With the rapid development of the renewable energy industry, the usage of lithium iron phosphate batteries has soared. Therefore, the recycling of spent batteries has become a social focus. The selective leaching method can effectively extract lithium, reduce impurities, and improve recycling efficiency. This paper systematically reviews various selective lithium leaching techniques, including chemical oxidation, acid-assisted leaching, electrochemistry, high-temperature roasting, mechanochemistry, and so on, which further compares their respective advantages and disadvantages from the aspects of technical economy and environmental benefits. The results indicate that the chemical oxidation method has advantages in cost control and operational flexibility, while the electrochemical method is more and environmentally friendly and green. For the selective recycling of spent lithium iron phosphate batteries, more efficient, environmentally friendly, and economical recycling solutions should be developed in the future. This will provide new ideas for exploring selective recycling strategies for lithium iron phosphate batteries, which can promote comprehensive and coordinated development of the economy, environment, and technology, and thereby build a virtuous cycle system of new quality productivity.

This study conducted X-ray fluorescence (XRF) and X-ray diffraction (XRD) experiments on 10 common types of solid waste. By employing non-parametric tests, the XRF and XRD fingerprint characteristics of solid waste were extracted. A normalized approach was adopted to combine the two fingerprint characteristics to form XRF-XRD coupled spectral fingerprint characteristics. A machine learning classification model was trained using the three fingerprint characteristics as a dataset. It was found that the random forest model exhibited the best classification recognition performance, with classification accuracy, recall rate, and precision rate in the validation set reaching 98.0%, 97.5%, and 97.6%, respectively. This confirmed that the classification performance of coupled spectral fingerprint characteristics was superior to that of single spectral fingerprint characteristics. A method for extracting multi-dimensional fingerprint characteristics of solid waste using XRF-XRD was developed, laying a methodological foundation for the identification of fingerprint characteristics of solid waste.

To investigate the effect of fulvic acid (FA) addition on heavy metal speciation during aerobic composting of sludge-based biomass waste, a 44-day aerobic composting experiment was conducted using sludge, straw, and food waste as raw materials. The effects of FA at 100, 200, and 400mg·kg^-1 on heavy metal transformation dynamics were examined. Results showed that FA addition increased peak temperature, cation exchange capacity (CEC), volatile solids (VS) degradation rate, and germination index (GI). FA notably facilitated the conversion of heavy metals into more stable residual fractions, with residual cobalt (RES-Co), nickel (RES-Ni), and copper (RES-Cu) contents increasing by 11.0%~16.9%, 4.1%~6.8%, and 0.8%~6.0%, respectively, compared to the control. By enhancing the accumulation of aromatic carbon in dissolved organic matter (DOM) and enriching specific microbial taxa (e.g., Proteobacteria and Bacteroidetes), FA accelerated humification and enhanced the immobilization of heavy metals. GI, CEC, pH, and RES-Ni were identified as key factors influencing microbial community shifts. The 400mg/kg FA treatment exhibited the most significant heavy metal passivation effect, primarily by accelerating the humification of dissolved organic matter and optimizing the microbial community structure.

To identify the key extracellular polymeric substance (EPS) fractions and elucidate the microbial mechanisms driving foaming in high solid anaerobic digestion (HSAD) of food waste, organic loading rate (OLR) perturbations were introduced in a semi-continuous anaerobic digestion (AD) reactor to induce the foaming phenomenon. The responses of physicochemical parameters and microbial community structure were systematically investigated. The results indicated that foaming height was positively correlated with hydrophobic proteins in soluble EPS, as well as with hydrophobic humic substances (HU) and hydrophobic proteins (PN) in total EPS. This suggests that these three EPS fractions are potential key contributors associated with foaming. Microbial analyses revealed a significant positive correlation between the abundance of Fastidiosipila, Rikenellaceae_RC9_gut_group, W5053, and W5 genera with foaming height and the concentrations of key EPS fractions (P≤0.05), indicating their role as key microorganisms contributing to AD foaming. Additionally, multivariate statistical analyses of physicochemical and microbial parameters indicated that, the continuous increase in OLR stimulated the accumulation of volatile fatty acids (VFA), which in turn promoted the proliferation of Fastidiosipila, Rikenellaceae_RC9_gut_group, W5053, and W5. These microorganisms subsequently synthesized substantial amounts of key EPS fractions in response to environmental stress. The over-secreted EPS were oriented and arranged on the surface of bubbles, enhancing the mechanical strength of the liquid membrane and slowing down bubble rupture. Unlike other key microorganisms that primarily act in the liquid phase, W5 also migrated with the bubbles to the foam layer, further promoting foam stabilization by secreting hydrophobic HU. This study provides a theoretical basis for developing defoaming strategies for AD systems treating food waste.

Improper export of hazardous waste may cause serious environmental pollution and regulatory risks. To improve the accuracy and scientific nature of export risk warning, this study constructed a hazardous waste export risk warning system based on K-means clustering and particle swarm optimization BP (PSO-BP) neural network. Based on multidimensional indicators of historical data, the export risk of hazardous waste was classified using the K-means clustering algorithm, and the initial parameters of the BP neural network were optimized by the PSO algorithm, thereby improving the accuracy and convergence efficiency of risk prediction. The experimental results showed that the consistency between the risk classification by K-means clustering and expert annotation was 93.2%, proving that the inherent risk structure of the data could be effectively revealed by this method. The prediction accuracy of the PSO-BP neural network reached 92.5%, and the mean square error was reduced to 0.012. Compared with the traditional BP neural network, the prediction accuracy was significantly improved, and the training convergence speed was increased by 40%. Based on the above model, a hazardous waste export risk warning system was developed in this study, through which data collection, risk assessment, model prediction, and warning visualization were achieved. The implementation and application of the model were verified using 30 types of hazardous waste as examples. The results showed that hazardous waste export data could be analyzed in real time, dynamic warnings could be provided based on risk prediction results, and the efficiency of hazardous waste export management could be effectively improved.

This study investigated the impacts of vegetation restoration patch patterns (blank control, checkerboard, horizontal strip, and diagonal strip) and scouring flow rates (3, 4.5, and 6L/min) on slope soil erosion characteristics and vegetation conservation benefits in a mining wasteland of Urat Front Banner. Key findings include: Runoff and sediment yield decreased on vegetation-restored slopes but increased with higher souring flow rates. The horizontal strip pattern slope exhibited the smallest increase in runoff and sediment yield with rising flow rate, achieving the highest overall runoff reduction rate (34.36%) and sediment reduction rate (79.50%), and sediment reduction capacity [35.09g/(min·m²)]. Runoff rates generally increased during scouring, while sediment yield rates varied across patterns. Sediment yield rate within vegetation patches were significantly lower than the slope average and often negative. The horizontal strip slope exhibited stable sediment yield rate, with the lowest patch sediment yield rate [-13.02g/(min·m²)]. Except for the horizontal strip slope, sediment yield rates correlated linearly with runoff rates. Scouring flow rates dominated runoff and runoff rates, contributing 79.37% and 66.21%, respectively. Moreover, vegetation patch patterns exerted stronger effects on erosion than runoff. In conclusion, the horizontal strip pattern is optimal for soil and water conservation in mining wastelands, and drainage design is crucial for erosion control in these areas.

Reclaimed water is an important irrigation source in the agricultural field, but it contains antibiotic resistance genes (ARGs), which are potential pollutants. There have been relatively few reports on the influence of reclaimed water irrigation volume on the level of soil antibiotic resistance. This study constructed a controlled experiment and conducted a comparative analysis of the above issues using metagenomic analysis. The results showed that a total of 442 ARGs belonging to 27 ARG types were identified in the reclaimed water-soil irrigation system. The abundance of ARGs in in reclaimed water irrigation soil increased by 4.04% -28.62%, with the greatest increases in the abundance of colistin, β-lactam, and multidrug resistance genes. During the irrigation process, the abundance, diversity, and risk of soil ARGs, as well as the contribution of reclaimed water, exhibit anoverall fluctuating trend of first increasing and then decreasing. High irrigation volume enhanced the level of soil antibiotic resistance, which was especially evident in the middle stage of irrigation. However, due to soil matrix and recovery capacity, the difference in irrigation volume did not significantly affect the antibiotic resistance of irrigated soil throughout the entire process (variance analysis, P>0.1). Network analysis and variance partitioning analysis (VPA) indicatedthat microbial communities are the main factor affecting the transmission of ARGs in reclaimed water-irrigated soil, while high irrigation volume increased the contribution of mobile genetic elements (MGEs) represented by the integrator intI1, to the transmission of ARGs, resulting in a significant weakening of source characteristics. The research results provide fundamental theoretical support for understanding the spread of antibiotic resistance in reclaimed water and soil, and offer scientific guidance for the risk prevention and control of soil antibiotic resistance and the utilization of reclaimed water.

This study investigated the effects of sugarcane bagasse biochar on the degradation of azoxystrobin and the structural composition of microbial communities in flooded paddy soils from South China using a microcosm system. Results demonstrated that biochar pyrolyzed at 300℃, 500℃, and 700℃ accelerated azoxystrobin degradation during the early incubation phase (10d), achieving degradation rates of 32.42%~34.87%, significantly higher than the 16.48% observed in the control (no biochar). However, it ultimately inhibited complete degradation by the late phase (50d), with final degradation rates of 88.78%~89.76% in biochar-amended soils versus 98.77% in the control, demonstrating an initial stimulation followed by suppression. The inhibitory effect intensified with increasing application rates of 700℃ biochar (BC700). Azoxystrobin acid, a key metabolite, was identified during this process. High-throughput 16S rRNA sequencing revealed that BC700 addition reduced total microbial species richness and Chao1index. Comparative analysis showed that 5% and 10% biochar treatments significantly decreased the relative abundance of Desulfobacterota while increasing Citrifermentans and Bacillus spp. compared to pristine soil and the 3% biochar treatment. Conversely, Clostridium_sensu_stricto_12 abundance declined.

In this study, five treatments (CK: control with no Pb input, Pb₃₀:30mg/kg soil, Pb₆₀:60mg/kg soil, Pb₁₂₀:120mg/kg soil, Pb₂₄₀:240mg/kg soil) were set up by adding PbCl₂ solution withdifferent Pb concentrations to atypical subtropical urban park soil. The indoor incubation experiments were carried out for 28d to investigate the response mechanism of potential N₂O emissions from urban park soilto different exogenous Pb additions. The results showed that the cumulative N₂O emissions from Pb₃₀~Pb₂₄₀ treatments were significantly higher than those from CK, which increased linearly with the increases of exogenous Pb additions and soil Pb contents, during the whole incubation period. After 14d of Pb addition, the activities of nitrite reductase and N₂O reductase increased and decreased with the increasing soil Pb content, respectively, which resulted in significant increases in the potential N₂O emission ratesfrom soil. After 14~28d of Pb addition, soil pH significantly decreased with the increasing soil Pb content, and the combined inhibitory effects of decreasing pH and increasing Pb content on the N₂O reductase activity were significantly enhanced. The combined effects of the above-mentionedprocesses ultimately resulted in significant increases in the potential N₂O cumulative emissionsfrom soilwith increasing Pb additions during the incubation period. This study indicates that the effects of Pb pollutants on nitrogen cycle and denitrification microorganisms should be paid more attention in the future, considering the accumulations of Pb pollutants in urban park soil will increase the risk of potential N₂O emission. This study can provide scientific guidance for management of urban park and formulating measures for the reduction of N₂O emissions from urban park soil.

Based on the investigation of 50 rural black and odorous water remediation projects in Chongqing, this study constructed a "Pressure-State-Response-Benefit" (PSRB) framework model, screened and determined the evaluation index from the four dimensions of Pressure, State, Response and Benefit, and formed an evaluation index system. Based on the investigation of 11 typical cases of black and odorous water specifically ponds, ditches, and rivers that had been remediated for over six months, an evaluation was conducted. Among these, the remediation effect of pond-type black and odorous water was tracked and evaluated in June, August, and October 2023. The results indicate that the weights of the four dimensions Pressure, State, Response and Benefit were 0.27, 0.21, 0.36, and 0.16, respectively. The negative indexes with higher weights (C₁₁, C₁₄, C₂₄, C₃₆) outnumber the positive indexes with higher weights (C₃₁, C₄₁). This suggests that although the remediation of rural black and odorous water has received a positive response, the water that have been remediated still face significant pressure and have limited benefits. Among them, the remediation effect of 10cases was rated as "Effective," while 1case was rated as "Passing." In the Pressure dimension, factors such as "high population load in the water area," "damage to sewage interception and pipe networks," and "residual black and odorous sludge," as well as in the Response dimension, "the investment in water body remediation is relatively high" and "insufficient implementation of operation and maintenance management" were the main adverse influencing factors of the remediation effect.