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Zhang Y, Duan J, Liu R, Petropoulos E, Feng Y, Xue L, Yang L, He S. Efficient magnetic capture of PE microplastic from water by PEG modified Fe 3O 4 nanoparticles: Performance, kinetics, isotherms and influence factors. J Environ Sci (China) 2025; 147:677-687. [PMID: 39003082 DOI: 10.1016/j.jes.2023.07.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/20/2023] [Accepted: 07/20/2023] [Indexed: 07/15/2024]
Abstract
Due to their resistance to degradation, wide distribution, easy diffusion and potential uptake by organisms, microplastics (MPs) pollution has become a major environmental concern. In this study, PEG-modified Fe3O4 magnetic nanoparticles demonstrated superior adsorption efficiency against polyethylene (PE) microspheres compared to other adsorbents (bare Fe3O4, PEI/Fe3O4 and CA/Fe3O4). The maximum adsorption capacity of PE was found to be 2203 mg/g by adsorption isotherm analysis. PEG/Fe3O4 maintained a high adsorption capacity even at low temperature (5°C, 2163 mg/g), while neutral pH was favorable for MP adsorption. The presence of anions (Cl-, SO42-, HCO3-, NO3-) and of humic acids inhibited the adsorption of MPs. It is proposed that the adsorption process was mainly driven by intermolecular hydrogen bonding. Overall, the study demonstrated that PEG/Fe3O4 can potentially be used as an efficient control against MPs, thus improving the quality of the aquatic environment and of our water resources.
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Yang B, Zhou D, Chu Q, Chen X, He S, Petropoulos E, Liang X, Wang P, Yang L, Xue L. Reutilization of post-adsorption lanthanum-loaded straw alleviates phosphorus pollution in rice-wheat system: Subsequent performance and underlying mechanisms. CHEMOSPHERE 2024; 364:143013. [PMID: 39111671 DOI: 10.1016/j.chemosphere.2024.143013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 07/29/2024] [Accepted: 08/02/2024] [Indexed: 08/10/2024]
Abstract
Adsorption technology for phosphorus (P) removal is considered promising and reutilization of post-adsorbent can contribute to promoting sustainable agricultural production. However, the long-lasting impact of the post-adsorbent on crop growth and P remains unclear. This study assessed the effects of P-adsorbed lanthanum-modified straw (La@straw-P) on the rice yield, P fractionation and associated water quality parameters. The findings indicated that, compared with traditional fertilizer regimes, La@straw-P expedited the P reduction in the flooding water achieving a rate of decline to the tertiary standard for surface water (0.20 mg/L) 3.8 times faster and enhanced increased the P harvest index by 17.00 %. Economic estimation proved the positive benefits of La@straw-P in planting-breeding combination system. Redundancy analysis (RDA) and co-occurrence network analysis (CONA) revealed that electrical conductivity (EC) and dissolved Fe played primary roles in regulating total P. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and soil P fractions collectively demonstrated that the abundant adsorption sites on La@straw-P could facilitate the transformation of active P into moderately Ca-bound P. This study proposes a strategy for recycling P-adsorbed materials to mitigate agricultural non-point P pollution.
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Luo S, Chen R, Han J, Zhang W, Petropoulos E, Liu Y, Feng Y. Urban green space area mitigates the accumulation of heavy metals in urban soils. CHEMOSPHERE 2024; 352:141266. [PMID: 38316278 DOI: 10.1016/j.chemosphere.2024.141266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/07/2024]
Abstract
Despite that the heavy metals in urban soils pose a threat to public health, the critical factors that influence their concentrations in urban soils are not well understood. In this study, we conducted a survey of surface soil samples from urban green spaces in Shanghai, to analyze the concentrations of the key heavy metals. The results showed that Zn was the most abundant metal with an average concentration of 122.99 mg kg-1, followed by Pb (32.72 mg kg-1) and Cd (0.23 mg kg-1). All concentrations were found to be below the risk screening values defined by the National Environmental Quality Standards for soils of development land in China (GB36600-2018), indicating no current risk in Shanghai. However, there was a clear accumulation of heavy metals, as the mean concentrations were significantly higher than the background values. Furthermore, we explored the relationships between key heavy metals with population density, GDP and green space area. Both Spearman correlation and Random Forest analysis indicated that per capita green space area (pGSA) and population density were the most crucial factors influencing the status of heavy metals in urban soils, unlike edaphic factors e.g. SOM content in farmland soils. Specifically, there was a significantly positive linear correlation between heavy metal concentrations and population density, with correlation coefficients ranging from 0.3 to 0.4. However, the correlation with pGSA was found to be non-linear. The nonlinear regression analysis revealed threshold values between heavy metals concentrations and pGSA (e.g Zn 22.22 m2, Pb 24.92 m2, and Cd 25.92 m2), with a sharp reduction in heavy metal concentrations below the threshold and a slow reduction above the threshold. It suggests that an increase in per capita green space area can mitigate the accumulation of heavy metals caused by growing population density, but the effect is limited after the threshold. Our findings not only provide insights into the distribution patterns of heavy metals in the urban soils at the local scale, but also contribute to the urban greening at the global scale and offer guidance for city planning in the face of increasing population densities over the coming decades.
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Ma R, Duan J, Xue L, Yin A, Petropoulos E, Suo Q, Yang L. Treatment of nitrogen and phosphorus from sewage tailwater in paddy rice wetlands: concept and environmental benefits. ENVIRONMENTAL MONITORING AND ASSESSMENT 2024; 196:174. [PMID: 38236448 DOI: 10.1007/s10661-024-12353-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/11/2024] [Indexed: 01/19/2024]
Abstract
Domestic sewage tailwater (DSTW) reuse for crop irrigation is considered a promising practice to reduce water demand, mitigate water pollution, and substitute chemical fertilization. The level of the above environmental benefits of this water reuse strategy, especially when applied to paddy wetlands, remains unclear. In this study, soil column experiments were conducted to investigate the nitrogen and phosphorus fate in paddy wetlands subjected to different tailwater irrigation and drainage strategies, specifically, (i) TW1 and TW2 for regular or enhanced irrigation-drainage without N fertilization, (ii) TW3 and TW4 for regular irrigation with base or tillering N fertilizer, (iii) conventional fertilization N210, and (iv) no-fertilization controls N0. The results showed that the total nitrogen (TN), nitrate (NO3-), and total phosphorus (TP) removal rates from the paddies irrigated by DSTW ranged between 51.92 and 59.34%, 68.1 and 83.42%, and 85.69 and 86.98% respectively. Ammonia emissions from the DSTW-irrigated treatments were reduced by 14.6~47.2% compared to those paddies subjected to conventional fertilization (N210), similarly for TN emissions, with the exception of the TW2 treatment. Overall, it is established that the paddy wetland could effectively remove residual N and P from surface water runoffs, while the partial substitution of chemical fertilization by DSTW could be confirmed. The outcome of this study demonstrates that DSTW irrigation is a promising strategy for sustainable rice production with a minimized environmental impact.
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Gao G, Li G, Liu M, Li P, Liu J, Ma S, Li D, Petropoulos E, Wu M, Li Z. Changes in soil stoichiometry, soil organic carbon mineralization and bacterial community assembly processes across soil profiles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166408. [PMID: 37597539 DOI: 10.1016/j.scitotenv.2023.166408] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/16/2023] [Accepted: 08/16/2023] [Indexed: 08/21/2023]
Abstract
Soil organic carbon (SOC) mineralization is essential to biogeochemical recycling in terrestrial ecosystem. However, the microbial mechanisms underlying the nutrient-induced SOC mineralization remain uncertain. Here, we investigated how SOC mineralization was linked to microbial assembly processes as well as soil nutrient availability and stoichiometric ratio in a paddy rice ecosystem at four soil profile levels. Our results showed a sharp decrease in SOC mineralization from topsoil (112.61-146.34 mg CO2 kg-1 day-1) to subsoil (33.51-61.41 mg CO2 kg-1 day-1). High-throughput sequencing showed that both abundance and diversity of specialist microorganisms (Chao1: 1244.30-1341.35) significantly increased along the soil profile, while the generalist microorganisms (Chao1: 427.67-616.15; Shannon: 7.46-7.97) showed the opposite trend. Correspondingly, the proportion of deterministic processes that regulate specialist (9.64-21.59 %) and generalist microorganisms (21.17-53.53 %) increased and decreased from topsoil to subsoil, respectively. Linear regression modeling and partial least squares path modeling indicated that SOC mineralization was primarily controlled by the assembly processes of specialist microorganisms, which was significantly mediated by available soil C:N:P stoichiometry. This study highlighted the importance of soil stoichiometry-mediated bacterial community assembly processes in regulating SOC mineralization. Our results have an important implication for the integration of bacterial community assembly processes into the prediction of SOC dynamics.
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Yu Y, Wu C, Li X, Wu L, Yang Q, Petropoulos E, Feng Y. The impact of Ag nanoparticles on methane emission in two typical paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 323:121215. [PMID: 36740168 DOI: 10.1016/j.envpol.2023.121215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 01/10/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Numerous applications of Ag nanoparticles (AgNPs) have increased the likelihood of their release and accumulation in agroecosystem. Thus far, few studies have evaluated the impacts of AgNPs to soil methane emissions and the microbial dynamics. In this study, microcosmic experiments were conducted to investigate the responses of methanogenic processes from two paddy soils (Cambisols and Ultisols) subjected to four AgNPs doses (0.1, 1, 10 and 50 mg/kg). The results showed that 0.1 and 1 mg/kg AgNPs had no significant effects on CH4 emissions, but 50 mg/kg AgNPs increased soil CH4 emissions in both paddy soils. The aggravation effect of AgNPs on CH4 emissions was more apparent in Ultisols compared to Cambisols paddy soils. Real-time PCR suggested that 50 mg/kg AgNPs significantly increased the ratio of methanogenic to bacterial gene for both paddy soils. Amplicon sequencing indicated that methanogenic community was clustered into a separate group after 50 mg/kg AgNPs exposure. Structural equation model illustrated that Methanosarcinales was both significantly responded to AgNPs in Cambisols and Ultisols soils; however, Methanocellales significantly responded to AgNPs only in Cambisols soils. Subsequently, uncontrolled use of AgNPs may account as an environmental risk due to the potentially increased soil CH4 emissions in paddy ecosystems.
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Ding C, Zhu Q, Yang B, Petropoulos E, Xue L, Feng Y, He S, Yang L. Efficient photocatalysis of tetracycline hydrochloride (TC-HCl) from pharmaceutical wastewater using AgCl/ZnO/g-C 3N 4 composite under visible light: Process and mechanisms. J Environ Sci (China) 2023; 126:249-262. [PMID: 36503753 DOI: 10.1016/j.jes.2022.02.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 06/17/2023]
Abstract
AgCl/ZnO/g-C3N4, a visible light activated ternary composite catalyst, was prepared by combining calcination, hydrothermal reaction and in-situ deposition processes to treat/photocatalyse tetracycline hydrochloride (TC-HCl) from pharmaceutical wastewater under visible light. The morphological, structural, electrical, and optical features of the novel photocatalyst were characterized using scanning electron microscopy (SEM), UV-visible light absorption spectrum (UV-Vis DRS), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and transient photocurrent techniques. All analyses confirmed that the formation of heterojunctions between AgCl/ZnO and g-C3N4 significantly increase electron-hole transfer and separation compared to pure ZnO and g-C3N4. Thus, AgCl/ZnO/g-C3N4 could exhibit superior photocatalytic activity during TC-HCl assays (over 90% removal) under visible light irradiation. The composite could maintain its photocatalytic stability even after four consecutive reaction cycles. Hydrogen peroxide (H2O2) and superoxide radical (·O2) contributed more than holes (h+) and hydroxyl radicals (·OH) to the degradation process as showed by trapping experiments. Liquid chromatograph-mass spectrometer (LC-MS) was used for the representation of the TC-HCl potential degradation pathway. The applicability and the treatment potential of AgCl/ZnO/g-C3N4 against actual pharmaceutical wastewater showed that the composite can achieve removal efficiencies of 81.7%, 71.4% and 69.0% for TC-HCl, chemical oxygen demand (COD) and total organic carbon (TOC) respectively. AgCl/ZnO/g-C3N4 can be a prospective key photocatalyst in the field of degradation of persistent, hardly-degradable pollutants, from industrial wastewater and not only.
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Sun L, Yu Y, Petropoulos E, Cui X, Wang S. Long-Term Manure Amendment Sustains Black Soil Biodiversity by Mitigating Acidification Induced by Chemical N Fertilization. Microorganisms 2022; 11:microorganisms11010064. [PMID: 36677356 PMCID: PMC9861357 DOI: 10.3390/microorganisms11010064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022] Open
Abstract
The long-term use of chemical N fertilization may have a negative impact upon soil fertility and quality. On the contrary, organic fertilization is considered a sustainable development agricultural strategy. However, the remediation effect of organic fertilization on agroecosystems remains unclear. This study was conducted in a long-term (1979−2020) field experiment to investigate the influence of organic and chemical fertilizers on the soil microbiome assembly processes. The experiment consisted of six treatments: chemical N fertilization (N), double N fertilization (N2), organic fertilization (M), organic and N fertilization (MN), double organic and N fertilization (M2N2), and unfertilized control. The chemical N fertilization (N and N2) treatments significantly decreased soil microbial diversity, as well as soil pH, compared to the Control treatments (p < 0.05). MN and M2N2 treatments increased microbial diversity compared to that of N and N2 treatments. The combination of organic and chemical N fertilizer recovered the decreased microbial diversity to the level of the Control and M treatments, but the application of double organic fertilizer (M2N2) still showed a significantly lower microbial diversity than that of the Control and M treatments. From the results of the microbial community assembly processes, it was found that environmental filtering was induced by N fertilization, while organic fertilization developed a stochastic process and mitigated the role of environmental filtering in the community assembly process. An ecological network analysis showed that the decrease in Acidobacteria in organic fertilization treatments played a key role in mitigating the soil acidification induced by 40-year chemical N fertilization. It indicated that organic fertilizer could mitigate the decrease in soil fertility induced by chemical N fertilization. Higher environmental filtering effects in M2N2 than those in MN treatments suggested that the mitigation effect of organic fertilizer was weakened when double chemical N fertilization was applied in black soils. These results are helpful for a unified understanding of the ecological processes for microbial communities in the development of sustainable agriculture.
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Yin X, Li X, Petropoulos E, Feng Y, Yang B, Xue L, Yang L, He S. Phosphate removal from actual wastewater via La(OH) 3-C 3N 4 adsorption: Performance, mechanisms and applicability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 814:152791. [PMID: 34990668 DOI: 10.1016/j.scitotenv.2021.152791] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/06/2021] [Accepted: 12/26/2021] [Indexed: 06/14/2023]
Abstract
In this study, La(OH)3 nanoparticles were immobilized on C3N4 to effectively restrict their aggregation and subsequently enhance the La utilization efficiency to promote phosphate adsorption. The prepared La(OH)3-C3N4 nanocomposite was characterized by SEM, XRD, FTIR, XPS, BET and Zeta potential analysis. Batch and continuously-fed (fixed-bed column) experiments to assess the adsorption performance of La(OH)3-C3N4 showed that the composite exhibits superior utilization efficiency, resulting to relatively quick adsorption with a short equilibrium time of 30 min. The theoretical maximum P adsorption capacity reached the 148.35 mg·g-1, efficiency that remained unaffected by the anions and HA present. The adsorption mechanism showed stability in a wide pH range (4.0-11.0) and is considered effective even after extensive use (five-cycles). The dynamics of the adsorption capacity and the half-penetration time values were estimated by 'Thomas' and 'Yoon-Nelson' models showed that are better represented from the experimental values obtained from the fixed-bed column trial. The adsorption mechanisms were attributed to surface precipitation, electrostatic attraction, and inner-sphere complexation via ligand exchange. Furthermore, La(OH)3-C3N4 demonstrated high efficiency in scavenging phosphate from both diluted and concentrated wastewater (natural pond and swine wastewater respectively). The above confirm that La(OH)3-C3N4 is a promising composite material for phosphate management in aqueous environments.
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Huang Z, Cui C, Cao Y, Dai J, Cheng X, Hua S, Wang W, Duan Y, Petropoulos E, Wang H, Zhou L, Fang W, Zhong Z. Tea plant-legume intercropping simultaneously improves soil fertility and tea quality by changing bacillus species composition. HORTICULTURE RESEARCH 2022; 9:uhac046. [PMID: 35184199 PMCID: PMC9123240 DOI: 10.1093/hr/uhac046] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/14/2022] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
Tea plant is an economically important crop in China, but long-term monoculture and substantial chemical nitrogen fertilizer input cause soil acidification, which in turn affects the nutrient supply and tea quality. Intercropping has drawn more attention in tea gardens because this pattern is expected to improve soil fertility and tea quality and change the soil microbial community composition. However, the roles of some key microorganisms in rhizosphere soils have not been well characterized. Hereby, a "soybean in summer and smooth vetch in winter" mode was selected to investigate the effects of intercropped legumes in a tea garden on soil fertility, tea quality, and the potential changes in beneficial bacteria such as Bacillus. Our data showed that when soybeans were turned into soil, intercropping system exhibited higher soil organic matter (SOM), total nitrogen (TN), tea quality indices and the expression of Camellia sinensis glutamine synthetase gene (CsGS). Notably, intercropping significantly affected the bacterial communities and decreased the relative abundance of Bacillus but increased its absolute abundance. Bacillus amyloliquefaciens BM1 was isolated from intercropped soil and showed outstanding plant growth-promoting (PGP) properties when coinoculated with rhizobia. In winter, intercropping with smooth vetch had a beneficial effect on soil properties and tea quality. Comparably, coinoculation with strain BM1 and Rhizobium leguminosarum Vic5 on smooth vetch (Vicia villosa) showed huge improvements in SOM, TN and quality of tea leaves, accompanied by the highest level of amino acids and lowest levels of polyphenol and caffeine (p < 0.05). According to these results, our findings demonstrate that intercropping with some legumes in the tea garden is a strategy that increases SOM, TN and tea quality, and some PGP Bacillus species are optional to obtain an amplification effect.
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Hou P, Jiang Y, Yan L, Petropoulos E, Wang J, Xue L, Yang L, Chen D. Effect of fertilization on nitrogen losses through surface runoffs in Chinese farmlands: A meta-analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 793:148554. [PMID: 34171810 DOI: 10.1016/j.scitotenv.2021.148554] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/30/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
Surface runoff is the main cause of farmland nitrogen (N) losses in plain areas, which adversely affect water quality. The impact of fertilization on N runoff loss often varies. A meta-analysis was performed using 245 observations from 31 studies in China, to estimate the response of N loss in both paddy and upland fields subjected to different fertilization strategies, and investigate the link between N runoffs, soil properties, as well as precipitation in the planting season. The results showed that compared to the control (without fertilization), N losses subjected to fertilization increased from 3.31 kg/ha to 10.03 kg/ha and from 3.00 kg/ha to 11.24 kg/ha in paddy and upland fields respectively. Importantly, paddy N loss was significantly correlated with fertilizer type and N application rate (predictors); in upland fields N application rate and seasonal precipitation were the main driving factors. For the N application rate, N loss increased with increase in rates for both paddies and upland fields. Moreover, the N loss from upland fields increased with the precipitation during planting season. Between the three fertilizers used in paddies, the increase in loss of CRF (controlled release fertilizer) or OF (organic fertilizer) was lower than that of CF (inorganic chemical fertilizer) with the lowest value in CRF. Subset analysis showed that the effect of CRF and OF in paddies was not affected by the predictors, revealing the steadily controlling property of CRF and OF in paddies. Also, all the predictors had an insignificant impact to N loss risk in paddies during the high application rate. Overall, the results confirm the importance of N dosage in N runoff loss from farmland. Fertilizer type is a key consideration for N loss control in paddies, while the seasonal precipitation should not be ignored in upland fields.
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Wu M, Li G, Li P, Jiang N, Wei S, Petropoulos E, Li Z. Assessing the ecological risk of pesticides should not ignore the impact of their transformation byproducts - The case of chlorantraniliprole. JOURNAL OF HAZARDOUS MATERIALS 2021; 418:126270. [PMID: 34102368 DOI: 10.1016/j.jhazmat.2021.126270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 05/10/2021] [Accepted: 05/28/2021] [Indexed: 06/12/2023]
Abstract
Risk assessments for pesticides typically focus on the compound itself ignoring the impact of its transformation byproducts. Challenges in isolating such byproducts (i.e. after application of pesticide in soil) often lead to underestimation of the real risk from such substances. The toxicological properties of these byproducts may differ from those of the parent pesticides; hence, special attention is required for these new emerging contaminants. In this study, two transformation byproducts of chlorantraniliprole were isolated from soil and identified, using nuclear magnetic resonance and high resolution mass spectrometry, as products of dechlorination (Z1) and bromination (Z2). Kinetic experiments revealed both byproducts degrade faster than chlorantraniliprole in soil (half-lives 38 & 43 d vs. 58 d). The ecological risk evaluation of chlorantraniliprole and its byproducts on soil bacterial community showed that they were all potentially harmful but they imposed different impacts on both alpha and beta diversities and co-occurrence networks of the bacterial community. Z2 had the biggest potential impact on soil bacteria and accounted as a high potential risk. By comparing their impacts on soil bacterial community, we confirm that ecological risk assessment necessitates the understanding of the environmental impacts of a substance as well as of its transformation byproducts.
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Yan L, Xue L, Petropoulos E, Qian C, Hou P, Xu D, Yang L. Nutrient loss by runoff from rice-wheat rotation during the wheat season is dictated by rainfall duration. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117382. [PMID: 34049130 DOI: 10.1016/j.envpol.2021.117382] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/20/2021] [Accepted: 05/13/2021] [Indexed: 06/12/2023]
Abstract
Clarifying the properties/features of nutrient loss from farmland surface runoff is essential for the mitigation of nutrient losses. Plough pan formation underneath topsoil is a common feature of long-term paddy soils that significantly affects water movement and nutrient runoff loss, especially during the upland season of paddy-upland rotation. To characterize the nutrients that are lost from wheat fields of paddy-wheat rotation with runoff, a field experiment was conducted in a wheat field using a simulated rainfall system from November 2019 to May 2020 in Nanjing, China. The aim of this study was to investigate the temporal characteristics of nitrogen (N) and phosphorus (P) loss under different rainfall intensities (low, 30 mm h-1; middle, 60 mm h-1; high, 90 mm h-1). The results showed that the time interval from the beginning of rain to the occurrence of runoff (time to runoff, Tr) was negatively correlated with "rainfall intensity" (Ri) (P<0.01) but unaffected by soil moisture. Different rainfall intensities had no effect on the runoff coefficient (the ratio of the runoff volume over the precipitation, 0.14-0.17). The N and P loss concentrations in the nutrient discharge followed a power-function relationship that decreased over time (P<0.01), and the peak nutrient concentration appeared during the initial runoff period (0-5 min). The N and P loss rates were the highest during the middle-to-late discharge period (15-30 min) for all intensities. In terms of cumulative nutrient losses, the amounts of TN lost were similar for all rainfall intensities, while TP significantly increased with intensity. The results revealed that nitrate-nitrogen (NOX--N) and particulate phosphorus (PP) were the predominant forms of N and P losses. Overall, during the initial runoff period, nutrient concentration peaks, whereas the nutrient loss rate is the highest during the middle-late phase of the phenomenon.
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Tabraiz S, Petropoulos E, Shamurad B, Quintela-Baluja M, Mohapatra S, Acharya K, Charlton A, Davenport RJ, Dolfing J, Sallis PJ. Temperature and immigration effects on quorum sensing in the biofilms of anaerobic membrane bioreactors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 293:112947. [PMID: 34289594 DOI: 10.1016/j.jenvman.2021.112947] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 04/25/2021] [Accepted: 05/10/2021] [Indexed: 06/13/2023]
Abstract
Quorum sensing (QS), a microbial communication mechanism modulated by acyl homoserine lactone (AHL) molecules impacts biofilm formation in bioreactors. This study investigated the effects of temperature and immigration on AHL levels and biofouling in anaerobic membrane bioreactors. The hypothesis was that the immigrant microbial community would increase the AHL-mediated QS, thus stimulating biofouling and that low temperatures would exacerbate this. We observed that presence of immigrants, especially when exposed to low temperatures indeed increased AHL concentrations and fouling in the biofilms on the membranes. At low temperature, the concentrations of the main AHLs observed, N-dodecanoyl-L-homoserine lactone and N-decanoyl-L-homoserine lactone, were significantly higher in the biofilms than in the sludge and correlated significantly with the abundance of immigrant bacteria. Apparently low temperature, immigration and denser community structure in the biofilm stressed the communities, triggering AHL production and excretion. These insights into the social behaviour of reactor communities responding to low temperature and influx of immigrants have implications for biofouling control in bioreactors.
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Tabraiz S, Shamurad B, Petropoulos E, Quintela-Baluja M, Charlton A, Dolfing J, Sallis PJ. Mitigation of membrane biofouling in membrane bioreactor treating sewage by novel quorum quenching strain of Acinetobacter originating from a full-scale membrane bioreactor. BIORESOURCE TECHNOLOGY 2021; 334:125242. [PMID: 33964813 DOI: 10.1016/j.biortech.2021.125242] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
A novel quorum quenching (QQ) strain, Acinetobacter guillouiae ST01, was isolated from a full-scale membrane bioreactor (MBR) and characterized for its QQ activities. Batch reactor studies at lab-scale showed that A. guillouiae ST01 exhibited higher QQ activity against acyl homoserine lactones (AHLs) with an oxo group compared to those without an oxo group. The organism was then inoculated (10%) in an MBR (Q-MBR) treating sewage over 48 days and was found to reduce quorum sensing (QS) activity by reducing AHL concentrations in the sludge and the biofilm of the Q-MBR. The concentration of polysaccharides was reduced up to 30% in both the biofilm and sludge relative to the control, whereas protein concentrations were reduced by 40% and 47% in the sludge and biofilm, respectively. The Q-MBR fouling rates were halved. These results indicate that A. guillouiae ST01 is a promising strain for biofouling reduction in MBR treating real wastewater.
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Hou P, Feng Y, Wang N, Petropoulos E, Li D, Yu S, Xue L, Yang L. Win-win: Application of sawdust-derived hydrochar in low fertility soil improves rice yield and reduces greenhouse gas emissions from agricultural ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 748:142457. [PMID: 33113706 DOI: 10.1016/j.scitotenv.2020.142457] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/29/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
As a good soil synergist, biochar has a wide prospect in improving soil fertility and crop production. Although hydrochar, produced by hydrothermal carbonization process has attracted attention due to production advantages, hydrochar application in low fertility soils as well as its impact to the associated greenhouse gas (GHG) emissions in farmlands is rarely reported. To advance our understanding on the effect of hydrochar addition on grain yield from low fertility soils and the corresponding CH4 and N2O emissions, a soil-column experiment, with two hydrochar types (sawdust-derived hydrochar (SDH), microbial-aged hydrochar (A-SDH)) at two application rates (5‰, 15‰; (w/w)), was conducted. The results showed that hydrochar addition evidently increased rice yield. The N2O emissions were mainly related to the substrate supply of the hydrochar itself and less affected by the denitrifiers (functional genes) present. Hydrochar amendment at low application rate (5‰; SDH05, A-SDH05) significantly decreased the cumulative N2O emissions by 26.32% ~ 36.84%. Additionally, hydrochar amendment could not increase the CH4 emissions due to the substrate limitation; the cumulative emissions were similar with those from the control, ranging between 11.1-12.8 g m-2. Regarding grain yield and global warming potential, greenhouse gas intensity from the soils subjected to hydrochar (SDH05, A-SDH05, A-SDH15) were significantly lower than that of the control, observation attributed to the high yield and low N2O emissions. Overall, hydrochar addition is an effective strategy to ensure grain yield in low fertility soils with relatively low/controlled GHG emissions, especially when the amendment is applied at low application rate.
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Shamurad B, Gray N, Petropoulos E, Dolfing J, Quintela-Baluja M, Bashiri R, Tabraiz S, Sallis P. Low-Temperature Pretreatment of Organic Feedstocks with Selected Mineral Wastes Sustains Anaerobic Digestion Stability through Trace Metal Release. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:9095-9105. [PMID: 32551555 DOI: 10.1021/acs.est.0c01732] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A low-cost approach for enhancing mesophilic (37 °C) anaerobic digestion (AD) of organic waste using a low-temperature (37 °C) pretreatment with different mineral wastes (MW) was investigated. A higher and stable methane production rate, in comparison to MW-free controls, was achieved for 80 days at organic loading rates of 1-2 g VS/L·d, using a feed substrate pretreated with incinerator bottom ash (IBA). The boiler ash and cement-based waste pretreatments also produced high methane production rates but with some process instability. In contrast, an incinerator fly ash pretreatment showed a progressive decrease in methane production rates and poor process stability, leading to reactor failure after 40 days. To avoid process instability and/or reactor failure, two metrics had to be met: (a) a methanogenesis to fermentation ratio higher than 0.6 and (b) a cell-specific methanogenic activity to cell-specific fermentation activity ratio of >1000. The prevalence of Methanofastidiosum together with a mixed community of acetoclastic (Methanosaeta) and hydrogenotrophic (Methanobacterium) methanogens in the stable IBA treatment indicated the importance of Methanofastidiosum as a potential indicator of a healthy and stable reactor.
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Hou P, Yu Y, Xue L, Petropoulos E, He S, Zhang Y, Pandey A, Xue L, Yang L, Chen D. Effect of long term fertilization management strategies on methane emissions and rice yield. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 725:138261. [PMID: 32298880 DOI: 10.1016/j.scitotenv.2020.138261] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 03/12/2020] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
Optimum fertilization is an efficient method to maintain rice yield and reduce N-losses. It is essential though to evaluate methane emissions from paddy fields, to further understand its impact on greenhouse gas budget. Therefore, a field experiment was conducted to investigate the effect of long-term optimum fertilization on CH4 emissions and rice yield. We collected data in the 7th and 8th year from a field experiment initiated in 2010. Four optimum fertilization strategies, reduced N-fertilizer and zero-P treatment (RNP, 200 kg N/ha), sulfur-coated urea combined with uncoated urea treatment (SCU, 200 kg N/ha), organic fertilizer combined chemical fertilizer treatment (OCN, 200 kg N/ha), organic fertilizer treatment (OF, 200 kg N/ha); and two controls, the farmers' N management (FN, 270 kg N/ha) and zero-N treatment (N0), were employed. The results showed the rice yields achieved for the optimum fertilization treatments (RNP, SCU, OCN, and OF) were similar with those for the FN. No significant differences in CH4 emissions among all treatments. Cumulative seasonal CH4 emissions were negatively correlated with grain yield (P < 0.05). In the RNP and SCU treatments, soil available K, mcrA gene and available P were the key variables affecting CH4 emissions; soil available K, available P and SOC contents were the key emissions factors for OCN and OF treatments. The SCU achieved the highest rice yield and lowest CH4 emission intensity among optimum fertilization treatments. These results suggest that long-term application of sulfur-coated urea combined with uncoated urea can maintain rice yield and reduce methane emissions from rice paddies.
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Shamurad B, Gray N, Petropoulos E, Tabraiz S, Sallis P. Improving the methane productivity of anaerobic digestion using aqueous extracts from municipal solid waste incinerator ash. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 260:110160. [PMID: 32090847 DOI: 10.1016/j.jenvman.2020.110160] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/10/2020] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
This study investigated the effects of mineral waste extracts (MWE) on laboratory-scale two-stage anaerobic digesters treating synthetic organic waste. MWE was prepared as aqueous extracts from different ash samples (incineration bottom ash (IBA), fly ash (FA) and boiler ash (BA) taken from a municipal solid waste incineration plant. At 20 days hydraulic retention time, all three MWE stimulated hydrogen production in their respective acidogenic reactor by around 35% (c.f. control acidogenic reactor), whilst no difference was seen in the methane productivity of the linked methanogenic reactors (average 527 ± 45 mL CH4/g VS, including control methanogenic reactor). Following a step reduction in hydraulic retention time from 20 to 10 days and a doubling of the organic loading rate from 2.5 g to 5 g VS/L. d, no significant change was seen in hydrogen production (p > 0.05) in the acidogenic reactor amended with MWE from IBA and BA, or the control acidogenic reactor. However, the acidogenic reactor receiving MWE from FA had 45% lower hydrogen productivity. The step change in hydraulic retention time and organic loading rates led to the failure of most methanogenic reactors (≤100 mL CH4/g VS), however, the one receiving feed containing MWE from IBA showed stable performance without signs of failure, and had higher volumetric methane productivity, albeit at lower methane yields (370 ± 20 mL CH4/g VS). 16S rRNA analysis using the Illumina sequencing platform revealed acidogenesis by Lactobacillaceae in the acidogenic reactor and syntrophic acetate oxidation by Synergistaceae linked to enrichment of the candidatus genus Methanofastidiosum, in the stable methanogenic reactor receiving MWE from IBA.
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Acharya K, Werner D, Dolfing J, Meynet P, Tabraiz S, Baluja MQ, Petropoulos E, Mrozik W, Davenport RJ. The experimental determination of reliable biodegradation rates for mono-aromatics towards evaluating QSBR models. WATER RESEARCH 2019; 160:278-287. [PMID: 31154125 DOI: 10.1016/j.watres.2019.05.075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/19/2019] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
Quantitative Structure Biodegradation Relationships (QSBRs) are a tool to predict the biodegradability of chemicals. The objective of this work was to generate reliable biodegradation data for mono-aromatic chemicals in order to evaluate and verify previously developed QSBRs models. A robust biodegradation test method was developed to estimate specific substrate utilization rates, which were used as a proxy for biodegradation rates of chemicals in pure culture. Five representative mono-aromatic chemicals were selected that spanned a wide range of biodegradability. Aerobic biodegradation experiments were performed for each chemical in batch reactors seeded with known degraders. Chemical removal, degrader growth and CO2 production were monitored over time. Experimental data were interpreted using a full carbon mass balance model, and Monod kinetic parameters (Y, Ks, qmax and μmax) for each chemical were determined. In addition, stoichiometric equations for aerobic mineralization of the test chemicals were developed. The theoretically estimated biomass and CO2 yields were similar to those experimentally observed; 35% (s.d ± 8%) of the recovered substrate carbon was converted to biomass, and 65% (s.d ± 8%) was mineralised to CO2. Significant correlations were observed between the experimentally determined specific substrate utilization rates, as represented by qmax and qmax/Ks, at high and low substrate concentrations, respectively, and the first order biodegradation rate constants predicted by a previous QSBR study. Similarly, the correlation between qmax and selected molecular descriptors characterizing the chemicals structure in a previous QSBR study was also significant. These results suggest that QSBR models can be reliable and robust in prioritising chemical half-lives for regulatory screening purposes.
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Shamurad B, Gray N, Petropoulos E, Tabraiz S, Acharya K, Quintela-Baluja M, Sallis P. Data of metal and microbial analyses from anaerobic co-digestion of organic and mineral wastes. Data Brief 2019; 24:103934. [PMID: 31080853 PMCID: PMC6502732 DOI: 10.1016/j.dib.2019.103934] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/11/2019] [Accepted: 04/12/2019] [Indexed: 01/28/2023] Open
Abstract
High concentrations of minerals, heavy metals are often found in mineral wastes (MWs) originated from municipal solid waste incineration plants, so as construction/demolition sites. Such by-products (minerals) often have buffering capacity. The current work provides analysis of total and soluble (dissolved) metal concentrations released by four different MWs (a. cement-based waste, b. incineration (bottom), c. fly and d. boiler ash) supplemented to anaerobic reactors of organic waste at 37 °C. The reactors (continuous stirred tank reactor (CSTR)) were ran for 75 days at hydrolytic retention time of 20 days. Genomic DNA extraction, and qPCR and Illumina HiSeq (16S V4) analyses were conducted to investigate microbial community population and composition in anaerobic digestate samples collected from these reactors. Output data from Illumina sequencing analysis were FastQ files analysed using the QIIME2 pipeline to produce a feature table listing the frequency of each assigned microbial taxa per samples. Additional study was conducted on the microbial data to visualise variations in microbial communities using the STAMP software and phyloseq R package. Detailed interpretation and discussion of the results can be found in the related research article [1].
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Shamurad B, Gray N, Petropoulos E, Tabraiz S, Acharya K, Quintela-Baluja M, Sallis P. Co-digestion of organic and mineral wastes for enhanced biogas production: Reactor performance and evolution of microbial community and function. WASTE MANAGEMENT (NEW YORK, N.Y.) 2019; 87:313-325. [PMID: 31109531 DOI: 10.1016/j.wasman.2019.02.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 02/06/2019] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
Abstract
Mineral wastes (MWs) from municipal solid waste incineration plants and construction demolition sites are rich in minerals, heavy metals and have acid neutralising capacity. This renders such MWs a promising source of bulk and trace elements to enhance and stabilize biogas production in anaerobic processes. However, finding a MW with typical heavy metal concentrations, which promotes anaerobic digestion (AD) without adverse effects on the microbial community of the reactor is of major importance. To investigate the impact of several MW additives (1. incineration bottom ash; 2. fly ash; 3. boiler ash; 4. cement-based waste) as AD co-substrates, six 5 L single stage mesophilic, continuously stirred tank reactors (CSTR) were setup. Two different feeding regimes were employed including: (a) a liquid-recycled feeding method (LRFM); (b) a draw-and-fill feeding method (DFFM). Under the LRFM regime, one gram MW per gram organic waste enhanced process stability (pH), increased methane production (25-45% increase), and yielded (450-520 mL CH4/g VS); DFFM enhanced digestibility to a lesser degree. Illumina HiSeq 16S rRNA community sequencing of reactors showed that the microbial community compositions were unaffected by the presence of MW additives in comparison to unamended controls, but MW amendment accelerated bacterial growth (determined by qPCR). In contrast, different feeding regimes altered the microbial communities; Methanoculleus (hydrogenotrophic) and Methanosaeta (acetoclastic) were the most abundant methanogenic genera in the LRFM reactors, and the more metabolically versatile Methanosarcina genus dominated under DFFM.
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Yu Y, Wu M, Petropoulos E, Zhang J, Nie J, Liao Y, Li Z, Lin X, Feng Y. Responses of paddy soil bacterial community assembly to different long-term fertilizations in southeast China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 656:625-633. [PMID: 30529966 DOI: 10.1016/j.scitotenv.2018.11.359] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/23/2018] [Accepted: 11/24/2018] [Indexed: 06/09/2023]
Abstract
Recent works have shown that long-term fertilization has a critical influence on soil microbial communities; however, the underlying ecological assemblage of microbial community as well as its linkage with soil fertility and crop yield are still poorly understood. In this study, using analysis of high-throughput sequencing of 16S rRNA gene amplicons, we investigate mean pairwise phylogenetic distance (MPD), nearest relative index (NRI), taxonomic compositions and network topological properties to evaluate the assembly of the soil microbial community developed in 30-year fertilized soils. The phylogenetic signal indicates that environmental filtering was a more important assembly process that structure the microbial community than the stochastic process. Increase of soil fertility indexes, such as cation exchange capacity (CEC), soil organic matter (SOM) and available P (AP), driven by balanced fertilizations and straw returning amendment, result in the decrease of environmental filtering on the bacterial community assembly. Network parameters show that the amendment of straw returning provides with more niches, which lead to more complex phylotype co-occurrence. Increase of crop yield under balanced fertilizations might due to the increase of soil microbial function traits, which is associated with decreasing influence of environmental filtering. The significantly increased bacterial genera, Candidatus Koribacter, Candidatus Solibacter, and Fimbriimonas, in straw returning treatments, might be the key species in the competition caused by long-term environmental filtering. These results are helpful for a unified understanding of the ecological processes for microbial communities in different fertilized agroecosystem and the development of sustainable agriculture.
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Steeves TL, Petropoulos E, Young B, Watson M, Khan W, Ribic C, Lepic K. P079High throughput HLA-B27 immunophenotyping; conversion to a 96 well plate. Hum Immunol 2018. [DOI: 10.1016/j.humimm.2018.07.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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He S, Hou P, Petropoulos E, Feng Y, Yu Y, Xue L, Yang L. High Efficient Visible-Light Photocatalytic Performance of Cu/ZnO/rGO Nanocomposite for Decomposing of Aqueous Ammonia and Treatment of Domestic Wastewater. Front Chem 2018; 6:219. [PMID: 29946540 PMCID: PMC6005899 DOI: 10.3389/fchem.2018.00219] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/28/2018] [Indexed: 11/26/2022] Open
Abstract
Photocatalytic removal of ammonium-nitrogen (NH4+-N) from water using solar energy is an approach of high interest and applicability due to the convenience in application. ZnO has a great potential in photocatalytic decomposition of NH4+-N and conversion of this nutrient to under visible light irradiations. However the applicability of pristine ZnO though is limited due to its reduced capacity to utilize light from natural light. Herein, we report a two-step ZnO-modified strategy (Cu-doped ZnO nanoparticles, immobilized on reduced graphene oxide (rGO) sheets) for the promotion of photocatalytic degradation of NH4+-N under visible light. UV-Vis spectra showed that the Cu/ZnO/rGO can be highly efficient in the utilization of photons from the visible region. Hence, Cu/ZnO/rGO managed to demonstrate adequate photocatalytic activity and effective NH4+-N removal from water under visible light compared to single ZnO. Specifically, up to 83.1% of NH4+-N (initial concentration 50 mg·L−1, catalyst dosage 2 g·L−1, pH 10) was removed within 2 h retention time under Xe lamp irradiation. From the catalysis, the major by-product was N2. The high ammonia degradation efficiency from the ZnO/Cu/rGO is attributed to the improvement of the reactive oxygen species (ROSs) production efficiency and the further activation of the interfacial catalytic sites. This study also demonstrated that such nanocomposite is a recyclable agent. Its NH4+-N removal capacity remained effective even after five batch cycles. In addition, Cu/ZnO/rGO was applied to treat real domestic wastewater, and it was found that chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies can reach 84.3, 80.7, and 90.3%, respectively. Thus, Cu/ZnO/rGO in the presence of solar light can be a promising photocatalyst in the field of wastewater treatment.
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