are also reviewed. Opportunities to dramatically improve the economic viability of biofuel production by exploiting the potential for resource recovery in the form of energy, organic/inorganic constituents and effluent reuse are discussed. Overall, the review culminates by highlighting recommendations for future work to accelerate the onset of an environmentally benign bio-refinery.


Assuntos
Biocombustíveis , Águas Residuárias/química , Etanol , Polímeros/isolamento & purificação , Reciclagem/métodos
5.
Chemosphere ; 241: 125020, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31614314

RESUMO

A nanocomposite of graphene and titanium dioxide (G/TiO2) was prepared using the sol-gel method for use in an electrochemical adsorption/regeneration process. The effect of annealing temperature on electrochemical characteristics of the nanocomposites was investigated by cyclic voltammetry and constant current electrochemical regeneration, using methylene blue (MB) as the adsorbate. The G/TiO2 could be regenerated more rapidly and with less corrosion than the bare graphene. The G/TiO2 annealed at 400 °C had a higher proportion of anatase phase TiO2 (ca. 7% rutile TiO2) compared to that annealed at 500 °C (ca. 40% rutile TiO2). Cyclic voltammetry indicated that the G/TiO2 annealed at 400 °C had a higher activity for MB oxidation than the nanocomposite annealed at 500 °C. Similarly, the regeneration of MB loaded G/TiO2 annealed at 400 °C was much faster than for the nanocomposite annealed at 500 °C. Complete regeneration of the G/TiO2 annealed at 400 °C was obtained after an electrochemical charge of 21 C per mg of adsorbate. The G/TiO2 annealed at 400 °C was regenerated in half the time required for the bare graphene. TEM studies showed that the bare graphene was rapidly corroded, while corrosion was not observed for the G/TiO2 nanocomposites.


Assuntos
Corantes/química , Técnicas Eletroquímicas/métodos , Grafite , Nanocompostos/química , Reciclagem/métodos , Titânio , Adsorção , Corrosão , Eletrodos , Azul de Metileno/química
6.
Chemosphere ; 245: 125689, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31881383

RESUMO

The present work investigated the treatment of the polyaniline (PANI) wastewater by anodic oxidation/electro-Fenton and reusing the treated PANI wastewater for the preparation of PANI. Organics were degraded by hydroxyl radical (OH) and sulfate radical (SO4-) formed simultaneously in the wastewater from electro-Fenton reaction and the anode surface. Under the conditions of 160 mL min-1 oxygen flow rate, constant current density 14 mA cm-2 and Fe2+ concentration 0.2 mM, 89% COD can be removed from the PANI wastewater after 360 min treatment. The energy consumption was 50 kWh (kg COD)-1 and the current efficiency was 27.8%. After the PANI wastewater treatment, the aniline, aniline derivatives and aniline oligomers were removed from the wastewater. The PANI obtained using fresh solution, treated PANI wastewater and untreated PANI wastewater were recorded PANI-F, PANI-T and PANI-U, respectively. In the preparation of PANI-U, the reaction of p-benzoquinone with aniline or aniline oligomers could change the nucleation and growth, leading to the production of aggregated nanoparticles and low specific capacitance. However, the morphology and specific capacitance of PANI-T were similar to that of PANI-F. The PANI-T is three-dimensional sphere of nanofibers with high specific capacitance about 446.7 F g-1. The yield of PANI-T using treated PANI wastewater could reach to 92.1%. These results demonstrate that the PANI wastewater treatment approach is efficient and environmentally friendly.


Assuntos
Compostos de Anilina/química , Técnicas Eletroquímicas/métodos , Peróxido de Hidrogênio/química , Águas Residuárias/química , Benzoquinonas , Eletrodos , Radical Hidroxila , Oxirredução , Reciclagem/métodos , Sulfatos
7.
Chemosphere ; 238: 124638, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31466006

RESUMO

In this study, we reported on the recycling of carbon materials from spent commercial supercapacitors and its application as low-cost adsorbent for high-efficiency removal of Ag(I) and Cr(VI) ions from aqueous solutions. Adsorption kinetics and isotherms, and effects of initial pH were carried out to investigate the adsorption performance of the recycled supercapacitor activated carbon (RSAC), whereas a series of characterizations such as SEM, EDX, BET, XPS, XRD and FTIR were employed to detailedly analyse the adsorption mechanism. The RSAC showed maximal adsorption capacity for Ag(I) and Cr(VI) of 104.0 and 96.3 mg g-1, respectively, with adsorbent dosage of 2 g L-1 and initial ions concentration of ∼2000 mg L-1 at room temperature (23 ±â€¯1 °C), and the adsorption was rapid and influenced by the initial pH value. The outstanding adsorption performance of RSAC was attributed to the high specific surface area (1403 m2 g-1) and abundant multifarious oxygenic groups which could participate in the electrostatic attraction and reduction reaction of Ag(I) and Cr(VI) during the adsorption process. Furthermore, the predominate species of the adsorbed toxic Ag(I) and Cr(VI) on the surface of RSAC was metallic silver particle (about 2 µm) and harmless Cr(III), respectively, thus it was possible for further recycling and disposal.


Assuntos
Carvão Vegetal/química , Cromo/isolamento & purificação , Reciclagem/métodos , Prata/isolamento & purificação , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Íons , Cinética , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
8.
Chemosphere ; 238: 124652, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31473524

RESUMO

This research aimed to find the best phenotype of the brown algae Fucus vesiculosus (kelp) which has the greater potential to become a sorption byproduct for Zn removal from contaminated waters. Thus, the Zn uptake capacity and sorption mechanisms of the kelp collected from the Baltic Sea shore was, for the first time, investigated under various conditions, and compared to the phenotype habiting on the Irish Sea shore. Sorption studies were performed investigating the effect of algal dosage, Zn sources as well as algal harvesting time of the year on Zn uptake capacity. The results suggested that the Baltic algae is a better bio-sorbent for Zn uptake. Sorption mechanisms were studied by employing various indirect and direct approaches, more importantly, including high resolution synchrotron X-Ray Fluorescence and X-Ray Absorption Spectroscopy (XAS) and molecular modelling (MM). The results revealed that alginate and cellulose are among the main polysaccharide bonding Zn at algal surface, via coordination with O atoms from carboxyl and hydroxyl groups. XAS results giving direct measurements of Zn bonding environment on algal surface are supported by MM outputs and suggested that Zn is surrounded by ca. 5 O atoms at interatomic distances varying from 1.94 to 2.02 Å. The results contribute to understanding sorption mechanisms which can further lead to finding the best eluent for Zn desorption from the used biomass, bio sorbent reconditioning and reuse in multiple sorption desorption cycles as well as process optimization before industrial scaling up.


Assuntos
Biodegradação Ambiental , Fucus/metabolismo , Zinco/isolamento & purificação , Absorção Fisico-Química , Alginatos/metabolismo , Biomassa , Celulose/metabolismo , Fucus/química , Reciclagem/métodos , Zinco/farmacocinética
9.
Environ Monit Assess ; 192(1): 33, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31823025

RESUMO

At present, wastewater reuse and recycling in water-stressed countries such as Iran has become a vital option for better management of water scarcity. However, despite the benefits of wastewater reuse, there is a probability of incomplete treatment of wastewater in accordance with the standards. Risk assessment of a wastewater treatment plant is required in order to determine the causes and consequences of failure in the treatment system. Among various methods used for risk assessment, the bow-tie (BT) approach is an efficient technique since it represents a failure event from causes to effects. In this method, for a wastewater treatment plant (WWTP), causes of an adverse event, including the violation of the effluent water quality from the standard limit is studied using fault tree analysis (FTA). Then, the impacts of these adverse events are classified in different scenarios by the use of event tree analysis (ETA). In this study, the BT technique was applied to assess the risk of the WWTP of the Moorchekhort industrial complex (MIC), located in the central part of Iran. The plant consists of two parts, including activated sludge and advanced treatment processes to provide reclaimed water for different industrial uses. Results showed a 41% risk of violation from the effluent standard limit in the MIC WWTP. In addition, analyzing the risk factors revealed that the human error had the largest contribution to the risk calculation of the WWTP failure. In this regard, a number of mitigation measures were proposed to improve the reliability of the WWTP.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Monitoramento Ambiental , Humanos , Indústrias , Irã (Geográfico) , Probabilidade , Reciclagem/métodos , Reprodutibilidade dos Testes , Medição de Risco/métodos , Purificação da Água/métodos , Qualidade da Água
12.
Artigo em Inglês | MEDLINE | ID: mdl-31878289

RESUMO

Daily life in today's dynamic world requires fast adaptation of people's behavior to new challenges emerged from environmental, health, urban housing, transportation, etc. problems. A strong and complex tool in changing behaviors, education consumes significant resources and requires time for effective impact. The present study proposes a roadmap, integrating advanced methods for industrial competitive development (QFD) in configuring efficient educational interventions for changing people's behavior on special thematic areas, such as environment and recycling. A literature review on applicable behavioral theories led to more than 30 behavioral factors (constructs) targetable by education, their specific impact evaluation being the subject of a survey among education professionals. Finally, to reach a mapping of efficient interventions with low costs, high impact and fast results criteria, educational interventions and behavioral factors were correlated by the QFD method on three dimensions addressing: teachers and trainers, contents and tools, respectively the national & institutional level. The current research results are focused particularly on changing recycling behaviors, but the overall concept and methodology can be expanded to incorporate any preoccupation in the areas of environment and health, as long-term drivers of public well-being.


Assuntos
Terapia Comportamental/educação , Terapia Comportamental/métodos , Conservação dos Recursos Naturais/métodos , Reciclagem/métodos , Ensino/organização & administração , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários
13.
Environ Sci Pollut Res Int ; 26(36): 36163-36183, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31773528

RESUMO

Bangladesh is 10th among the major plastic waste contributor countries of the globe. Throughout the world, plastic waste disposal is a major concern since it is being nonbiodegradable in nature and hazardous, because of its potential harmful effect on human health and to the environment. Various studies have shown that waste PET (polyethylene terephthalate) plastic bottle filled with sand or other inorganic materials can serve as a useful building material where plastic waste management or recycling process is not very effective and particularly, in low-income communities. Plastic brick use in existing Rohingya refugee camp and newly proposed displacement camp in the coast island-Bhasan Char-as construction material to build new shelters, can be a sustainable use and management of country's plastic waste, and a feasible solution against the shelter issues of Rohingya people. The vulnerability due to heavy wind, monsoon rains, cyclones, and the gaps and lack in funding to build new rigid and safe shelters can be effectively mitigated by using this low-cost, environment-friendly plastic brick as building block in refugee camps.


Assuntos
Materiais de Construção , Polietilenotereftalatos/química , Reciclagem/métodos , Campos de Refugiados , Eliminação de Resíduos/métodos , Bangladesh , Humanos
14.
Environ Sci Pollut Res Int ; 26(36): 36287-36295, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713827

RESUMO

Preparation of the value-added products from e-waste resources is an important step in the recycling process. The present paper aims to propose a methodology for the recovery of In from scrap LCD panel via preparation of InBO3 nanostructure. Discarded LCD panel was subjected to a recycling process through crushing, milling, and oxalic acid leaching to prepare In2(C2O4)3·6H2O. Through the leaching process, B(OH)3 from glass part (alumina borosilicate) has been leached out along with indium oxalate hydrated. Further thermal treatment on these extracted materials at 600 °C could result in the formation of InBO3 nanostructures with an average particle size of 20 nm. A multistep mechanism based on thermodynamic calculations for the recycling of the InBO3 form extracted precursors was proposed. Graphical abstract.


Assuntos
Resíduo Eletrônico , Cristais Líquidos/química , Nanoestruturas/química , Reciclagem/métodos , Compostos de Boro/química , Vidro/química , Temperatura Alta , Índio/química , Ácido Oxálico/química , Tamanho da Partícula
15.
Environ Pollut ; 255(Pt 1): 113043, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31622958

RESUMO

High performance activated carbon (HPAC) supported nanoscale zerovalent iron (nZVI) was prepared and used for recovery of silver. This composite material was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The removal amount of Ag+ increased with pH values and temperature. The removal process achieved equilibrium within 40 min and the maximum removal capacity was 986.5 mg/g at 298 K. The composite material showed fast adsorption rate and high adsorption capacity because the presence of high surface area activated carbon could effectively inhibit aggregation of nanoscale zerovalent iron, thus enhancing its reactivity. The Ag+ removal followed pseudo-second-order kinetic model and Langmuir isotherm model. XPS and XRD characterizations were performed to elucidate removal mechanism. It could be concluded that both coordination adsorption and reductive precipitation contributed to removal of Ag+ on the nZVI/HPAC.


Assuntos
Carvão Vegetal/química , Ferro/química , Nanocompostos/química , Reciclagem/métodos , Prata/análise , Poluentes Químicos da Água/análise , Adsorção , Biomassa , Cinética , Oryza/química , Caules de Planta/química , Propriedades de Superfície , Águas Residuárias/química , Purificação da Água/métodos
16.
Chemosphere ; 236: 124841, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545182

RESUMO

Hydrochars derived from municipal sewage sludge was analyzed for its feasibility for value-added recycling. Results of carbon content and elemental composition suggested that the hydrochars might not be comparable with pyrochars regarding to the carbon sequestration, long-term stability and fuel quality. Application as soil amendment would be a better approach for hydrochar utilization. To examine the potential benefits and risks of that, the total and available content of nutrients (i.e. N, P, and K) were measured, and the potentially toxic elements (PTEs, i.e. Zn, Cu, Pb, Ni and Cd) were analyzed for the total content, speciation, and leaching potential. Compared with pyrochars derived from the same feedstock, hydrochars had lower pH and higher cation exchange capacity. The available content of N (1.58-6.87 g/kg), P (0.270-0.901 g/kg), and K (0-0.873 g/kg) in the chars was less than the feedstock sludge (3.33 g/kg N, 3.02 g/kg P, 2.07 g/kg K), but still far higher than that of the agricultural soil (i.e. 0.014-0.488 g/kg N, 0.02 g/kg P, <0.1-0.272 g/kg). Remarkably, hydrochars showed better nutritional balance than pyrochars for its higher available K content. Risk of potentially toxic elements contamination by the sludge was efficiently reduced in either hydrochars or pyrochars, except the high leaching potential of Zn in pyrochars. Overall, in addition to the advantages of the hydrothermal carbonization process as energy saving and value-added liquid by-products, the hydrochars derived from sludge, with sufficient and balanced nutrients and limited PTEs pollution risk, can be a feasible and value-added material as soil amendment.


Assuntos
Agricultura/métodos , Nutrientes/química , Reciclagem/métodos , Esgotos/química , Solo/química , Carbono/análise , Sequestro de Carbono , Estudos de Viabilidade , Poluentes do Solo/análise
17.
Environ Sci Pollut Res Int ; 26(29): 29908-29916, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31410830

RESUMO

As one of the hard-templating methods, MgO-templating was employed to recycle cotton to produce activated carbon with magnesium acetate as MgO precursor. Results showed that cotton carbonized while magnesium acetate decomposed to nanoscale MgO particles based on thermogravimetric and X-ray diffraction analysis. Carbonized residuals of cotton were able to replicate the MgO morphology thus creating pores. The size of MgO varied with impregnation ratio, treatment temperature, and time. Overall, the optimum conditions were MgO/cotton impregnation ratio 0.25, temperature 800 °C, and treatment time 60 min. Cotton-based activated carbon thus produced manifested surface area and total pore volume of 1139 m2/g and 0.85 cm3/g respectively. Both micropores and mesopores were detected based on iodine, methylene blue adsorption values, and N2 adsorption-desorption studies.


Assuntos
Acetatos/química , Carvão Vegetal/análise , Fibra de Algodão , Compostos de Magnésio/química , Óxido de Magnésio/química , Reciclagem/métodos , Têxteis , Resíduos , Adsorção , Carvão Vegetal/química , Temperatura Alta , Iodo/análise , Azul de Metileno/análise , Porosidade , Propriedades de Superfície
18.
Environ Sci Pollut Res Int ; 26(27): 27930-27939, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31350688

RESUMO

The objective of the study was to determine the factors that influence community participation in the management of electronic waste. A survey of community willingness to participate in the management of electronic waste was conducted using questionnaires. Survey locations covered western areas of the city of Surabaya, Indonesia, where 238 respondents were selected proportionally from high-, medium-, and low-income groups during 2014. The group was divided by land and building taxes, which represents the socio-economic conditions of the community. Processing and statistical data analysis were performed with structural equation modeling. Results showed that one factor influencing the willingness of communities to manage e-waste was behavior, while factors influencing the willingness of communities to pay more included behavior, attitudes, and knowledge. Strategies to increase community participation can be applied through education and community assistance, the provision of recycling facilities, and applied regulations about e-waste management and extended producer responsibility.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos/métodos , Atitude , Cidades , Participação da Comunidade , Características da Família , Humanos , Indonésia , Reciclagem/métodos , Inquéritos e Questionários
19.
Environ Sci Pollut Res Int ; 26(35): 35629-35647, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31346938

RESUMO

The purpose of this work is to assess the environmental impacts of the collection of mixed municipal solid waste (MSW) in a selected neighbourhood of the Portuguese city of Aveiro. To this purpose, the main elements necessary for the collection process (carrier bags, dustbins, street containers and vehicles) were analysed applying the life cycle assessment methodology, making use of locally gathered data. The main impacts associated with this activity are mostly related to the use of polyethylene plastic bags to carry the waste from the household to the waste container, and to the fuel consumption of collection vehicle that picks MSW from street containers and transports it to the treatment facility. The impacts associated with the plastic bags were primarily due to their disposal in a sanitary landfill after use and secondarily to the consumption of fossil raw materials required for their production. Given the relative high impact of the plastic bags, alternative scenarios were tested: using bags entirely produced with recycled polyethylene and bags produced with bio-based plastics derived from starch (TPS) and from wastewater (PHA). PHA bio-based bags were found to perform slightly better than conventional high-density polyethylene (HDPE) bags, but HDPE bags with 100% recycled content remained as the environmentally best option. A sensitivity analysis was performed to check the influence of bag size. Regarding the fuel consumption by collection vehicles, a comparison was performed to check how site-specific conditions can influence the impact of this activity, resulting in remarkably higher consumptions when local data were used instead of reference databases.


Assuntos
Plásticos , Eliminação de Resíduos/métodos , Cidades , Meio Ambiente , Portugal , Reciclagem/métodos , Resíduos Sólidos , Instalações de Eliminação de Resíduos , Gerenciamento de Resíduos/métodos
20.
Artigo em Inglês | MEDLINE | ID: mdl-31344800

RESUMO

The recycling of waterworks sludge has become a trending issue because it not only solves the problem of difficult disposal but also saves land resources. This paper aimed to provide a new idea for the utilization of waterworks sludge to form ceramsite and to purify sewage. The specific surface area, average pore size, and pore volume of the made ceramsite were 8.15 m2/g, 8.53 nm, and 1.88 cm2/g, respectively. The made ceramsite was applied in a vertical-flow constructed wetland, and the removal efficiency of nitrogen, phosphorus and organic matter in sewage were investigated under the conditions of different start-up periods, hydraulic retention times, matrix filling heights and water quality. The removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) in the constructed wetlands were stable at 70%, 60%, and 79%, respectively. This constructed wetland with a ceramic matrix has certain advantages in the total amount of denitrifying microorganisms, with a proportion of 14.92%. The results prove the feasibility of preparing ceramsite from waterworks sludge and applying it as a matrix in a constructed wetland to purify sewage.


Assuntos
Amônia/metabolismo , Misturas Complexas , Nitrogênio/metabolismo , Fósforo/metabolismo , Reciclagem/métodos , Esgotos , Eliminação de Resíduos Líquidos/métodos , Análise da Demanda Biológica de Oxigênio , Carbono , Desnitrificação , Ferro , Áreas Alagadas
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