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Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool to characterize DOM that interacts with heavy metals in MSWI bottom ash (IBA). Here, two fresh IBA samples collected from large MSWI plants were subjected to 33 days of accelerated weathering. Carbon content and fluorescence characterization of DOM and leaching behavior of heavy metals (Cu, Ba, Cr, Ni, and oxyanions) were monitored during the weathering. The mineralogical and chemical properties of IBA during the weathering process were also characterized. EEM combined with parallel factor analysis showed that fluorescent DOM could be decomposed into humic-like (C1, C2) and tryptophan-like substances (C3), while the accelerated weathering process can be further divided into three phases. Fitted cubic polynomials described well the changes in the specific intensity of fluorescence components. Humification and freshness indexes and SUVA results suggested the leached DOM contained a higher proportion of condensed aromatic structures and/or conjugation of aliphatic chains post-weathering. The results also revealed that adsorption of humic-like substances onto neo-formed reactive surfaces occurred quickly in the early stage of accelerated weathering; thereafter, biodegradation of lower molecular mass-hydrophilic organic carbon fraction plays a vital role in further reduction of Cu and Cr leaching in subsequent weathering. Oxyanions (Mo and Sb) became more mobile after 3 days of accelerated weathering, but their leaching was effectively reduced after the weathering process. A novel method for an IBA weathering treatment combined with enhanced microbial degradation is proposed. These findings provide new and inspiration for improving accelerated weathering technology.

Biochar has attracted great interest in both CO2 capture and supercapacitor applications due to its unique physicochemical properties and low cost.

Porous carbons are excellent sorbents for removing organic pollutants. Green conversion of biowaste into advanced porous carbons is crucial for industrialized production and practical applications, which, however, have rarely been investigated. This study develops a coassisted carbonization method for the preparation of porous carbons with the environmentally friendly agents HCOOK and (HCOO)

Contaminated soils have caused serious harm to human health and the ecological environment due to the high toxicity of organic and inorganic pollutants, which has attracted extensive attention in recent years. Because of its low cost, simple operation and high efficiency, soil washing technology is widely used to permanently remove various pollutants in contaminated soils and is considered to be the most promising remediation technology. This review summarized the recent developments in the field of soil washing technology and discusses the application of conventional washing agents, advanced emerging washing agents, the recycling of washing effluents and the combination of soil washing and other remediation technologies. Overall, the findings provide a comprehensive understanding of soil washing technology and suggest some potential improvements from a scientific and practical point of view.

Precise estimation of vegetable nitrogen (N) status is critical in optimizing N fertilization management. However, nondestructive and accurate N diagnostic methods for vegetables are relatively scarce. In our two-year field experiment, we evaluated whether an active canopy sensor (GreenSeeker) could be used to nondestructively predict N status of bok choy (Brassica rapa subsp. chinensis) compared with a chlorophyll meter. Results showed that the normalized difference vegetation index (NDVI) and ratio vegetation index (RVI) generated by the active canopy sensor were well correlated with the aboveground biomass (AGB) (r = 0.698–0.967), plant N uptake (PNU) (r = 0.642–0.951), and root to shoot ratio (RTS) (r = −0.426 to −0.845). Compared with the chlorophyll meter, the active canopy sensor displayed much higher accuracy (5.0%–177.4% higher) in predicting AGB and PNU and equal or slightly worse (0.54–1.82 times that of the chlorophyll meter) for RTS. The sensor-based NDVI model performed equally well in estimating AGB (R2 = 0.63) and PNU (R2 = 0.61), but the meter-based model predicted RTS better (R2 = 0.50). Inclusion of the days after transplanting (DAT) significantly improved the accuracy of sensor-based AGB (19.0%–56.7% higher) and PNU (24.6%–84.6% higher) estimation models. These findings suggest that the active canopy sensor has a great potential for nondestructively estimating N status of bok choy accurately and thus for better N recommendations, especially with inclusion of DAT, and could be applied to more vegetables with some verification.

Thermophilic solid-state anaerobic digestion (SS-AD) of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, was carried out in this study. The effects of temperature (40-60°C), initial solid content (ISC, 17.5-32.5%), and C/N ratio (15-32 : 1) on biogas production were evaluated using a Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). The results showed that optimization of process parameters is important to promote the SS-AD performance. All the factors, including interactive terms (except the ISC), were significant in the quadratic model for biogas production with SS-AD. Among the three operation parameters, the C/N ratio had the largest effect on biogas production, followed by temperature, and a maximum biogas yield of 241.4 mL gVS-1 could be achieved at 47.3°C, ISC = 24.81 % , and C / N = 22.35 . After 20 d of SS-AD, the microbial community structure under different conditions was characterized by high-throughput sequencing, showing that Firmicutes, Bacteroidetes, Chloroflexi, Synergistetes, and Proteobacteria dominated the bacterial community, and that Firmicutes had a competitive advantage over Bacteroidetes at elevated temperatures. The biogas production values and relative abundance of OPB54 and Bacteroidia after 20 d of SS-AD can be fitted well using a quadratic model, implying that OPB54 and Bacteroidia play important roles in the methanogenic metabolism for agricultural waste thermophilic SS-AD.

Excellent biochar properties are crucial for sorption performance, and a developed pore structure is especially important. Herein, novel porous carbon/porous biochar (PC/PB) composites, in which the porous biochar and porous carbon were prepared at the same time, were synthesized via a green method from algal biomass with the help of the self-activation of citrate for the first time, and the composites were evaluated for the sorption of sulfamethoxazole (SMX). Many micro/meso/macropores were introduced into the PC/PB composites, which showed high specific surface areas (up to 1415 m

In contrast to the efforts dedicated to applying porous biochars in environmental remediation, the search for green synthesis methods, which are crucial for industrialized production, is often neglected. Herein, oxygen-doped porous biochars were prepared for the first time by the assisted carbonization of hydrochar with a novel noncorrosive activator, potassium formate, and these biochars displayed a porous structure with large amounts of micropores (surface area: 1242 ∼ 1386 m

As a potential adsorbent material, loose, porous livestock manure biochar provides a new approach to livestock manure resource utilization. In this study, coconut husks (CH) and livestock manure, i.e., cow dung (CD), pig manure (PM), and chicken manure (CM) were used as biomass precursors for preparation of biochar via high-temperature pyrolysis and CO2 activation. Characterization technologies, such as scanning electron microscopy, Fourier transform infrared spectroscopy, adsorption–desorption isotherms, and pore size distributions, were used to study the microscopic morphologies and physicochemical properties of unactivated and activated biochar materials. The results showed that CD biochar provides better adsorption performance (up to 29.81 mg H2S/g) than CM or PM biochar. After activation at 650° for 1 h, the best adsorption performance was 38.23 mg H2S/g. For comparison, the CH biochar removal performance was 30.44 mg H2S/g. Its best performance was 38.73 mg H2S/g after 1 h of activation at 750 °C. Its best removal performance is equivalent to that of CH biochar activated at a temperature that is 100 °C higher. Further material characterization indicates that the H2S removal performance of livestock-manure–derived biochar is not entirely dependent on the specific surface area, but is closely related to the pore size distribution.

A one-pot co-pyrolysis of potassium/calcium carbonate with biowaste-derived hydrochar strategy was proposed to prepare hierarchical porous biochars (HPBs) for the first time. The pore structure, especially the pore size distribution, could be designed by adjusting the mass ratios of different carbonates. HPBs were hydrophobic, nitrogen doped, graphitized, and contained surface functional groups. HPBs showed unexpected sorption quantity for diethyl phthalate (DEP) that reached 657 mg g

In-season nitrogen (N) nutrition diagnosis and N requirement (NR) estimation are critical to precision management of crop fertilization. Although many studies focus on the diagnosis of in-season crop N nutrition, few of them associated the N status with crop NR or topdressing N fertilizer. The objective of this study was bridging the gap between crop N nutrition status and crop NR for easy implementation of precision fertilization. Field experiments were conducted with different N levels and six rice (Oryza sativa L.) varieties in eastern China during 2010–2014. Rice in-season NR and N nutrition index (NNI) were calculated with plant chemical analysis and pre-established critical N dilution curve. Results showed a significant linear relationship between in-season rice NR and NNI based on the long-term field experiment, and the NR-NNI regression slope changed with days after transplanting (DAT) in a regular pattern. Based on this data changing pattern, a novel NR estimation model was established with three easy-obtained independent variables (DAT, N-fertilizer recovery efficiency and NNI). Independent model validation results showed very good performance on different rice varieties and growth stages, with root mean square error (RMSE) of 5.93, 6.96, 8.74 and 6.43 kg ha−1 for three japonica rice and one indica rice varieties, respectively. This model will significantly facilitate the estimation of in-season rice NR and provide strong technical support for the precision management of N fertilization.

Efficient and precise yield prediction is critical to optimize cabbage yields and guide fertilizer application. A two-year field experiment was conducted to establish a yield prediction model for cabbage by using the Greenseeker hand-held optical sensor. Two cabbage cultivars (Jianbao and Pingbao) were used and Jianbao cultivar was grown for 2 consecutive seasons but Pingbao was only grown in the second season. Four chemical nitrogen application rates were implemented: 0, 80, 140, and 200 kg·N·ha−1. Normalized difference vegetation index (NDVI) was collected 20, 50, 70, 80, 90, 100, 110, 120, 130, and 140 days after transplanting (DAT). Pearson correlation analysis and regression analysis were performed to identify the relationship between the NDVI measurements and harvested yields of cabbage. NDVI measurements obtained at 110 DAT were significantly correlated to yield and explained 87–89% and 75–82% of the cabbage yield variation of Jianbao cultivar over the two-year experiment and 77–81% of the yield variability of Pingbao cultivar. Adjusting the yield prediction models with CGDD (cumulative growing degree days) could make remarkable improvement to the accuracy of the prediction model and increase the determination coefficient to 0.82, while the modification with DFP (days from transplanting when GDD > 0) values did not. The integrated exponential yield prediction equation was better than linear or quadratic functions and could accurately make in-season estimation of cabbage yields with different cultivars between years.

Organic fertilizers are generally thought to be an effective way to sustain soil fertility and plant growth. To promote the productivity of chrysanthemum, five sources of liquid organic fertilizers (L1–L5), as well as a chemical fertilizer, were applied at an early stage of the growth cycle to investigate their effects on plant growth. In the short-term pot experiment, the liquid organic fertilizers significantly promoted root and aboveground growth by 10.2–77.8% and 10.7–33.3%, respectively, compared with the chemical fertilizer. The order of growth promotion was: L1 (shrimp extracts) > L2 (plant decomposition) > L4 (seaweed extracts)/L5 (fish extracts) > L3 (vermicompost). Morphological and chemical analyses indicated that, compared with other organic fertilizers, the treatment with shrimp extract (L1) produced the greatest increases in root dry weight, total length, surface area, volume, tips, and thick root length, respectively. Furthermore, the shrimp extract treatment significantly increased the nutrient contents and altered the soil’s functional microbial community at the rhizospheric level compared with the chemical fertilizer treatment. Thus, the shrimp extract liquid organic fertilizer could be part of an effective alternative to chemical fertilization during the early stage of chrysanthemum growth.