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1.
Bioresour Technol ; : 123912, 2020 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32741699

RESUMO

The synergistic pyrolysis of municipal solid waste (MSW) were recently explored. This review aims to provide an overview on the synergistic pyrolysis studies of MSW, focusing on the synergy occurred during co-pyrolysis of different constituents of MSW. The interactions of intermediates released during pyrolysis can shift end product distributions, accelerate pyrolysis rates, and preferred production of specific compounds, which were categorized into four basic types with discussions. The pyrolysis synergy is proposed to be the key for success of pyrolytic practice of MSW that can handle the waste with maximal resource recovery and minimal carbon emission.

2.
Bioresour Technol ; 315: 123811, 2020 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-32673981

RESUMO

The high costs involved in sewage sludge treatment and disposal in wastewater treatment plants (WWTPs) not only bring about improper sludge disposal and thus environmental pollutions, but also limit the investment on construction of WWTPs, especially in rural areas or low-income regions. This comparative study examined the effect of biogas recirculation coupled with chemical addition in a semi-continuous anaerobic digester for sludge treatment, which was proven to achieve biogas upgrading, phosphorus conservation and sludge conditioning simultaneously, largely reducing the sludge treatment cost. Results show that FeCl3 addition coupling biogas recirculation can improve sludge dewaterability by 94% in comparison to 75% by equivalent MgCl2 addition, and 97% phosphorus in digestate can be conserved in solid with formation of vivianite-like crystals. Biogas recirculation can enhance CH4 yield and content by 13% and 11%, respectively, likely attributable to the increased relative abundances of both hydrogenotrophic Methanomicrobiales and acetoclastic Methanosarcinales.

3.
Chemosphere ; 255: 127011, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32679630

RESUMO

The environmental toxicity of tetracycline antibiotics to aquatic organisms has attracted increasing attention. The adverse impacts of tetracycline antibiotics on ciliates should be detailed considering the significant roles of protozoa in the microfood web in the soils and other eco-systems. This study for the first time investigated the toxicity of two typical tetracycline antibiotics, tetracycline (TC) and tetracycline hydrochloride (HTC) on two primary model ciliates, Stentor coeruleus and Stylonychia lemnae. The concentrations for 50% of maximal effect (24h‒EC50) of TC and HTC to Stentor coeruleus were 94.4 mg/L and 8.39 mg/L, respectively. Correspondingly, the 24h‒EC50 values of TC and HTC to Stylonychia lemnae were 40.1 mg/L and 14.0 mg/L, respectively. The TC and HTC inhibited the growth rates, reduced the activities of antioxidant enzymes, and damaged the ultra-structures of the tested ciliate cells, with the latter having larger impacts than the former. Based on the experimental works reported herein, the two model protozoan species were proposed to be the toxicity indicators for tetracycline antibiotics, which could work as supplements with the other existing protocols, such as Brochydanio rerio (zebrafish), Limnodrilus (a worm), Chlorogonium elongatum (a green alga) also studied herein.


Assuntos
Antibacterianos/toxicidade , Cilióforos/efeitos dos fármacos , Tetraciclina/toxicidade , Antioxidantes/farmacologia , Tetraciclina/farmacologia , Testes de Toxicidade
4.
Sci Total Environ ; 742: 140646, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32640395

RESUMO

The sulfur ions generated during the microbial treatment of sulfate wastewater could cause secondary pollution problem, however, the application of the biomineralization technique could convert sulfur ions into sulfide nanocomposites with diverse properties. This study constructed a multi-stage process for sulfate wastewater treatment and CdS nanocomposites (CdS-NCs) recovery by using biomineralization, which simultaneously achieved the removal of pollutants and recovery of functional nanocomposites. In this process, about 97% of the sulfate could be removed, and the CdS-NCs with a diameter of 16.0-20.2 nm were collected at different pHs. The results of FTIR and Raman proved that the biomacromolecules derived from microorganisms participated in the formation of CdS-NCs. The Mott-Schottky curve suggested that the CdS-NCs belonged to n-type semiconductors with the energy gap of 2.29-2.38 eV and could be applied as the photocatalyst, and up to 78.2% of 200 mg/L tetracycline was photodegraded catalytically by CdS-NCs obtained at pH 6.5. In the application of CdS-NCs as anodes of lithium-ion batteries, all the batteries assembled by CdS-NCs exhibited a very strong cycle performance of more than 500 cycles. This research not only effectively recovered nanocomposites with great application potential from sulfate wastewater but also provided a perspective for the utilization of recovered resources.

5.
Int J Mol Sci ; 21(13)2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32630069

RESUMO

The development of stimuli-responsive supramolecular micelles with high drug-loading contents that specifically induce significant levels of apoptosis in cancer cells remains challenging. Herein, we report photosensitive uracil-functionalized supramolecular micelles that spontaneously form via self-assembly in aqueous solution, exhibit sensitive photo-responsive behavior, and effectively encapsulate anticancer drugs at high drug-loading contents. Cellular uptake analysis and double-staining flow cytometric assays confirmed the presence of photo-dimerized uracil groups within the irradiated micelles remarkably enhanced endocytic uptake of the micelles by cancer cells and subsequently led to higher levels of apoptotic cell death, and thus improved the therapeutic effect in vitro. Thus, photo-dimerized uracil-functionalized supramolecular micelles may potentially represent an intelligent nanovehicle to improve the safety, efficacy, and applicability of cancer chemotherapy, and could also enable the development of nucleobase-based supramolecular micelles for multifunctional biomaterials and novel biomedical applications.

6.
Bioresour Technol ; 314: 123748, 2020 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-32622283

RESUMO

Sustainable sewage sludge management is a worldwide issue in wastewater treatment plants (WWTPs). This work developed a new strategy for sewage sludge treatment involving the integration of hydrothermal treatment (HT) with anaerobic co-digestion (AcoD), particularly on the feasibility of mesophilic AcoD of anaerobically digested sludge (DS) hydrolysate and waste activated sludge (WAS). Results show that AcoD of DS hydrolysate from HT 170℃ for 30 min with WAS achieved the highest CH4 production of 205.39 mL CH4/g-VSfed. By adopting the new AD-HT170-AcoD strategy, 61.88 mL CH4/g-tVSfed higher CH4 yield and 22.2% more total solids (TS) reduction were obtained in addition to much better sludge settleability and 7.6% wt. less sludge cake production compared to the conventional mono AD. Although negative energy gain was obtained, the proposed AD-HT170-AcoD strategy is promising, economically feasible, and sustainable when the final sludge disposal of WAS is concerned in the context of whole WWTP.

7.
Bioresour Technol ; 312: 123615, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32517890

RESUMO

In recent years, extensive studies have been carried out to improve our knowledge of the reactor operations and system performance in thermal pyrolysis of municipal solid wastes (MSW). However, the fundamentals of MSW pyrolysis and their engineering applications remain unsatisfactorily explored. This paper is a review of the pyrolysis of MSW and synergistic co-pyrolysis of the constituents of MSW with reference to pyrolytic performance, the distribution and energy content of the end products, and the mechanisms of the synergistic effects. The prospects for, and challenges of, the MSW pyrolysis process are provided. A MSW pyrolytic process with maximal energy recovery and minimal carbon footprint is proposed.


Assuntos
Eliminação de Resíduos , Resíduos Sólidos , Pegada de Carbono , Pirólise
8.
Chemosphere ; 257: 127244, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32512335

RESUMO

The industrial waste streams with excess phosphorus acid (H3PO4) was generated in semiconductor industries that has extremely low pH rendering commercial adsorbents unfit for adsorption recycling of valuable materials. This study for the first time use covalent organic framework EB-COF:Br to adsorb phosphoric acid from extremely acidic H3PO4 solutions at pH ranging 0.86 to -0.65. The EB-COF:Br could maintain structural stability with these extremely acidic solutions. At 25 °C, 95% adsorption could be completed within 10 min of contact; while the adsorption capacities of EB-COF:Br from 75% H3PO4 solution ranged 6520‒6980 mg-H3PO4/g during 25-45 °C. The adsorption is regarded isoenthalpic with no heat effects. Water washing is efficient for H3PO4 desorption, and the washed COF can be reused as an efficient adsorbent under extremely acidic environment. The interactions between (‒N+=) and (‒CO) groups, and part of the (‒NH‒) groups participated in the adsorption process with adsorbed H3PO4 molecules. The adsorbed H3PO4 molecules then formed H-bonding to trap the excess free H3PO4 molecules to the internal cavity of the COF.

9.
Bioresour Technol ; 313: 123663, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32562968

RESUMO

Occurrence of filamentous bulking would lead to excess biomass washout to fail the polyhydroxyalkanoate (PHA) production process. A strategy using sodium chloride (NaCl) addition to enhance sludge settleability so that high PHA productivity could be retained was tested in two sequencing batch reactors (SBR #1 and #2) fed with different organic acid mixtures but at identical NaCl gradients (0, 5 and 10 g/L). Significant improved sludge settleability was observed at 10 g/L NaCl regardless of occurrence of filamentous bulking. The NaCl addition strategy suppressed the growth of principal filamentous bacterium, Meganema, and enriched the PHA producers (Paracoccus and Thauera) to reach enhanced PHA productivities of 0.244-0.298 g/L-1 d-1 for the present studied system.


Assuntos
Poli-Hidroxialcanoatos , Biomassa , Reatores Biológicos , Esgotos , Cloreto de Sódio
10.
Sci Total Environ ; 741: 140183, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32563780

RESUMO

This study examined the feasibility of cultivation and harvesting of oil-producing microalgae (i.e. Ankistrodesmus falcatus var. acicularis) via biogranulation in two identical sequencing batch reactors (SBRs) fed with synthetic anaerobic digestion liquor. Easily settled algae granules with compact structure appeared around day 90 and mature granules were obtained after 150 days' operation. The microalgae settleability was remarkably improved, signaling by the substantial decrease of sludge volume index (SVI30) from initially >3000 to 53.44 ± 3.31 mL/g, with settling velocity correspondingly increased from nearly 0 to 18.47 ± 0.23 m/h. Although the percentage of the target microalgae (Ankistrodesmus falcatus var. acicularis) decreased along with the granulation process, the biomass concentration (2-4 g/L) and biomass productivity (130-270 mg/L/d) using biogranulation were 10-20 times and 16-34 times that by the traditional suspension method. Compared to the seed microalgae cells, more extracellular polymeric substances (EPS) (162.54 ± 3.60 mg/g-mixed liquor volatile suspended solids (MLVSS)) with a higher proteins/polysaccharides ratio (7.62) were excreted from the mature algae granules. Moreover, the mature microalgae granules showed comparable nutrients removal, averagely 96% and 86% of dissolved organic carbon (DOC) and NH4+-N from the digestion liquor, respectively, reflecting its great potential for simultaneous microalgae cultivation, harvesting and wastewater treatment.

11.
J Environ Manage ; 268: 110734, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32510454

RESUMO

Oily sludge is the main hazardous waste produced by the petroleum industry, and its harmless disposal and recycling have become urgent problems. In this study, the pyrolysis technique was used to prepare oily sludge biochar at different temperatures (400 °C, 500 °C, 600 °C, and 700 °C). The characteristics of the biochar, including weight reduction, elemental composition, and molecular structure, were comprehensively investigated. From the perspective of the electrochemical properties of biochar, the relationship between the structure of the biochar and the redox capacity was discussed, and the feasibility of biochar as a battery cathode material was explored. The results suggested that the improper pyrolysis temperature could reduce the content of the quinone structure which was related to the redox capacity, the biochar prepared at 600 °C should have the strongest electron transfer capability. Moreover, the highest degree of condensation and aromaticity of pyrolysis products could be obtained at a higher pyrolysis temperature (700 °C), which might result in the relatively high discharge-charge capacity and good cycle performance of biochar which was used as an electrode material of a battery. This study explored the feasibility of pyrolysis as a disposal route for oily sludge waste and provided a reference for the electrochemical application of biochar prepared from oil sludge waste.


Assuntos
Pirólise , Esgotos , Carvão Vegetal , Óleos
12.
Water Res ; 178: 115848, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32361288

RESUMO

Micro-aerobic enhancement technology has been developed as an effective tool to enhance simultaneous removal of sulfide, nitrate and organic carbon during the integrated autotrophic-heterotrophic denitrification (IAHD) process under high loading; however, its mechanism of enhancement for functional bacteria remains ambiguous. In this study, we discovered that heterotrophic sulfide-oxidizing nitrate-reducing bacteria (h-soNRB) are responsible for enhancing IAHD performance under micro-aerobic conditions with high sulfide loading. In a continuous IAHD bioreactor, aeration rate of 2.6 mL min-1·L-1 promoted 2 to 4 times higher removal efficiencies of sulfide, nitrate and acetate with an influent sulfide concentration of 18.75 mmol/L. Metagenomic analysis revealed that trace oxygen stimulated the abundance of genes responsible for sulfide oxidation (sqr, glpE, pdo, sox and cysK), which were upregulated by 15.2%-129.9%, and the genes encoding nitrate reductase were up-regulated by 67.4%. The increased acetate removal efficiency was attributed to upregulation of ack, pta and TCA cycle related genes. The h-NRB Pseudomonas, Azoarcus, Thauera and Halomonas were detected and regarded as h-soNRB in our bioreactor. According to Illumina MiSeq sequencing, these genera were absolutely dominant in the micro-aerobic microbial community at relative abundances ranging from 82.72% to 90.84%. The sulfide, nitrate and acetate removal rates of Pseudomonas C27, a typical h-soNRB, were at least 10 times higher under micro-aerobic conditions than under anaerobic conditions. Besides, the sulfur, nitrogen and carbon metabolic network was constructed based on the Pseudomonas C27 genome. The pdo and cysK genes found in this strain may be the most advantageous for autotrophic sulfide oxidizing nitrate reducing bacteria (a-soNRB), which are closely related to the high-efficiency sulfide, nitrate and acetate removal performance under high sulfide concentrations and a limited oxygen supply. In addition, after micro-aerobic cultivation, the anaerobic sulfide loading tolerance of the IAHD bioreactor increased from 18.75 to 37.5 mmol/L with sulfide, nitrate and acetate removal efficiencies increasing 1.5 to 3 times, which suggests that intermittent micro-aeration might be a more economical and efficient regime for high-sulfide IAHD regulation.


Assuntos
Processos Autotróficos , Desnitrificação , Bactérias , Reatores Biológicos , Nitratos , Oxirredução , Sulfetos
13.
Bioresour Technol ; 310: 123463, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32387978

RESUMO

This study investigated the effects of operational temperature on cathodic performances of five bioelectrochemical reactors operated in parallel at 25-7 °C, and on the biofilm microbial community at the end of tests. Compared with the anodic biofilm, the cathodic biofilm has high stability subjected to temperature shift in the aspect of cathode potentials, redox activities, and internal resistances. The maximum power density was reduced linearly with temperature at a rate of 1.1 W/m3 °C. The bacterial community at 7 °C cathodic biofilm was dominated by four phyla including Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes with percentages of 81.7%, 8.9%, 3.3% and 1.3%, and the predominant genera were affiliated with Azoarcus sp. (56.45%), Acidovorax sp. (7.32%), Rhodococcus sp. (5.02%), Halomonas sp. (2.6%). The most vigorous metabolism of cathodic biofilm at low temperature was proposed to be biosynthesis and energy generation. The cathodic biofilm has resilient microbial community to temperature challenges.


Assuntos
Fontes de Energia Bioelétrica , Bactérias , Biofilmes , Eletrodos , Temperatura
14.
J Colloid Interface Sci ; 575: 452-463, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32388291

RESUMO

HYPOTHESIS: The dispersive and polar components of surface energy are influenced by the effective molecular size and the intra-molecular configurations of the polar groups, respectively. The surface energy was hypothesized that the surface energy of a polyepichlorohydrin (PECH)-triazole polymer can be reduced by adding an end hydroxyl group (a polar group) which can interact with the nitrogen on the triazole group to reduce the net dipole of the molecule and to reduce the increase in dispersive surface energy by the addition of alkyl chain (dispersive group). EXPERIMENTS: The chlorine atom on PECH rubber was firstly substituted by an azide group, which was then converted to triazole groups linked with alkyl-ol that contained 1-4 carbon atoms. The polymers thus-produced were then spin-coated onto a silicon wafer to form a thin film characterized by static contact angles (30 s contact) and dynamic contact angles for drops of water and diiodomethane. FINDINGS: The newly synthesized materials have sufficient thin film-formation capacity. Dual interactions that involve interactions between alkyl-ol hydroxyl group and amine nitrogen and the interaction between ether oxygen and imine nitrogen cause the dispersive surface energy to decrease as the alkyl chain length increases. Consequently, a very low polar surface energy of 0.14 mJ/m2 was obtained for PECH-triazole-propyl-ol, a material without any halogen atoms.

15.
Bioresour Technol ; 309: 123451, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32361619

RESUMO

Micro-aeration is an effective tool that helps integrated autotrophic and heterotrophic denitrification process to withstand high sulfide concentration by making heterotrophic sulfide-oxidizing nitrate-reducing bacteria (h-soNRB) prevail. For further understanding of the dominance of h-soNRB, Pseudomonas C27 was selected as the typical bacterium and its metabolic characteristics responding to sulfide and oxygen stimulation were studied. Under high sulfide concentration condition, addition of trace oxygen led to a two-stage sulfide oxidation process, and sulfide oxidation rate in the first stage was 1.4 times more than that under anaerobic condition. According to transcriptome analysis, the pdo gene significantly up-regulated 2.36 and 2.57 times with and without oxygen under stimulation of high sulfide concentration. Additionally, two possible enhanced sulfide removal pathways coping with high sulfide concentration, namely sqr-cysI-gpx-gor-glpE and cysK-gshA-gshB-pdo-glpE, caused by oxygen were proposed in Pseudomonas C27. These findings provide a theoretical basis for locating high-efficiency sulfur oxidase in h-soNRB.


Assuntos
Oxigênio , Pseudomonas , Bactérias , Reatores Biológicos , Desnitrificação , Nitratos , Oxirredução , Sulfetos
17.
Bioresour Technol ; 311: 123479, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32413644

RESUMO

Nanobubble water (NBW) has been proven to efficiently improve methane production from organic solid wastes. However, the increase in reactor volume due to addition of NBW hinders its practical applications. In this study, anaerobically digested sludge was first pre-augmented by N2-NBW and O2-NBW using corn straw as sole substrate for methane production with electron transfer activity being monitored. 20%, 33% and 38% of cellulose and 29%, 35% and 35% of hemicellulose were reduced respectively from the control, N2-NBW and O2-NBW pre-augmented sludge reactors. N2-NBW and O2-NBW pre-augmented sludge reactors achieved methane yields of 127 and 142 mL/g-VS, about 10% and 22% higher than that from the control. Results show that use of NBW pre-augmented anaerobically digested sludge as inoculum can remarkably enhance methane yield from corn straw, providing a novel concept for NBW-based anaerobic digestion system with no increase of reactor volume and construction cost in practice.


Assuntos
Esgotos , Zea mays , Anaerobiose , Reatores Biológicos , Metano , Água
18.
Bioresour Technol ; 310: 123376, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32334358

RESUMO

Sustainable treatment of wastewaters generated from paint production is increasingly posing an environmental concern. Recalcitrant paint wastewaters are mostly treated by energy and cost intensive physicochemical methods like incineration, distillation or advanced oxidation. This paper reported for the first time a case study applying biological treatment processes to properly handle a high-strength recalcitrant paint wastewater with 5-day biochemical oxygen demand (BOD5)/chemical oxygen demand (COD) less than 0.02. A biological treatment scheme integrating anaerobic granular sludge blanket reactor, aerobic carrier biofilm reactor and aerobic activated sludge bioreactor was proposed and examined. Laboratory and full-scale trials demonstrated satisfactory operation with overall COD removal up to 99%. Besides yielding consistent effluent quality conforming to the discharge limits, the full-scale plant gained considerable savings in operating cost over a 5-year operation. With proper microbial adaptation and cultivation, as well as adequate reactor and process designs, the scheme offers a good feasibility for efficient and cost-effective treatment of the high strength and recalcitrant paint wastewater.


Assuntos
Esgotos , Águas Residuárias , Anaerobiose , Biofilmes , Reatores Biológicos , Pintura , Eliminação de Resíduos Líquidos
19.
Chemosphere ; 253: 126736, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302910

RESUMO

The covalent organic framework (COF) is made light elements linked by covalent networks. This study synthesize and characterized, and for the first time applied the produced EB-COF:Br as adsorbent for phosphate and arsenate removal from nearly neutral waters. The synthesized COF was first proven structurally stable in solutions of 75% H3PO4, 6 M HCl, or 6 M NaOH. Then the phosphate adsorption onto the EB-COF:Br was shown to be an endothermic process with maximum adsorption capacity at 25, 35 and 45 °C as 25.3, 34.7 and 35.3 mg/g COF, respectively; and the corresponding arsenate adsorption process being an exothermic process with maximnum adsorption capacity as 53.1, 27.5 and 5.1 mg/g, respectively. The synthesized COF could also effectively adsorb phosphate and arsenate ions from river water (pH 7.45) but at reduced adsorption capacities. The electrostatic interactions between the negative charge on phosphate or arsenate ions and the positively charged (N+-) of COF, and the hydrogen bondings between H atom on phosphate or arsenate ions and the (-CO) group of COF were the dominating mechanisms for the present adsorption process. The strong electrostatic interactions for arsenate contributed to its higer adsorption capacity than noted for phosphate at 25 °C. However, the disturbed hydrogen bonding induced by mismatched sizes of arsenate ion and the adsorption sites surrounded by the (N+-) and the (-CO) groups reduced the stability of arsenate to against temperature and external anion challenges. The use of the EB-COF; Br as industrial adsorbent was also discussed.


Assuntos
Arseniatos/análise , Estruturas Metalorgânicas/química , Fosfatos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Temperatura
20.
Bioresour Technol ; 306: 123113, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32163867

RESUMO

Aiming to improve the economy and sustainability of biodiesel production, the scale-up of lipid production by heterotrophic Thraustochytrium sp. BM2 utilizing crude glycerol as a low cost carbon source was optimized in stirred tank fermenter. The issues of impurities such as excess ions, methanol, soap and other organic impurities as well as different pretreatment techniques were explored and tackled for industrial application of crude glycerol as carbon source. For process engineering strategies to enhance lipid production, semi-batch operation outperformed fed-batch cultivation and achieved higher lipid yield and overall lipid productivity primarily due to shorter fermentation time. The two-step esterification/transesterification method achieved high fatty acid methyl ester (FAME) conversion rate up to 91.8%, which was two to three folds higher compared with the one-step process.

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