Compensatory growth of Microcystis aeruginosa after copper stress and the characteristics of algal extracellular organic matter (EOM).

Cyanobacterial blooms can impair drinking water quality due to the concomitant extracellular organic matter (EOM). As copper is often applied as an algicide, cyanobacteria may experience copper stress. However, it remains uncertain whether algal growth compensation occurs and how EOM characteristics change in response to copper stress. This study investigated the changes in growth conditions, photosynthetic capacity, and EOM characteristics of M. aeruginosa under copper stress. In all copper treatments, M. aeruginosa experienced a growth inhibition stage followed by a growth compensation stage. Notably, although chlorophyll-a fluorescence parameters dropped to zero immediately following high-intensity copper stress (0.2 and 0.5 mg/L), they later recovered to levels exceeding those of the control, indicating that photosystem II was not destroyed by copper stress. Copper stress influenced the dissolved organic carbon (DOC) content, polysaccharides, proteins, excitation-emission matrix spectra, hydrophobicity, and molecular weight (MW) distribution of EOM, with the effects varying based on stress intensity and growth stage. Principal component analysis revealed a correlation between the chlorophyll-a fluorescence parameters and EOM characteristics. These results imply that copper may not be an ideal algicide. Further research is needed to explore the dynamic response of EOM characteristics to environmental stress.

Research on the Material Basis and Mechanism of Kudzu Root in Preventing and Treating Cerebral Ischemia based on Network Pharmacology.

BACKGROUND: It has been shown that Kudzu root has significant pharmacological effects such as improving microcirculation, dilating coronary arteries, and increasing cerebral and coronary blood flow, but its material basis and mechanism of action are not clear. OBJECTIVE: The aim of this study was to investigate the mechanism of action of Kudzu root in the prevention and treatment of cerebral ischemia (CI) through network pharmacology combined with animal experiments. METHODS: The components of kudzu root were screened by using the Chemistry Database, Chinese Academy of Science. Linpinski's five rules were used to perform pharmacophore-like analysis to obtain the active ingredients of Kudzu root. The Swiss Target Prediction Service database was used to predict the potential protein targets of kudzu root components associated with CI. An active ingredient-target network was constructed by using Cytoscape 3.6.0. A rat model of middle cerebral artery occlusion (MCAO) was established, then the main targets and signaling pathways predicted were verified by observing the area of cerebral infarction and Western blot experiments. RESULTS: In total, 84 major active compounds and 34 targets included gerberoside, belonging to the isoflavone class, gallic acid, amino acid class, 4-Methylphenol, phenolic class, and quercetin, and flavonoid class (Flavonoids). The targets covered were proteins related to excitatory amino acids and calcium overload, including Excitatory amino acid transporter 2 (SLC1A2), Glutamate receptor ionotropic, kainate 1 (GRIK1), Glutamate receptor ionotropic, NMDA 1 (GRIN1), Glutamate receptor 2(GRIA2), Calcium/calmodulin-dependent protein kinase II (CaMKII), Neuronal nitric oxide synthase(nNOS). Glutamatergic energy is prominent, and calcium transport across the membrane is central to the network and occupies an important position. CONCLUSION: Kudzu root can significantly reduce neurological damage in rats with CI, and also significantly reduce the rate of cerebral infarction. It is worth noting that Kudzu root can prevent and treat CI by reducing excitatory amino acid toxicity and improving calcium overload.

Effect of magnetite particle size on propionate degradation in the propionate-based anaerobic system.

The size effect of magnetite (Fe3O4) on the degradation of propionate (PA) in the PA-based anaerobic system was investigated. The sequential bench-scale experiments were conducted. Results showed that the effects of different sized magnetite particles on PA degradation varied, and reaction cycles also played a role in substrate removal/degradation. With the increase of reaction cycle, nano-magnetite promoted PA degradation and CH4 production, which caused faster PA degradation rate (0.997 g/L·d) than the control group (CK) without magnetite (0.834 g/L·d), whereas the groups with micron- and millimeter-sized magnetite had slower PA degradation rates (0.746 and 0.636 g/L·d) than CK group. The particle size or surface characteristics of the magnetite may become the main factor determining the PA degradation rate. Furthermore, the analysis of PA conversion and volatile fatty acids (VFAs) distribution showed the C6-dismutation pathway, which converses PA to butyrate, enhanced by the introduction of magnetite. Microbial community analysis showed that PA was degraded mainly by methyl-malonyl-CoA (MMC) pathway. The relative abundance of Syntrophobacter that catalyze MMC pathway in the group with nano-magnetite were much higher after three reaction cycles at 39 %, as compared to micro-magnetite at 28 %, and millimeter-sized magnetite at 27 %, which contributed to faster degradation of PA. Functional enzyme-encoding genes for the four methanogenesis pathways were identified with reference to KEGG database entries. The methanogenesis pathway using acetate was the most abundant pathway in all groups. The observations have important implications for enhancing the PA removal in PA-inhibited anaerobic digester.

Evidence-based complementary and alternative medicine bioinformatics approach through network pharmacology and molecular docking to determine the molecular mechanisms of Erjing pill in Alzheimer's disease.

Erjing pill, a Traditional Chinese Medicine (TCM) formulation composed of Polygonatum sibiricum and Lycium chinense, has an important role in the treatment of Alzheimer's disease (AD). However, the underlying mechanisms of the action of Erjing pill in AD have remained elusive. In the present study, the key ingredients of Erjing pill were investigated and the active components and their mechanisms of action on AD were analyzed based on networks pharmacology. By using the TCM and TCM Systems Pharmacology and databases, the components of Erjing pill were screened and the data were captured using Discovery Studio. The SwissTarget webserver database was used to predict the potential protein targets of Erjing pill components for pathologies related to AD. The data were further analyzed with the disease targets of AD based on analysis of the Online Mendelian Inheritance in Man, DiGSeE and Therapeutic Target Database. Subsequent analysis of mechanistic pathways of the screened components and protein targets allowed us to construct a network by using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, which revealed potential molecular mechanisms of Erjing pill against AD. Finally, the protective effect of three active components on neurons was verified using an in vitro injury model of PC12 cells induced by Aß25-35. The results indicated that 65 bioactive components of Erjing pill, including lauric acid and zederone, and 6 targets, including acetylcholinesterase, butylcholinesterase and amyloid protein precursor, were closely associated with the prevention and treatment of AD. The molecular components of Erjing pill were indicated to be involved in various biological signaling processes, mainly in synaptic signal transmission, transsynaptic signal transmission and chemical synaptic transmission. Furthermore, related pathways targeted by Erjing pill in AD included the regulation of neuroactive ligand-receptor interactions, the PI3K-Akt signaling pathway, serotoninergic synapses, calcium signaling pathways and dopaminergic synapses. A cell viability assay indicated that the compounds (polygonatine A, polygonatine C and 4',5-dihydroxyflavone) assessed were able to significantly improve the survival rate and increase the Ca2+ level in a PC12 cell model of AD induced by amyloid-ß25-35. The present study revealed that the mechanisms of action of Erjing pill to prevent and treat AD included a multicompound, multitarget and multipathway regulatory network.

Solid digestate disposal strategies to reduce the environmental impact and energy consumption of food waste-based biogas systems.

This study examined the environmental impacts and energy consumption of three solid digestate treatment scenarios to quantify their impacts on the entire food waste (FW)-based biogas system: (1) incineration; (2) composting, and; (3) landfill. The results showed that composting had the largest net energy consumption, but least total environmental impact of 57.3 kWh and 8.75 E-03, respectively, whereas landfill showed the opposite pattern. Moreover, there were significant differences (p < 0.05) and relatively high contributions between the digestate treatment subunits among the three scenarios. The most significant contributions of digestate subunits in methods 1-3 to the 100-year global warming potential (GWP100) were 70.5%, 52.5%, and 103.4%, respectively. The results indicated that solid digestate treatment had a significant impact, and reasonable disposal of solid digestate could significantly reduce the environmental impacts and energy consumption of the entire FW-based biogas system.

Acute impact of Hg2+, Cu2+, and Ag+ on the formation of biopolymers and nitrogenous soluble microbiological products in activated sludge for wastewater treatment.

In the present work, acute impact of heavy metals on activated sludge was investigated, specifically the release of biopolymers and nitrogenous soluble microbiological products (N-SMP) that significantly impact tertiary effluent quality. Based on the previously reported studies, Hg2+ and Ag+ were selected as representative "non-essential" heavy metals, while Cu2+ was selected as the "essential" heavy metal. Stress tests show that under the present experimental conditions, adding a higher concentration of heavy metals to the activated sludge increases the concentration of biopolymers and SMP in the supernatant; N-SMP increased more significantly than carbonaceous products, implying a greater risk of formation of toxic nitrogenous disinfection by-products or membrane fouling in relevant tertiary treatment processes. The severity of the release of SMP into the supernatant depended on the heavy metal, with an order of Hg2+ > Ag+ > Cu2+ ("non-essential" > "essential") under identical molar concentrations. The mass balance of typical organics (e.g., biopolymers) in SMP and extracellular polymeric substances (EPS) in activated sludge was analyzed, and a negative correlation between the organics in the SMP and tightly bound EPS was observed, implying that a significant fraction of the SMP could be quickly released from the tightly bound EPS under heavy metal shock conditions and could be related to cell response or damage.

Network pharmacology-based strategy to investigate pharmacological mechanisms of Tinospora sinensis for treatment of Alzheimer's disease.

ETHNOPHARMACOLOGICAL RELEVANCE: Tinospora sinensis (Lour.) Merr. belongs to the family Menispermaceae. It is called LeZhe and is widely used as a kind of folk medicine especially in the Tibetan Plateau of China. T. sinensis has the functions of clearing away heat and detoxification, dispelling wind and dredging collaterals, calming and soothing the nerves. T. sinensis is an effective medicine for the prevention and treatment of aging diseases such as Alzheimer's disease (AD) in the Tibetan Plateau of China, whereas its material basis and underlying mechanisms are not clear. The aim of this study was to investigate the material basis and potential mechanisms of T. sinensis in the treatment of AD by using network pharmacology and molecular docking. MATERIALS AND METHODS: In this study, targets were collected from DrugBank database, Therapeutic Target Database (TTD) and literatures reports for the treatment of AD. Compounds were searched by literatures and systematic separation from T. sinensis. The molecular docking experiment was carried out by using Autodock Vina software to screen the bioactive compounds in T. sinensis and target proteins for AD. Then, the "compound-target network" was constructed by Cytoscape software. The drug-like properties of the active compounds were analyzed by pKCSM performs, and the protein-protein interaction (PPI) network was constructed by Search Tool for the Retrieval of Interacting Genes/Proteins (STRING). The Kyoto Encyclopedia of Genes and Genomes (KEGG) target pathway enrichment analysis was carried out by Database for Annotation, Visualization and Integrated Discovery (DAVID). Furthermore, the protective effect of neurons of two active compounds were verified with the injury cell model of PC12 and primary hippocampus neurons induced by Aß25-35. Finally, the key proteins of related pathways were quantitatively analyzed with Western blot method. RESULTS: In total, 105 compounds and 38 targets have been screened. The main active compounds contained berberine, which belongs to alkaloids, Aurantiamide acetate, N-P-coumaroyltyramine, which belongs to amides, Trans-syringin and 3-demethyl-phillyrin, which belongs to phenylpropanoids. The targets covered inflammation-related proteins, including Protein kinase B (AKT), Phosphoinositide 3-kinase (PI3K), Tyrosine-protein kinase JAK1 (JAK1), mammalian target of rapamycin (mTOR), tumor necrosis factor alpha (TNF-α), Neuronal NOS (NOS1), and cholinergic function-related proteins, including α4-Nicotinic acetylcholine receptor (α4 nAChR), Muscarinic acetylcholine receptor M1 (Muscarnic M1). Inflammation and cholinergic dysfunction were the center of the network and occupy a dominant position. And the results of enrichment analysis shown the pathways mainly contained phosphoinositide-3-kinase/Akt (PI3K/Akt) signal pathway, neurotrophic factors (NTFs) signal pathway, Hypoxia-inducible factor 1 (HIF-1) signal pathway, mechanistic Target of Rapamycin (mTOR) signal pathway, Tumor necrosis factor (TNF) signal pathway, insulin resistance (IR). The results of in vitro assays showed that the tested compounds could significantly improve the survival rate and inhibit the apoptosis of PC12 cells and primary hippocampal neurons injured by Aß25-35. Western blot results showed that T. sinensis had a significant effect on the expression of protein PI3K and Akt. CONCLUSION: Our results revealed that T. sinensis could prevent and treat AD through a multi-compound-multi-target-multi-pathway regulatory network. Our work also expected to provide new ideas and theoretical bases for searching for the active compounds in T. sinensis and potential mechanism in the prevention and treatment of AD by the network pharmacology and molecular docking. The results of in vitro assay and in vivo assay supported the results of molecular docking.

Impact of heavy metals on the formation and properties of solvable microbiological products released from activated sludge in biological wastewater treatment.

This study investigated the acute impact of heavy metals on activated sludge with respect to the amount properties of biopolymers and other solvable microbiological products (SMPs) released from the sludge. Ten heavy metals were selected for the evaluation. Under the experimental conditions, exposing activated sludge to different metals led to an increase in SMPs, with a more significant increase in nitrogenous organics than in carbonaceous ones, where Hg2+, Ag+, Cu2+, and Cr6+ led to the highest increase in SMP species, while Cd2+, Ni2+, Mn2+, Pb2+, and Co2+ caused limited increase in the middle and small SMP molecules, and Zn2+ and Cr3+ resulted in a decrease in SMP content. To probe the molecular impact of heavy metals and the association between cellular stress and SMP formation, the toxicity of heavy metals was evaluated using a toxicogenomics assay. Based on a correlation analysis between the increase in SMP and the molecular toxicity index-transcriptional effect level index (TELI) of different genes under corresponding stress conditions, eight genes demonstrated a strong correlation with SMP properties and were pre-assumed to have the most significant influence on the increment in SMPs. We further validated the correlation equation established to predict SMP production based on the molecular disturbance of the eight key biomarkers, using arsenic As3+ and vanadium V5+ as tests, and by quantifying the amount of SMPs released from the activated sludge under the influence of these metals using a TELI-derived equation. In addition, the heavy metals that generated greater amounts of reactive oxygen species also caused larger increases in SMPs.

Variation of effluent organic matter (EfOM) during anaerobic/anoxic/oxic (A2O) wastewater treatment processes.

Here, we studied seasonal variation of effluent organic matter (EfOM), based on molecular weight distribution and fluorescent components, during the traditional anaerobic/anoxic/oxic (A2O) wastewater treatment processes. Microbial community structure and effect of temperature on some isolated pure strains were analyzed to explain the related mechanism. Results showed that the anaerobic process played a key role in EfOM removal by removing building blocks, low molecular weight (LMW) neutrals, biopolymers, and protein-related substances (C4 and C5), thus determining the fate of EfOM during the A2O processes. On the other hand, humic substances, LMW neutrals, large molecular-sized hydrophobic humic-like compounds (C3), and aromatic proteins (C4) were generated during the anoxic process in summer and winter. Proteobacteria (Gamma-, Beta-, and Alpha-proteobacteria) and Bacteroidetes constituted over 50% of the sludge community. Temperature was found to be positively correlated with the generation of soluble microbial products (SMP) based on the performance of the mixture of isolated Herbaspirillum sp. (Beta-proteobacteria) and Pseudomonas sp. (Gamma-proteobacteria). Through comprehensive analysis of the co-action of Proteobacteria and temperature, we proposed the Synergetic Effect of Temperature and Proteobacteria as a possible mechanism of the seasonal variation of EfOM. These findings are important for understanding the fate of EfOM during the wastewater treatment processes and therefore be helpful for better EfOM control.

[Response of the Water Quality of a Stratified Reservoir to an Extreme El Niño Event During Summer].

Global warming can intensify the El Niño phenomenon that recurs every 2-7 years, which will lead to a great interannual variability of climate and may induce the deterioration of the water quality of reservoirs. To study the influence of the extreme El Niño events on the water quality of stratified reservoirs during summer, field surveys were conducted in Zhoucun Reservoir and its inflow rivers from May to August in a normal year (2012) and a strong El Niño year (2015). Temporal variations of physical and chemical index were investigated during monitoring. The results showed that the Zhoucun Reservoir was stratified during the study period. The precipitation in the summer of the normal year was significantly higher than that in the El Niño year at the same period. In the summer of the normal year, the water level increased from 124.26 m to 127.14 m and the hypolimnion thickness increased by 3.1 m. However, in 2015, the rapid decrease of the water level from May to August (from 121.65 m to 119.46 m) led to the decrease of the hypolimnion thickness (by 3.2 m). The inflow rivers belonged to surface current and its nutrients concentrations were obviously higher than those in the epilimnion. The inflow nutrients loads increased significantly in the summer of the normal year, as a result, total nitrogen increased from 1.00 mg·L-1 to 2.06 mg·L-1, nitrate increased from 0.19 mg·L-1 to 1.28 mg·L-1, and total phosphorus increased from 0.023 mg·L-1 to 0.088 mg·L-1 in the lacustrine zone of the reservoir. In contrast, the nutrients concentrations changed little in the summer of the El Niño year due to the decrease in runoff. Nonetheless, the reducing pollutants concentrations of the hypolimnion in the El Niño year were significantly higher than those in the normal year, which may be due to the temporal variations of hypolimnion thicknesses. The maximum concentrations of iron, manganese, ammonium and sulfide in the summer of the El Niño year were 0.38, 1.36, 2.36 and 1.67 mg·L-1, respectively. All these index exceeded the standards for surface water Class Ⅲ. We conclude that the extreme El Niño event has an apparent influence on the nutrients concentrations in the epilimnion and the pollutants concentrations in the hypolimnion in Zhoucun Reservoir.

Abnormal increase of Mn and TP concentrations in a temperate reservoir during fall overturn due to drought-induced drawdown.

Due to global warming, some regions of Earth may face frequent and severe droughts in the future, leading to the deterioration of surface water quality. In this study, we investigated the effects of drought-induced drawdown on the water quality of the Zhoucun Reservoir, Shandong Province, East China, during the fall overturn. Field surveys were conducted during stratification (April-November) over three standard years 2012, 2013, and 2014, and over the El Niño event of 2015. Temporal and vertical variations of the physical and chemical indexes were investigated during monitoring. Results show that after the formation of stratification, the hypolimnion rapidly shifted to anaerobic conditions, with the accumulation of pollutants such as manganese (Mn) and total phosphorous (TP). Due to the extreme El Niño event in 2015, both the upper and lower metalimnion limits moved down along with the water level in summer, which resulted in the transfer of hypolimnion water to the metalimnion. In summer 2015, large amounts of pollutants were measured in the metalimnion: a phenomenon that did not occur at the same period of the standard years. At the beginning of the overturn in 2015, the water quality of the whole reservoir deteriorated when the metalimnion water shifted to the epilimnion. Mn and TP concentrations in the epilimnion reached 0.202mg/L and 0.086mg/L, respectively, which are significantly higher than those in the standard years. Although the tributary rivers entered the epilimnion of the reservoir during the overturn, Mn and TP concentrations of the inflow were only of 0.049-0.072mg/L and 0.033-0.047mg/L, respectively, indicating that these rivers were not the source of the high TP and high Mn concentrations in the epilimnion. Hence, we conclude that more attention should be paid to the metalimnion position and the vertical distribution of pollutants when studying lakes and reservoirs experiencing droughts.

[Seasonal Stratification and the Response of Water Quality of a Temperate Reservoir--Zhoucun Reservoir in North of China].

In order to reveal the seasonal stratification and the response of water quality of a temperate reservoir Zhoucun Reservoir in North of China. The physical, chemical and phytoplankton indexes were continuously monitored from July 2014 to June 2015. The results showed that the thermal stratification was monomictic, which lasted from April to October. The thermal stratification played an important role in the change of water environment. The hypoxia in the bottom water caused hy thermal stratification led to the release of nutrients and reductants from sediment. During the stratification period, the mean concentrations of total nitrogen, total phosphorus, manganese and sulfide were 1.18, 0.11, 0.47 and 0.48 mg · L⁻¹, respectively. The vertical distribution of phytoplankton was significantly influenced by water temperature stratification. During the thermal stratification period, phytoplankton abundance was higher and the average phytoplankton ahundance was 16.35 x 106 cells · L⁻¹ in the upper water of the reservoir, while remained at low levels at the bottom.

Nitrogen removal characteristics of indigenous aerobic denitrifiers and changes in the microbial community of a reservoir enclosure system via in situ oxygen enhancement using water lifting and aeration technology.

Indigenous aerobic denitrifiers of a reservoir system were enhanced in situ by water lifting and aeration technology. Nitrogen removal characteristics and changes in the bacterial community were investigated. Results from a 30-day experiment showed that the TN in the enhanced water system decreased from 1.08-2.02 to 0.75-0.91mg/L and that TN removal rates varied between 21.74% and 52.54% without nitrite accumulation, and TN removal rate of surface sediments reached 41.37±1.55%. The densities of aerobic denitrifiers in the enhanced system increased. Furthermore, the enhanced system showed a clear inhibition of Fe, Mn, and P performances. Community analysis using Miseq showed that diversity was higher in the in situ oxygen enhanced system than in the control system. In addition, the microbial composition was significantly different between systems. It can be concluded that in situ enhancement of indigenous aerobic denitrifiers is very effective in removing nitrogen from water reservoir systems.

The Variation Characteristic of Sulfides and VOSc in a Source Water Reservoir and Its Control Using a Water-Lifting Aerator.

Sulfides and volatile organic sulfur compounds (VOSc) in water are not only malodorous but also toxic to humans and aquatic organisms. They cause serious deterioration in the ecological environment and pollute drinking water sources. In the present study, a source water reservoir--Zhoucun Reservoir in East China--was selected as the study site. Through a combination of field monitoring and in situ release experiments of sulfides, the characteristics of seasonal variation and distribution of sulfides and VOSc in the reservoir were studied, and the cause of the sulfide pollution was explained. The results show that sulfide pollution was quite severe in August and September 2014 in the Zhoucun Reservoir, with up to 1.59 mg·L(-1) of sulfides in the lower layer water. The main source of sulfides is endogenous pollution. VOSc concentration correlates very well with that of sulfides during the summer, with a peak VOSc concentration of 44.37 µg·L(-1). An installed water-lifting aeration system was shown to directly oxygenate the lower layer water, as well as mix water from the lower and the upper layers. Finally, the principle and results of controlling sulfides and VOSc in reservoirs using water-lifting aerators are clarified. Information about sulfides and VOSc fluctuation and control gained in this study may be applicable to similar reservoirs, and useful in practical water quality improvement and pollution prevention.

Nitrogen removal characteristics of enhanced in situ indigenous aerobic denitrification bacteria for micro-polluted reservoir source water.

Indigenous oligotrophic aerobic denitrifiers nitrogen removal characteristics, community metabolic activity and functional genes were analyzed in a micro-polluted reservoir. The results showed that the nitrate in the enhanced system decreased from 1.71±0.01 to 0.80±0.06mg/L, while the control system did little to remove and there was no nitrite accumulation. The total nitrogen (TN) removal rate of the enhanced system reached 38.33±1.50% and the TN removal rate of surface sediment in the enhanced system reached 23.85±2.52%. TN removal in the control system experienced an 85.48±2.37% increase. The densities of aerobic denitrifiers in the enhanced system ranged from 2.24×10(5) to 8.13×10(7)cfu/mL. The abundance of nirS and nirK genes in the enhanced system were higher than those of in the control system. These results suggest that the enhanced in situ indigenous aerobic denitrifiers have potential applications for the bioremediation of micro-polluted reservoir system.

A study of the impact of moist-heat and dry-heat treatment processes on hazardous trace elements migration in food waste.

UNLABELLED: Using laboratory experiments, the authors investigated the impact of dry-heat and moist-heat treatment processes on hazardous trace elements (As, Hg, Cd, Cr, and Pb) in food waste and explored their distribution patterns for three waste components: oil, aqueous, and solid components. The results indicated that an insignificant reduction of hazardous trace elements in heat-treated waste-0.61-14.29% after moist-heat treatment and 4.53-12.25% after dry-heat treatment-and a significant reduction in hazardous trace elements (except for Hg without external addition) after centrifugal dehydration (P < 0.5). Moreover, after heat treatment, over 90% of the hazardous trace elements in the waste were detected in the aqueous and solid components, whereas only a trace amount of hazardous trace elements was detected in the oil component (<0.01%). In addition, results indicated that heat treatment process did not significantly reduce the concentration of hazardous trace elements in food waste, but the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk considerably. Finally, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment on the removal of external water-soluble ionic hazardous trace elements. IMPLICATIONS: An insignificant reduction of hazardous trace elements in heat-treated waste showed that heat treatment does not reduce trace elements contamination in food waste considerably, whereas the separation process for solid and aqueous components, such as centrifugal dehydration, could reduce the risk significantly. Moreover, combined with the separation technology for solid and liquid components, dry-heat treatment is superior to moist-heat treatment for the removal of external water-soluble ionic hazardous trace elements, by exploring distribution patterns of trace elements in three waste components: oil, aqueous, and solid components.