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    Dan Xiao, Zhaofeng Lyu, Shiheng Chen, Yang Huo, Wei Fan, Mingxin Huo
    Frontiers of Environmental Science & Engineering, 2022, 16(9): 112.

    Cryptosporidium in WWTPs in a cold region was investigated in different seasons.

    • The overall removal efficiency of Cryptosporidium in WWTPs was over 84%.

    • The infectivity rate declined below 53% in effluents mainly due to disinfection.

    • The infectivity of Cryptosporidium increased with a seasonal drop in temperature.

    • Low temperature promotes binding protein retention and virulence genes expression.

    This study investigated the occurrence, species, infectivity and removal efficiency of Cryptosporidium spp. across typical wastewater treatment train. Samples from different process units were collected seasonally and synchronously from four wastewater treatment plants (WWTPs) in Northeastern China. Live Cryptosporidium oocysts were identified in most samples from both influent (97.50%) and effluent (90.00%) wastewaters of the four WWTPs, at an average density of 26.34 and 4.15 oocysts/L, respectively. The overall removal efficiency was 84.25%, and oocysts were mainly removed (62.01%) by the modified secondary sedimentation process. Ten Cryptosporidium species were identified in the effluent samples. C. andersoni, C. bovis, and C. ryanae were the three most prevalent species. Oocyst viability assays indicated no reduction of excystation rate during the primary and secondary wastewater treatments (varied in the range of 63.08%–68.50%), but the excystation rate declined to 52.21% in the effluent after disinfection. Notably, the Cryptosporidium oocysts showed higher infection intensity in the cold season (winter and spring) than that in summer and autumn. The influences of environmental temperature on virulence factors of Cryptosporidium were further examined. It was observed that more extracellular secretory proteins were bound on the oocyst surface and several virulence genes were expressed relatively strongly at low temperatures, both of which could facilitate oocyst adhesion, invasion, and host immune evasion. This research is of considerable interest since it serves as an important step towards more accurate panoramic recognition of Cryptosporidium risk reduction in WWTPs, and especially highlights the potential health risk associated with Cryptosporidium in cold regions/seasons.

    Shuyi Wang, Xiang Qi, Yong Jiang, Panpan Liu, Wen Hao, Jinbin Han, Peng Liang
    Frontiers of Environmental Science & Engineering, 2022, 16(8): 97.

    • Antibiotic azithromycin employed in graphite electrode for EAB biosensor.

    • Azithromycin at 0.5% dosage increased the sensitivity for toxic formaldehyde.

    • Azithromycin increased the relative abundance of Geobacter.

    • Azithromycin regulated thickness of electroactive biofilm.

    Extensive research has been carried out for improved sensitivity of electroactive biofilm-based sensor (EAB-sensor), which is recognized as a useful tool in water quality early-warning. Antibiotic that is employed widely to treat infection has been proved feasible in this study to regulate the EAB and to increase the EAB-biosensor’s sensitivity. A novel composite electrode was prepared using azithromycin (AZM) and graphite powder (GP), namely AZM@GP electrode, and was employed as the anode in EAB-biosensor. Different dosages of AZM, i.e., 2 mg, 4 mg, and 8 mg, referred to as 0.25%, 0.5% and 1% AZM@GP were under examination. Results showed that EAB-biosensor was greatly benefited from appropriate dosage of AZM (0.5% AZM@GP) with reduced start-up time period, comparatively higher voltage output, more readable electrical signal and increased inhibition rate (30%-65% higher than control sensor with GP electrode) when exposing to toxic formaldehyde. This may be attributed to the fact that AZM inhibited the growth of non-EAM without much influence on the physiologic or metabolism activities of EAM under proper dosage. Further investigation of the biofilm morphology and microbial community analysis suggested that the biofilm formation was optimized with reduced thickness and enriched Geobacter with 0.5% AZM@GP dosage. This novel electrode is easily fabricated and equipped, and therefore would be a promising way to facilitate the practical application of EAB-sensors.

    Yan Guo, Zibin Luo, Junhao Shen, Yu-You Li
    Frontiers of Environmental Science & Engineering, 2022, 16(7): 84.

    • The PNA, denitratation/anammox, and DAMO/anammox process are reviewed together.

    • Denitratation/anammox-based process is promising in mainstream treatment.

    • DAMO and denitratation processes realize the higher nitrogen removal efficiency.

    • The utilization of metabolism diversity of functional microbe is worth exploring.

    • An effective waste treatment system concept is proposed.

    Anammox technology has been widely researched over the past 40-year from the laboratory-scale to full-scale. It is well-known that in actual applications, the solo application of anammox is not feasible. Since both ammonium and nitrite are prerequisites based on the reaction mechanism, the pre-treatment of wastewater is necessary. With the combination of anammox process and other pre-treatment processes to treat the actual wastewater, many types of anammox-based processes have been developed with distinct nitrogen removal performance. Thus, in order to heighten the awareness of researchers to the developments and accelerate the application of these processes to the treatment of actual wastewater, the main anammox-based processes are reviewed in this paper. It includes the partial nitritation/anammox process, the denitratation/anammox (PD/A) process, the denitrifying anaerobic methane oxidation/anammox (DAMO/A) process, and more complex deuterogenic processes. These processes have made the breakthroughs in the application of the anammox technology, such as the combination of nitrification and PD/A process can achieve stability and reliability of nitrogen removal in the treatment of mainstream wastewater, the PD/A process and the DAMO/A have brought about further improvements in the total nitrogen removal efficiency of wastewater. The diversity of functional microbe characteristics under the specific condition indicate the wide application potential of anammox-based processes, and further exploration is necessary. A whole waste treatment system concept is proposed through the effective allocation of above mentioned processes, with the maximum recovery of energy and resources, and minimal environmental impact.

    Yanlin Li, Bo Wang, Lei Zhu, Yixing Yuan, Lujun Chen, Jun Ma
    Frontiers of Environmental Science & Engineering, 2022, 16(6): 68.

    • LDHs and MMOs was synthesized by ultrasound-assisted one-step co-precipitation.

    • MMOs performs the best for Cr(VI) and E. coliNDM-1 simultaneous removal.

    • Possible antibacterial pathways of Cr-MMOs were proposed.

    Herein we provide a novel high-efficiency nanocomposite for bacterial capture based on mixed metal oxides (MMOs) with deleterious chromium properties. With both the layer structure of layered double hydroxides (LDHs) and the magnetic properties of Fe, MMOs enrich the location of ionic forms on the surface, providing a good carrier for adsorption of the heavy metal Cr(VI). The capacity for adsorption of Cr(VI) by MMOs can be as high as 98.80 mg/g. The prepared Cr(VI)-MMOs achieved extremely expeditious location of gram-negative antibiotic-resistant E. coliNDM-1 by identifying lipid bilayers. Cr-MMOs with a Cr loading of 19.70 mg/g had the best bactericidal effect, and the concentration of E. coliNDM-1 was decreased from ~108 to ~103 CFU/mL after 30 min of reaction. The binding of nitrogen and phosphorus hydrophilic groups to chromate generated realistic models for density functional theory (DFT) calculations. The specific selectivity of MMOs toward bacterial cells was improved by taking Cr(VI) as a transferable medium, thereby enhancing the antibacterial activity of Cr-MMOs. Under the combined action of chemical and physical reactions, Cr(VI)-MMOs achieved high capacity for inactivation of bacteria. Moreover, the metallic elements ratio in Cr-MMOs remained stable in their initial valence states after inactivation. This guaranteed high removal efficiency for both heavy metals and bacteria, allowing recycling of the adsorbent in practical applications.

    Yang Yang, Qi Zhang, Baiyang Chen, Liangchen Long, Guan Zhang
    Frontiers of Environmental Science & Engineering, 2022, 16(5): 55.

    • UV/VUV/I induces substantial H2O2 and IO3 formation, but UV/I does not.

    • Increasing DO level in water enhances H2O2 and iodate productions.

    • Increasing pH decreases H2O2 and iodate formation and also photo-oxidation.

    • The redox potentials of UV/VUV/I and UV/VUV changes with pH changes.

    • The treatability of the UV/VUV/I process was stronger than UV/VUV at pH 11.0.

    Recently, a photochemical process induced by ultraviolet (UV), vacuum UV (VUV), and iodide (I) has gained attention for its robust potential for contaminant degradation. However, the mechanisms behind this process remain unclear because both oxidizing and reducing reactants are likely generated. To better understand this process, this study examined the evolutions of hydrogen peroxide (H2O2) and iodine species (i.e., iodide, iodate, and triiodide) during the UV/VUV/I process under varying pH and dissolved oxygen (DO) conditions. Results show that increasing DO in water enhanced H2O2 and iodate production, suggesting that high DO favors the formation of oxidizing species. In contrast, increasing pH (from 6.0 to 11.0) resulted in lower H2O2 and iodate formation, indicating that there was a decrease of oxidative capacity for the UV/VUV/I process. In addition, difluoroacetic acid (DFAA) was used as an exemplar contaminant to verify above observations. Although its degradation kinetics did not follow a constant trend as pH increases, the relative importance of mineralization appeared declining, suggesting that there was a redox transition from an oxidizing environment to a reducing environment as pH rises. The treatability of the UV/VUV/I process was stronger than UV/VUV under pH of 11.0, while UV/VUV process presented a better performance at pH lower than 11.0.

    Ruobin Dai, Hongyi Han, Yuting Zhu, Xi Wang, Zhiwei Wang
    Frontiers of Environmental Science & Engineering, 2022, 16(4): 40.

    • PA layer properties tune the primary nanochannels in MIL-101(Cr) TFN NF membranes.

    • The dense PA layer induced transition of primary nanochannels of TFN NF membranes.

    • Nanochannels around MOF contributed to the improved flux with a loose PA structure.

    • Nanochannels in MOFs dominated the separation performance with a dense PA structure.

    Metal organic framework (MOF) incorporated thin-film nanocomposite (TFN) membranes have the potential to enhance the removal of endocrine disrupting compounds (EDCs). In MOF-TFN membranes, water transport nanochannels include (i) pores of polyamide layer, (ii) pores in MOFs and (iii) channels around MOFs (polyamide-MOF interface). However, information on how to tune the nanochannels to enhance EDCs rejection is scarce, impeding the refinement of TFN membranes toward efficient removal of EDCs. In this study, by changing the polyamide properties, the water transport nanochannels could be confined primarily in pores of MOFs when the polyamide layer became dense. Interestingly, the improved rejection of EDCs was dependent on the water transport channels of the TFN membrane. At low monomer concentration (i.e., loose polyamide structure), the hydrophilic nanochannels of MIL-101(Cr) in the polyamide layer could not dominate the membrane separation performance, and hence the extent of improvement in EDCs rejection was relatively low. In contrast, at high monomer concentration (i.e., dense polyamide structure), the hydrophilic nanochannels of MIL-101(Cr) were responsible for the selective removal of hydrophobic EDCs, demonstrating that the manipulation of water transport nanochannels in the TFN membrane could successfully overcome the permeability and EDCs rejection trade-off. Our results highlight the potential of tuning primary selective nanochannels of MOF-TFN membranes for the efficient removal of EDCs.

    Athiyanam Venkatesan Ramya, Manoj Balachandran
    Frontiers of Environmental Science & Engineering, 2022, 16(3): 27.

    • Transformation of agro-industrial waste to value-added material via green chemistry.

    • Orange peel is valorized into fluorescent nanodiamond-like carbon (fNDC) sensor.

    • fNDC detects potentially hazardous drug atropine sulfate (AS).

    • fNDC recognizes AS in biological fluids and pharmaceuticals.

    • fNDC assures applications in clinical and forensic toxicology.

    Millions of tonnes of agro-industrial waste are generated each year globally, with the vast majority of it going untreated, underutilized, and disposed of by burning or landfilling, causing severe environmental distress and economic downturn. A practical solution to this global issue is to use green chemistry to convert this waste into value-added products. Accordingly, in the present study, agro-industrial orange peel waste was valorized into fluorescent nanodiamond-like carbon sensor via a green route involving hydrothermal treatment of microwave carbonized orange peel waste. The developed sensor, used for the fluorescence detection of potentially hazardous drug atropine sulfate, exhibits unique dual linearity over concentration ranges of 300 nM to 1 M and from 1 M to 10 M, as well as ultra-low sensitivity of 34.42 nM and 356.46 nM, respectively. Additionally, the sensor demonstrates excellent reproducibility, high stability, and satisfactory recovery when used to identify and quantify atropine sulfate in biological samples and commercially available pharmaceuticals, indicating promising multidisciplinary applications.

    Jian Lu, Cui Zhang, Jun Wu
    Frontiers of Environmental Science & Engineering, 2022, 16(2): 15.

    •Steroid hormones could be removed efficiently from mariculture system using seaweed;

    Caulerpa lentillifera was the most efficient seaweed for removal of steroid hormones;

    • More than 90% of E2 or EE2 were removed within 12 h using Caulerpa lentillifera;

    • The removal included the rapid biosorption and the slow bio-accumulation;

    •The hormones and nutrients in mariculture wastewater could be simultaneously removed.

    The removal of steroid hormones from the mariculture system using seaweeds (Caulerpa lentillifera, Ulva pertusa, Gracilaria lemaneiformis, and Codium fragile) was investigated. The results illustrated that both 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) could be removed by the seaweeds at different levels, and the Caulerpa lentillifera was the most efficient one. More than 90% of E2 or EE2 at concentration of 10 μg/L was removed by Caulerpa lentillifera within 12 h. Processes including initial quick biosorption, the following slow accumulation, and biodegradation might explain the removal mechanisms of E2/EE2 by Caulerpa lentillifera. E2/EE2 removal was positively related to the nutrient level and the initial concentration of steroid hormone. A significant linear relationship for E2 and EE2 existed between the initial pollutant concentration and the average removal rate. The highest removal kinetic constant (k) value was obtained at 30°C as 0.34 /h for E2 and at 20°C as 0.28 /h for EE2, demonstrating the promising application potential of Caulerpa lentillifera in the water purification of the industrialized mariculture system with relatively high water temperature. Simultaneous and efficient removal of E2 and EE2 by Caulerpa lentillifera was still achieved after 3 cycles in the pilot-scale experiment. The steroid hormones and nutrients in mariculture wastewater could also be simultaneously removed using Caulerpa lentillifera. These findings demonstrated that Caulerpa lentillifera was the promising seaweed for the removal of steroid hormones in mariculture systems.

    Qinghui Sun, Juan Li, Chen Wang, Anqi Chen, Yanli You, Shupeng Yang, Huihui Liu, Guibin Jiang, Yongning Wu, Yanshen Li
    Frontiers of Environmental Science & Engineering, 2022, 16(1): 1.

    • Microplastics are widely found in both aquatic and terrestrial environments.

    • Cleaning products and discarded plastic waste are primary sources of microplastics.

    • Microplastics have apparent toxic effects on the growth of fish and soil plants.

    • Multiple strains of biodegradable microplastics have been isolated.

    Microplastics (MPs) are distributed in the oceans, freshwater, and soil environment and have become major pollutants. MPs are generally referred to as plastic particles less than 5 mm in diameter. They consist of primary microplastics synthesized in microscopic size manufactured production and secondary microplastics generated by physical and environmental degradation. Plastic particles are long-lived pollutants that are highly resistant to environmental degradation. In this review, the distribution and possible sources of MPs in aquatic and terrestrial environments are described. Moreover, the adverse effects of MPs on natural creatures due to ingestion have been discussed. We also have summarized identification methods based on MPs particle size and chemical bond. To control the pollution of MPs, the biodegradation of MPs under the action of different microbes has also been reviewed in this work. This review will contribute to a better understanding of MPs pollution in the environment, as well as their identification, toxicity, and biodegradation in the ocean, freshwater, and soil, and the assessment and control of microplastics exposure.

    Zongqun Chen, Wei Jin, Hailong Yin, Mengqi Han, Zuxin Xu
    Frontiers of Environmental Science & Engineering, 2021, 15(6): 111.

    • A way for overflow control based on on-site coagulation/flocculation was proposed.

    • Coagulant and flocculant dose were optimized based on pollutant removal performance.

    • Settling time of 5 min is enough in a proper transmission distance.

    • Fast removal of particulate pollutants could be achieved under varied flow.

    The pollution caused by wet weather overflow in urban drainage systems is a main factor causing blackening an odorization of urban rivers. The conventional overflow treatment based on coagulation/flocculation in terminal drainage systems requires relatively large space and long retention time demand that makes it not applicable in crowded urban drainage systems or under heavy rains. On-site coagulation/flocculation in terminal drainage pipes was proposed in this study which was aimed to transfer the coagulation/flocculation process to the inside of pipes at the terminal drainage system to save space and reduce the retention time of the coagulation/flocculation process. The optimized dose of chemicals was studied first which was 80 mg/L of coagulant and 0.8 mg/L of flocculant. Settling for only 5 min can remove most of the pollutants at 406.5 m of transmission distance. In addition, the relation of wet weather overflow rate and concentration of pollution load on the on-site coagulation/flocculation process was investigated, which indicated that high removal of pollutant was gained at a large range of flow velocity and pollutant concentration. Finally, the study confirmed electric neutralization, bridging, and net capture as the major mechanisms in this process, and further optimization was proposed. The proposed process can reduce much turbidity, chemical oxygen demand, and total phosphorous, but hardly remove soluble ammonia and organics. This work provides scientific guidance to address wet weather overflow in terminal drainage pipes.