Environmental Technology

Chen, Liuxiao; Liu, Tangzhi; Tang, Boming; Xiang, Hao; Sheng, Qijin

doi: 10.1080/09593330.2020.1734098pmid: 32081080

As classical traffic noise prediction models lack a deeper consideration of the impact of the gradient, the characteristics of longitudinal gradients from multiple roads were collected as data in the mountain city of Chongqing county, which was chosen as the entry point, to study the noise characteristics for a wide range of road gradients and to build a traffic noise prediction model based on artificial neural networks (ANNs). The field data consisted of traffic volumes, heavy-vehicle ratios, average vehicle speeds, road gradients, and corresponding equivalent sound pressure levels. An optimal ANN model was determined and compared with two classical models. The results demonstrated that a one-hidden-layer ANN model was suitable for traffic noise prediction in mountain cities and presented better predictive performance than the conventional models. The best-performing ANN model yielded a determination coefficient of 0.9447 and a mean-squared error of 0.2708 dBA. Moreover, this study confirmed that road gradients were significant for constructing traffic noise prediction models.

Temnuch, Natcha; Suwattanamala, Akapong; Inpaeng, Saowaluk; Tedsree, Karaked

doi: 10.1080/09593330.2020.1740328pmid: 32149580

Acid-functionalized multi-walled carbon nanotube (MWCNTs-COOH) was prepared by acid treatment followed by decoration with magnetite (Fe3O4) nanoparticles (Fe3O4/MWCNTs-COOH) by co-precipitation of Fe2+/Fe3+ in the colloidal suspension of MWCNTs-COOH. The adsorption capacity and separation efficiency of these two adsorbents were investigated for the removal of Cu2+ ions in aqueous solution as water treatment adsorbents. The effect of reaction conditions, such as contact time, initial concentration of Cu2+ ions, and adsorbent dosage, on the adsorption capacity of MWCNTs-COOH was investigated. It was found that contact time of 10 min, adsorbent dosage of 0.2 g/L and 15 mg/L as initial concentration of Cu2+ ions are ideal conditions for maximum adsorption capacity (10.45 mg/g). The adsorption capacity of synthesized Fe3O4/MWCNTs-COOH containing different weight percent of Fe3O4 (10, 25, 50 wt%) was explored for removal of Cu2+ ions from aqueous solution and the best results achieved with 25 wt% Fe3O4/MWCNTs-COOH, which exhibited optimum adsorption capacity of 9.50 mg/g and 97% separation efficiency. Further, Langmuir and Freundlich isotherm models were applied to validate experimental data obtained in this work for Cu2+ adsorption.

Wang, Jingling; Lin, Wensong; Dong, Manru; Xing, Yue; Zhang, Qicheng

doi: 10.1080/09593330.2020.1737243pmid: 32216539

In this work, the CdS quantum dots (QDs) decorated Bi2MoO6/Bi2Mo3O12 (BMO) heterojunction photocatalyst (C/BMO) has been successfully synthesized using a facile two-step hydrothermal method. The as-prepared photocatalysts were characterized by XRD, FTIR, XPS, FESEM, TEM, UV-vis DRS, PL and photoelectrochemical measurements to investigate the effects of CdS(QDs) and BMO heterojunction on the structure, morphology, optical and charge carrier transmission characteristics of the photocatalysts. Narrow band gap and superior catalytic activities were found in C/BMO as compared with pure BMO. Moreover, the C/BMO photocatalyst containing twice CdS content (2-C/BMO) exhibits even higher photocatalytic activity and stability. After exposure to visible light for 30 min, the degradation rate of Rhodamine B (RhB), Methylene blue (MB) and Ofloxacin (OFX) by 2-C/BMO reached 95%, 92% and 76%, respectively. Radicals scavenging experiments and electron spin-resonance spectroscopy (ESR) investigations indicated that the superoxide radical anions ( ), hole (h+) and hydroxyl radicals (•OH) are the dominating active species in the photodegradation processes. and h+ are the key factors in the degradation of RhB and OFX solutions, and •OH is the major determinant in removal of MB. The process and photocatalytic mechanism on 2-C/BMO was discussed. Well absorption of visible light, effective separation of photoelectron-hole pairs and the transportation of photogenerated carriers at the interfaces of ternary semiconductor heterojunction are suggested as the key factors to enhance the photocatalytic performance of the photocatalysts.

Carvalho Costa, Antonio Wilson Macedo; Guerhardt, Flavio; Ribeiro Júnior, Silvestre Eduardo Rocha; Cânovas, Geovana; Vanale, Rosangela Maria; de Freitas Coelho, Diego; Ehrhardt, Daniela Diniz; Rosa, Jorge Marcos; BasileTambourgi, Elias; Curvelo Santana, José Carlos; de Souza, Roberto Rodrigues

Liu, Tao; Jia, Guangyue; Xu, Jiawei; He, Xiaolu; Quan, Xie

doi: 10.1080/09593330.2020.1735526pmid: 32097578

Moving-Bed Biofilm Reactor (MBBR) process is an ideal preference for simultaneous nitrification and denitrification (SND) attributing to the longer sludge age and aerobic/anoxic microenvironment along biofilm. However, conventional carriers generally exhibit negative charge and surface hydrophobicity, which are unbeneficial for biofilm formation. In this study, novel surface-modified carriers with favourable hydrophilicity (surface contact angle dropped to 60.2 ± 2.3°) and positive surface charge (+11.7 ± 1.1 mV, pH 7.0) were prepared via polymer blending and implemented for SND in continuous flow MBBR system. Results indicated SND started up quickly with more biomass in MBBR filled with surface-modified carriers. At the operation condition of low dissolved oxygen level (0.75 ± 0.25 mg/L), pH of 7.5 ± 0.5, 23 ± 2°C and C/N ratio of 7, COD, NH4 +-N and TN removal efficiencies were 90.5%, 88.6% and 76.6% respectively in MBBR filled with surface-modified carriers, which ensured the effluent met the first grade A of the Discharge Standard of China. On the contrary, COD, NH4 +-N and TN removal efficiencies were 89.7%, 82.3% and 60.4% respectively in the control reactors filled with conventional polyethylene carriers. The worse performance of the control reactor was mainly attributed to the less biomass and lower functional bacteria abundance developed on conventional carriers. Moreover, novel carriers provided a favourable niche for more types of functional bacteria, of which autotrophic nitrification, anoxic denitrification, heterotrophic nitrification and aerobic denitrification co-existed and participated in nitrogen removal.

Hungría, J.; Siles, J. A.; Chica, A. F.; Gil, A.; Martín, M. A.

doi: 10.1080/09593330.2020.1737735pmid: 32114938

Grapes are one the world’s leading fruit crops, with close to 77 million tonnes harvested per year. Grapes are commonly used to produce wine; a process which generates different wastes such as grape mark waste (skins, seeds and stalks), lees and other residues. This study evaluates the treatment of winery waste derived from ecological cultivation by anaerobic digestion to produce energy in the form of methane. Grape marc waste, Verdejo and Pedro Ximenez (PX) wine lees were digested under stable conditions at mesophilic conditions. The PX lees showed the highest methane yield production (433 LSTP CH4/kg VS) with a maximum OLR of 4.58 kg VS/m3·d. In the evaluated range the process was stable with a range of biodegradability of 51–79%. Due to different types of winery waste are generated at consecutive stages of the main production process, the sequential treatment of PX lees, Verdejo lees and grape marc waste in the same anaerobic digester could be an interesting option. This procedure would facilitate the management of the residual streams generated in wineries during the year and promotes the circular economy in the Montilla-Moriles Protected Designation of Origin.

Naresh Yadav, D.; Naz, Iffat; Anand Kishore, K.; Saroj, Devendra

doi: 10.1080/09593330.2020.1737736pmid: 32114965

The present investigation is focused on development of aerobic biofilm on tire-derived rubber (TDR) media and then evaluation of such system for bioremediation of Methylene blue (MB) dye for 9 weeks. After 9 weeks of operation, the COD, BOD, ammonia and color values have been declined by 89.2%, 98.3%, 99.61% and 99.81%, respectively, While SEM-EDX results showed a variance in weight percent of various elements in TDR without biofilm i.e. raw TDR media, as well as in the 1st and 9th-week samples. Moreover, fine and strong peaks were observed in both the MB simulated wastewater and 9th week TDR samples at 1190, 1300, 1400, 1450, 1500 and 1618 cm−1 respectively by Raman Spectroscopic analysis. Further, FTIR analysis was performed for the MB simulated wastewater, and absorbance peaks ranging from 1591 to 1363 cm-1 and 3410 cm−1 were observed in all the samples with different intensities. To assess the biodeterioration of the TDR media, ATR was performed for the raw, 1st, 2nd and 9th week TDR media samples and in the raw TDR, two important bands, 842 and 2962 cm−1 were noticed representing –CH = CH and –CH3. A clear variation of bands and peak intensities were observed in different support media samples. The results indicate that TDR media is a resilient, chemically resistant material and could be employed for the biofilm growth for biological treatment of textile dye wastewater.

Madaeni, S. S.; Falsafi, M.; Ghaemi, N.; Daraei, P.

doi: 10.1080/09593330.2020.1740329pmid: 32149564

The membrane fouling has always been a big issue for developing membrane applications. Surface morphology and roughness affect remarkably on the membrane tendency to fouling. In this study, a biomimetic technique, as a simple, cost-effective and time-saving method was employed to replicate Tropaeolum majus (nasturtium) leaf surface on the surface of a commercial thin-film composite (TFC) reverse osmosis (RO) membrane using polyethersulfone (PES) moulds. Morphology of surface and hydrophilicity of membranes were investigated by scanning electron microscope (SEM), atomic force microscope (AFM) and water contact angle measurements. AFM and SEM photos of membrane surface declared that replication of nasturtium leaf improved the surface characteristics of membranes. The average roughness of membranes heated at 130°C and 150°C was 81.1 and 152.4 nm, respectively. The similar measurement was lower for the virgin membrane. Also, the roughened membranes showed higher hydrophilicity than the virgin membrane. In addition, the performance of the membrane was assessed by evaluating pure water flux (PWF) and flux recovery (FR) after the filtration of whey solution as a severe foulant for membranes. The findings exhibited that the replicated membranes had higher PWF and FR values, indicating the lower fouling tendency of modified membranes.

El Ayeb, Nesrine; Béjaoui, Mustapha; Muhr, Hervé; Touaylia, Samir; Mahmoudi, Ezzeddine

doi: 10.1080/09593330.2020.1740332pmid: 32149584

The phosphate fertilizer and phosphoric acid industries increase phosphogypsum levels in the aquatic environment leading to various disturbing effects. In the present work, we investigated the bio-uptake of heavy metals following the exposure of Ruditapes decussatus to three concentrations of phosphogypsum, 10, 20 and 40 g kg−1, under laboratory conditions. The amounts of Zn, Cd and Pb in several organs of the clam Ruditapes decussatus was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Phosphogypsum acts on the behaviour of R. decussatus by increasing filtration rates. The most treatments showed significantly higher metal concentration in all tissues than the controls. Excavation behaviour was altered in treated bivalves compared to controls. The filtration rate (FR) of clams was significantly affected by exposure to phosphogypsum. Indeed, FR increased in clams exposed to phosphogypsum. Phosphogypsum has decreased SOD, CAT and MDA activities in the gills, digestive gland, gonad and muscles according to the concentration indicating a defense against oxidative stress. AChE was significantly inhibited in clams from all the sampling sites compared to controls. The considered parameters could be useful biomarkers for the evaluation of phosphogypsum toxicity in threatened biota. This study was conducted as part of a further investigation into the use of a comprehensive approach combining chemical and biological parameters to assess the health status of the Gabes gulf population. It provides the first database referring to phosphogypsum contamination and its biological effect in this ecosystem. The present study fills in a needed gap in the literature.

Saha, Swastika; Shukla, Sushil Kumar; Singh, Hare Ram; Pradhan, Kishanta Kumar; Jha, Santosh Kumar

doi: 10.1080/09593330.2020.1737737pmid: 32114960

Bioflocculant-producing bacteria were isolated from various water reservoirs and sediments of the water treatment plant. Four promising strains were identified by standard biochemical methods and 16s rRNA gene sequencing. Bioflocculants were produced in a batch bioreactor of 3 L under optimized conditions. Fourier transformed infrared spectroscopy and scanning electron microscopy (SEM) were used to confirm the chemical and morphological nature of bioflocculants. Anionic and cationic textile dyes congo red (CR) and rhodamine-B (RB) decolourization efficiency by ethanol precipitated bioflocculants were accessed under different values of pH, temperature, dose of flocculant and presence of monovalent, divalent and trivalent cations. Bioflocculants of all the four isolates were found to be highly efficient in decolourization of dye from an aqueous medium with the removal rate up to 99.56%. The removal rate of CR and RB from aqueous medium was largely influenced by the physiochemical condition of the solution viz. pH, temperature, concentration of ions and dose of flocculants. The microbial bioflocculants are biodegradable and highly stable as well as possess abroad range of pH, temperature and ions tolerance range. So, they may be economical and can be greener substitutes for the present harsh chemical-based wastewater effluent treatment methods.