Exploring the maximum nitrite production rate through the granular sludge-type reactor to match the needs of anammox process realizing efficient nitrogen removal.

The reliable and efficient nitrite production rate (NPR) through nitritation process is the prerequisite for the efficient running of subsequent processes, like the anammox process and the nitrite shunt. However, there has been scant research on stable and productive nitritation process in recent years. In this study, at a stable hydraulic retention time of 12.0 h and with precise and strict DO control, the upper limit of the NPR was initially investigated using a continuous-flow granular sludge reactor. The NPR of 1.69 kg/m3/d with a nitrite production efficiency of 81.97% was finally achieved, which set a record until now in similar research. The median sludge particle size of 270.0 µm confirmed the development of clearly defined granular sludge. The genus Nitrosomonas was the major ammonium oxidizing bacteria. In conclusion, this study provides valuable insights for the practical application of the effective nitritation process driving subsequent nitrogen removal processes.

The leaching behavior of hazardous element under different leaching procedure utilizing slag-fly ash-based agent: Chromium, antimony, and lead.

Low-carbon cementitious materials based on blast furnace slag (BFS) and municipal solid waste incineration (MSWI) fly ash play a pivotal role in the construction industry by substituting cement clinker. This innovation significantly reduces CO2 emissions and enables the extensive utilization of both industrial solid waste and hazardous urban waste on a large scale. However, the application of MSWI fly ash as a precursor for alkali-activated cementitious materials presents a significant leaching risk of heavy metal during the extended reaction process, posing a critical barrier to the efficient and widespread utilization of these solid waste. Three static leaching methods [horizontal vibration (HV), sulphuric acid & nitric acid (SN), and acetic acid buffer solution (AAB)], along with acid neutralization capacity (ANC) leaching tests, were applied in BFS-fly ash-based cementitious materials (BFCM) to assess the leaching behavior of high-risk elements-Cr, Sb, and Pb-within MSWI fly ash. The A4 matrix (BFS: MSWI fly ash:FGDG = 70:20:10) exhibits a compressive strength of 72.51 MPa at 180 day, with the leaching concentrations of target elements remaining below the standard limit under chemical attack (H+ and OH-). The critical pH determined is 9.2 from the ANC leaching test results. Visual MINTEQ simulation illustrates the occurrence states of Cr, Sb, and Pb as (CrO4)2-, [Sb(OH)6]-, and Pb(OH)3- within the BFCM system, respectively. The "double salt effect", intended to enhance the dissociation degree of BFS, acts as the driving force behind the long-term hydration reaction. It also serves as an assurance in controlling the long-term leaching risk of object elements. The dissociation degree of BFS within A4 matrix increased by 38.71 %, with the relative content of the typical low-solubility double salt "Ettringite" reaching 29 % at 180 d. This study provides novel theoretical and data-driven evidence to investigate the leaching behavior associated with MSWI fly ash and the accomplishment of replacing cement clinker with low-carbon BFCM.

Stabilization of heavy metals in municipal solid waste incineration fly ash using organic chelating agents: Insight into risk assessment and function mechanism.

Landfill treatment of municipal solid waste incineration fly ash (MSWI FA) after stabilization is the primary disposal technology. However, only few studies have assessed the stability of MSWI-FA-chelated products in different landfill scenarios. In this study, three commonly used dithiocarbamate (DTC)-based organic chelating agents (CAs) (TS-300, SDD, and PD) were selected to stabilize heavy metals (HMs) in MSWI FA. In addition, the leaching toxicity and environmental risks of the chelated products were assessed in different disposal environments. The results demonstrate that the HM leaching concentrations of the chelated products met the concentration limits of the sanitary landfill standard (GB16889-2008; mixed Landfill Scenario) for the three CAs at a low additive level (0.3 %). However, in the compartmentalized landfill scenario (the leaching agent was acid rain), the leaching of HMs from the chelated products met the standard when TS-300, SDD, and PD were added at 1.5 %, 6.0 %, and 8.0 %, respectively. Additionally, Pb, Zn, and Cd in the chelated products from the 1.5 %-TS-300 and 6.0 %-SDD groups met the leaching limits within the pH ranges 6-12 and 7-12, 6-12 and 7-12, and 8-12 and 8-12, respectively. This was primarily due of TS-300's multiple DTC groups forming stable chain-like macromolecular chelates with Pb. However, although the environmental risks associated with Pb, Zn, and Cd in the initial (0-d) chelated products of the 1.5 %-TS-300 and 6.0 %-SDD groups were minimized to low and negligible levels, there was a significant increase in the leaching of the three HMs after 28 d of storage. Therefore, with appropriate CA addition, although the leaching concentration of HMs in the chelated product may comply with the GB16889-2008 standards, it remains essential to consider its environmental risk, particularly in highly acidic or alkaline environments and during prolonged storage of the product.

Effect of biodrying of lignocellulosic biomass on humification and microbial diversity.

By optimizing the carbon to nitrogen (C/N) ratio, this study accomplished an improved level of humification and microbial diversity in the biodrying process of lignocellulosic biomass. The results demonstrated that C/N ratio of 20 accelerated the decomposition of refractory lignocellulose, resulting in lower greenhouse gas emissions and the production of highly mature fertilizer with a germination index of 119.0% and a humic index of 3.2. Moreover, C/N ratio of 20 was found to diversify microbial communities, including Pseudogracilibacillus, Sinibacillus, and Georgenia, which contributed to the decomposition of lignocellulosic biomass and the production of humic acid. Hence, it is recommended to regulate the C/N ratio to 20:1 during the biodrying of biogas residue and wood chips to promote the economic feasibility and bioresource recycling.

Solidification/stabilization and risk assessment of heavy metals in municipal solid waste incineration fly ash: A review.

Incineration is currently the most common method of treating municipal solid waste. Municipal solid waste incineration fly ash (MSWI FA) contains a high concentration of toxic heavy metals (HMs), making it a hazardous waste. A series of detoxification treatments are required to reduce the toxicity of fly ash. Furthermore, the environmental risk of MSWI FA after treatment is becoming a cause of concern. This paper reviews the primary ash properties, pH, liquid-solid ratio, and other factors (microorganism, type of leaching agents, etc.) that affect the leaching of HMs from MSWI FA, compares and summarizes the most widely applied solidification/stabilization (S/S) techniques. In particular, models and methods for the environmental risk assessment and prediction of HMs are classified and described in detail. Finally, the inadequacy of current S/S techniques for MSWI FA is pointed out, which may be useful for upcoming studies on this topic.

From waste to wealth: Innovations in organic solid waste composting.

Organic solid waste (OSW) is not only a major source of environmental contamination, but also a vast store of useful materials due to its high concentration of biodegradable components that can be recycled. Composting has been proposed as an effective strategy for recycling OSW back into the soil in light of the necessity of a sustainable and circular economy. In addition, unconventional composting methods such as membrane-covered aerobic composting and vermicomposting have been reported more effective than traditional composting in improving soil biodiversity and promoting plant growth. This review investigates the current advancements and potential trends of using widely available OSW to produce fertilizers. At the same time, this review highlights the crucial role of additives such as microbial agents and biochar in the control of harmful substances in composting. Composting of OSW should include a complete strategy and a methodical way of thinking that can allow product development and decision optimization through interdisciplinary integration and data-driven methodologies. Future research will likely concentrate on the potential in controlling emerging pollutants, evolution of microbial communities, biochemical composition conversion, and the micro properties of different gases and membranes. Additionally, screening of functional bacteria with stable performance and exploration of advanced analytical methods for compost products are important for understanding the intrinsic mechanisms of pollutant degradation.

Economic and environmental evaluation for a closed loop of crude glycerol bioconversion to biodiesel.

Crude glycerol, a byproduct of biodiesel production, was utilized as a carbon source to produce microbial lipids by the oleaginous yeast Rhodotorula toruloides in this study. The maximum lipid production and lipid content were 10.56 g/L and 49.52%, respectively, by optimizing fermentation conditions. The obtained biodiesel met the standards of China, the United States, and the European Union. The economic value of biodiesel produced from crude glycerol increased by 48% compared with the sale of crude glycerol. In addition, biodiesel production from crude glycerol could reduce 11,928 tons of carbon dioxide emissions and 55 tons of sulfur dioxide emissions. This study provides a strategy for a closed loop of crude glycerol to biofuel and ensures sustainable and stable development of the biodiesel industries.

Product spectrum analysis and microbial insights of medium-chain fatty acids production from waste biomass during liquor fermentation process: Effects of substrate concentrations and fermentation modes.

Substrate toxicity would limit the upgrading of waste biomass to medium-chain fatty acids (MCFAs). In this work, two fermentation modes of electro-fermentation (EF) and traditional fermentation (TF) with different concentration of liquor fermentation waste (20%, 40%, 60%) were used for MCFAs production as well as mechanism investigation. The highest caproate (4.04 g/L) and butyrate (13.96 g/L) concentrations were obtained by EF at 40% substrate concentration. TF experiments showed that the substrate concentration above 40% severely inhibited ethanol oxidation and products formation. Compared with TF mode, the total substrates consumption and product yields under EF mode were significantly increased by 2.6%-43.5% and 54.0%-83.0%, respectively. Microbial analysis indicated that EF effectively alleviated substrate toxicity and enriched chain elongation bacteria, particularly Clostridium_sensu_stricto 12, thereby promoting ethanol oxidation and products formation. Caproiciproducens tolerated high-concentration substrates to ensure normal lactate metabolism. This study provides a new way to produce MCFAs from high concentration wastewater.

In-situ utilization of nitrogen-rich wastewater discharged from a biotrickling filter as a moisture conditioning agent for composting: Insights into nitrogen transformation behavior and microbial mechanism.

An NH4+-NO2--rich wastewater discharged from a composting-biotrickling filter coupled system can be reused as a composting moisture adjustment agent. To investigate the impact mechanism of reuse, NH4+-NO2--rich wastewater, NH4+-rich wastewater, NO2--rich wastewater, and distilled water were added into the composting (i.e., AMN, AAN, ANO2, and ADW groups). Results show that compost of all groups met the corresponding criteria for stabilization, humification, and non-phytotoxicity of mature compost. AMN increased organic-N and NO3--N content and reduced NH3 emissions, like AAN or ANO2, and avoid stimulating N2O emission in AAN and ANO2. Furthermore, LEfSe analysis of microorganisms revealed that AMN reduced NH3 emissions and increase organic-N content probably due to the inhibition of Alphaproteobacteria by ammonium, and increased nitrate content probably due to the stimulation of Aquamicrobium by nitrite. The avoided N2O emission is probably due to a negative synergistic effect on the stimulation from ammonia and nitrite to denitrifying bacteria (eg., Sphingobacteriaceae).

In-situ untilization of nitrogen-rich wastewater discharged from a biotrickling filter as a moisture conditioning agent for composting: Effect of nitrogen composition.

Although the composting-biotrickling filter coupled system removed ammonia-based odor pollution, other pollutants (nitrogen-rich wastewater) arose. This study intended to determine the effect of in-situ disposal of different kinds of nitrogen-rich wastewater [i.e., multi-nitrogen (NH4+, NO2-, and NO3-)-rich (STL1), NO2--rich (STL2), and NO3--rich (STL3)] as a moisture adjustment agent during the composting thermophilic period on nitrogen transformation. Results indicated that nitrogen-rich wastewater addition did not impair the compost maturation, whereas raised the total nitrogen content of fertilizer by 15.8%-46.7% compared to the control group (i.e., tap water group). Moreover, adding STL1 has the potential to reduce CO2 and NH3 emissions and avoid incomplete organic nitrogen decomposition. Furthermore, nitrogen flow analysis unveiled that STL1 addition increased nitrogen content by strengthening ammonification, dissimilatory nitrite reduction to ammonium, and high-temperature nitrification pathways. Thus, in-situ disposal of STL1 from biotrickling filters via composting is a suitable technique for coupled systems to achieve zero discharge.

Prediction Model of Hemorrhage Transformation in Patient with Acute Ischemic Stroke Based on Multiparametric MRI Radiomics and Machine Learning.

Intravenous thrombolysis is the most commonly used drug therapy for patients with acute ischemic stroke, which is often accompanied by complications of intracerebral hemorrhage transformation (HT). This study proposed to build a reliable model for pretreatment prediction of HT. Specifically, 5400 radiomics features were extracted from 20 regions of interest (ROIs) of multiparametric MRI images of 71 patients. Furthermore, a minimal set of all-relevant features were selected by LASSO from all ROIs and used to build a radiomics model through the random forest (RF). To explore the significance of normal ROIs, we built a model only based on abnormal ROIs. In addition, a model combining clinical factors and radiomics features was further built. Finally, the models were tested on an independent validation cohort. The radiomics model with 14 All-ROIs features achieved pretreatment prediction of HT (AUC = 0.871, accuracy = 0.848), which significantly outperformed the model with only 14 Abnormal-ROIs features (AUC = 0.831, accuracy = 0.818). Besides, combining clinical factors with radiomics features further benefited the prediction performance (AUC = 0.911, accuracy = 0.894). So, we think that the combined model can greatly assist doctors in diagnosis. Furthermore, we find that even if there were no lesions in the normal ROIs, they also provide characteristic information for the prediction of HT.

Bioconversion of biowaste into renewable energy and resources: A sustainable strategy.

Due to its high amount of organic and biodegradable components that can be recycled, biowaste is not only a major cause of environmental contamination, but also a vast store of useful materials. The transformation of biowaste into energy and resources via biorefinery is an unavoidable trend, which could aid in reducing carbon emissions and alleviating the energy crisis in light of dwindling energy supplies and mounting environmental difficulties related with solid waste. In addition, the current pandemic and the difficult worldwide situation, with their effects on the economic, social, and environmental aspects of human life, have offered an opportunity to promote the transition to greener energy and sources. In this context, the current advancements and possible trends of utilizing widely available biowaste to produce key biofuels (such as biogas and biodiesel) and resources (such as organic acid, biodegradable plastic, protein product, biopesticide, bioflocculant, and compost) are studied in this review. To achieve the goal of circular bioeconomy, it is necessary to turn biowaste into high-value energy and resources utilizing biological processes. In addition, the usage of recycling technologies and the incorporation of bioconversion to enhance process performance are analyzed critically. Lastly, this work seeks to reduce a number of enduring obstacles to the recycling of biowaste for future use in the circular economy. Although it could alleviate the global energy issue, additional study, market analysis, and finance are necessary to commercialize alternative products and promote their future use. Utilization of biowaste should incorporate a comprehensive approach and a methodical style of thinking, which can facilitate product enhancement and decision optimization through multidisciplinary integration and data-driven techniques.

Role of multistage inoculation on the co-composting of food waste and biogas residue.

Effect of diverse Lactobacillus amylophilus, Geobacillus thermoleovorans, and Bacillus subtilis inoculation patterns on the co-composting performance of food waste and biogas residue was explored. Experimental results revealed that, compared to the single-stage inoculation and non-inoculation groups, the multistage inoculation pattern prolonged the thermophilic period during composting, consequently improving organic matter decomposition and humification [with a high germination index (120.9%)]. In addition, it could promote the development of humic substances [with a high humus index (4.3) and biological index (1.4)] and lower emissions of carbon dioxide (CO2), methane (CH4), and ammonia (NH3). Additionally, it could improve the microbial variety and the amounts of functional bacteria (i.e., Chloroflexi) in compost, which might be advantageous for the decomposition of refractory organic materials and plant growth. Therefore, the multistage inoculation pattern is recommended for organic waste composting in terms of its gas emissions, compost quality and efficacy benefits.

Semi-continuous mesophilic-thermophilic two-phase anaerobic co-digestion of food waste and spent mushroom substance: Methanogenic performance, microbial, and metagenomic analysis.

The methanogenic efficiency and system stability of anaerobic co-digestion of food waste (FW) and spent mushroom substance (SMS) are important for its application. A 90-day semi-continuous study was conducted to compare the co-digestion performance of an ethanologenic-methanogenic two-phase system and an acidogenic-methanogenic system using FW and SMS as substrates. The results showed that the ethanologenic-methanogenic system increased the contents of ethanol and acetate in the hydrolytic acidification phase. Microbial-community analysis showed that ethanologenic-methanogenic system enriched hydrolytic acidifying bacteria and methanogens such as Methanoculleus, resulting in an increase in the average methane yield of methanogenic phase by 1.91-2.43 times at the same organic loading rate (OLR = 3.0-4.0 g-VS·L-1·d-1). Metagenomic analysis indicated that the ethanologenic-methanogenic system increased the abundance of enzyme-encoding genes and promoted the degradation of acetate and CO2/H2, thereby enhancing methanogenic metabolic pathways, compared to the acidogenic-methanogenic system.

Fusion of multimodality image and point cloud for spatial surface registration for knee arthroplasty.

BACKGROUND: Image-guided computer-aided navigation system is an indispensable part of computer assisted orthopaedic surgery. However, the location and number of fiducial markers, the time required to localise fiducial markers in existing systems affect their effectiveness. METHOD: The study proposed that spatial surface registration between the point cloud on the surface of the fusion model based on preoperative knee MRI and CT images and the point cloud on the cartilage surface captured by intraoperative laser scanner could solve the above limitations. RESULTS: The experimental results show that the registration error of the method is less than 2 mm, but the total time from scanning the point cloud on patient's cartilage surface to registering it with the point cloud in preoperative image space is less than 2 min. CONCLUSION: The method achieves the registration accuracy similar to existing methods without selecting anatomical corresponding points, which is of great help to the clinic.

Biodrying of biogas residue through a thermophilic bacterial agent inoculation: Insights into dewatering contribution and microbial mechanism.

Biogas residue (BR) is difficult to transport and compost due to its high moisture content. The purpose of this study was to elucidate the dewatering and microbial mechanisms underlying the inoculation of a thermophilic bacterial agent (TBA) onto BR with a high moisture content (i.e., 90.4%). TBA accounted for 78.7% of the water loss rate in BR, dramatically higher than the effects of aeration, external heat, or indigenous microorganisms (i.e., 1.8%, 0.1%, and 19.4%, respectively). Furthermore, TBA inoculation resulted in a stable product [with a low moisture content (9.4%) and a high seed germination index (107.3%)]. Finally, TBA increased microbial diversity and the abundance of functional bacteria (Proteobacteria and Bacteroidota), which might be beneficial for refractory organic compound decomposition and plant growth. Thus, biodrying BR via inoculation with a TBA is recommended economically.

Heavy metal leaching behaviour and long-term environmental risk assessment of cement-solidified municipal solid waste incineration fly ash in sanitary landfill.

Cement solidification is a commonly used pre-treatment method for municipal solid waste incineration fly ash (MSWIFA) prior to sanitary landfill. However, the long-term environmental risk of cement-solidified MSWIFA blocks in the exposed scenario of zoning sanitary landfill remains unclear. In this study, the leaching characteristics of different heavy metals in cement-solidified MSWIFA blocks under deionized water and acid rain scenarios were firstly investigated. The leaching control mechanisms of heavy metals were also explored and applied to established mechanical models for the estimation of long-term environmental risk. Results revealed that Pb leaching from cement-solidified MSWIFA blocks was controlled by diffusion; Cu, Cr and As leaching was mainly controlled by surface wash-off and diffusion; and Ni leaching was mainly controlled by diffusion and dissolution. Additionally, the established bulk diffusion, first-order reaction/diffusion and diffusion/dissolution models could accurately fit the abovementioned three types of heavy metals with different leaching control mechanisms (R2 > 0.95). Under acid rain scenarios， according to the prediction results of the calibrated models, the cumulative leaching amount of Pb in 718 d was higher than the limit in GB16889-2008, the cumulative leaching amount of Cu, Cr, As and Ni did not exceed the limit in GB 16889-2008 even in 50 years. Therefore, the long-term environmental risk was relatively high for Pb but was low for Cu, Cr, As and Ni in cement-solidified MSWIFA blocks. This finding could be attributed to the strong alkali environment of cement-solidified MSWIFA blocks (pH > 12) that induced Pb salts (e.g. Pb(OH)2 and PbSO4) dissolution. Therefore, the removal of partially soluble Pb salts from freshly made cement-solidified MSWIFA blocks by water or natural rainwater (e.g. without final cover system) washing in the initial landfilling stage (e.g. the leachate drainage system remains functional) is an effective countermeasure to reduce the environmental risks in zoning sanitary landfill.

Research trend analysis of composting based on Web of Science database.

Bibliometric analysis was used in this study for the quantitative evaluation of current research trends on composting. The research articles indexed from the Science Citation Index-Expanded in Web of Science database published from 2000 to 2019 were investigated. The USA, China and Spain were the top three countries considering the number of papers. Amongst the research institutes, CSIC of Spain, Chinese Academy of Sciences and Agriculture & Agri-Food Canada ranked the top three in total publication amount. Journals that published a significant number of literature regarding topics of composting included Environmental Sciences & Ecology, Agriculture and Engineering. In terms of research content, keywords such as heavy metal, heavy metal and biodegradation appeared frequently. In addition, the analysis of keywords revealed the following research hotspots in future studies: investigation of heavy metal passivator, optimisation of composting conditioner, development of all kinds of microorganisms, rational management of the composting process and improvement of solid waste life cycle assessment. To some extent, it helps to understand the current global status and trends of the related research.

Mesophilic condition is more conducive to methane production yield and tylosin removal on tylosin fermentation dreg anaerobic digestion.

Anaerobic digestion (AD) of antibiotic fermentation dreg is effective because of its satisfactory methanogenic performance and antibiotic removal rate. Thermophilic AD, an important branch, has not been studied. This study explored the effects of mesophilic and thermophilic AD on tylosin fermentation dreg (TFD) alone-digestion and co-digestion with food waste. The methane production (245-420 mL/g-VS) of mesophilic AD was 20.7%-28.6% higher than thermophilic AD, but the maximum methane production rate (RM), lag period (λ), and hydrolysis rate constant (kh) of thermophilic AD were 1.81, 0.236 and 3.16 times higher than those of mesophilic AD, respectively. However, the residual tylosin in mesophilic AD was always higher than that in thermophilic AD. The addition of food waste increased the methane production rate and yield under both temperature conditions. Therefore, due to the higher rate and yield of methane production, mesophilic AD, especially co-digestion, is more suitable for the treatment of TFD.