Environmental Technology

Wang, Haizhen; Gao, Qiang; Liu, Shufeng; Chen, Qian

doi: 10.1080/09593330.2020.1739147pmid: 32149576

Agrobacterium sp. LAD9 capable of heterotrophic-aerobic nitrogen removal was applied into a single biological aerated filter (BAF) for bioaugmented treatment of municipal wastewater. The achievement of simultaneous nitrogen and carbon removal in the bioaugmented system was systematically evaluated by ratios of COD to nitrogen (COD/N), ranging from 1 to 20. The results showed that at an appropriate COD/N ratio of 10, the BAF exhibited excellent carbon and nutrients removal, the averaged removal efficiencies for COD, NH4 +-N and TN were 92.3%, 100% and 80.0%, respectively. Long-term operation of the bioaugmented system also confirmed the stability of the treatment efficiency. Further comparisons of SOUR and PCR-DGGE profiles between the bioaugmented and the control system revealed that the introduction of strain LAD9 greatly changed the structure of original microbial community and facilitated their capabilities of aerobic nutrients removal. The proposed bioaugmentation strategy is of particular importance to upgrading or retrofitting concurrent municipal wastewater treatment systems.

Boczonádi, Imre; Jakab, Ágnes; Baranyai, Edina; Tóth, Csilla Noémi; Daróczi, Lajos; Csernoch, László; Kis, Gréta; Antal, Miklós; Pusztahelyi, Tünde; Grawunder, Anja; Merten, Dirk; Emri, Tamás; Fábián, István; Kothe, Erika; Pócsi, István

Sun, Yu; Huang, Liang; Lai, Changmiao; Li, Huiqiang; Yang, Ping

doi: 10.1080/09593330.2020.1739750pmid: 32149585

Shale gas fracturing flowback fluid contains various degradation difficulty organic compounds after hydraulic fracturing. A hybrid treatment method was developed for treating flowback and produced water (FPW) using pre-treatment (NaClO) followed by the expanded granular sludge bed (EGSB) and moving bed biofilm reactor (MBBR). Gas chromatography–mass spectrometry (GC-MS) was employed to detect organic composition in the FPW, the pre-treated FPW, EGSB and MBBR effluent. FPW had high chemical oxygen demand (COD) (3278 mg/L) and the majority of organic compounds in the FPW composed of alkanes and heteroatomic compounds with polymers and polarity. 20% COD removal was achieved after adding 5 g/L of NaClO in FPW (pH = 7, stirring for 20 mins) as pre-treatment and > C30 alkanes in FPW were decomposed a lot in the pre-treatment process. The pre-treated FPW was diluted (volumetric ratio of 20%/50%) with synthetic wastewater/pure water. In the final stage of operation, Cl− and COD concentration of influent to EGSB-MBBR system was around 7000 ± 100 mg/L and 3000 mg/L. EGSB-MBBR system achieved 93.84% COD removal rate, in which EGSB dominated COD removal (>80%). According to the GC-MS results, EGSB had an increase of C11-C30 compounds and a decrease of less C1-C10 content due to the consumption of  > C30 compounds and low molecular weight (LWM) compounds. Meanwhile, aerobic microorganisms in MBBR metabolized LWM organics which contributed a lot to the COD removal (25.06∼68. 22%). The results indicated that the pre-treatment and biological EGSB-MBBR system could be an efficient option used for FPW treating.

Dobrucka, Renata; Szymanski, Marcin; Przekop, Robert

doi: 10.1080/09593330.2020.1740331pmid: 32149570

The unique properties of nanoparticles create broad opportunities as regards their application in almost all disciplines of science and technology. There are many reports about the negative influence of nanoproducts on the environment and humans. Therefore, it is of vital importance to explore the impact of metal nanoparticles on plants. This is why this work is concerned with the phytotoxic activity of ZnO nanoparticles synthesized biologically from Betonica officinalis extract against the seed of Lepidium sativum, Linum flavum, Zea mays and Salvia hispanica-Chia. The obtained ZnO nanoparticles were characterized by UV-Vis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM). Those methods made it possible to assess the structure and size of the obtained ZnO nanoparticles, which was 5 nm. The obtained ZnO nanoparticles exhibited significant toxic properties throughout the range of the tested concentrations. ZnO nanoparticles were the most toxic to Lepidium sativum, for which the IC50 value was 0.0000112 [mg/ml]. The solution of Zn(NO3)2 was toxic as well, as it inhibited the growth of the tested sample throughout the range of the tested concentrations.

Bueno, Rodrigo de Freitas; Faria, Júlia Kersul; Uliana, Dárcio Pinheiro; Liduino, Vitor Silva

doi: 10.1080/09593330.2020.1740798pmid: 32148171

This study aimed at investigating the treatment of landfill leachate using the aerobic granular sludge process in a lab-scale sequential batch reactor (SBR-AGS). The leachate from a giant sanitary landfill localized in the State of São Paulo (Brazil) exhibited high concentration of organic matter (COD 5,300 ± 78 mg L−1) and total nitrogen (TKN 2,630 ± 355 mg L−1). Comparatively, the leachate was added to wastewater in three different volumetric ratios (5, 10 and 20%) and the mixtures were characterized over treatment. The results indicated that there were no significant changes in the behaviour of the biological process even at the highest leachate ratio. The granulation of the aerobic sludge occurred after 90 days of operation and the granules had a diameter of 485–1585 μm. SBR-AGS exhibited removal efficiency of 87–89% for organic matter and at least 98% for total nitrogen, regardless of the leachate ratio. The treated effluent that received 20% of leachate showed 2.7 mg L−1 ammonia and 1.1 mg L-1 nitrate. This study shows that SBR-AGS was able to form large granules, thus promoting a simultaneous nitrification and denitrification (SND) process. We highlighted that SND occurred in low dissolved oxygen concentrations (< 1.5 mg L−1) for 120 days, without compromising aerobic granule integrity. These results suggest that the aerobic granular sludge process is a promising alternative for the co-treatment of landfill leachate and domestic wastewater under tropical climate conditions and its use should be encouraged.

López-Velázquez, Khirbet; Villanueva-Rodríguez, Minerva; Mejía-González, Gamaliel; Herrera-López, David

doi: 10.1080/09593330.2020.1740799pmid: 32155103

In aquatic systems, some substances considered as endocrine disruptors have been detected, which can be due to their incomplete elimination in wastewater treatment plants (WWTPs) and inadequate disposal of pharmaceuticals. Among these contaminants are 17α-ethinylestradiol (EE2) and caffeine (CAF). Moreover, it has been reported that this kind of contaminants may provoke different adverse effects in many aquatic organisms. Because of that, in the present study, up-flow anaerobic sludge blanket reactors (UASB) coupled with the Fenton process was evaluated for EE2 and CAF removal spiked in wastewater samples. First, the best reaction conditions were established in each process. For UASB reactor, two hydraulic retention times (HRT 8 and 24 h) were evaluated, achieving the highest chemical organic demand (COD) removal (70 %) and drug elimination (84 %–86 %) with HRT 24 h. Subsequently, Fenton process was conducted at pH 3 with different levels of Fe2+ (0.05–0.5 mmol/L) and molar ratios Fe2+:H2O2 (1:1–1:10). Better results were obtained with 0.5 mmol Fe2+/L, and 1:10 ratio molar Fe2+:H2O2. Finally, UASB-Fenton coupled system allowed 80 % of COD decrease, almost complete removal of drugs and the toxicity of samples on Vibrio fischeri was reduced from 73 % to 30 %, demonstrating that this coupled system is a promising and efficient system for pharmaceutical compounds removal from wastewater.

Palli, Laura; Tilli, Silvia; Gregorio, Simona Di; Scozzafava, Andrea; Gori, Riccardo

doi: 10.1080/09593330.2020.1752814pmid: 32249698

A two-stage biological process using fungi and bacteria was set-up and tested for treating a petrochemical wastewater containing naphthalene sulphonic acid polymers. The fungal treatment was carried out through a trickling filter inoculated with Pleurotus ostreatus attached on Luffa cylindrica acting as both physical support and carbon source. The fungal reactor was operated in non-sterile conditions setting two pH values (5 and 6) and two hydraulic retention times (2 d and 3 d). The effluent was then sent to an activated sludge reactor operating the second stage of the treatment. Using an HPLC-based technique, it was observed that the fungal reactor was capable of reducing the polymerization grade of naphthalene sulphonic acid polymers up to 35%, thus increasing significantly the biodegradability of the petrochemical wastewater, from the initial 9% to 46%. The two-stage process allowed to remove about 50% of the total COD much higher than 9% that can be achieved with activated sludge alone. The use of Luffa cylindrica as support for fungi allowed to limit bacterial contamination of the trickling filter and enhanced enzymatic production (on average 20 U/L of Laccase) without any release of non-biodegradable by-products in the effluent. Extraction and PCR-amplification of fungal DNA was carried out along with over 70 d running process in order to monitor the changes of the fungal community inside the reactors. Results showed that Meyerozyma, Fusarium and Thricoderma, spp. developed inside the reactor with Thricoderma, spp. representing the main constituent of fungal biomass at the end of the experiment.

Liu, Wenting; Ren, Dajun; Wu, Jian; Wang, Zhaobo; Zhang, Shuqin; Zhang, Xiaoqin; Gong, Xiangyi

doi: 10.1080/09593330.2020.1743367pmid: 32167412

In this study, rice straw was used as the raw materials of biomass carbon to prepare biochar at different temperatures (400°C, 500°C, 600°C, 700°C, and 800°C). In addition, cetyl trimethyl ammonium bromide (CTAB) modified biochar was used to treat 2,4-dichlorophenol (2,4-DCP) in water. The influences of adsorbent dosage, solution pH, adsorption time, and initial solubility of the 2,4-DCP solution on the adsorption properties were investigated. The physicochemical properties of biochar were investigated using SEM, FT-IR, BET surface area, and pore size analysis. The results showed that the pyrolysis temperature had a great influence on the biochar structure. CTAB provided hydrophilic and hydrophobic groups to the modified biochar, which had increased adsorption capacity comparing to unmodified biochar. The pH also had a significant effect on the adsorption performance of biochar, and the adsorption performance of biochar decreased significantly under alkaline conditions. The maximum adsorption capacities of modified biochar and unmodified biochar were 59.81 and 20.89 mg/g, respectively, indicating that the adsorption capacity of modified biochar was significantly higher than that of unmodified biochar. The adsorption process of 2,4-DCP by rice straw biochar conformed to the Second-order kinetic model and the Freundlich isotherm adsorption model.

Li, Tianpeng; Fan, Jing; Sun, Tingting

doi: 10.1080/09593330.2020.1743368pmid: 32167410

The study aims to remove methylene blue dye from water with a fixed-bed column packed with Cu2O nanocomposite ceramsites. The column showed the advantages of fixed-bed column adsorption and photocatalytic oxidation. The Cu2O nanocomposite ceramsites with strong photocatalytic oxidation activity and well-developed porous structure were successfully prepared with the chemical vapour deposition process, which also met with the China’s industrial standard of CJ/T 299–2008 and China’s national standard of GB 5085.3-2007. In the column experiments under the experimental conditions (initial pH was 3, reaction temperature was 25°C and flow rate was 33 mL/min), the breakthrough curve was much more smooth. The breakthrough time and saturation time under ultraviolet radiation were 36.0% and 26.83% longer than those under the conditions without ultraviolet radiation, because the micro-pore structure of ceramsite was closely related to optical excitation properties of nano-Cu2O. The Yoon-Nelson and Adams-Bohart models were applied to describe the obtained breakthrough curves using non-linear regression, in which the Yoon-Nelson model gave the better prediction results for breakthrough curves, with R2>0.98. Besides, amines were the dominant intermediates at saturation point and final products were inorganic anions. This study confirmed that the fixed-bed column packed with Cu2O nanocomposite ceramsites could efficiently treat methylene blue dye wastewater, due to the structure–function relationship between ceramsite and nano-Cu2O.

Zhang, Lu; Fang, Qian; Huang, Dingwu; Liu, Yu; Zeng, Yunyi; Xie, Yihan; Luo, Jin

doi: 10.1080/09593330.2020.1743369pmid: 32290782

In this study, the effects of inoculating Saccharomyces cerevisiae (S. cerevisiae) on the production of volatile fatty acids (VFAs) via anaerobic fermentation of organic solid waste peanut meal were investigated. At 35°C (temperature of the medium), inoculums consisting of six different S. cerevisiae-peanut meal ratios were used in sequencing batch anaerobic fermentation, and the changes in VFA, protein, glycogen, pH, , and soluble chemical oxygen demand (SCOD) levels during the fermentation process were studied. Results showed that after inoculation with S. cerevisiae, the anaerobic fermentation of peanut meal mainly produced even-chain VFAs (acetic acid and n-butyric acid); in the early stage of fermentation, inoculation of S. cerevisiae enhanced protein dissolution efficiency and degradation rate, and completely degraded soluble glycogen. The utilization ratio of the protein and soluble glycogen improved. Analysis of significant difference showed that compared to the peanut meal control, the experimental group correlated significantly with the VFAs. The VFA obtained with the inoculum: peanut meal ratio of 0.15 g g−1 was mainly acetic acid, with peak concentration of 10,797.09 mg L−1, which was 1.82 times higher than that obtained with only the peanut meal fermentation. Response surface methodology predicted that the inoculation ratio was 0.15 g g−1, and the effect of producing VFAs was the best when the fermentation time was 8.63d. The results showed that S. cerevisiae inoculation may improve VFA production and increase the proportion of even acids.