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Showing 31 of 146 peer-reviewed papers with full Graphical Abstracts.

Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506005• Jan 15, 2026

Analysis of National and Local Policies for Medical Waste Treatment and Disposal in China

Authors: LI Mu, CHEN Yiming, WANG Jiaqing, HUANG Guanzhong, WANG Zeng, WANG Zhaolong, CHEN Weixing, GAO Wenfang

The escalating generation of medical waste, driven by healthcare expansion and frequent medical activities, poses significant environmental and public health risks. Under the framework of ecological civilization, China is developing a comprehensive policy system for medical waste treatment and disposal, yet the current framework remains nascent and exhibits inconsistencies between national and local policies. This study systematically analyzes the status of national and local policies from 2003 to 2024, collecting 413 policy documents (166 from national ministries and 247 from provincial governments). The analysis examines temporal evolution, regional distribution, and policy focus, alongside the influence of medical waste output, treatment technologies, facility infrastructure, and major epidemic responses. Findings reveal distinct policy phases: initial self-disposal, exploratory management, foundational system building, and rapid development. Regional disparities are pronounced, with eastern coastal areas showing more advanced policies due to greater technical and financial resources. The surge in medical waste, particularly during the COVID-19 pandemic, underscores the need for enhanced regulatory guidance. Non-incineration technologies are gaining traction for their environmental and cost benefits, and facility coverage has improved but remains uneven. The study proposes five policy principles to foster technological innovation and industrial upgrading, ensuring safe medical waste management and environmental protection.

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Analysis of National and Local Policies for Medical Waste Treatment and Disposal in China

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507064• Jan 15, 2026

Kinetic Analysis and Simulation of Pollutant Removal in Sewage Networks

Authors: FENG Ruodan, LI Cuimei, ZHU Chunwei, ZHOU Lifen, ZUO Shu, ZHANG Jian

This study investigates pollutant removal characteristics and kinetic behaviors in sewage networks, and analyzes their impact on the carbon-to-nitrogen ratio (C/N, as COD/TN) of influent to wastewater treatment plants. Source water quality sampling at drainage outlets revealed spatial and temporal variations in C/N, with domestic sewage exhibiting higher C/N than industrial sewage, and diurnal peaks reaching 6.92 versus 4.71 during off-peak hours. Using a pilot-scale adjustable sewage network system in Kunshan, experiments were conducted under high (0.491 m·s−1) and low (0.089 m·s−1) flow velocities, monitoring pollutant removal over 144 hours. Pseudo-first-order kinetics were applied to model COD and TN removal. Results showed that COD (including SCOD and PCOD), BOD5, and SS achieved approximately 80% removal within 144 h, with higher removal at low flow velocity. TN, NH3-N, and TP exhibited lower overall removal rates. Kinetic fitting revealed that COD removal rate constants (kCOD) were significantly higher than those for TN (kTN), and both decreased with increasing flow velocity: at low velocity, kCOD=0.0167 h−1 and kTN=0.0029 h−1; at high velocity, kCOD=0.0127 h−1 and kTN=0.0020 h−1. Simulations based on actual source pollutant concentrations indicated that the time for C/N to drop to the denitrification critical value of 4.50 was 12.24 h at high velocity, but shortened to 9.49 h at low velocity. These findings demonstrate that increasing flow velocity effectively retards the decline of C/N. Therefore, regulating network flow velocity to reduce hydraulic retention time is a key strategy for maintaining adequate C/N at the terminal and ensuring denitrification efficiency in wastewater treatment plants.

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Kinetic Analysis and Simulation of Pollutant Removal in Sewage Networks

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506081• Jan 15, 2026

Preparation of Trimetallic-Carbon Composite Catalysts and Their Application in Catalytic Ozonation of Industrial Wastewater

Authors: CAO Xu, MEI Hong, WANG Yan, PENG Lijing, LIU Xianwei, JU

Advanced oxidation processes (AOPs) are promising for degrading organic pollutants in water treatment. Heterogeneous catalytic ozonation (HCO) has gained attention due to its high oxidation efficiency, strong interference resistance, and low secondary pollution. In this study, a series of trimetallic-carbon composite ozone catalysts were prepared via an organic precursor calcination method using γ-Al2O3 as support. This method enhanced catalytic activity and mechanical strength while overcoming the limitations of carbon materials (low mechanical strength) and metal-based materials (poor mass transfer). The optimized catalyst, CA-FeCoCu, comprising Fe, Co, Cu, carbon, and alumina, exhibited excellent performance in phenol degradation and real industrial wastewater treatment. Characterization revealed that the synergistic effect of trimetals and the introduction of multiple carbon types increased specific surface area and hydroxyl radical (·OH) generation. In a pilot-scale fixed-bed reactor, the CA-FeCoCu/O3 system reduced COD from 120 mg·L−1 to below 40 mg·L−1, with an O3 consumption ratio (O/C) of less than 1, effectively lowering operational costs. This work provides a new strategy for developing efficient and stable heterogeneous O3 catalysts and offers a reference for the practical application of HCO in industrial wastewater treatment.

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Preparation of Trimetallic-Carbon Composite Catalysts and Their Application in Catalytic Ozonation of Industrial Wastewater

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507085• Jan 15, 2026

Differentiated Characteristics of Suspended Particulate Matter and Their Effects on Water Quality in the Middle and East Routes of the South-to-North Water Diversion Project

Authors: ZHANG Junzhi, CHEN Borong, DONG Chenyu, CHANG Zhibing, ZHONG Mingyuan, ZHU Wenhao, YU Jianwei, ZHANG Honggang

This study investigates the spatiotemporal differentiation of suspended particulate matter (SPM) characteristics, sources, and their impacts on water quality between the Middle Route (closed artificial channel) and East Route (open natural water system) of the South-to-North Water Diversion Project. Thirty sampling sites (13 on the Middle Route, 17 on the East Route) were established, and samples were collected during dry and wet seasons. Water quality parameters and SPM characteristics were analyzed, including particle size distribution, total suspended solids (TSS), chlorophyll a, and stable carbon and nitrogen isotopes. Results show that the Middle Route maintains good and stable water quality, with SPM dominated by coarse particles (>63 μm, 61.43%–94.68%), total phosphorus (TP) <0.01 mg·L−1, and a significant positive correlation between chlorophyll a and coarse particles (r=0.60), indicating algal aggregation dominates particle formation. In contrast, the East Route exhibits high and fluctuating nitrogen and phosphorus concentrations, with SPM dominated by fine particles (<20 μm, 51.26%–88.61%), TP ranging from 0.03 to 1.11 mg·L−1, and a positive correlation with fine particles, suggesting significant external inputs. Carbon and nitrogen isotope analysis reveals that Middle Route SPM primarily originates from autochthonous algae (contribution >46.75%), while East Route SPM is influenced by both terrestrial C3 plants and algae. The distinct engineering and management approaches of the two routes lead to significant differences in SPM characteristics and sources, thereby affecting water quality dynamics. The Middle Route requires an 'algal reduction and hydrodynamic optimization' strategy to control algal-derived coarse particle deposition, whereas the East Route benefits from 'retention-sedimentation and wetland purification' to reduce external fine particles and pollutant inputs. This research provides theoretical support and practical guidance for differentiated SPM management in long-distance water diversion systems.

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Differentiated Characteristics of Suspended Particulate Matter and Their Effects on Water Quality in the Middle and East Routes of the South-to-North Water Diversion Project

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507110• Jan 15, 2026

Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water

Authors: DENG Qiujin, LU Zhifeng, CHEN Ben, CHEN Sa, LIANG Qifeng, SONG Chuqi, YANG Qiujian, JIA Yanyan, LYU Hui

Algal-derived taste and odor compounds (2-methylisoborneol, 2-MIB, and geosmin, GSM) in drinking water sources are poorly removed by conventional treatment. This study systematically evaluated the standalone and combined performance of ozone micro-nano bubbles (O3-MNBs) oxidation and powdered activated carbon (PAC) adsorption for removing 2-MIB, GSM, and algal cells from source water. Results showed that O3-MNBs pre-oxidation achieved >97.5% removal of odorants at 400 ng·L−1 and 67.2% algal cell removal within 30 min. When applied as a deep treatment stage, the degradation rate constant (k) was 10.1%–25.6% higher than in pre-oxidation due to lower background matrix interference. Both pre-oxidation and deep treatment reduced effluent concentrations of 2-MIB and GSM to below 10 ng·L−1, with oxidation kinetics fitting pseudo-first-order models (R²>0.95). PAC adsorption of both compounds followed pseudo-second-order kinetics (R²>0.99), with GSM equilibrium adsorption capacity approximately 20.0% higher than that of 2-MIB. In pure water, adsorption capacity increased by >10.0% compared to raw water. Based on kinetic models, a quantitative prediction method was established for O3-MNBs oxidation and PAC adsorption processes, aiming to achieve efficient odorant removal and cost optimization, providing theoretical support for advanced drinking water purification and smart water plant construction.

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Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507111• Jan 15, 2026

Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge

Authors: WANG Xuzhong, ZHANG Ning, ZHANG Pengyu, MIAO Juan, ZHANG Ruichang, ZHOU Ming, WEI Xuefeng

This study investigated the effects of a ring-shaped pulsed electric field (PEF) (1.5 V, 4 h on-time per cycle) on nitrogen removal performance and microbial community structure of anammox granular sludge (AnGS). Two anaerobic sequencing batch reactors (R1 control, R2 with PEF) were operated under stepwise increasing nitrogen loading rates (NLR). At NLR below 1,155 mg·(L·d)−1, R2 exhibited total nitrogen removal efficiency (TRE) 7.5%–17.0% higher than R1, with biomass, specific anammox activity (SAA), and extracellular polymeric substances (EPS) increased by 5%–7%, 21%–71%, and 54%–77%, respectively. However, at NLR above 1,320 mg·(L·d)−1, the toxic effect of nitrite dominated, and PEF enhancement diminished or even reversed to inhibition. Microbial community analysis revealed that at low-to-moderate NLR, PEF increased the relative abundance of Planctomycetes and key anammox bacteria (Candidatus Brocadia and Candidatus Jettenia), along with enhanced community richness (Chao1) and diversity (Shannon/Simpson indices). At high NLR, PEF decreased microbial richness compared to R1. Principal component analysis and redundancy analysis indicated that PEF was the key factor driving community differences at low-to-moderate NLR, whereas nitrite concentration became the dominant factor at high NLR. This study provides theoretical support for enhancing the resilience and engineering application of anammox processes.

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Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506019• Jan 15, 2026

Behavior and Mechanism of Uranium Removal from Acidic Uranium-Contaminated Groundwater by Sandstone Particle/Hydroxyapatite Composite

Authors: DING Dexin, LIU Junyu, LANG Tao, DING Yang, LI Feng, HU Nan, WANG Nieying, ZHANG Hui

Acidic in-situ leaching of sandstone-type uranium deposits leaves residual acid and uranium in groundwater, posing environmental risks. This study investigated the feasibility of loading hydroxyapatite (HAP) onto aquifer sandstone particles for in-situ remediation. Sandstone particles were collected from an aquifer and reacted with a HAP-generating solution for 52 days to produce sandstone/HAP composite. Batch experiments examined the effects of initial pH, initial uranium concentration, composite dosage, and interfering ions on uranium removal. Results showed successful HAP loading on sandstone surfaces. At initial pH 3, uranium concentration 5 mg/L, composite dosage 3 g/L, and 24 h reaction, uranium removal reached 95.6%. Interfering ions suppressed removal in the order Fe3+ > Mn2+ > Ca2+ > Mg2+ > SO4^2-. Removal mechanisms included electrostatic adsorption, ion exchange, and dissolution-reprecipitation, with good stability of immobilized uranium. This work validates the concept of in-situ HAP loading in aquifers and provides a basis for practical application in acidic uranium-contaminated groundwater remediation.

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Behavior and Mechanism of Uranium Removal from Acidic Uranium-Contaminated Groundwater by Sandstone Particle/Hydroxyapatite Composite

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507062• Jan 15, 2026

Construction of a VIKOR Composite Index-Based Probabilistic Prediction Model for Urban Water Blackening and Odor Recurrence Using Multi-Method Feature Selection

Authors: ZHANG Qi, ZHANG Jie, WANG Song, ZHOU Zhen, TANG Rui

The construction of predictive models for the recurrence of blackening and odor in urban water bodies has become a critical foundation for refined management of urban water environments. Based on water quality monitoring data from 16 cities in the Yangtze River Basin from 2020 to 2023, this study systematically evaluated six typical comprehensive index calculation methods and proposed a probabilistic prediction model for water blackening and odor recurrence centered on the VIKOR composite index. Through sampling analysis and literature review, a power-law relationship between transparency (y) and turbidity (x) was established (y = 3.12x−0.66), leading to a critical turbidity threshold of 46.9 NTU for blackening and odor. Using ANOVA, recursive feature elimination, and random forest, five indicators—turbidity, dissolved oxygen (DO), total phosphorus (TP), permanganate index (CODMn), and ammonia nitrogen (NH3-N)—were selected as the model's indicator system, with importance ranking: turbidity > DO > TP > CODMn > NH3-N. The VIKOR composite index exhibited the most robust mapping relationship with blackening probability, achieving high accuracy (RMSE = 0.029, MAE = 0.020) and consistency (NSE = 0.918, R2 = 0.918), whereas models based on other indices yielded R2 values below 0.84. The model demonstrated good predictive performance across the Yangtze, Pearl, Haihe, and Yellow River basins. This model offers a universal decision-making tool for precise identification, early warning, and targeted management of water blackening and odor recurrence, with potential integration into urban water smart platforms.

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Construction of a VIKOR Composite Index-Based Probabilistic Prediction Model for Urban Water Blackening and Odor Recurrence Using Multi-Method Feature Selection

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506010• Jan 15, 2026

Interpretation and Implementation Recommendations for the Technical Specification for Comprehensive Utilization of Titanium Gypsum (GB/T 45015-2024)

Authors: ZHANG Dongqi, HE Yi, XU Jie, QI Xiangzhao, LI Li, CHEN Gang

To facilitate accurate understanding and implementation of the provisions in the Technical Specification for Comprehensive Utilization of Titanium Gypsum (GB/T 45015-2024), and to promote technological capability in comprehensive utilization while effectively controlling environmental risks during utilization, this paper analyzes the current status and existing problems of titanium gypsum generation, management, and utilization technologies in China. The standard is systematically interpreted. It is concluded that the implementation of this standard will promote resource utilization of titanium gypsum, foster energy conservation and carbon reduction in the titanium dioxide industry, and further safeguard ecological and environmental security. China produces over 3,120×10^4 t of titanium gypsum annually (2023), yet its comprehensive utilization rate is only about 10%, far lower than that of phosphogypsum (~40%) and desulfurization gypsum (~80%). The standard, as the first national standard dedicated to titanium gypsum resource utilization, establishes technical pathways for building materials and ecological restoration, sets limits for soluble impurities, and specifies pollution control indicators throughout the utilization process. It addresses the long-standing gaps in technical standards, product quality variability, and environmental supervision, providing critical support for the green and low-carbon transformation of the sulfuric acid process titanium dioxide industry.

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Interpretation and Implementation Recommendations for the Technical Specification for Comprehensive Utilization of Titanium Gypsum (GB/T 45015-2024)

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507054• Jan 15, 2026

Adaptability of Machine Learning Prediction Models for Chlorine Consumption to Monitoring Frequency of Residual Chlorine in Wastewater Treatment Plants

Authors: PENG Xilin, MAO Zehong, GUO Jiaxin, MA Mingliang, ZHENG Xingyu, YAO Jie, TANG Hong, YAO Juanjuan

In many Chinese wastewater treatment plants (WWTPs), residual chlorine is still manually monitored at low frequencies, leading to imprecise disinfectant dosing. This study systematically compared four machine learning models—backpropagation (BP) neural network, long short-term memory (LSTM) neural network, random forest (RF), and support vector regression (SVR)—for predicting chlorine consumption (i.e., the difference between chlorine dose and residual chlorine) during non-monitoring periods under different residual chlorine monitoring frequencies (every 1, 2, 4, 6, and 8 h). Using data from Plant A (equipped with online residual chlorine monitoring) and Plants B and C (manual monitoring every 6 h and 8 h, respectively), input variables included online water quality indicators (temperature, flow, NH3-N, CODCr, TP, TN) and chlorine dose. Results showed that at 1-h intervals, LSTM achieved the highest prediction accuracy; at 2–4-h intervals, RF performed best; at 6-h or lower frequencies, BP was superior; SVR performed worst across all frequencies. Validation on Plants B and C confirmed BP's optimal performance under low-frequency conditions, and particle swarm optimization (PSO) significantly improved its accuracy. These findings provide a basis for selecting appropriate machine learning models for chlorine consumption prediction under varying monitoring frequencies, particularly low-frequency manual monitoring, thereby supporting precise disinfectant dosing control.

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Adaptability of Machine Learning Prediction Models for Chlorine Consumption to Monitoring Frequency of Residual Chlorine in Wastewater Treatment Plants

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507041• Jan 15, 2026

Performance and Microbial Mechanisms of Aerobic Granular Sludge for Textile Dyeing Wastewater Treatment

Authors: CAO Xianzhong, LOU Huiqing, YIN Ying, SHEN Yifeng

This study investigated the cultivation of aerobic granular sludge (AGS) in a sequencing batch reactor (SBR) for the treatment of real textile dyeing wastewater, focusing on the influence of organic loading rate (OLR) on granulation and pollutant removal. After 60 days of cultivation, dense granules of approximately 1 mm diameter were formed, with extracellular polymeric substances (EPS) content of 92.22 mg·L−1, achieving COD and color removal efficiencies of 88.5% and 73.3%, respectively. OLR significantly regulated sludge characteristics: at an OLR of 3.0 kg·(m3·d)−1, the average granule size reached a maximum of 1.38 mm, EPS content peaked at 95.21 mg·g−1, and the highest COD and color removals were observed (92.73% and 86.35%, respectively). However, an excessive OLR of 5.0 kg·(m3·d)−1 led to sludge bulking and disintegration. Microbial community analysis revealed that Proteobacteria (44.06%–49.17%) and Bacteroidetes (27.49%–29.64%) were the dominant phyla, with their abundances significantly correlated with EPS protein secretion and pollutant removal efficiency. This study elucidates the mechanism by which OLR optimizes textile wastewater treatment through modulation of microbial community structure and EPS secretion, providing a theoretical basis and technical support for the practical application of AGS in textile dyeing wastewater treatment.

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Performance and Microbial Mechanisms of Aerobic Granular Sludge for Textile Dyeing Wastewater Treatment

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507059• Jan 15, 2026

Application of Immobilized White Rot Fungi in the Treatment of Anaerobic Digestion Sludge

Authors: LIU Wang, ZHU Xuefeng, WANG Ziyi, CHENG Shicai, FANG Zexian, XU Wenjing, TONG Wanzi, LIU Hongbo

Anaerobic digestion sludge (ADS) contains recalcitrant organic matter and exhibits poor dewaterability, posing challenges for disposal. This study evaluated the immobilization of white rot fungi (WRF) on four carriers—polyvinyl alcohol, cotton thread, wood chips, and sodium alginate—for ADS treatment. Cotton thread immobilization yielded the earliest and most sustained enzyme activity, highest biomass retention, and minimal biomass loss. WRF treatment achieved a 10.09% removal of total chemical oxygen demand (TCOD) and significantly disrupted extracellular polymeric substances (EPS), selectively degrading soluble EPS. To maintain fungal activity, periodic carrier replacement was required. Compared to the control, the experimental group showed an 8.9 mg·L−1 reduction in total protein and polysaccharide content in soluble EPS, a 27.33% decrease in capillary suction time (CST), and improved sludge dewaterability. These results demonstrate the potential of WRF for ADS treatment.

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Application of Immobilized White Rot Fungi in the Treatment of Anaerobic Digestion Sludge

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202508004• Jan 15, 2026

Thermoelectric Generator-Driven Electrodeposition for Efficient Treatment of Low-Concentration Copper-Containing Wastewater

Authors: HUANG Huiting, YAO Han, YANG Zhengwu, ZHU Jun, FU Dan, ZHENG Meng, JIA Daqing, ZHANG Lehua

Industrial processes generate substantial low-grade waste heat and cold, which can be harnessed via thermoelectric generators (TEGs) based on the Seebeck effect. However, the low-voltage output of TEGs poses application challenges. This study investigates a TEG-driven electrodeposition system for efficient treatment of low-concentration copper-containing wastewater from electroplating, integrated circuit, and energy industries. The TEG system, comprising two series-connected semiconductor modules, achieved a maximum power of 0.36 W at a temperature difference (ΔT) of 130 °C. Optimal operating parameters for the coupled system were determined: ΔT = 90 °C, counter-current flow (two-side inlet), flow rate of 20 mL·min⁻¹, initial Cu²⁺ concentration of 500 mg·L⁻¹, and electrode gap of 0.7 cm. Under these conditions, after 60 min of electrodeposition, copper removal efficiency reached 99.42%, current efficiency was 67.93%, and the energy conversion efficiency of the TEG-electrodeposition system was 36.96%. The system also treated real copper-containing wastewater, achieving 95.83% removal within 100 min. Characterization via SEM, XRD, and XPS revealed that the electrodeposited product consisted of metallic copper and cuprous oxide, with metallic copper accounting for approximately 60%. This work provides a promising approach for utilizing industrial waste heat and cold to achieve low-energy, high-efficiency treatment of heavy metal wastewater.

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Thermoelectric Generator-Driven Electrodeposition for Efficient Treatment of Low-Concentration Copper-Containing Wastewater

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507036• Jan 15, 2026

Integrated Barrier and Anti-Seepage Technology for Iron Tailings Pond: Application and Environmental Evaluation

Authors: XIAO Rui, CHEN Ming

This study addresses the deficiencies in material and structural stability and the singular evaluation system in iron tailings pond pollution remediation. Based on an integrated design-construction-evaluation concept, we developed a three-dimensional anti-seepage system incorporating iron tailings sand-bentonite mixtures and a composite liner structure. The system was applied to an actual remediation project in Qichun County, Hubei Province, China, covering an area of 18.72×10^4 m^2 with 43.42×10^4 m^3 of tailings. Theoretical calculations of leachate generation, material testing, and structural optimization were performed. The optimized mixture achieved a permeability coefficient (k) reduction from 10^-4 cm/s to 10^-8 cm/s as bentonite content increased from 0% to 9%, meeting the engineering standard of k≤10^-7 cm/s. A novel 'pre-embedded pipe + expansion bolt' technique enhanced sealing at structural nodes. Post-remediation monitoring showed significant reductions in heavy metal concentrations in surrounding farmland soil (11.14%–72.41% decrease), all below risk screening values. Iron (Fe) and chromium (Cr) interception rates reached 97.17% and 96.76%, respectively. The Nemerow comprehensive pollution index dropped from 2.39 (moderate pollution) to 0.62 (no pollution), and the potential ecological risk index decreased from 288.50 (moderate risk) to 148.73 (slight risk), representing a reduction of 1–3 pollution levels. The project achieved a 2.78% increase in tailings resource utilization and a 4.71% reduction in engineering cost. This integrated technical system provides a viable approach for tailings pollution control and sustainable waste management.

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Integrated Barrier and Anti-Seepage Technology for Iron Tailings Pond: Application and Environmental Evaluation

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506041• Jan 15, 2026

Synergistic Composting of Urban and Rural Multi-Source Organic Waste and Product Quality Evaluation: A Case Study of a Treatment Center in the Taihu Lake Region

Authors: YAO Sheng, TANG Ruolan, MA Ruonan, MA Jingyuan, PAN Jiapeng, LI Ji, LI Guoxue, YUAN Jing

Urban and rural multi-source organic waste faces bottlenecks including high compositional heterogeneity, single resource recovery pathways, and uneven product quality. In the Taihu Lake region, active tourism and catering, high greening, and dense water networks generate large volumes of diverse waste with high moisture content, exacerbating these issues. This study evaluated a coupled bio-drying and aerobic composting process at a demonstration center in Linhu Town, Suzhou, Jiangsu Province, employing a three-stage control strategy: gradient dewatering, high-temperature stabilization, and maturation enhancement. Continuous operation showed that kitchen waste moisture content decreased from 77.70% to 58.69% after 1 day of bio-drying, to 23.22% after 7 days of silo reactor composting, and to 17.70% after at least 20 days of maturation. The aerobic composting phase maintained temperatures above 55°C for over 5 days, reaching a maximum of 68.1°C, meeting the harmless treatment requirements of CJJ 52—2014. After 20 days of maturation, the organic fertilizer product had an electrical conductivity below 4.00 mS·cm−1, organic matter content of 51.22%, total nutrient content of 5.61%, and heavy metal concentrations below the limits of NY/T 525—2021. The results provide technical support for efficient treatment and resource utilization of urban and rural organic waste.

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Synergistic Composting of Urban and Rural Multi-Source Organic Waste and Product Quality Evaluation: A Case Study of a Treatment Center in the Taihu Lake Region

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507021• Jan 15, 2026

Health Risk Assessment of Heavy Metals in Soil Around a Landfill Based on Monte Carlo Simulation

Authors: QIN Mengyuan, HE Qiuping, CHEN Dan, MEN Ruixue, JIA Lijuan, MA Linzhuan

The accumulation of heavy metals in soil around municipal solid waste landfills poses potential risks to human health. This study selected a municipal solid waste landfill and monitored the concentrations of eight heavy metals (Zn, Pb, Cd, Ni, Hg, Cu, As, Cr) in surrounding soil. The geo-accumulation index method was used for pollution assessment, and a health risk assessment model recommended by the USEPA, combined with Monte Carlo uncertainty analysis, was employed to evaluate the pollution status and health risks to nearby residents. Results showed that among the eight metals, Pb, Ni, and Cd exceeded risk screening values at 4.26%, 6.38%, and 4.26% of sampling points, respectively. Geo-accumulation indices indicated overall clean conditions (mean < 0), but slight pollution by Pb, Zn, Ni, Hg, and Cd at some points. Probabilistic risk assessment based on Monte Carlo simulation revealed that for both adults and children, the cumulative non-carcinogenic risk was negligible, while carcinogenic risk was acceptable. However, there was a very low probability (approximately 0.2%) of non-carcinogenic risk for children, and probabilities of unacceptable carcinogenic risk were 0.64% for adults and 3.21% for children. Nickel was the primary contributor to carcinogenic risk, and children faced higher health risks than adults. These findings provide a reference for pollution prevention and health risk management of soil around municipal solid waste landfills.

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Health Risk Assessment of Heavy Metals in Soil Around a Landfill Based on Monte Carlo Simulation

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506021• Jan 15, 2026

Differences in Root Surface Iron Plaque Components between Main and Ratoon Crops of Different Rice Varieties and Their Effects on Cadmium Accumulation in Brown Rice

Authors: ZOU Xinyi, WU Weijian, MA Qiao, ZHANG Qiying, TAN Xiaoyu, ZHENG Feiyu, DAI Rui, YANG Yang, ZENG Qingru, DENG Xiao

To elucidate the seasonal variation in cadmium (Cd) accumulation in ratoon rice and its relationship with root surface iron plaque, this study compared Cd concentrations in brown rice and the characteristics of iron plaque components (amorphous Fe, Am-Fe; crystalline Fe, Cry-Fe) between the main and ratoon crops of six rice varieties under different stubble heights. A field experiment was conducted in a Cd-contaminated paddy in Liuyang, Hunan (soil total Cd: 0.56 ± 0.06 mg·kg⁻¹). Ratoon crop treatments included low stubble (20 cm) and high stubble (60 cm). Brown rice Cd concentrations varied by variety, season, and stubble height. Low stubble generally increased brown rice Cd in the ratoon crop compared to high stubble; high stubble reduced Cd in most varieties relative to the main crop. Health risk assessment indicated that low stubble in the ratoon crop posed higher non-carcinogenic risk than the main crop and high stubble, while carcinogenic risks exceeded acceptable levels across all treatments. Iron plaque Am-Fe and Cry-Fe concentrations in the ratoon crop were generally lower than in the main crop, with Am-Fe consistently exceeding Cry-Fe. In the main crop, total Fe, Am-Fe, and Cry-Fe on root surfaces were significantly negatively correlated with brown rice Cd (P < 0.05), but correlations were not significant in the ratoon crop. High stubble reduced Cd accumulation and non-carcinogenic risk in most varieties, yet carcinogenic risk remained. Iron plaque significantly impeded Cd uptake in the main crop but its effect weakened in the ratoon crop. Selecting low-Cd-accumulating varieties and optimizing stubble height are key strategies for safe ratoon rice production in Cd-contaminated areas.

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Differences in Root Surface Iron Plaque Components between Main and Ratoon Crops of Different Rice Varieties and Their Effects on Cadmium Accumulation in Brown Rice

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506020• Jan 15, 2026

Multi-objective optimization of high-quality lithium extraction from lepidolite roasting based on neural network coupled modeling

Authors: DUAN Yunlong, LI Huiquan, LIU Changfeng, ZHANG Chenmu, SHI Yao, LIU Shanjun, YAN Chengsheng, FAN Bo, YU Xiuyuan, LI Zhihong, SHI Jingjing, ZHANG Jinlei

The rotary kiln roasting of lepidolite for lithium extraction faces challenges of unstable lithium conversion rates and high energy consumption. To address this, a multi-objective optimization method coupling improved neural network simulation with a multi-objective genetic algorithm was proposed, targeting the synergistic optimization of lithium conversion rate (TRLi) and natural gas consumption intensity (EIng). Using long-term industrial time-series data of batching parameters and kiln operating variables, back-propagation (BP) neural network and its particle swarm optimization (PSO) improved variant were developed to model TRLi and EIng. The PSO-BP model demonstrated superior accuracy in capturing the complex nonlinear relationships, reducing mean absolute percentage errors (MAPE) to 0.278 and 0.284 for TRLi and EIng, respectively. Subsequently, the non-dominated sorting genetic algorithm II (NSGA-II) was employed to construct a multi-objective optimization model, yielding a Pareto-optimal set of process parameters that maximize TRLi and minimize EIng. The results revealed that under NSGA-II optimized conditions, TRLi could be stabilized between 82.45% and 87.96%, an average increase of 3.61 percentage points over baseline operations, while EIng could be reduced to 53.7 m3 per ton of clinker. For an annual processing capacity of 3.2×105 tons of lepidolite concentrate and sulfate mixture, this corresponds to an additional 127.1 tons of lithium metal recovery, a reduction of 1,964,912 m3 in natural gas consumption, and a decrease of 3,763.84 tons in CO2 emissions annually. This study provides theoretical and technical support for the green, high-quality, and low-carbon supply of critical raw materials for the lithium battery new energy industry.

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Multi-objective optimization of high-quality lithium extraction from lepidolite roasting based on neural network coupled modeling

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507038• Jan 15, 2026

Simplified Estimation of Indoor Air Quality Based on Material Pollutant Emission Rates and Concentration Responses

Authors: SUN Mingzhuo, SHEN Chao, BI Xuesong, WANG Fang, DENG Weicai

To enhance the engineering practicality of pollutant pre-assessment, this study conducted environmental chamber tests for formaldehyde and TVOC emissions from 34 common decoration materials (25 solid and 9 liquid categories). Using the IndoorPACT software, variations in indoor pollutant concentrations under different material area loading rates and air change rates were simulated. Taking Harbin as a case study, concentration response ranges for various single materials under different area loading and ventilation conditions were simulated, leading to the construction of a simplified concentration prediction reference table. Results indicate that indoor pollutant concentrations from both solid and liquid materials peak on the second day after decoration, but decay rates differ significantly: liquid materials decrease by 70%–90% within about one week, and given their typically higher area loading rates in real projects, they exert a more significant impact on indoor air quality in the early post-decoration period. In contrast, solid materials decay more slowly and become the dominant long-term pollution source. The simplified estimation method based on these emission characteristics demonstrates good engineering applicability, providing effective reference for material selection, scheme comparison, and preliminary indoor air quality prediction and control in actual decoration projects.

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Simplified Estimation of Indoor Air Quality Based on Material Pollutant Emission Rates and Concentration Responses

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507027• Jan 15, 2026

Field Real-Time Monitoring of Ammonia Nitrogen in Different Water Bodies Using GPMCS

Authors: ZHANG Tongtong, WANG Zhengguo, YAN Haojie, LI Zhaoxing, WANG Zijing, ZHANG Wenjun, LI Tianling

Ammonia nitrogen (NH3-N) is a common water pollutant that can induce eutrophication and threaten aquatic ecosystems and human health. Accurate monitoring is essential for water safety. This study applied a self-developed gas-permeable membrane-based conductivity sensor (GPMCS) for real-time in-situ monitoring of NH3-N in two water bodies. In the Qunying River (surface river water), GPMCS captured concentration fluctuations linked to pump operations and sewage intrusion, with mean inlet and outlet concentrations of 4.67 and 3.42 mg/L, respectively. In Swan Lake (landscape aquaculture water), concentrations reached up to 11.16 mg/L, with site means of 6.42 and 7.04 mg/L, influenced by aquaculture activities, weather, and location. GPMCS results correlated strongly with national standard methods (r1=0.8132, r2=0.7483), confirming accuracy and reliability. Compared to existing techniques, GPMCS offers high selectivity, strong anti-interference, portability, no sample pretreatment, low cost, and environmental friendliness, making it suitable for long-term in-situ monitoring. This technology provides robust support for sustainable water environment management.

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Field Real-Time Monitoring of Ammonia Nitrogen in Different Water Bodies Using GPMCS

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506053• Jan 15, 2026

Low-Temperature Micro-Oxidation-Driven Synergistic Dealkalization and Soil Reconstruction of Red Mud with Coal

Authors: XIE Erman, ZENG Wei, LI Zhesong, SONG Haoran, TIAN Senlin, HU Xuewei, JU

Red mud, a highly alkaline industrial solid waste from alumina production, poses severe environmental risks due to its high alkalinity, low organic matter content, and poor aggregation, which critically impede its soil reconstruction and ecological utilization. This study proposes a novel approach of low-temperature micro-oxidation to drive the synergistic soil reconstruction of red mud and coal. By constructing a low-temperature micro-oxidation atmosphere, the soil properties of the reaction products were investigated, the decomposition and reconstruction of alkaline minerals and alkali release were analyzed, and the oxidation of carbon-based minerals and organic matter transformation in coal were examined. The mechanism of the synergistic reaction between red mud and coal under low-temperature micro-oxidation was elucidated. Results showed that at 250 °C under micro-oxidation, the pH of the product decreased to 8.47, organic matter content increased to 12.98%, and the proportion of aggregates >0.250 mm increased. Alkaline minerals such as cancrinite and grossular in red mud underwent decomposition and reconstruction in the low-temperature hydrothermal environment, releasing substantial free alkali. The condensed aromatic rings of carbon-based minerals in coal were oxidized by free radicals, leading to ring-opening and bond cleavage, producing small-molecule organic acids and macromolecular humic acids. The continuous oxidation of carbon-based minerals in coal generated acids, which neutralized the alkali released from red mud, driving sustained dealkalization. The inorganic particles of red mud flocculated with macromolecular humic acids, forming micro-aggregates and significantly improving soil properties. This research provides technical support for the rapid ecological utilization of red mud at industrial scale.

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Low-Temperature Micro-Oxidation-Driven Synergistic Dealkalization and Soil Reconstruction of Red Mud with Coal

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507030• Jan 15, 2026

Spectrophotometric Method for Rapid Determination of As(V) and As(III) in Industrial Wastewater

Authors: ZHOU Guotao, KONG Linghao, ZHAO Yanxia, WANG Enquan, PENG Xianjia

Arsenic is a toxic metalloid predominantly present in water as As(V) and As(III), whose speciation governs toxicity and mobility. Conventional speciation methods (HPLC-ICP-MS, IC-HG-AFS) offer ultralow detection limits but suffer from high cost, long analysis times, and non-portability, hindering on-site rapid monitoring. This study presents a sulfide-based spectrophotometric method exploiting the quantitative reaction between As(V) and S2− to form monothioarsenate (H3AsO3S) with a characteristic absorption at 233 nm. Under optimized conditions (H+ concentration 1 mol·L−1, Na2S dosage 5 mmol·L−1, reaction time 3 min, N2 purging 2 min), As(V) is directly quantified. Total arsenic is determined after complete oxidation of As(III) to As(V) using NaClO (10 mmol·L−1, pH 12, 5 min), and As(III) is obtained by difference. The method exhibits linearity over 0.5–50 mg·L−1 (A = 0.0209c + 0.0627, R² = 0.999), a detection limit of 0.17 mg·L−1, spike recoveries of 101.9%–104.1%, and relative standard deviation of 1.06%. Validation against real industrial wastewater samples showed relative deviations <10% compared with HPLC-ICP-MS and IC-HG-AFS. Total analysis time is within 15 min. The method is simple, cost-effective, and suitable for field monitoring.

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Spectrophotometric Method for Rapid Determination of As(V) and As(III) in Industrial Wastewater

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507032• Jan 15, 2026

Emission Reduction Effects and Costs of Energy Policies under Carbon Neutrality Pathways in Guangdong Province

Authors: LIU Jiangtao, LIU Zhen, LIAO Cuiping, HUANG Ying

To mitigate global warming, regional carbon neutrality pathways are critical. Based on the Guangdong Energy Policy Simulator (EPS) model, this study simulates total energy consumption and greenhouse gas (GHG) emissions under baseline, Carbon Neutral 60 (CN60), and Carbon Neutral 50 (CN50) scenarios, and analyzes the emission reduction effects and costs of various energy policies. Results show that by 2060, total energy consumption under CN60 and CN50 decreases by 39% and 44% relative to baseline, respectively. Primary electricity and other energy, natural gas, oil, and coal account for 56%, 26%, 14%, and 4% under CN60, and 60%, 24%, 13%, and 3% under CN50. GHG emissions under CN60 drop to 80×10^6 tCO2e by 2060, an 89% reduction from 2020; under CN50, emissions reach 92 and 55×10^6 tCO2e in 2050 and 2060, respectively, reductions of 87% and 92% from 2020. Policies such as increasing clean electricity share, industrial electrification (hydrogen), increasing green power purchases, building electrification, F-gas reduction, and improving industrial energy efficiency standards show significant reduction effects, with clean electricity share being the primary source. Policies like improving industrial energy efficiency standards, increasing industrial product utilization, and increasing clean energy vehicle market penetration are cost-effective; increasing clean electricity share, green power purchases, building electrification, and F-gas reduction effectively balance reduction effects and costs. Industrial electrification (hydrogen) contributes >5% cumulative reduction but faces economic challenges for full-scale promotion in the short term; industrial carbon capture and storage and electrolytic hydrogen contribute <2% cumulative reduction with high costs. Therefore, Guangdong should prioritize cost-effective policies, promote balanced policies, gradually optimize energy structure, achieve clean electricity, and foster green industrial transformation to achieve carbon neutrality at lower economic cost.

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Emission Reduction Effects and Costs of Energy Policies under Carbon Neutrality Pathways in Guangdong Province

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507043• Jan 15, 2026

Thermal Steel Ball-Enhanced Rotary Drum Drying of Sludge: Drying Characteristics, Moisture Diffusion Behavior, and Mechanisms

Authors: YU Shilin, ZHU Jinwei, LU Zhengnan, DENG Shuanghui, ZHOU Ao, WANG Xuebin, TAN Houzhang, PAN Zhicheng

Municipal sludge with high moisture content and strong viscosity tends to form a dense crust during conventional rotary drum drying, reducing heat and mass transfer efficiency and prolonging drying time. This study proposes a thermal steel ball-enhanced rotary drum drying method that introduces high heat capacity, high thermal conductivity steel balls to achieve synergistic contact heat conduction and mechanical disturbance. An evaluation system incorporating dimensionless moisture ratio (MR), drying rate (DR), characteristic drying time (tdry), effective moisture diffusivity (Deff), and volumetric evaporation intensity (U) was established. Results show that compared with conventional drying, steel ball-enhanced drying increased maximum drying rate (DRmax) by 22.59%–41.19%, U by 38.06%–93.43%, and shortened tdry by 27.56%–48.30%, with more pronounced advantages under high load conditions. Deff was significantly higher throughout the process, with maximum increase up to 48.30%, indicating that ball rolling and collision effectively disrupt the crust and promote moisture migration. Mechanistic analysis reveals that the performance enhancement arises from the dual action of thermal-mechanical coupling and mechanical disturbance, which enhances local heat flux via contact conduction and dynamically renews the drying interface, shortening diffusion paths. This study elucidates the heat and mass transfer mechanisms of thermal steel ball-enhanced sludge drying, providing theoretical support and technical reference for efficient sludge volume reduction and dryer design optimization.

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Thermal Steel Ball-Enhanced Rotary Drum Drying of Sludge: Drying Characteristics, Moisture Diffusion Behavior, and Mechanisms

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507029• Jan 15, 2026

Environmental Risk Assessment of Aerated Concrete Prepared by Synergistic Utilization of Incineration Fly Ash and Multi-Source Solid Wastes

Authors: SHI Songwei, ZHANG Wenpei, ZHAO Cheng, SUN Yansong, ZHANG Yan, YAN Mi

This study systematically evaluates the environmental risks associated with the resource utilization of municipal solid waste incineration (MSWI) fly ash in the production of aerated concrete, co-prepared with multiple solid wastes. The focus is on the leaching behavior and total content of heavy metals (Cr, Pb, Cd, Cu, Zn) under CO2 curing and chelating agent stabilization. Water washing pretreatment parameters (liquid-to-solid ratio, washing time, ash-to-slag ratio) were optimized for chloride removal. Results demonstrate that CO2 curing suppresses the leaching of most metals; leaching concentrations of Cr, Pb, Cd, and Zn decrease with reduced fly ash content, whereas Cu leaching increases when fly ash is absent. The addition of 17.5% organic sulfur stabilizer (DTC) significantly outperforms inorganic sulfide (Na2S) in immobilizing heavy metals, achieving compliance with national standards without compromising compressive strength or carbon sequestration. Water washing effectively reduces soluble chloride content to below 1% (mass fraction), meeting the HJ 1134-2020 regulatory limit. Optimal parameters include a liquid-to-solid ratio of 5, washing time of 20 min, and a raw material ratio of incineration bottom slag:fly ash:slag = 40:20:40. Under these conditions, the final product exhibits a compressive strength of 1.50 MPa, with heavy metals and soluble chlorides fully compliant. This work provides key technical support for the safe recycling of MSWI fly ash in building materials.

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Environmental Risk Assessment of Aerated Concrete Prepared by Synergistic Utilization of Incineration Fly Ash and Multi-Source Solid Wastes

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507051• Jan 15, 2026

Dynamic Ammonia Emission Patterns and Recovery from Growing-Finishing Pig Houses

Authors: SONG Yanan, WAN Junfeng, GUO Xiaoying, ZHANG Jie, WANG Yan

This study investigated the dynamic characteristics and recovery of ammonia emissions from a growing-finishing pig house in Yanshi District, Luoyang City, Henan Province, China. High-sensitivity electrochemical sensors and an ammonia absorption recovery device were employed for continuous monitoring and treatment of exhaust air. The results revealed periodic fluctuations in ammonia emission concentrations, strongly correlated with indoor temperature and humidity. Over the entire monitoring period, the average daily ammonia concentration in exhaust air was 9.852 mg·m−3, below the national emission limit of 25 mg·m−3. However, during high-temperature periods (>30 °C), localized concentrations reached 38.36 mg·m−3. Humidity, particularly from spray cooling, temporarily suppressed ammonia volatilization, but its effect was modulated by temperature. Total ammonia emitted during the study was 1380.4 kg, with an average per-pig emission rate of 0.034 kg·d−1. After treatment with the exhaust gas absorption device, the average daily ammonia concentration dropped to 0.437 mg·m−3, achieving a mean recovery efficiency of 93.5%. These findings demonstrate that controlling environmental factors and employing external air absorption devices can significantly reduce ammonia emissions, offering a viable pathway for mitigating nitrogen pollution from livestock operations and promoting resource recovery.

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Dynamic Ammonia Emission Patterns and Recovery from Growing-Finishing Pig Houses

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202506031• Jan 15, 2026

Preparation and Engineering Scale-Up of Cyanobacteria-Based Columnar Activated Carbon

Authors: WU Jing, HUANG Dongxu, WU Nan, PU Tian, ZHU Ge, ZHENG Jinxing, ZHENG Zhiyong, LIU He

The production of activated carbon from waste biomass such as cyanobacteria from Lake Taihu represents a promising resource utilization route. However, existing studies are mostly confined to laboratory scale, and the gap between laboratory processes and industrial production hinders the evaluation of technical feasibility and economic viability. This study optimized the process for producing cyanobacteria-based columnar activated carbon by co-processing cyanobacteria with garden waste (sawdust), and validated the process on an engineering-scale production line with a daily capacity of 5 t of raw materials. Economic feasibility was also assessed. Results showed that the optimized activated carbon exhibited a particle strength of 91.3% and a specific surface area of 571.44 m2·g−1. The engineering-scale line processed 5 t of raw materials daily, yielding approximately 1.18 t of activated carbon with stable quality: strength of 94.3% and specific surface area of 471.42 m2·g−1, featuring a microporous-dominant structure with coexisting micropores and mesopores. Cost analysis indicated a production cost of 3,595.65 CNY per ton of activated carbon, demonstrating favorable economic benefits. This work provides a basis for larger-scale production and application of cyanobacteria-based activated carbon.

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Preparation and Engineering Scale-Up of Cyanobacteria-Based Columnar Activated Carbon

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507046• Jan 15, 2026

Carbon Footprint Accounting Method for Electromechanical Products Based on Life Cycle Assessment

Authors: WEI Xikai, RUAN Jiatong, TAN Xiaoshi

Addressing the insufficient applicability and accuracy of carbon footprint accounting for electromechanical products due to data gaps, this study proposes an accounting method based on life cycle assessment (LCA). Using LCA as the overall framework with a system boundary of "cradle to gate", the method constructs a carbon footprint accounting approach combining substitution algorithms and correction coefficients for different data missing scenarios from suppliers, manufacturers, and databases. Data quality indicators and Monte Carlo simulation are employed to quantify data quality and uncertainty, while single-factor and multi-factor sensitivity analyses identify key influencing factors. Taking an optical gyrocompass as a case study, the carbon footprints and uncertainties under eight typical data missing scenarios are explored, and robustness checks are conducted on five typical products including transformers, high-speed diesel engines, and wind turbines. As data missing degree deepens, the carbon footprint deviation of the optical gyrocompass increases from 0.05% to 3.03%, and uncertainty rises from 2.65% to 5.45%. Under mixed data missing scenarios, the carbon footprint uncertainties of all five electromechanical products remain below 10%. The method exhibits wide applicability, strong implementability, and high accuracy, effectively supporting carbon footprint accounting for electromechanical products, reducing carbon tariff risks, optimizing emission reduction strategies, and promoting green development.

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Carbon Footprint Accounting Method for Electromechanical Products Based on Life Cycle Assessment

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507055• Jan 15, 2026

Rapid Identification of Industrial Wastewater Discharges in Municipal Sewer Networks Based on Three-Dimensional Fluorescence Spectroscopy and Spectral Angle Mapping

Authors: JI Yuxi, HU Wei, ZHU Huifeng, ZHAO Zhonghua, ZHANG Guanyi, YU Xubiao

The increasing complexity of pollutant sources in municipal wastewater networks, driven by unauthorized industrial discharges, poses significant risks to the stable operation of wastewater treatment plants. This study, conducted in an industrial park in Ningbo, Zhejiang Province, developed a source apportionment method using excitation-emission matrix (EEM) fluorescence spectroscopy combined with spectral angle mapping (SAM). A pollution fingerprint database was constructed from wastewater samples of six representative enterprises (A–F) and municipal sewer samples. The SAM algorithm demonstrated high sensitivity and stability in detecting changes in water composition, with spectral angle values showing a strong linear correlation (R² > 0.88) with the volume ratio of enterprise wastewater in mixed samples. This enabled both qualitative identification and quantitative estimation of pollution sources. Field application over a 12-hour monitoring period identified two enterprises as major contributors to organic matter and nitrogen during critical pollution episodes, consistent with trends in DOC, TN, and UV254. The proposed EEM+SAM approach offers a non-invasive, high-throughput method for real-time monitoring and source tracing of multi-source pollution in complex sewer systems, providing a scientific basis for pollution accountability and precise enforcement.

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Rapid Identification of Industrial Wastewater Discharges in Municipal Sewer Networks Based on Three-Dimensional Fluorescence Spectroscopy and Spectral Angle Mapping

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202512072• Jan 15, 2026

Intelligent Detection of Drainage Pipeline Defects Based on Cross-Frame Annotation and Recall Optimization

Authors: XU Xingquan, CHEN Ben, ZHU Zeyu, LIU Shaohui, SUN Yiye, CHEN Hangbiao, CHEN Zhanli, LYU Hui

Drainage pipeline defect detection predominantly relies on closed-circuit television (CCTV) inspection, which is labor-intensive, inefficient, and prone to missed detections. Although deep learning-based object detection has been applied, it suffers from low precision, recall, and speed in practical scenarios. This study proposes an engineering-oriented detection scheme achieving high recall and low miss rates. The annotation phase employs a cross-frame strategy combining manual labeling of first and last frames with interpolation and tracking-based refinement. Data preprocessing introduces perceptual hashing to identify similar images, enhancing training efficiency. For detection, a Faster R-CNN model is enhanced with Focal Loss to focus on hard examples, defect classification and grading, and a dynamic threshold strategy to improve recall. Validated on 5,068.72 m of real pipeline data, the method achieves a recall rate exceeding 98% across 16 defect categories, a miss rate of only 2% for grade 4 defects, and a 425% improvement in per-segment detection efficiency compared to manual screening. These results demonstrate the method's effectiveness in balancing recall, miss rate, and speed for engineering deployment.

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Intelligent Detection of Drainage Pipeline Defects Based on Cross-Frame Annotation and Recall Optimization

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Original ResearchVol. 20, Issue 3 • pp. 100-112DOI: 10.12030/j.cjee.202507057• Jan 15, 2026

Rapid Detection of Trace Pb(II) in Water Using a Rod-Shaped Bismuth-Based Electrode

Authors: WANG Chencan, YANG Yuxi, WAN Junfeng, GUO Xiaoying, XU Zicong, YANG Jinghe, ZHANG Jie, JU

This study presents a novel electrochemical sensor for the rapid detection of trace lead ions (Pb(II)) in water, utilizing a rod-shaped bismuth-based electrode. The electrode was fabricated by modifying a glassy carbon electrode (GCE) with basic bismuth nitrate [Bi6O5(OH)3](NO3)5·3H2O, synthesized via a chemical precipitation method. The sensor was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), electron probe microanalysis (EPMA), and energy-dispersive X-ray spectroscopy (EDS), confirming the rod-like morphology and composition. Electrochemical detection was performed using differential pulse voltammetry (DPV) in a 0.1 mol·L−1 NaAc-HAc buffer (pH 4.3). The sensor exhibited a linear detection range for Pb(II) from 1 to 90 μg·L−1, with a detection limit of 0.34 μg·L−1 and a sensitivity of 106 μA·(μmol·L−1)−1. The electrode demonstrated excellent anti-interference capability and reproducibility. Recovery tests in real water samples (tap water and campus lake water) yielded high recovery rates, indicating practical applicability. This work provides a simple, cost-effective, and reliable method for monitoring trace Pb(II) in environmental water, particularly relevant for public swimming pools and similar aquatic facilities.

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Rapid Detection of Trace Pb(II) in Water Using a Rod-Shaped Bismuth-Based Electrode

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