Publications by authors named "Huijie Hou"

68 Publications

Pretreatment of sludge with sodium iron chlorophyllin-HO for enhanced biogas production during anaerobic digestion.

Environ Res 2022 Mar 21;204(Pt C):112223. Epub 2021 Oct 21.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, 430074, PR China. Electronic address:

This study investigated a novel sodium iron chlorophyllin-HO (SIC-HO) sludge pretreatment strategy before anaerobic digestion to enhance methane production. The efficiencies and mechanism of the proposed strategy to enhance sludge biodegradability were explored. The SIC-HO pretreatment could enhance the oxidation performance for sludge floc disintegration to dissociate TB-EPS into S-EPS increased SCOD to 521.38 mg/L. The increase of solubilization and release of EPS with the pretreatment facilitate the biogas production at 702 L kg VS, which was 3-folds of the control and significantly higher than other pretreatments. The result of excitation-emission matrix and parallel factor (EEM-PARAFAC) analysis showed that the SIC-HO pretreatment enhanced the dissociation of TB-EPS fractions, especially the protein-like and soluble microbial by-product-like substances. Electron paramagnetic resonance (EPR) results provided evidence for homolytic catalysis HO for the generation OH and the production of high-valent (Por)Fe(O) intermediates. Synergistic effects of reactive oxygen species (OH, HO and /HO) and (Por)Fe(O) enhanced the EPS disintegration during SIC-HO pretreatment. The mixed-acid type fermentation provided continuous VFAs supply under the enrichment of Chloroflexi and Actinobacteria and multiplication Methanosaeta also promoted methane production. This research provides a feasible pretreatment strategy increase sludge biodegradability and enhance biogas production in the anaerobic digestion process.
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http://dx.doi.org/10.1016/j.envres.2021.112223DOI Listing
March 2022

Enhanced silicon bioavailability of biochar derived from sludge conditioned with Fenton's reagent and lime.

Sci Total Environ 2022 Feb 12;806(Pt 4):150941. Epub 2021 Oct 12.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Wuhan, Hubei 430074, China; Hubei Provincial Research Center of Water Quality Safety and Water Pollution Control Engineering Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China. Electronic address:

Biological wastewater treatment generates a large quantity of sewage sludge that requires proper treatments. In this study, the biochar pyrolyzed by sludge conditioned with Fenton's reagent and lime (referred to as Fenton-lime system) was first used as an efficient silicon fertilizer for rice cultivation. When the pyrolysis temperature was 750 °C, the dissolved silicon and available silicon contents in biochar derived from sludge conditioned with Fenton-lime system were much higher than those in raw sludge derived biochar without conditioning (3.49 vs. 0.72, 77.25 vs. 2.33 mg/g dry solid, respectively). The enhanced available silicon content was attributed to the newly formed calcium aluminosilicate from the reactions between the added lime and silicon-rich phases in sludge. The rice cultivated with biochar derived from Fenton-lime conditioned sludge showed improved biomass of stem and root by 76.85% and 36.11%, respectively, compared to blank group without the addition of Si source. Heavy metals and the reactive oxygen species (ROS) accumulation in rice were not observed after a culture period of 30 days in the application of sludge-derived biochar as silicon fertilizer. This study provides a promising approach for sewage sludge recycling as an efficient silicon fertilizer in silicon-deficiency land.
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http://dx.doi.org/10.1016/j.scitotenv.2021.150941DOI Listing
February 2022

Synergistic effect of floatable hydroxyapatite-modified biochar adsorption and low-level CaCl leaching on Cd removal from paddy soil.

Sci Total Environ 2022 Feb 8;807(Pt 2):150872. Epub 2021 Oct 8.

Brook Byers Institute for Sustainable Systems, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States.

The utilization of recycled biochar combined with chemical leaching is an appropriate method to remove cadmium (Cd) from paddy soil. Some Cd-rich soil clay particulates (particulate Cd) are reported to be removed via biochar adsorption and the potential impact of biochar on soil properties need further study. The removal efficiencies and mechanisms of Cd from soil by using floatable hydroxyapatite modified biochar (HBC) combined with CaCl were studied. Synergetic removal efficiencies of total Cd (46.5%) and bioavailable Cd (37.9%) from the paddy soil were achieved with 2% HBC and 1 mM CaCl. The increased soluble Cd in soil pore water by CaCl leaching could be efficiently adsorbed on HBC, and removed by HBC collection, reducing the risk of the residual soluble Cd in soil pore water to rice plants caused by the inefficient drainage in the field. The suspendability of clay particulates in overlying water was little affected by the low-level CaCl based on Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation. Moreover, low-level CaCl facilitated the accumulation of particulate Cd on the floating HBC via decreasing the interaction energy (by 25%) between clay particulates and HBC. HBC-mediated Cd migration contributed ~70% of total Cd removal, while soluble and particulate Cd removed through the drainage accounted for ~30%. Soil clay proportion maintained at 25.3% due to the replenishment of HBC residues. In addition, soil nutrient and physicochemical conditions were improved with HBC residues. This work provides a novel soil remediation method by using floatable biochar combined with low-level CaCl for Cd-contaminated paddy soil remediation.
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http://dx.doi.org/10.1016/j.scitotenv.2021.150872DOI Listing
February 2022

Prediction on the combined toxicities of stimulation-only and inhibition-only contaminants using improved inverse distance weighted interpolation.

Chemosphere 2022 Jan 28;287(Pt 3):132045. Epub 2021 Aug 28.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei, 430074, China; Hubei Provincial Research Center of Water Quality Safety and Water Pollution Control Engineering Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

The evaluation of ecological risks of contaminant mixtures to organisms is very challenging due to the non-linear response of organisms to each component, especially under the co-existence of both stimulators and inhibitors. Whether the stimulatory effect can reduce or even offset the inhibitory effect would be critical to the risk assessment and the treatment measures of mixed pollutants. Here, the combined toxicity of sodium fluoride (NaF), a stimulator with stimulation rate >100%, and six compounds that cannot induce hormesis (four ionic liquids (ILs) and two pesticides) were studied. The time-dependent toxicity of each toxicant on Vibrio qinghaiensis sp.-Q67 was investigated at 0.25, 2, 4, 6, 8, 10 and 12 h. Results showed that four ILs and two pesticides failed to induce hormesis, while NaF induced hormesis from 2 to 6 h and induced stimulation only after 6 h and reached its maximum (650%) at 12 h. All mixture rays with NaF induced hormesis at different times. In the four NaF-IL mixture systems, the absolute value of maximum stimulation demonstrated an upwards and then a downwards trend with the increasing of mixture ratio of IL. In two NaF-pesticide systems, the maximum stimulation effect declined with the increasing of the mixture ratio of pesticide. The toxicities of the mixture were successfully predicted by the improved inverse distance weighted interpolation, which are not able to be predicted by the commonly used concentration addition or independent action models. This paper shed lights on evaluating the hormesis of mixtures and the ecological risk of fluoride.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132045DOI Listing
January 2022

Efficient degradation of refractory pollutant in a microbial fuel cell with novel hybrid photocatalytic air-cathode: Intimate coupling of microbial and photocatalytic processes.

Bioresour Technol 2021 Nov 4;340:125717. Epub 2021 Aug 4.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Wuhan, Hubei 430074, PR China. Electronic address:

A microbial fuel cell-photocatalysis system with a novel photocatalytic air-cathode (MFC-PhotoCat) was proposed for synergistic degradation of 2,4,6-trichlorophenol (TCP) with simultaneous electricity generation. Stable electricity generation of 350 mV was achieved during 130 days of operation. Besides, 50 mg L TCP was completely degraded within 72 h, and the rate constant of 0.050 h was 1.8-fold higher than MFC with air-cathode without N-TiO photocatalyst. Degradation pathway was proposed based on the intermediates detected and density functional theory (DFT) calculation, with two open-chain intermediates (2-chloro-4-keto-2-hexenedioic acid and hexanoic acid) detected. Furthermore, hierarchical cluster and PCoA revealed significant shifts of microbial community structures, with enriched exoelectrogen (55.2% of Geobacter) and TCP-degrading microbe (7.1% of Thauera) on the cathode biofilm as well as 61.8% of Pseudomonas in the culture solution. This study provides a promising strategy for synergic degradation of recalcitrant contaminants by intimate-coupling of MFC and photocatalysis.
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http://dx.doi.org/10.1016/j.biortech.2021.125717DOI Listing
November 2021

Microplastics affect rice (Oryza sativa L.) quality by interfering metabolite accumulation and energy expenditure pathways: A field study.

J Hazard Mater 2022 01 6;422:126834. Epub 2021 Aug 6.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China. Electronic address:

Microplastic accumulation in agricultural soils can stress plants and affects quality of the products. Current research on the effects of microplastics on plants is not consistent and the underlying mechanisms are yet unknown. Here, the molecular mechanisms of the stress response were investigated via metabolomic and transcriptomic analyses of rice Oryza sativa L. II Y900 and XS123 under the exposure of polystyrene microplastics (PS-MPs) in a field study. Distinct responses were obtained in these two rice subspecies, showing decreased head rice yield by 10.62% in Y900 and increase by 6.35% in XS123. The metabolomics results showed that PS-MPs exposure inhibited 29.63% of the substance accumulation-related metabolic pathways and 43.25% of the energy expenditure-related metabolic pathways in the Y900 grains; however, these related pathways were promoted in the XS123 grains. The transcriptomics results indicated that the expression of genes encoding proteins involved in the tricarboxylic acid cycle in the Y900 grains was inhibited, but it was enhanced in the XS123 grains. The XS123 subspecies could response against microplastic exposure stress through the metabolite accumulation and energy expenditure pathways, while the Y900 could not. The results provide insight into the perturbation of rice grains in farmlands with microplastics contamination.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126834DOI Listing
January 2022

Recirculation of reject water in deep-dewatering process to influent of wastewater treatment plant and dewaterability of sludge conditioned with Fe/HO, Fe/Ca(ClO), and Fe/NaSO: From bench to pilot-scale study.

Environ Res 2022 01 5;203:111825. Epub 2021 Aug 5.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Research Center of Water Quality Safety and Water Pollution Control Engineering Technology, Wuhan, Hubei, 430074, China.

Deep dewatering of sewage sludge pretreated with advanced oxidation processes (AOPs) is a strategy for efficient sludge reduction and subsequent disposal. The pretreatment and dewatering performance of sludge conditioned with three types of AOPs (Fe/HO, Fe/Ca(ClO), and Fe/NaSO), compared with sludge conditioned with traditional conditioner (Fe/CaO), were investigated in both bench and pilot-scale tests. All of those conditioner systems could reduce the water content of dewatered sludge cake to below 60 wt% in bench-scale (about 16 kg raw sludge per round) and pilot-scale (approximate 800 kg raw sludge per round) diaphragm filter press dewatering. Compared with raw sludge, the deep-dewatering filtrate after different conditioning and dewatering processes had higher ammonia nitrogen (NH-N) and chemical oxygen demand (COD) contents due to the degradation of organic matter, and much lower total phosphorus (TP) content due to the formation of iron phosphate precipitate. A better biodegradability (i.e. higher BOD/COD ratio) was found in the deep-dewatering filtrate of sludge conditioned with Fe/HO (25.2 %) and Fe/Ca(ClO) (17.4 %). Most of the heavy metals (Cr, Cu, Ni, and Pb) (>79 wt%) have remained in the dewatered sludge cake, and most of the Cl element (>90 wt%) in the sludge pretreated by Fe/Ca(ClO) and Fe/CaO was kept in the filtrate, rather than the dewatered sludge cake. Based on the pilot-scale experimental results, if all the filtrate in the deep-dewatering process returned to the influent of WWTP, the loading ratios of TP, NH-N, COD in the four conditioner systems were less than 3 wt%. The above results proved that the AOPs conditioned sludge could achieve deep-dewatering in pilot-scale and the direct recirculation of deep-dewatering filtrate to the influent of wastewater treatment plant was feasible.
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http://dx.doi.org/10.1016/j.envres.2021.111825DOI Listing
January 2022

Deciphering the impacts of composition of extracellular polymeric substances on sludge dewaterability: An often overlooked role of amino acids.

Chemosphere 2021 Dec 22;284:131297. Epub 2021 Jun 22.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Water Quality Safety and Water Pollution Control Engineering Center, Luoyu Road 1037, Wuhan, Hubei, 430074, China. Electronic address:

An investigation was conducted for waste activated sludge pretreated by different methods (e.g., ultrasonic, thermal, ozone, and acid/alkaline) in order to establish correlations between amino acids and parameters related to sludge dewaterability (e.g., capillary suction time (CST), specific resistance to filtration (SRF), proteins (PN) and polysaccharides (PS) in different fractions of extracellular polymeric substances (EPS), zeta potential, and particle sizes). The results indicated that glycine, serine, and threonine were the key identified amino acids correlated with parameters related to sludge dewaterability. To be exemplified, glycine showed positive correlations with the normalized CST (regression coefficient (R) = 0.72, p < 0.05), the normalized SRF (R = 0.74, p < 0.05), PN in soluble EPS (R = 0.89, p < 0.05), PS in soluble EPS (R = 0.56, p < 0.05), tryptophan-like PN in soluble EPS (R = 0.60, p < 0.05), and tryptophan-like PN in loosely-bound EPS (R = 0.58, p < 0.05). After adding extra glycine, serine, and threonine into sludge samples, sludge dewaterability was deteriorated. The hydrophilic functional groups of CO and C-OH were found to be more predominant in sludge with the presence of these amino acids. The Lewis acid-base interaction predominated in determining the net attraction among sludge flocs. Moreover, the presence of glycine, serine, and threonine resulted in high repulsive hydrophilic interaction, which deteriorated sludge dewaterability. This study emphasized the importance of amino acids in sludge dewatering and amino acids might be incorporated into parameters reflecting sludge dewaterability.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131297DOI Listing
December 2021

An efficient hydrodynamic-biokinetic model for the optimization of operational strategy applied in a full-scale oxidation ditch by CFD integrated with ASM2.

Water Res 2021 Apr 3;193:116888. Epub 2021 Feb 3.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China. Electronic address:

Oxidation ditches (ODs) are often used for wastewater treatment. However, limitations of ODs like high energy expenditure and increased sludge sedimentation hinder its wide application. In this study, the computational fluid dynamics (CFD) model integrated with Activated Sludge Model No. 2 (ASM2) was proposed and applied in a full-scale OD. The integrated model provided heterogeneous information on the characteristics of hydrodynamics and biokinetics of OD, especially with respect to the simulation of total phosphorus removal by CFD-ASM2 integration model for the first time. The simulated values of flow velocities, suspended solids (SS), dissolved oxygen, chemical oxygen demand, total nitrogen, ammonium nitrogen, and total phosphorus concentrations were well validated with the measured results, with the standard deviation errors of less than 5.56%, 0.28%, 0.74%, 7.39%, 3.17%, 5.27%, and 7.40%, respectively. Based on the integrated model, four different operational strategies were simulated. The proposed operational strategy of operating 7 surface aerators and 10 submerged impellers not only met the standard discharge requirements (GB 18918-2002) but also consumed less energy by 22.3%, compared with the original strategy of operating 9 surface aerators and 13 submerged impellers. Meanwhile, this proposed operational strategy also reduced the SS concentrations in the second and fourth channels, which was beneficial to elimination of sludge sedimentation. Moreover, the proposed operational strategy was successfully applied and validated in full-scale OD. The foregoing results collectively suggest that the CFD-AMS2 integration model is numerically capable to optimize the operational strategy of ODs.
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http://dx.doi.org/10.1016/j.watres.2021.116888DOI Listing
April 2021

Degradation of refractory organics in dual-cathode electro-Fenton using air-cathode for HO electrogeneration and microbial fuel cell cathode for Fe regeneration.

J Hazard Mater 2021 06 1;412:125269. Epub 2021 Feb 1.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China.

The electrogeneration of HO and electro-regeneration of ferrous are conflicting matters in electro-Fenton system. In this research, the degradation of Rhodamine B, methyl orange (MO) and 4-chlorophenol (4-CP) was investigated using a novel dual-cathode microbial fuel cell (MFC) electro-Fenton (EF) hybrid system. An air-cathode of an EF system was used for HO electrogeneration and a carbon felt cathode of a MFC was used to accelerate Fe regeneration. Synergistic improvement of MFC power generation and the degradation of the above refractory organics through EF reaction was achieved. The EF air-cathode was fabricated by adopting activated carbon/graphite powder mixture and PVDF binder, which showed higher HO generation but slower Fe reduction rate than MFC carbon felt cathode. The Rhodamine B removal rate constant and mineralization current efficiency of the MFC coupled EF were 64% and 42% higher than that of uncoupled EF, respectively. The MFC-EF coupled system also exhibited significantly higher removal efficiency for MO and 4-CP than that of un-coupled EF system. Moreover, the power density of MFC was greatly enhanced by coupling EF due to higher Fe/Fe redox potential than oxygen reduction.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125269DOI Listing
June 2021

Simultaneous heavy metal removal and sludge deep dewatering with Fe(II) assisted electrooxidation technology.

J Hazard Mater 2021 03 9;405:124072. Epub 2020 Oct 9.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan 430074, PR China. Electronic address:

A hybrid sludge conditioning strategy with electrooxidation and Fe(II) addition was used for heavy metal removal from sewage sludge and industrial sludge, with simultaneous sludge dewatering and stabilization. With the addition of 82 mg/g DS Fe(II) and treatment time of 4.5 h, heavy metal removals of 72.95% and 78.49% for Cu, 66.29% and 84.26% for Zn, and 36.52% and 36.99% for Pb were achieved from sewage sludge and industrial sludge samples respectively. The system pH decreased to 2.33 and 2.98 and the oxidation-reduction potential (ORP) values increased to 435.90 mV and 480.60 mV in sewage sludge and industrial sludge samples, respectively, which was conducive to the desorption and dissolution of heavy metals from sludge structures and the degradation of the organic compounds that complexed with heavy metals. In addition, the hybrid conditioning process demonstrated excellent dewatering performance due to the efficient electrochemical disintegration of sludge flocs together with the coagulation of sludge particles by Fe(III) generated via electrooxidation. The strong acidic and oxidative environment produced by the enhanced electrooxidation process was also responsible for pathogen inactivation.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124072DOI Listing
March 2021

The evaluation of long term performance of microbial fuel cell based Pb toxicity shock sensor.

Chemosphere 2021 May 29;270:129455. Epub 2020 Dec 29.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, PR China; School of Environmental Science and Engineering, Hubei Polytechnic University, Huangshi, 435003, PR China.

Microbial fuel cell (MFC) sensor exhibits attractive prospects for online monitoring of water toxicity as an early warning device. However, the accumulation of dead cells in anode biofilm might decrease the sensing sensitivity of MFC during long term operation. In addition, with repeated exposure to toxins, the microbial community of anode biofilm would also adjust to build up higher endurance to environmental toxicity. In this study, the long term sensing sensitivity of MFC sensor and the microbial community changes were characterized with Pb as the target toxin. The results show that newly formed biofilm with higher live/dead cell ratio exhibited higher sensitivity than mature biofilm. Modification of anodic biofilm via high current stimulation was applied to increase the ratio of live cells, which led to enhanced sensing sensitivity of MFC with mature anode biofilm. However, the enhancement was relatively limited for biofilm that was previously exposed to repeated Pb shocks. Microbial community analysis revealed that the proportions of microbial species possessing higher environmental robustness, such as Hyphomicrobiaceae and Cloacibacillus, significantly increased in the anode biofilm after long term repeated Pb shocks.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129455DOI Listing
May 2021

Enhancing waste activated sludge dewaterability by reducing interaction energy of sludge flocs.

Environ Res 2021 05 17;196:110328. Epub 2020 Oct 17.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

How to efficiently improve waste activated sludge (WAS) dewaterability is a common challenge in WAS treatment and management throughout world. The interaction energy of sludge flocs is of great importance for sludge dewaterability. In this study, the relationship among the repulsive force of sludge flocs, hydrophilic/hydrophobic characteristics of sludge flocs, and sludge dewaterability have been quantitatively and qualitatively investigated based on extended Derjaguin-Landau-Verwey-Overbeek theory for the first time. The energy barrier of sludge flocs has good correlations with sludge dewaterability (p < 0.05). Trivalent cations (Al and Fe) and Fenton's reagent reduced the interfacial free energy (ΔG) from 9.4 mJ/m of raw sludge to -34.2 (Al), -60.5 (Fe), and -63.2 (Fenton) mJ/m, respectively, indicating that the hydrophilic surfaces of the sludge flocs converted to hydrophobic (△G < 0), and decreasing Lewis acid-base interaction energy (W) of sludge flocs. In addition, most of the trivalent cations (Al and Fe) were attached to sludge flocs, leading to neutralize negative charges and mitigate electrostatic interaction energy (W) of sludge flocs. The reduction of W and W eliminated energy barrier of sludge flocs and repulsive force between sludge flocs. In comparison, monovalent (Na and K) and bivalent (Ca and Mn) cations cannot completely change the hydrophilic surface characteristic and negative charge of sludge flocs. The existed energy barrier prevented sludge flocs to agglomerate with each other, thus resulting in a worse dewaterability. This study illustrated that reducing interaction energy of sludge flocs played a critical role to improve sludge dewaterability.
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http://dx.doi.org/10.1016/j.envres.2020.110328DOI Listing
May 2021

Occurrence and exposure risk evaluation of polyhalogenated carbazoles (PHCZs) in drinking water.

Sci Total Environ 2021 Jan 13;750:141615. Epub 2020 Aug 13.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China. Electronic address:

Although polyhalogenated carbazoles (PHCZs) can be generated and detected in drinking water, their occurrence and potential health risks to humans via drinking water ingestion are not well known. In this study, 11 PHCZs were screened in drinking water samples from Wuhan, the most populous city in central China. The total concentration of PHCZs could be up to 53.48 ng/L with a median level of 8.19 ng/L, which was comparable to polychlorinated biphenyls and poly- and perfluoroalkyl substances reported in the literatures for drinking water. Composition profiles revealed that 3,6-dichlorocarbazole, 3-chlorocarbazole, 3-bromocarbazole and 3,6-dibromocarbazole were the predominant PHCZ congeners in the tested samples. Regional differences in the levels and patterns of PHCZs suggested that anthropogenic releases should be the dominant source compared to natural generation. Boiling of the water samples caused no significant change in PHCZs concentrations after correcting the volume change due to evaporation. Potential health risks associated to the levels of PHCZs in drinking water were assessed using the toxic equivalent (TEQs) method. The estimated daily intake of PHCZs via drinking water ingestion is up to 0.38 pg-TEQ/kg body weight/day for infants, nearly 4.5 times higher than that for adults, and appears to reach the maximum permissible concentration set by certain authority agencies. Overall, drinking water ingestion represents an important exposure pathway for PHCZs. This is the first comprehensive study on the abundance and health risks of PHCZs in drinking water.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141615DOI Listing
January 2021

Integration of electrochemical and calcium hypochlorite oxidation for simultaneous sludge deep dewatering, stabilization and phosphorus fixation.

Sci Total Environ 2021 Jan 8;750:141408. Epub 2020 Aug 8.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei 430074, PR China. Electronic address:

A hybrid electrochemical process with Ca(ClO) addition for simultaneous sludge dewaterability, stabilization and phosphorus fixation was proposed. Under optimal conditions (150 mg/g VS Ca(ClO), 15 V), the capillary suction time (CST) and specific resistance to filtration (SRF) were decreased by 88% and 92%, respectively. Efficient sludge stabilization with E. coli colonies of less than 1000 MPN/g TS was achieved. Phosphorus of 99% was removed from the filtrate and successfully fixed in the sludge cake and on the electrode surface. The integration of electrochemical and hypochlorite oxidation could effectively degrade the tightly bound extracellular polymeric substances (TB-EPS) structure with a total organic carbon (TOC) reduction of 52%. Besides, the disintegration of microbial cell envelopes was also achieved, with a reduction of living cell fraction of 98%. Furthermore, system pH could be maintained at near neutral (7.45) and the conversion of Fe(II) to Fe(III) was also facilitated with the addition of Ca(ClO), resulting in improved electrocoagulation process for enhanced sludge dewatering and phosphorus fixation. The multifunctional effects were achieved with the cooperated extracellular electrooxidation for EPS destruction and the active chlorine for intracellular microbial cell disintegration. This research provides a promising strategy for integrated sludge treatment and recycling for possible land utilization.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141408DOI Listing
January 2021

Improvement of sludge dewaterability by ammonium sulfate and the potential reuse of sludge as nitrogen fertilizer.

Environ Res 2020 12 20;191:110050. Epub 2020 Aug 20.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycle Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China.

A novel method to enhance sludge dewaterability with ammonium sulfate ((NH)SO) was proposed, and the potential reuse of dewatered sludge cake and filtrate as nitrogen fertilizers was evaluated. Compared with raw sludge, 87.91% reduction of capillary suction time (CST) and 88.02% reduction of specific resistance to filtration (SRF) after adding 80% (m/m) (NH)SO were achieved, with 38.49% of protein precipitated simultaneously. The (NH)SO dose destroyed cell membrane, resulting in the release of intracellular water by converting bound water into free water, thus enhancing sludge dewaterability. In the solid phase, the content of protein-N increased, and larger protein aggregates were formed. The (NH)SO dose destroyed the hydration shell, making proteins to exhibit hydrophobic interactions, and to be aggregated, and precipitated from the liquid phase. When incubated Pennisetum alopecuroides L. with the dewatered sludge cake and filtrate after dewatering and conditioning with (NH)SO, the germination rate of grass seed and shoot lengths both increased while compared with those incubated with dewatered sludge cake and filtrate of the raw sludge. This study might provide insights into sustainable sludge treatment by integrating sludge dewatering and the potential reuse of dewatered sludge cake and filtrate as nitrogen fertilizer via treatment with (NH)SO.
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http://dx.doi.org/10.1016/j.envres.2020.110050DOI Listing
December 2020

Performance evaluation of microbial fuel cell for landfill leachate treatment: Research updates and synergistic effects of hybrid systems.

J Environ Sci (China) 2020 Oct 23;96:1-20. Epub 2020 May 23.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.

Over half of century, sanitary landfill was and is still the most economical treatment strategy for solid waste disposal, but the environmental risks associated with the leachate have brought attention of scientists for its proper treatment to avoid surface and ground water deterioration. Most of the treatment technologies are energy-negative and cost intensive processes, which are unable to meet current environmental regulations. There are continuous demands of alternatives concomitant with positive energy and high effluent quality. Microbial fuel cells (MFCs) were launched in the last two decades as a potential treatment technology with bioelectricity generation accompanied with simultaneous carbon and nutrient removal. This study reviews capability and mechanisms of carbon, nitrogen and phosphorous removal from landfill leachate through MFC technology, as well as summarizes and discusses the recent advances of standalone and hybrid MFCs performances in landfill leachate (LFL) treatment. Recent improvements and synergetic effect of hybrid MFC technology upon the increasing of power densities, organic and nutrient removal, and future challenges were discussed in details.
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http://dx.doi.org/10.1016/j.jes.2020.05.005DOI Listing
October 2020

Metabolomics revealing the response of rice (Oryza sativa L.) exposed to polystyrene microplastics.

Environ Pollut 2020 Nov 7;266(Pt 1):115159. Epub 2020 Jul 7.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

Large amounts of microplastics accumulate in the agricultural soil. Microplastics would stress the crops but the underlying mechanism remains unclear. Herein, a laboratory exposure and field trials were carried out to investigate the response of rice (Oryza sativa L. II You. 900) to stress induced by polystyrene microplastics (PS-MPs) using a metabolomic approach. After laboratory exposure for 21 days, the decreases in shoot biomass of rice exposed to low, medium and high doses of PS-MPs were 13.1% (CV = 4.1%), 18.8% (CV = 3.7%), and 40.3% (CV = 9.2%), respectively, while the antioxidant enzymes showed an inverted upper-U shape when exposed to PS-MPs. A total of 24 samples from three exposure dose levels were included in the metabolic analysis. The metabolites of 12 amino acids, 16 saccharides, 26 organic acids and 17 others (lipids and polyols) in leaves decreased after the exposure to both 50 mg L and 250 mg L PS-MPs doses with hydroponically-cultured. The inhibition of perturbed biological pathway causes the biosynthesis of amino acids, nucleic acids, fatty acids and some secondary metabolites decreased which indicate that the energy expenditure exceeded the substance accumulation. In order to further validate the effects of PS-MPs on rice leaves obtained from the laboratory-scale experiments, a field-trial experiment was conducted. After 142 days of cultivation in farmland, the results with a maximum of 25.9% lower biomass in the crops exposed with PS-MPs. As such, the presence of PS-MPs may affect rice production by altering the metabolic systems of rice. Long-term exposure of PS-MPs to rice might be a potential risk to rice safety and quality.
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http://dx.doi.org/10.1016/j.envpol.2020.115159DOI Listing
November 2020

Enhanced sludge dewaterability with sludge-derived biochar activating hydrogen peroxide: Synergism of Fe and Al elements in biochar.

Water Res 2020 Sep 13;182:115927. Epub 2020 Jun 13.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

Reuse of sludge-derived Fe-rich biochar as sludge conditioner is an attractive route for management of waste activated sludge at source. Homogeneous and heterogeneous Fenton reactions have been proved in sludge conditioning with Fe-rich biochar activating HO to enhance sludge dewaterability. The FeAlO phase in Fe-rich biochar was first identified during pyrolysis of sewage sludge after adding both FeO and AlO, since Fe and Al elements are two of major metal elements in Fe-rich sludge. Compared with the Fe-rich biochar that did not comprise FeAlO phase, the capillary suction time (CST) and specific resistance to filterability (SRF) of the sludge conditioned with the Fe-rich biochar comprising FeAlO phase could be efficiently decreased by 23% and 44%, respectively. The results indicated that FeAlO phase in Fe-rich biochar could improve sludge dewaterability by enhancing heterogeneous Fenton reaction. Synergistic effect between Fe and Al in FeAlO contributed to weak the O-O bond in HO and reduce the activation energy of HO decomposition for enhancing ·OH generation, which could be explained by density functional theory (DFT) calculations for the first time. Thus, the decomposition rate of HO and the amount of ·OH generation were obviously promoted by FeAlO phase in sludge-derived biochar during sludge conditioning, attributing to the destruction of sludge flocs, the release of bound water, and the improvement of sludge dewaterability.
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http://dx.doi.org/10.1016/j.watres.2020.115927DOI Listing
September 2020

Enhanced treatment of landfill leachate with cathodic algal biofilm and oxygen-consuming unit in a hybrid microbial fuel cell system.

Bioresour Technol 2020 Aug 21;310:123420. Epub 2020 Apr 21.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037, Luoyu Road, Wuhan, Hubei 430074, PR China. Electronic address:

An innovative cathodic algal biofilm microbial fuel cell equipped with a bioactive oxygen consuming unit (AB-OCU-MFC) was proposed for enhancing the leachate treatment containing biorefractory organic matters and high strength of ammonium nitrogen. The proposed AB-OCU-MFC performed better with regard to COD, NH-N, TN removals and algal biomass yield than standalone algal biofilm-MFC and control reactors. AB-OCU-MFC with OCU of 2 cm thickness removed more than 86% of COD, 89.4% of NH-N, 76.7% of TN and produced a maximum voltage of 0.39 V and biomass productivity of 1.23 g·L·d. The High-throughput sequencing of DNA showed a significant change in microbial community of reactors implemented with OCU, in which the ratio of exoelectrogenic bacteria of anode and denitrifying bacteria on cathode were significantly increased. The results obtained by cathodic algal biofilm MFC with low cost and bioactive barrier of OCU, would provide a new sight for practical application of MFC.
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http://dx.doi.org/10.1016/j.biortech.2020.123420DOI Listing
August 2020

Sludge-derived biochar with multivalent iron as an efficient Fenton catalyst for degradation of 4-Chlorophenol.

Sci Total Environ 2020 Jul 1;725:138299. Epub 2020 Apr 1.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.

Fe-rich biochar with multivalent iron compounds (Fe, FeC, FeO, and FeAlO) pyrolyzed from sludge cake conditioned with Fenton's reagent and red mud was utilized as an efficient Fenton catalyst for the degradation of 4-chlorophenol (4-CP). Effects of pyrolysis temperature and sludge conditioner composition on the transformation of iron compounds were studied. Both homogeneous Fenton reaction initiated by Fe leached from both low-valent Fe and FeC, and heterogeneous Fenton reaction initiated by solid iron phases of FeO and FeAlO were revealed to contribute to the degradation of 4-CP. The removal efficiency of 4-CP remained 100% after five successive degradation rounds. The homogeneous Fenton reaction mainly works in the first degradation round, and the heterogeneous Fenton reaction dominates in subsequent degradation rounds. The findings of this study suggest that sewage sludge derived Fe-rich biochar could be utilized as an efficient Fenton catalyst for recalcitrant organics degradation.
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http://dx.doi.org/10.1016/j.scitotenv.2020.138299DOI Listing
July 2020

Profiling of amino acids and their interactions with proteinaceous compounds for sewage sludge dewatering by Fenton oxidation treatment.

Water Res 2020 May 28;175:115645. Epub 2020 Feb 28.

School of Environmental Science & Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling, Luoyu Road 1037, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China. Electronic address:

During advanced oxidation treatment for enhancing sludge dewaterability, the peptide chains of protein can be decomposed into amino acids. Protein exhibits a great impact on sewage sludge dewaterability. However, the role of amino acids in sludge dewatering remains unclear. In this study, among the 23 types of amino acids investigated, tryptophane (Trp) and lysine (Lys) were identified as the key amino acids affecting sludge dewaterability during Fenton oxidation treatment. The content of lysine showed positive correlations with capillary suction time (CST), specific resistance to filtration (SRF), and bound water content, and the concentrations of total protein, low molecular weight protein, amines and amides, and 3-turn helix of proteinaceous compounds in bound extracellular polymeric substances (EPS), while the content of tryptophane showed negative correlations with the above parameters. The amino acids may be sourced from damage of the membrane and ribosomal proteins by hydroxyl radicals, and the peptide bonds connected with tryptophane were more inclined to be decomposed than other amino acids. Particularly, more amino acids of tryptophane can result in more hydrophobic interaction, and less necessary energy barrier for aggregation of particles. As such, regulating protein degradation towards production of tryptophane may be related with enhanced sludge dewaterability by Fenton oxidation treatment.
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http://dx.doi.org/10.1016/j.watres.2020.115645DOI Listing
May 2020

Phosphorus recovery from the liquid phase of anaerobic digestate using biochar derived from iron-rich sludge: A potential phosphorus fertilizer.

Water Res 2020 May 23;174:115629. Epub 2020 Feb 23.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei, 430074, China.

A novel technique for phosphorus recovery from the liquid phase of anaerobic digestate was developed using biochar derived from iron-rich sludge (dewatered sludge conditioned with Fenton's reagent). The biochar pyrolyzed from iron-rich sludge at a low temperature of 300 °C (referred to as Fe-300 biochar) showed a better phosphorus (P) adsorption capacity (most of orthophosphate and pyrophosphate) than biochars pyrolyzed at other higher temperatures of 500-900 °C, with the maximum P adsorption capacity of up to 1.843 mg g for the liquid phase of anaerobic digestate. Adsorption isotherms study indicated that 70% P was precipitated through chemical reaction with Fe elements, i.e., Fe(II) and Fe(III) existed on the surface of the Fe-300 biochar, and other 30% was through surface physical adsorption as simulated by a dual Langmuir-Langmuir model using the potassium dihydrogen orthophosphate (KHPO) as a model solution. The seed germination rate was increased up to 92% with the addition of Fe-300 biochar after adsorbing most of P, compared with 66% without the addition of biochar. Moreover, P adsorbed by the chemical reaction in form of iron hydrogen phosphate can be solubilized by a phosphate-solubilizing microorganism of Pseudomonas aeruginosa, with the total solubilized P amount of 3.045 mg g at the end of an incubation of 20 days. This study indicated that the iron-rich sludge-derived biochar could be used as a novel and beneficial functional material for P recovery from the liquid phase of anaerobic digestate. The recovered P with biochar can be re-utilized in garden soil as an efficient P-fertilizer, thus increasing the added values of both the liquid phase of anaerobic digestate and the iron-rich sludge.
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http://dx.doi.org/10.1016/j.watres.2020.115629DOI Listing
May 2020

Enhanced 2,4,6-trichlorophenol degradation and biogas production with a coupled microbial electrolysis cell and anaerobic granular sludge system.

Bioresour Technol 2020 May 4;303:122958. Epub 2020 Feb 4.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China. Electronic address:

A coupled microbial electrolysis cell - anaerobic granular sludge system (MEC-AGS) was established to explore the degradation efficiency of 2,4,6-trichlorophenol (TCP) with synchronous biogas production. Results showed that MEC-AGS yielded a higher proportion of CH than MEC (83.8 ± 0.4% vs 82.0 ± 1.0%, P < 0.05) with sodium acetate (NaAc) as the only carbon source. Moreover, MEC-AGS had higher tolerance to the addition of TCP, with the highest TCP degradation efficiency of 45.5 ± 0.5% under 5 mg L of TCP addition in 24 h. Furthermore, microbial community structures were significantly changed based on community composition, hierarchical cluster and PCoA analysis, which proved that MEC-AGS favored the enrichment of dechlorination-related microbes such as Pseudomonas, Desulfovibrio and Longilinea, as well as their syntrophic bacteria of Anaerolineacea, Syntrophobacter, Arcobacter, etc. The coupled system provides a promising strategy for biogas production from wastewater with recalcitrant organics.
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http://dx.doi.org/10.1016/j.biortech.2020.122958DOI Listing
May 2020

Oxygen vacancy mediated surface charge redistribution of Cu-substituted LaFeO for degradation of bisphenol A by efficient decomposition of HO.

J Hazard Mater 2020 May 10;389:122072. Epub 2020 Jan 10.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, PR China. Electronic address:

The novel catalyst LaCuFeO with oxygen vacancies (OVs) was prepared and demonstrated excellent stability and activity for the degradation of bisphenol A. The removal rate of 92.1 % and HO utilization efficiency of 70.4 % were obtained due to the efficient hydroxyl radical generation mediated by OVs. The density functional theory calculation showed that the substitution of Cu and formation of OVs significantly increases the charge density near the active sites. Bader charge analysis revealed that the charge offset accelerated the reduction of Fe. The elevation of electron transfer efficiency also promotes the valence transition of copper and iron atoms. The reversible electronic transition between Fe ⇆ Fe, Cu ⇆ Cu and Cu ⇆ Fe involved in this reaction were considered to be enhanced and the homolytic bond clearage of HO was simultaneously promoted, facilitated by the electron-rich region combined with OVs on the surface of LaCuFeO.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122072DOI Listing
May 2020

Insight into effects of organic and inorganic phosphorus speciations on phosphorus removal efficiency in secondary effluent.

Environ Sci Pollut Res Int 2020 Apr 23;27(11):11736-11748. Epub 2020 Jan 23.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, 430074, Hubei, China.

Most previous studies of phosphorus (P) removal focused on investigation of the soluble, and particulate P, but ignoring the difference between organic and inorganic P. In this study, the effects of various flocculants, namely polyacrylamide (PAM) and polyaluminum chloride (PAC), on flocculation efficiency in different P speciations (organic and inorganic P) were investigated. A modified method to differentiate between organic and inorganic P content in secondary effluent samples was developed. The results showed that P speciation based on organic/inorganic P (Pearson's correlation R = 0.915, p < 0.05) was more effective than those based on soluble/particulate P (p > 0.05) in evaluating the P content in secondary effluents. The liquid P nuclear magnetic resonance measurements results indicated that PAM was more effective in removing organic P (phosphonates and orthophosphate monoesters) rather than inorganic P. However, PAC was more effective in removing inorganic P (particularly orthophosphate) rather than organic P. Based on the modeled results of a response surface methodology (RSM), doses of PAM and PAC were optimized for secondary effluent containing different amounts of organic and inorganic P from the two typical wastewater treatment plants (WWTPs) in Wuhan city, China.
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http://dx.doi.org/10.1007/s11356-020-07774-9DOI Listing
April 2020

Stabilization treatment of arsenic-alkali residue (AAR): Effect of the coexisting soluble carbonate on arsenic stabilization.

Environ Int 2020 02 19;135:105406. Epub 2019 Dec 19.

Environmental Science Research Institute, School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.

Arsenic-alkali residue (AAR) from antimony smelting is highly hazardous due to its ready leachability of As, seeking for proper disposal such as stabilization treatment. However, As stabilization in AAR would be challenging due to the high content of coexisting soluble carbonate. This study conducted the stabilization treatments of AAR by ferrous sulfate and lime, respectively, and revealed the significant influence of coexisting carbonate. It was found that ferrous sulfate was more efficient than lime, which required only one-tenth of dosages of lime to reduce the As leaching concentration from 915 mg/L to a level below 2.5 mg/L to meet the Chinese regulatory limit. The combining qualitative and quantitative analyses based on XRD, SEM-EDS, and thermodynamic modeling suggested that the formation of insoluble arsenate minerals, ferrous arsenate or calcium arsenate, was the predominant mechanism for As stabilization in the two treatment systems, and their efficiency difference was primarily attributed to the coexisting carbonate, which had a slight effect on ferrous arsenate but severely obstructed calcium arsenate formation. Moreover, the examination of As leaching concentrations in 1-year-cured samples indicated that the long-term stability of ferrous sulfate treatment was far superior to that of lime treatment. This study provides ferrous salts as a promising and green scheme for stabilization treatment of AAR as well as other similar As-bearing solid wastes with coexisting soluble carbonate.
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http://dx.doi.org/10.1016/j.envint.2019.105406DOI Listing
February 2020

Biogas and phosphorus recovery from waste activated sludge with protocatechuic acid enhanced Fenton pretreatment, anaerobic digestion and microbial electrolysis cell.

Sci Total Environ 2020 Feb 23;704:135274. Epub 2019 Nov 23.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, Wuhan 430074, PR China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, PR China. Electronic address:

Biogas and phosphorus recovery from waste activated sludge (WAS) with sequential homogeneous protocatechuic acid (PCA) enhanced Fenton pretreatment, anaerobic digestion (AD) and microbial electrolysis cell (MEC) were investigated. The cumulation of biogas production of WAS-Fenton-AD was 330.4 mL/g VS, which was 2.05-fold of the control without pretreatment (WAS-AD) during anaerobic digestion. Biogas production of 178 mL/L/d from WAS-Fenton-AD-MEC was achieved, which was 5.23-fold of the WAS-MEC, 2.28-fold of WAS-Fenton-MEC and 1.46-fold of WAS-AD-MEC, respectively. Enhanced phosphorus recovery in form of struvite reached 1.72 g/g TS (18.03% of total P) with a purity of 74.4%. Microbial community richness and diversity analysis revealed that the pretreatment process under circumneutral condition improved the diversity of microbial community, which was consisted of Bacteroidetes (33.90%), Proteobacteria (33.14%), and Chloroflexi (10.14%), compared to a majority of Firmicutes (70.81%) in WAS-AD. This study provides a feasible strategy for the recovery of biogas combined with phosphorus from WAS.
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http://dx.doi.org/10.1016/j.scitotenv.2019.135274DOI Listing
February 2020

Predicting the higher heating value of syngas pyrolyzed from sewage sludge using an artificial neural network.

Environ Sci Pollut Res Int 2020 Jan 6;27(1):785-797. Epub 2019 Dec 6.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, People's Republic of China.

Sludge pyrolysis is a complex process including complicated reaction chemistry, phase transition, and transportation phenomena. To better evaluate the use of syngas, the monitoring and prediction of a higher heating value (HHV) is necessary. This study developed an artificial neural network (ANN) model to predict the HHV of syngas, with the process variables (i.e., sludge type, catalyst type, catalyst amount, pyrolysis temperature, and moisture content) as the inputs. In the first step, through optimizing various sets of parameters, a three-layer network including 8 input neurons, 15 hidden neurons, and 1 output neuron was established. Then, in the second step, an ANN model has been successfully used to predict the HHV of syngas, with a fitting correlation coefficient of 0.97 and a root mean square error (MSE) value of 14.62. The relative influence of input variables showed that the pyrolysis temperature and moisture content were the determining factors that affected the HHV of syngas. The results of optimization experiments showed that when temperature was 895 °C and the moisture content was 45.63 wt%, the highest HHV can be obtained as 438.22 kcal/m-N. Moreover, the ANN model showed a higher prediction accuracy than other models like multiple linear regression and principal component regression. The model developed in this work may be used to predict the HHV of syngas using conventional operational parameters measured from in situ experiments, thus further providing predictive information for the use of syngas as energy and fuel.
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http://dx.doi.org/10.1007/s11356-019-06885-2DOI Listing
January 2020

Enhanced quorum sensing of anode biofilm for better sensing linearity and recovery capability of microbial fuel cell toxicity sensor.

Environ Res 2020 02 12;181:108906. Epub 2019 Nov 12.

School of Environmental Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan, Hubei, 430074, PR China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China. Electronic address:

MFC toxicity sensor has major hindrances that limit its practical application, such as the poor concentration-response relationship and inferior recovery capability after high toxicity shock. Till now, the direct influence of intrinsic properties on the performance of MFC toxicity sensor has not been well understood. Quorum sensing (QS) is a cell-to-cell communication strategy that indirectly affects the intrinsic properties of electroactive biofilms. In this work, commercially available QS autoinducers (AHLs) were applied to MFC toxicity sensor to manipulate anode biofilm for better sensing performance. The results showed that the addition of AHLs (C6-HSL, 3-OXO-C12-HSL) led to higher sensing linearity to a wider range of Pb. The voltage of MFC sensors with AHLs addition fully recovered even after 10 mg/L Cu shock, indicating an enhanced recovery capability of MFC toxicity sensor. It was found that higher live/dead cells ratio and increased exoelectrogen Geobacter abundance were responsible for the superior sensing linearity and recovery capability of MFC toxicity sensor. Our work presented a novel and effective way to advance the process of MFC toxicity sensor application from the perspective of EABs.
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http://dx.doi.org/10.1016/j.envres.2019.108906DOI Listing
February 2020
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