Comprehensive molecular analyses of a 7-m6A-related lncRNAs signature for prognosis, tumor immunity and therapeutic effect in patients with hepatocellular carcinoma.

Hepatocellular carcinoma is the most common form of liver tumor. m6A modification and noncoding RNA show indispensable roles in HCC. We sought to establish and verify an appropriate m6A-related long noncoding RNA prognostic tool for predicting hepatocellular carcinoma progression. We extracted the RNA expression levels and the clinicopathologic data from GTEx and TCGA databases. Multivariate Cox regression analysis and receiver operating characteristic curves were performed to test the model's predictive ability. We further built a nomogram for overall survival according to the risk score and clinical features. A competing endogenous RNA network and Gene Ontology assessment were implemented to identify related biological mechanisms and processes. By bioinformatics analysis, a risk model comprising GABPB1-AS1, AC025580.1, LINC01358, AC026356.1, AC009005.1, HCG15, and AC026368.1 was built to offer a prognostic prediction for hepatocellular carcinoma independently. The prognostic tool could better prognosticate hepatocellular carcinoma patients' survival than other clinical characteristics. Then, a nomogram with risk score and clinical characteristics was created, which had strong power to calculate the survival probability in hepatocellular carcinoma. The immune-associated processes involving the differentially expressed genes between the two subgroups were displayed. Analyses of prognosis, clinicopathological characteristics, tumor mutation burden, immune checkpoint molecules, and drug response showed significant differences among the two risk subtypes, hinting that the model could appraise the efficacy of immunotherapy and chemotherapy. The tool can independently predict the prognosis in patients with hepatocellular carcinoma, which benefits drug selection in hepatocellular carcinoma patients.

Nomogram for the preoperative prediction of Ki-67 expression and prognosis in stage IA lung adenocarcinoma based on clinical and multi-slice spiral computed tomography features.

OBJECTIVE: This study developed and validated a nomogram utilizing clinical and multi-slice spiral computed tomography (MSCT) features for the preoperative prediction of Ki-67 expression in stage IA lung adenocarcinoma. Additionally, we assessed the predictive accuracy of Ki-67 expression levels, as determined by our model, in estimating the prognosis of stage IA lung adenocarcinoma. MATERIALS AND METHODS: We retrospectively analyzed data from 395 patients with pathologically confirmed stage IA lung adenocarcinoma. A total of 322 patients were divided into training and internal validation groups at a 6:4 ratio, whereas the remaining 73 patients composed the external validation group. According to the pathological results, the patients were classified into high and low Ki-67 labeling index (LI) groups. Clinical and CT features were subjected to statistical analysis. The training group was used to construct a predictive model through logistic regression and to formulate a nomogram. The nomogram's predictive ability and goodness-of-fit were assessed. Internal and external validations were performed, and clinical utility was evaluated. Finally, the recurrence-free survival (RFS) rates were compared. RESULTS: In the training group, sex, age, tumor density type, tumor-lung interface, lobulation, spiculation, pleural indentation, and maximum nodule diameter differed significantly between patients with high and low Ki-67 LI. Multivariate logistic regression analysis revealed that sex, tumor density, and maximum nodule diameter were significantly associated with high Ki-67 expression in stage IA lung adenocarcinoma. The calibration curves closely resembled the standard curves, indicating the excellent discrimination and accuracy of the model. Decision curve analysis revealed favorable clinical utility. Patients with a nomogram-predicted high Ki-67 LI exhibited worse RFS. CONCLUSION: The nomogram utilizing clinical and CT features for the preoperative prediction of Ki-67 expression in stage IA lung adenocarcinoma demonstrated excellent performance, clinical utility, and prognostic significance, suggesting that this nomogram is a noninvasive personalized approach for the preoperative prediction of Ki-67 expression.

Life-cycle assessment of two sewage sludge-to-energy systems based on different sewage sludge characteristics: Energy balance and greenhouse gas-emission footprint analysis.

Anaerobic digestion and incineration are widely used sewage sludge (SS) treatment and disposal approaches to recovering energy from SS, but it is difficult to select a suitable technical process from the various technologies. In this study, life-cycle assessments were adopted to compare the energy- and greenhouse gas- (GHG) emission footprints of two sludge-to-energy systems. One system uses a combination of AD with incineration (the AI system), whereas the other was simplified by direct incineration (the DI system). Comparison between three SS feedstocks (VS/TS: 57.61 -73.1 ds.%) revealed that the AI system consistently outperformed the DI system. The results of sensitivity analyses showed that the energy and GHG emission performances were mainly affected by VS content of the SS, AD conversion efficiency, and the energy consumption of sludge drying. Furthermore, the energy and GHG emission credit of the two systems increased remarkably with the increase in the VS content of the SS. For the high-organic-content sludge (VS/TS: 55%-80%), the energy and GHG emission credit of the AI system increase with the increase of AD conversion efficiency. However, for the low organic content sludge (VS/TS: 30%-55%), it has the opposite effect. In terms of energy efficiency and GHG performance, the AI system is a good choice for the treatment of high-organic-content sludge (VS/TS>55%), but DI shows superiority over AI when dealing with low organic content sludge (VS/TS<55%).

Passivation of lead and cadmium and increase of the nutrient content during sewage sludge composting by phosphate amendments.

As an efficient and cost-effective biological treatment method for sewage sludge, composting has been widely used worldwide. To passivate heavy metals and enhance the nutrient content in compost, in the present study, phosphate rock, calcium magnesium phosphate, and monopotassium phosphate were added to the composting substrate. According to the Community Bureau of Reference sequential extraction procedure, phosphate rock and monopotassium phosphate amendments exhibit a good passivation effect on Cd and Pb. The X-ray diffraction patterns proved the formation of Pb3(PO4)2 and Cd5(PO4)2SiO4 crystals, and X-ray absorption near-edge structure spectroscopy illustrated the change in P speciation after phosphate amendment. Furthermore, phosphate amendment increased the contents of total P and available P, and it reduced the loss of N during sewage sludge composting. The germination index showed that the target phosphate amendments in sewage sludge compost had no negative effects on seed germination, and this method has great potential to be used as a soil amendment.

Perlite as the partial substitute for organic bulking agent during sewage sludge composting.

Composting is an efficient and cost-effective technology for sewage sludge treatment, and bulking agents are essential in sewage sludge composting. In this study, perlite was chosen as inorganic bulking agent to partially substitute for the organic bulking agent. Variations in the temperature, bulk density, moisture content, pH, electrical conductivity, organic carbon, nitrogen, phosphorus and potassium were detected during sewage sludge composting. The treatment with a mass ratio of spent mushroom substrate to perlite at 3:1 exhibited the highest pile temperature and the best effect on reducing bulk density and moisture content. In addition, Fourier transform infrared spectra showed that perlite promotes the degradation of organic matter during the composting process, and the germination index showed that the compost from all treatments was safe for agricultural application. When the mass ratios of spent mushroom substrate and perlite at 3:1 and 2:2 were chosen as bulking agents, the sewage sludge compost product could be used to produce plant cultivation substrate, and economic benefits could be obtained from sewage sludge composting according to comprehensive cost analysis.

Effect of phosphate amendments on improving the fertilizer efficiency and reducing the mobility of heavy metals during sewage sludge composting.

Composting has been globally applied as an effective and cost-efficient process to manage and reuse sewage sludge. In the present study, four different phosphates as well as a mixture of ferrous sulfate and monopotassium phosphate were used in sewage sludge composting. The results showed that these phosphate amendments promoted an increase in temperature and the degradation of organic matter as well as reduction on nitrogen loss during 18 days of composting. In addition, ferrous sulfate and phosphate had a synergistic effect on reducing nitrogen loss. The contents of total phosphorus and available phosphorus in the compost with addition of 1% phosphate were 40.9% and 66.1% higher than the compost with control treatment. Using the BCR (Community Bureau of Reference) sequential extraction procedure, the addition of calcium magnesium phosphate significantly reduced the mobility factor of Cd, Zn and Cu by 24.2%, 1.7% and 18.8%, respectively. The mobility factors of Pb were increased in all samples, but the monopotassium phosphate treated sample exhibited the greatest Pb passivation ability with the lowest mobility factor increase (1.8%) among all treatments. The X-ray diffraction patterns of compost samples indicated that the passivation mechanism of Cu and Zn may be the forming CuFeS2 and ZnCu(P2O7) crystals during sewage sludge composting. The germination index showed that the compost of all treatments was safe for agricultural application; the germination index of the calcium magnesium phosphate treatment was 99.9 ±â€¯11.8%, which was the highest among all treatments.

Oxygen Monitoring Equipment for Sewage-Sludge Composting and Its Application to Aeration Optimization.

Oxygen is an important parameter for organic-waste composting, and continuous control of the oxygen in a composting pile may be beneficial. The oxygen consumption rate can be used to measure the degree of biological oxidation and decomposition of organic matter. However, without having a real-time online device to monitor oxygen levels in the composting pile, the adjustment and optimization of the composting process cannot be directly implemented. In the present study, we researched and developed such a system, and then tested its stability, reliability, and characteristics. The test results showed that the equipment was accurate and stable, and produced good responses with good repeatability. The equilibrium time required to detect oxygen concentration in the composting pile was 50 s, and the response time for oxygen detection was less than 2 s. The equipment could monitor oxygen concentration online and in real time to optimize the aeration strategy for the compost depending on the concentration indicated by the oxygen-measuring equipment.

Spatial and temporal dynamics of sewage sludge phosphorus recovery potential in the cities of Yangtze River Zone in China: Implications for regional recycling policies.

Sewage sludge phosphorus (P) recovery presents opportunities to sustainably recycle P from cities to agriculture and alleviate global P scarcity. However, limited research explores sustainable recovery targets considering spatial-temporal variations in sludge generation and implications based on city-level local P demand. This study analyzed sludge production form 2009-2021 across 130 cities in China's Yangtze River Zone, which increased by almost 35 % from 2009 to 2021. Per capita gross domestic product (GDP), influent chemical oxygen demand (COD), and per capita drainage infrastructure were identified as the main significant influencing factors. City-level analysis revealed pronounced spatial-temporal disparities, with yearly sludge generation spanning five orders of magnitude (62-5.4 × 105 t/a). An indicator, "Potential of P recovery to local P demand", was defined, indicating the average city-level P recycle contribution increased from 5.3 % to 18.9 % from 2009-2021. A novel frame paradigm classified cities into six types based on the local P supply-demand characteristics, prioritizing sludge P recovery and implementing strategic management. City-specific dynamics and possibilities of broader "city clusters" to match supply and demand should be considered for policy implement. Recovering P from livestock manure and kitchen waste alongside sludge can further strengthen urban P cycles. This study provides novel city-scale analysis and strategic considerations for regional sludge P recycling policies in China and beyond.

Start-up of a full-scale two-stage partial nitritation/anammox (PN/A) process treating reject water from high solid anaerobic sludge digestion (HSAD).

High solid anaerobic digestion (HSAD) achieves the benefits of high volumetric loading rates and lower reject water production, which, however, results in much more concentrated reject water with a remarkable increase in organics and nitrogen compared with that from conventional AD with low solid content. The high concentrations of ammonium (2000-3500 mg/L) and COD (3000-4000 mg/L) were reported to exert inhibition on anammox bacteria (AnAOB), posing challenges to the application of the partial nitritation/anammox (PN/A). To date, no cases of PN/A process start-up for sludge HSAD reject water were reported. This study demonstrated the start-up process of a 480 m3/d PN/A project without anammox sludge inoculation and treating HSAD reject water from a centralized dewatered sludge treatment plant. The project did not construct new infrastructures but utilized previously constructed tanks to upgrade the process from existing short-cut nitrification-denitrification to a two-stage PN/A process. Although no external anammox sludge inoculation was performed to save seeding sludge cost, the start-up was successfully achieved in about 9 months (273 days) based on a three-step method of "AnAOB enrichment - sludge acclimation - capacity doubling". During start-up, the relative abundance of AnAOB (Candidatus_Kuenenia) increased from near zero to 12.0%. After start-up, the total inorganic nitrogen (TIN) removal load reached 0.74 kgN/(m3•d), with a total nitrogen removal efficiency of over 90%. Compared to the traditional nitrification-denitrification process, the PN/A process remarkably reduces the addition of organic chemicals and aeration energy consumption, saving approximately 4.2 million yuan (RMB) in operational costs annually. In summary, this research provides a full-scale reference for the start-up of the PN/A process treating sludge HSAD reject water.

A Dataset of Distribution and Characterization of Underground Wastewater Treatment Plants in China.

Underground wastewater treatment plants (U-WWTPs) have emerged as a novel paradigm for urban wastewater pollutants management, offering benefits such as alleviating the Not-in-my-backyard (NIMBY) effect and utilizing land resources efficiently. China stands at the forefront, witnessing swift advancements in U-WWTP technology and deployment. However, the absence of a thorough understanding of their geographical distribution and operational characteristics could lead to misaligned planning and construction, resulting in inefficient resource allocation and treatment capacities for urban wastewater treatment. This dataset provides an up-to-date overview of the spatial distribution, process selection, and discharge standards for all U-WWTPs in China (with a total number of 201) constructed since 1995. To enhance comparative analysis, the dataset has been supplemented with information on conventional aboveground wastewater treatment plants (A-WWTPs), comprising a total of 2464 records, which enriches a more comprehensive evaluation of different wastewater treatment approaches. Utilizing this dataset can provide essential data support for the strategic management of urban wastewater systems and serve as a valuable reference for the paradigmatic renovation of existing wastewater treatment plants.

Fluidized bed photobioreactor based on diatomite powder and high light intensity improved microalgae harvesting, nutrient removal and lipid accumulation: Performance and microscopic mechanism.

Cultivation of microalgae using anaerobic digestate is a gain-win strategy for algal biomass production and achieving environmental benefits. However, the low biomass concentration and high harvest cost of the conventional suspended microalgae culture system are troublesome issues. In this study, a novel fluidized bed photobioreactor (FBPBR) based on diatomite powder was constructed for cultivating Scenedesmus quadricauda and treating diluted anaerobic digestate. The optimized diatomite carrier dosage of 750 mg/L increased microalgal biomass concentration to 1.58 g/L compared to suspended microalgae without carrier (0.99 g/L). When the light intensity was increased from 100 to 200 µmol/m2/s, the microalgal biomass in the FBPBR increased to 1.84 g/L and the settling efficiency increased to 93.58 %. This was due to the 1.60-fold enhancement of extracellular polymeric substance (EPS) secretion and changes in EPS properties. The increase in hydrophobic functional groups of EPS under high light intensity, coupled with the reconstitution of protein secondary structure, facilitated the initial attachment of algae to diatomite and the thickening of microalgal biofilm. Moreover, transcriptomic analysis demonstrated that diatomite promoted antioxidant defense and photosynthesis in S. quadricauda cells, alleviating the adverse effect of anaerobic digestate stress. The diatomite addition and elevated light intensity contributed to the highest lipid content (60.37 %), which was owing to the upregulated genes encoding fatty acid and triacylglycerol synthesis under the stress of localized nutrient starvation in the inner layer of microalgae biofilms. Furthermore, the regulation of phosphorus metabolism and NH4+-N assimilation improved nutrient removal (93.24 % and 96.86 % for NH4+-N and TP removal). This work will provide guidance for the development of FBPBR based on diatomite powder.

Footprints of total coliforms, faecal coliforms and E. coli in a wastewater treatment plant and the probabilistic assessment and reduction of E. coli infection risks.

Wastewater contains various pathogenic microorganisms, and the disease of workers caused by exposure to wastewater at the wastewater treatment plants (WWTPs) is a growing concern. The footprints of total coliforms (TC), faecal coliforms (FC) and Escherichia coli (E. coli) in a conventional activated sludge WWTP during 12 consecutive months were clarified. It was found that TC, FC and E.coli in influent were significantly removed (log 4.71, log 4.43 and log 4.62, respectively) by WWTP with sand filtration playing a key role, and excess sludge was a major potential pathway for them flowing to the environment. Through quantitative microbial risk assessment (QMRA), hand-to-mouth ingestion of untreated wastewater and wastewater in secondary/efficient sedimentation tanks, as well as accidental ingestion of sludge in dewatering workshop presented the highest infection risks of pathogenic E.coli in the WWTP, considerably exceeded the U.S. EPA benchmark (≤1 × 10-4 pppy). PPE application and E.coli concentration reduction in wastewater or sludge were recommended to reduce the infection risks at these stages. Further, partial ozonation and dissolved ozone flotation thickening were investigated able to reduce the infection risks at the stages of secondary and tertiary treatment of wastewater or sludge treatment by 90- 98 %. The findings of this study would assist in selecting appropriate processes for the further sanitation of WWTPs.

New strategy of drinking water sludge as conditioner to enhance waste activated sludge dewaterability: Collaborative disposal.

Drinking water sludge (DWS) and waste activated sludge (WAS) are usually treated separately. With the continuous deepening understanding of the characteristics of two types sludge, the research and application of the collaborative disposal is worth considering. The heated modification DWS (HDWS) rich in inorganic matter and aluminum (Al2O3) can be used as a conditioner to enhance WAS dewaterability using its properties with physical skeleton and chemically catalyzed ozone (O3). The results showed that the minimum values of capillary water time (CST) and specific resistance filtration (SRF) for WAS were 20.9±2.40 s and 1.07±0.19×1013 m/kg at pH=4, O3 dosage=60 mg/g VS and HDWS dosage=700 mg/g VS, corresponding to the reduction of sludge cake water content (Wc) to 60.37±0.97 %. The mechanism of HDWS+O3 enhanced WAS dewaterability was systematically elucidated through pyridine-infrared analysis and density functional theory (DFT) calculations. The surface of Al2O3 in HDWS had more Lewis acidic sites, and the oxygen atoms of O3 combined with Al atoms to form Al-O bonds and undergo electron transfer, while O3 molecules dissociated to produce more hydroxyl radicals (·OH). With the oxidation of ·OH, the extra-microcolony/cellular polymers (EMPS/ECPS) structure were destroyed and became looser, promoting the conversion of internal moisture to free moisture. Zeta potential tended to zero, particle size increased, and the surface was more hydrophobic. Correlation analysis revealed that the component content, protein (PN) secondary structure and molecular weight (MW) in ECPS were positively and more strongly correlated with the sludge dewaterability compared to EMPS. The discovery of HDWS+O3 applied to effectively enhance WAS dewaterability provided an inspiring perspective on the emerging DWS and WAS co-processing disposition.

Insights into the effect mechanism of back-mixing inoculation on sewage sludge biodrying process: Biodrying characteristics and microbial community succession.

Back mixing was frequently used to replace conventional bulking agenting, however, however, the internal effect mechanism was unclear. This study compared four bulking agents: mushroom residue (MR), MR + primary BM (BM-P), BM-P, and secondary BM (BM-S). The effect mechanism of back mixing (BM) inoculation was assessed based on biodrying performance and microbial community succession. Four trials (Trial A, Trial B, Trial C, and Trial D) reached maximum temperatures of 61.9, 68.8, 73.7, and 69.9 °C on days 6, 3, 2, and 2, respectively. Application of BM increased pile warming rate and resulted in higher temperatures. Temperature changes and microbial competition lead to decline in microbial diversity and richness during the biodrying process. Microbial diversity increased of four biodried products. The number of microorganisms shared by Trial A, Trial B, Trial C, and Trial D were 90, 119, 224, and 300, respectively. The addition of BM improved microbial community stability, and facilitating the initiation of biodrying process. Microbial genera that played an important role in the biodrying process included Ureibacillus, Bacillus, Sphaerobacter, and Tepidimicrobium. Based on these results, it was concluded that BM was efficient method to enhanced the microbial activity and reduced the usage of bulking agent.

[In-situ Sludge Reduction Technology Based on Ozonation].

The process parameters and sludge properties of an in-situ sludge ozone-reduction system were investigated under different ozone dosages and sludge ages. Subsequently, 75 mg·g-1 (as O3/MLVSS) was selected as the appropriate ozone dosage to satisfy the wastewater treatment capacity and in-situ sludge ozone-reduction. The calibration coefficient results of the sludge yield formula indicated that Yh was reduced from 0.331 g·g-1 to 0.326 g·g-1 (to MLVSS/COD m) by ozone treatment and Kd was increased from 0.046 d-1 to 0.050 d-1 at 75 mg·g-1. The effluent quality of the SBR system was satisfactory when the sludge age was 10 d. The ozone dosage of 75 mg·g-1 and sludge age of 10 d were selected as the appropriate process conditions, at which the excess sludge was reduced by 12%. The high-throughput sequencing results concluded that the microorganisms in the excess sludge after ozonation were different in phylum and genus. After ozone treatment, the abundance of Bacteroidetes increased by 1.2 times and the relative abundance of Proteobacteria with nitrification and denitrification ability decreased from 24% to 18%. The reduction in the abundance of nitrobacteria affected the denitrification capacity of the sewage treatment system, but the total effluent nitrogen still met the I B discharge standard of pollutants for municipal wastewater treatment plants. The relative abundance of Lactococcus increased from 0.4% to 21.6%. Simultaneously, the concentration of macromolecular organic substances in the EPS of the excess sludge increased from 40.6 mg·g-1 to 54.6 mg·g-1, while the CST increased from 15 s to 17 s after ozone treatment. The zeta potential decreased from -10.04 mV to -15.20 mV and the SVI of the excess sludge increased from 54 mL·g-1 to 62 mL·g-1, thereby indicating that the sedimentation performance and dewaterability were affected to some extent. However, the SS of the effluent and the solids content of the sludge cake after extraction did not change significantly, the system could still operate stably, and the subsequent dewaterability of the excess sludge was not significantly affected.

Identification of a novel CpG methylation signature to predict prognosis in lung squamous cell carcinoma.

BACKGROUND: DNA methylation plays a vital role in modulating genomic function and warrants evaluation as a biomarker for the diagnosis and treatment of lung squamous cell carcinoma (LUSC). OBJECTIVE: In this study, we aimed to identify effective potential biomarkers for predicting prognosis and drug sensitivity in LUSC. METHODS: A univariate Cox proportional hazards regression analysis, a random survival forests-variable hunting (RSFVH) algorithm, and a multivariate Cox regression analysis were adopted to analyze the methylation profile of patients with LUSC included in public databases: The Cancer Genome Atlas (TCGA), and the Gene Expression Omnibus (GEO). RESULTS: A methylated region consisting of 3 sites (cg06675147, cg07064331, cg20429172) was selected. Patients were divided into a high-risk group and a low-risk group in the training dataset. High-risk patients had shorter overall survival (OS) (hazard ratio [HR]: 2.72, 95% confidence interval [CI]: 1.82-4.07, P< 0.001) compared with low-risk patients. The accuracy of the prognostic signature was validated in the test and validation cohorts (TCGA, n= 94; GSE56044, n= 23). Gene set variation analysis (GSVA) showed that activity in the cell cycle/mitotic, ERBB, and ERK/MAPK pathways was higher in the high-risk compared with the low-risk group, which may lead to differences in OS.Interestingly, we observed that patients in the high-risk group were more sensitive to gemcitabine and docetaxel than the low-risk group, which is consistent with results of the GSVA. CONCLUSION: We report novel methylation sites that could be used as powerful tools for predicting risk factors for poorer survival in patients with LUSC.

Preservation of nitrogen and sulfur and passivation of heavy metals during sewage sludge composting with KH2PO4 and FeSO4.

Composting is an effective method for treating sewage sludge. The aim of this work was to study preservation of nitrogen and sulfur and passivation of heavy metals during sewage sludge composting with KH2PO4 and FeSO4. The results show the loss rate of N decreased by 27.5% while that of S was increased by 32.1% compared with the control treatment during composting when KH2PO4 and FeSO4 were added. X-ray absorption near-edge structure spectra show that S was converted to a highly oxidizable state during sewage sludge composting with added KH2PO4. The mobility factors of Cu, Zn, and Pb after composting were found to decrease by 13.6%, 21.6%, and 3.8%, respectively, compared with those before composting when KH2PO4 was added. Adding these two materials to Cu and Zn inhibits Zn3(PO4)2(H2O)4 and Cu5(PO4)2(OH)4 from transforming into more mobile forms, while adding these materials to Pb promotes Pb3(PO4)2 formation.

Emission characteristics of VOCs and potential ozone formation from a full-scale sewage sludge composting plant.

Volatile organic compounds (VOCs) are the major components of the odor emitted from sewage sludge composting plants and are generally associated with odorous nuisances and health risks. However, few studies have considered the potential ozone generation caused by VOCs emitted from sewage sludge composting plants. This study investigated the VOC emissions from a full-scale composting plant. Five major treatment units of the composting plant were chosen as the monitoring locations, including the dewatered room, dewatered sludge, blender room, fermentation workshop, and product units. The fermentation workshop units displayed the highest concentration of VOC emissions at 2595.7 ±â€¯1367.3 µg.m-3, followed by the blender room, product, dewatered sludge, and dewatered room units, whose emissions ranged from 142.2 ±â€¯86.8 µg.m-3 to 2107.6 ±â€¯1045.6 µg.m-3. The detected VOC families included oxygenated compounds, alkanes, alkenes, sulfide compounds, halogenated compounds, and aromatic compounds. Oxygenated compounds, particularly acetone, were the most abundant compounds in all samples. Principal component analysis revealed that the dewatered room and dewatered sludge units clustered closely, as indicated by their similar component emissions. The product units differed from the other sampling units, as their typical compounds were methanethiol, styrene, carbon disulfide, and hexane, all of which were the products of the latter stages of composting. Among the treatment units, the fermentation workshop units had the highest propylene equivalent (propy-equiv) concentration. Dimethyl disulfide and limonene were the major contributors. Limonene had the highest propy-equiv concentration, which contributed to the increased atmospheric reactivity and ozone formation potential in the surrounding air. To control the secondary environmental pollution caused by the VOC emissions during sewage sludge composting, the emission of limonene and dimethyl disulfide must be controlled from the blender room and fermentation workshop units.

Application of ceramsite and activated alumina balls as recyclable bulking agents for sludge composting.

Composting is a major sludge-treatment method and bulking agents are very important in sludge composting. In this study, ceramsite and activated alumina balls were chosen as recyclable bulking agents for sludge composting. Variations in the temperature, pH, electrical conductivity, organic matter, dissolved organic carbon, moisture content, and heavy metals were detected during composting with different bulking-agent treatments as well as differences in the germination index values. The results showed that both bulking agents could ensure the maturity of the compost; further, ceramsite treatment resulted in the best water removal efficiency. According to the sequential extraction procedure, both ceramsite and activated alumina balls could stabilize Cd but they also increased the mobility of Zn. After comparing the effects of different particle sizes of ceramsite on composting, 20 mm was determined to be the most optimal value. Additionally, the recovery rates of ceramsite and activated alumina balls were 96.9% and 99.9%, respectively.

Vacuum ammonia stripping from liquid digestate: Effects of pH, alkalinity, temperature, negative pressure and process optimization.

High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste. Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen, which has attracted a lot of attention in recent years. To investigate the parameter effects on the efficiency and mass transfer, five combination conditions (53 °C 15 kPa, 60 °C 20 kPa, 65 °C 25 kPa, 72 °C 35 kPa, and 81 °C 50 kPa) were conducted for ammonia stripping of sludge digestate. The results showed that 80% of ammonia nitrogen was stripped in 45 min for all experimental groups, but the ammonia transfer coefficient varied under different conditions, which increased with the rising of boiling point temperature, and reached the maximum value (39.0 mm/hr) at 81 °C 50 kPa. The ammonia nitrogen removal efficiency was more than 80% for 30 min vacuum stripping after adjusting the initial pH to above 9.5, and adjustment of the initial alkalinity also affects the pH value of liquid digestate. It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency, while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity. In terms of the mechanism of vacuum ammonia stripping, it underwent alkalinity destruction, pH enhancement, ammonia nitrogen dissociation, and free ammonia removal. In this study, two-stage experiments of alkalinity destruction and ammonia removal were also carried out, which showed that the two-stage configuration was beneficial for ammonia removal. It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste.