Utilization strategy for algal bloom waste through co-digestion with kitchen waste: Comprehensive kinetic and metagenomic analysis.

Anaerobic co-digestion (AcoD) with kitchen waste (KW) is an alternative utilization strategy for algal bloom waste (AW). However, the kinetic characteristic and metabolic pathway during this process need to be explored further. This study conducted a comprehensive kinetic and metagenomic analysis for AcoD of AW and KW. A maximum co-digestion performance index (CPI) of 1.13 was achieved under the 12% AW addition. Co-digestion improved the total volatile fatty acids generation and the organic matter transformation efficiency. Kinetic analysis showed that the Superimposed model fit optimally (R2Adj = 0.9988-0.9995). The improvement of the kinetic process by co-digestion was mainly reflected in the increase of the methane production from slowly biodegradable components. Co-digestion enriched the cellulolytic bacterium Clostridium and the hydrogenotrophic methanogenic archaea Methanobacterium. Furthermore, for metagenome analysis, the abundance of key genes concerned in cellulose and lipid hydrolysis, pyruvate and methane metabolism were both increased in co-digestion process. This study provided a feasible process for the utilization of AW produced seasonally and a deeper understanding of the AcoD synergistic mechanism from kinetic and metagenomic perspectives.

Dissolved organic carbon spurs bacterial-algal competition and phosphorus-paucity adaptation: Boosting Microcystis' phosphorus uptake capacity.

Dissolved organic carbon (DOC) can alter the availability of background nutrients by affecting the proliferation of heterotrophic bacteria, which exerts a notable influence on algal growth and metabolism. However, the mechanism of how allochthonous DOC (aDOC) precipitates shifts in bacterial-algal interactions and modulates the occurrence of cyanobacteria blooms remains inadequately elucidated. Therefore, this study investigated the relationship between bacteria and algae under aDOC stimulation. We found that excess aDOC triggered the breakdown and reestablishment of the equilibrium between Microcystis and heterotrophic bacteria. The rapid proliferation of heterotrophic bacteria led to a dramatic decrease in soluble phosphorus and thereby resulted in the inhibition of the Microcystis growth. When the available DOC was depleted, the rapid death of heterotrophic bacteria released large amounts of dissolved phosphorus, which provided sufficient nutrients for the recovery of Microcystis. Notably, Microcystis rejuvenated and showed higher cell density compared to the carbon-absent group. This phenomenon can be ascribed that Microcystis regulated the compositions of extracellular polymeric substances (EPS) and the expression of relevant proteins to adapt to a nutrient-limited environment. Using time of flight secondary ion mass spectrometry (TOF-SIM) and proteomic analysis, we observed an enhancement of the signal of organic matter and metal ions associated with P complexation in EPS. Moreover, Microcystis upregulated proteins related to organic phosphorus transformation to increase the availability of phosphorus in various forms. In summary, this study emphasized the role of DOC in algal blooms, revealing the underestimated enhancement of Microcystis nutrient utilization through DOC-induced heterotrophic competition and providing valuable insights into eutrophication management and control.

Novel cost-effective oxygen-enriched melting method for MSWI fly ash.

Herein, a novel oxygen- enriched melting process for fly ash, which uses the biogas produced from the leachate of municipal solid waste incineration (MSWI) plants, is proposed to reduce the high cost of conventional fly ash - melting technology. The fly ash composition was estimated via X-ray fluorescence analysis; the six constituent elements detected in fly ash in the decreasing order of their content were calcium, chlorine, silicon, sulfur, sodium, and potassium. Based on literature and actual production data, the average yield of the leachate was 15% of the total waste entering the MSWI plants and the COD of leachate was 30,000-75,000 mg/L. The amount of biogas that can be used per ton of fly ash was calculated to be 62.0-157.0 m3. The analysis of melting thermal equilibrium revealed the amount of biogas required per ton of fly ash as 57.8 m3. The aforementioned research findings indicate that the biogas produced by MSWI plants can successfully meet the demands of the oxygen- enriched melting of fly ash produced in these plants. By establishing an oxygen- enriched- melting pilot platform, the pilot tests of melting were conducted on fly ash; the results revealed the good melting effects of fly ash. The X-ray diffraction analysis of the slag demonstrated that the content of the vitreous body met the technical requirements for glassy substances. Furthermore, the leaching toxicity test results revealed that heavy metals were well solidified in the slag. This study presents a novel fly ash - melting scheme for MSWI fly ash, namely, biogas oxygen- enriched melting strategy, which has the advantages of technical feasibility and cost- effectiveness. The proposed technique exhibits considerable prospects for widespread application in MSWI plants in China and can play an important role in the safe disposal of fly ash.Implications: In this paper, a low- cost melting method of municipal solid waste incineration(MSWI) fly ash is proposed. This method uses the biogas generated by MSWI plant itself as fuel for melting. Through research, it has been found that the production of biogas can meet the demand for fly ash melting. Adopting biogas as a molten fuel can significantly reduce the cost of melting, thereby significantly reducing the cost of fly ash melting. This study established a pilot scale platform for the melting of biogas and conducted pilot scale experiments on fly ash and additives. The experimental results showed that the melting system operated well and achieved the vitrification of fly ash. The leaching test results of the molten slag showed that heavy metals were well solidified in the slag. The research results can be extended to the MSWI plant for application, which can significantly reduce the cost of fly ash melting disposal, and has broad application prospects.

Integrated control strategy for dual sludge ages in the high-concentration powder carrier bio-fluidized bed (HPB) technology: Enhancing municipal wastewater treatment efficiency.

The high-concentration powder carrier bio-fluidized bed (HPB) technology is an emerging approach that enables on-site upgrading of wastewater treatment plants (WWTPs). HPB technology promotes the formation of biofilm sludge with micron-scale composite powder carriers as the core and suspended sludge mainly composed of flocs surrounding the biofilm sludge. This study proposed a novel integrated strategy for assessing and controlling the sludge ages in suspended/bio-film activated sludge supported by micron-scale composite powder carrier. Utilizing the cyclone unit and the corresponding theoretical model, the proposed strategy effectively addresses the sludge ages contradiction between denitrifying bacteria and polyphosphate-accumulating organisms (PAOs), thereby enhancing the efficiency of municipal wastewater treatment. The sludge age of the suspended (25 d) and bio-film (99 d) sludge, calculated using the model, contribute to the simultaneous removal of nitrogen and phosphorus. Meanwhile, the model further estimates distinct contributions of suspended and bio-film sludge to chemical oxygen demand (COD) and total nitrogen (TN), which are 55% and 42% for COD, 20% and 57% for TN of suspended sludge and bio-film sludge, respectively. This suggests that the contribution of suspended sludge and bio-film sludge to COD and TN removal efficiency can be determined and controlled by the operational conditions of the cyclone unit. Additionally, the simulation values for COD, ammonia nitrogen (NH4+-N), TN and total phosphorus (TP) closely align with the actual values of WWTPs over 70 days (p < 0.001) with the correlation coefficients (R2) of 0.9809, 0.9932, 0.9825, and 0.837, respectively. These results support the theoretical foundation of HPB technology for simultaneous nitrogen and phosphorus removal in sewage treatment plants. Therefore, this model serves as a valuable tool to guide the operation, design, and carrier addition in HPB technology implementation.

Intelligent upgrade of waste-activated sludge dewatering process based on artificial neural network model: Core influential factor identification and non-experimental prediction of sludge dewatering performance.

Owing to the extremely complex compositions and origins of waste-activated sludge (WAS), the multiple physiochemical properties of WAS have impacts on its dewaterability, and there is a complex interaction relationship among the multiple physiochemical properties, which makes it difficult to identify the controlling factors on WAS dewaterability. Accordingly, there is still no unified certainty in the appropriate ranges of physiochemical properties for the optimal dewaterability of sludge from different sources, resulting in a lack of clear theoretical basis for technical selection and optimization of sludge dewatering processes. The large consumption of conditioning chemicals and low process efficiency stand for the major deficiency of existing sludge conditioning technologies. This study proposed to use a non-linear, adaptive and self-organizing artificial neural network (ANN) model to integrate the multiple physiochemical properties of WAS affecting its dewaterability, and WAS dewatering performance under certain conditioning schemes could be predicated by ANN model with the multiple physiochemical properties and conditioning operation parameters as the input arguments. Thus, the laborious filtration experiments for screening conditioning chemicals could be replaced by the input adjustment of ANN model. Rooted mean squared error (RMSE) of 6.51 and coefficient of determination (R2) of 0.73 confirmed the satisfied stability and accuracy of established ANN model. Furthermore, the predictor-exclusive method revealed that the exclusion of polar interface free energy decreased most, which reflected the importance of surface hydrophilicity reduction in sludge dewaterability improvement. All the contributions presented here were believed to provide an intelligent insight to improve the experience operation status of WAS dewatering process.

Crystallization-driven evolution of water occurrence states with implications on dewaterability improvement of waste-activated sludge.

This study proposed to improve the dewaterability of waste-activated sludge (WAS) through crystallization-driven evolution of water occurrence states. Primarily, the feasibility of clathrate hydrate (i.e., CO2 hydrate) formation in WAS was examined. The thermodynamic analysis indicated that the CO2 hydrate formation with the excessive water in WAS followed pseudo-first-order kinetics, and fit of the data yielded a kobs value of 3.905 × 10-5 L∙mol-1∙s-1 for 274.15 K. With the water conversion efficiency of 100%, the crystallization-dissociation process of CO2 hydrate significantly improved the dewaterability of WAS in term of capillary suction time (CST) decreasing from 251.5 s to 57.4 s. Also, the relief of gas pressure can induce the hydrate dissociation, which creates a novel way to recycle CO2 gas and save the consumption of chemicals required by sludge dewatering process. Regarding the mechanism of hydrates-based sludge dewatering, the evolution of water occurrence state was investigated. The in-situ synchrotron X-ray computed microtomography visually analyzed the micro-scale porosity and interstitial water of WAS flocs. The model of three-dimensional pore structure was established and the porosity parameters of solid aggregates were determined. It was found that the volume of connected pores and the total pore volume fraction of solid compositions increased. But the mean volume and mean area of isolated pores simultaneously decreased by 14.6% and 12.4%, respectively, which meant that the steric hindrance caused by isolated pores was weakened due to the reduced solid-water contact area. In addition, the crystallization of water caused the reformation of conformation arrangement of vicinal water and solid molecules, which highly organized the water molecules into the crystal structure. Accordingly, an estimation method for vicinal water layer thickness was developed based on atom force microscope. The thickness of vicinal water layer was found to be reduced by 77.4% and the hydration repulsion among solid compositions was correspondingly weakened, which facilitated the aggregation of solid compositions, and the relatively separated hydrate phase and solid phase could be formed. All the above results open up a novel strategy for enhanced water-solid separation of WAS through the crystallization-driven evolution of water occurrence states. As distinguished from the conventional approaches, the hydrates-based sludge dewatering enhances the water-solid separation only with regulating the spatial arrangement of water-solid molecules, but without altering the chemical compositions. Thus, more chances can be created to increase the environmentally friendly attributes related to WAS dewatering.

Strengthen high-loading operation of wastewater treatment plants by composite micron powder carrier: Microscale control of carbon, nitrogen, and sulfur metabolic pathways.

The concentration of activated sludge is a crucial factor influencing the capacity and efficiency of sewage wastewater treatment plants (WWTPs). However, high sludge concentrations can lead to sludge loss in the secondary sedimentation tank, resulting in reduced processing capacity, particularly during low-temperature stages and sludge bulking. This study investigated the impact of adding composite micron powder carriers (CMPC) in high-concentration powder carrier biofluidized bed (HPB) technology to the biochemical units of WWTPs on sludge concentration and settling performance. For the traditional activated sludge method (ASM), its hydraulic retention time (HRT) was 8 h, with an average effluent total nitrogen (TN) of 15.14 mg/L. Sludge bulking was prone to occur in low-temperature environments, resulting in a high average sludge volume index (SVI) of 560 mL/g. Conversely, with a CMPC dosage of 4 g/L, the HRT of HPB technology was 4.8 h, and the average effluent TN was 11.40 mg/L, with a removal efficiency of 67.43 %. During operation of HPB technology under high sludge concentration conditions (8 g/L), the average SVI remained at 85 mL/g, indicating excellent settling characteristics. Moreover, in the sequencing batch reactor (SBR), the SVI value of bulking sludge decreased from the original 695 to 111 mL/g by the 9th day of operation with the CMPC dosage of 2 g/L. At the same time, the filamentous bacteria almost disappeared, suggesting that CMPC inhibit the growth of filamentous bacteria. Metagenomic analysis demonstrated that CPMC enhance the utilization of small molecular fatty acids in activated sludge and promote electron transfer between nitrate and nitrite, thereby improving wastewater treatment capacity. Additionally, CMPC enhanced the relative abundance of Saprospiraceae in sludge, which accelerate the degradation of polysaccharides in extracellular polymeric substances, weaken sludge's hydrophilic properties, and improve sludge's settling performance. Overall, these findings suggested that CMPC effectively strengthen the high-loading operation of WWTPs by improving sludge concentration and sedimentation performance.

Rapid start-up and long-term stable operation of the anammox reactor based on biofilm process: Status, challenges, and perspectives.

Anammox-biofilm processes have great potential for wastewater nitrogen removal, as it overcomes the slow growth and easy loss of AnAOB (anaerobic ammonium oxidation bacteria). Biofilm carrier is the core part of the Anammox-biofilm reactor and plays a key role in the start-up and long-term operation of the process. Therefore, the research on the biofilm carrier of Anammox-based process was summarized and discussed in terms of configurations and types. In the Anammox-biofilm process, fixed bed biofilm reactor is a relatively mature biofilm carrier configuration and has advantages in terms of nitrogen removal and long-term operational stability, while moving bed biofilm reactor has advantages in terms of start-up time. Although the long-term operational stability of fluidized bed biofilm reactor is good, its nitrogen removal performance needs to be improved. Among the different biofilm carrier categories, the inorganic biofilm carrier has an advantage in start-up time, due to the enhancement of the growth and metabolic of AnAOB by inorganic materials (such as carbon and iron). Anammox-based reactors using organic biofilm carriers, especially suspension carriers, are well-established and more stable in long-term operation. Composite biofilm carriers combine the advantages of several materials, but their complex preparation procedures lead to high costs. In addition, possible research directions for accelerating the start-up and keeping the long-term stable operation of Anammox reactor by biofilm process were highlighted. It is hoped to provide a possible pathway for the rapid start-up of Anammox-based process, and references for the optimization and promotion of process.

Ordered Heterostructured Aerogel with Broadband Electromagnetic Wave Absorption Based on Mesoscopic Magnetic Superposition Enhancement.

Demand for lightweight and efficient electromagnetic wave (EW) absorbers continues to increase with technological advances in highly integrated electronics and military applications. Although MXene-based EW absorbers have been extensively developed, more efficient electromagnetic coupling and thinner thickness are still essential. Recently, ordered heterogeneous materials have emerged as a novel design concept to address the bottleneck faced by current material development. Herein, an ordered heterostructured engineering to assemble Ti3 CNTx MXenes/Aramid nanofibers/FeCo@SiO2 nanobundles (FS) aerogel (AMFS-O) is proposed, where the commonly disordered magnetic composition is transformed to ordered FS arrays that provide more powerful magnetic loss capacity. Experiments and simulations reveal that the anisotropy magnetic networks enhance the response to the magnetic field vector of EW, which effectively improves the impedance matching and makes the reflection loss (RL) peaks shift to lower frequencies, leading to the thinner matching thickness. Furthermore, the temperature stability and excellent compressibility of AMFS-O expand functionalized applications. The synthesized AMFS-O achieves full-wave absorption in X and Ku-band (8.2-18.0 GHz) at 3.0 mm with a RLmin of -41 dB and a low density of 0.008 g cm-3 . These results suggest that ordered heterostructured engineering is an effective strategy for designing high-performance multifunctional EW absorbers.

Accelerating the granulation of anammox sludge in wastewater treatment with the drive of "micro-nuclei": A review.

Anammox granule sludge (AnGS) has great potential in the field of wastewater nitrogen removal, but its development and promotion have been limited by the slow granulation speed and fragile operating stability. Based on the reviews about the AnGS formation mechanism in this paper, "micro-nuclei" was found to play an important role in the granulation of AnGS, and adding "micro-nuclei" directly into the reactor may be an efficient way to accelerate the formation of AnGS. Then, accelerating AnGS granulation with inert particles, multivalent positive ions, and broken granule sludge as "micro-nuclei" was summarized and discussed. Among inert particles, iron-based particles may be a more advantageous candidate for "micro-nuclei" due to their ability to provide attachment sites and release ferric/ferrous ions. The precipitations of multivalent positive ions are also a potential option for "micro-nuclei" that can be generated in-situ, but a suitable dosing strategy is necessary. About broken granular sludge, the broken active AnGS may have advantages in terms of anaerobic ammonium oxidation bacteria-affinity and granulation speed, while using inactive granular sludge as "micro-nuclei" can avoid interfering bacterial invasion and has a higher cost performance than broken active AnGS. In addition, possible research directions for accelerating the formation of AnGS by dosing "micro-nuclei" were highlighted. This paper is intended to provide a possible pathway for the rapid start-up of AnGS systems, and references for the optimization and promotion of the AnGS process.

Mechanistic insights into polyhydroxyalkanoate-enhanced denitrification capacity of microbial community: Evolution of community structure and intracellular electron transfer of nitrogen metabolism.

Denitrification is the key driving force of nitrogen cycle in surface water and plays an important role in eutrophication water remediation. Compared with some other common carbon sources, such as glucose and sodium acetate, polyhydroxyalkanoates (PHAs) were found to have the distinguished advantages in screening specific denitrifying bacteria of natural surface water bodies. In this study, the large ensembles of taxa were obtained from surface water samples and then sub-cultured with PHA or glucose as the sole carbon source. The microbial community that could be screened by PHA was identified, and the environmental functions of these bacteria were analyzed. At the genus level, the main communities regulated by PHA included Pseudomonas (56.30 %), Acinetobacter (27.75 %), Flavobacterium (10.19 %) and Comamonas (3.14 %), which all had good denitrification ability. The changes in carbon source, nitrogen source and biomass (expressed by DNA) were simultaneously monitored when culturing the model strain (P. stuzeri) with PHA or glucose. Compared with the glucose group, less PHA was consumed to remove the same amount of nitrate within a shorter incubation time, and there was no significant difference in bacterial growth with PHA or glucose as the carbon source (glucose:ΔN:ΔC:ΔDNA = 1:18:0.072; PHA:ΔN:ΔC:ΔDNA = 1:11:0.063). PHA improved the denitrification efficiency by increasing the expression of NarGHI, NirB, NirK and NorB, i.e., the key enzymes in the denitrification process. In addition, PHA accelerated the assimilating rate of extracellular nitrate by bacteria through increasing the expression of NarK. Finally, PHA-regulated electron transfer during denitrification was studied by observing the changes in NADH and NAD+. PHA could use a large proportion of NADH to offer electrons for denitrification, which increased the rate of denitrification. Improved mechanistic insights into the PHA-enhanced denitrification capacity of the microbial community can provide novel options for the in-situ remediation of eutrophic surface water.

In Situ Remediation Technology for Heavy Metal Contaminated Sediment: A Review.

Sediment is an important part of the aquatic ecosystem, which involves material storage and energy exchange. However, heavy metal pollution in sediment is on the increase, becoming an important concern for the world. In this paper, the state-of-art in situ remediation technology for contaminated sediment was elaborated, including water diversion, capping, electrokinetic remediation, chemical amendments, bioremediation and combined remediation. The mechanisms for these techniques to reduce/immobilize heavy metals include physical, electrical, chemical and biological processes. Furthermore, application principle, efficiency and scope, advantages and disadvantages, as well as the latest research progress for each restoration technology, are systematically reviewed. This information will benefit in selecting appropriate and effective remediation techniques for heavy metal-contaminated sediment in specific scenarios.

PHA stimulated denitrification through regulation of preferential cofactor provision and intracellular carbon metabolism at different dissolved oxygen levels by Pseudomonas stutzeri.

Denitrification, a typical biological process mediated by complex environmental factors, i.e., carbon sources and dissolved oxygen (DO), has attracted great attention due to its contribution to the control of eutrophication and the biochemical cycling of nitrogen. However, the effects of carbon source on electron distribution and enzyme expression for enhanced denitrification under competition of electron acceptors (DO and nitrate) remain unclear. Here, we profile the carbon metabolic pathway of polyhydroxybutyrate (PHB) and glucose (Glu) at high and low DO levels (50% and 10% saturated DO, respectively). It was found that PHB enhanced the growth of Pseudomonas stutzeri (model denitrifying bacterium) and improved the specific nitrogen removal rate (SNRR) at all DO levels. The functional proteins had a better affinity for the cofactor nicotinamide-adenine dinucleotide (NADH) than for nicotinamide adenine dinucleotide phosphate (NADPH); thus, more electrons were involved in nitrogen reduction and intracellular PHB production in the PHB groups than in the Glu groups. Furthermore, the expression difference of enzymes in glucose and PHB metabolism was demonstrated by metaproteomic and target protein analysis, implying that PHB-driven intracellular carbon accumulation could optimize the intracellular electron allocation and correspondingly promote nitrogen metabolism. Our work integrated the mechanisms of intracellular carbon metabolism with preferences for electron transfer pathways in denitrification, providing a new perspective on how the selective parameters regulated microbial functions involved in denitrification.

Mechanism insights into liquid polarity regulation for enhanced dewatering of waste-activated sludge: Specifically focusing on the solid-liquid affinity reduction depending on phase-transfer and conformational features of amphiphilic protein.

This study proposed that decreasing liquid polarity could weaken the intermolecular polar force at solid-liquid interface of waste-activated sludge (WAS). Accordingly, a process for enhanced sludge dewatering through liquid polarity regulation was established. The liquid polarity was quantified by dielectric constant and the decrease of liquid dielectric constant below 50 was found to significantly improve the solid-liquid separation performance of WAS in terms of filterability by >70%. The differential scanning calorimeter (DSC) coupled with mass spectrum (MS) identified that 60 °C was the appropriate temperature for liquid amendment (i.e., acetonitrile) recovery from filtered sludge cake, and the corresponding energy consumption was calculated to be at most 799.0 J/g, which was substantially lower than that of water evaporation by sludge drying. The NaCl addition with 75% of saturated concentration could non-thermally recover 91.7 ± 4.9% of acetonitrile amendment from filtrate by salting-out. The great potentials in energy saving and recycle of chemicals make the newly proposed approach act as alternatives for the conventional process (i.e., mechanically dewatering + drying). Regarding the mechanism of liquid polarity regulation for enhanced WAS dewatering, the solid-liquid interfacial free energy was found to be reduced by 39.4% with the liquid dielectric constant decreasing from 78.50 to 41.00. Also, Tandem Mass Tags (TMT) proteomics tracked the phase-transfer of amphiphilic proteins with decreasing liquid polarity, which found that the solubilization of proteins involved in the Gene Ontology (GO) classifications of "membrane protein complex" and "membrane protein complex/outer membrane" could facilitate the enhanced solid-liquid separation of WAS. The conformational analysis on those differential proteins was further conducted to reveal the structure attributes of amphiphilic proteins for the phase-transfer feature. The proteins with more exposed amino acid residues (i.e., average solvent accessibility index over 1.8) tended to dissolve in the liquid phase with lower polarity, which was accompanied with the reduced interfacial free energy of WAS. On the contrary, the proteins with buried amino acid residues (e.g., the central hydrophobic ß-sheet is surrounded by the hydrophilic α-helix) precipitated in the solid phase with the decreasing liquid polarity. All these findings are expected to create a novel option for dewatering WAS with recyclable liquid conditioning agents, and provide the improved mechanistic insights into the migration of interfacial compositions controlling the dewaterability of WAS.

Influential mechanism of water occurrence states of waste-activated sludge: Over-focused significance of cell lysis to bound water reduction.

The rigid cell membrane structure is widely thought to retain the intracellular water and positively contributes to the presence of bound water in waste-activated sludge (WAS), which is the main obstacle of its highly-efficient dewatering. However, few studies realized the quantification of intracellular water fraction in the total bound water. Thus, there still may be some debates on whether and what extent of cell lysis is optimal for the dewaterability improvement. This study specifically focused on the effect of microbial cell lysis on the water occurrence states of WAS. The sonication, cyclic freezing-thawing and dimethyl sulfoxide (DMSO) amendment were used as the non-chemical means for cell lysis without altering the chemical compositions of WAS. The extent of cell lysis was quantified by the aqueous lactate dehydrogenase (LDH) released from intracellular cytoplasm and the water occurrence states of WAS were characterized by the transverse relaxation time (T2) spectra of low-field nuclear magnetic resonance (NMR). The results indicated that 8 h sonication (60 W/g dry matter, solid content of WAS: 23.10±0.30 g/L) completely lysed the microbial cells, but only increased the moderately mobile water fraction from 0.555% to 2.370%; similarly, it could be estimated that nearly 15% of cells were destructed after 5 times of freezing-thawing, but the fraction of moderately mobile water only rose from 0.555% to 0.805%. The transmission electron microscope (TEM) with ultrathin sections visually tracked the WAS micro-morphology accompanied with the cell lysis; the sonication caused the notable lysis of microbial cells and dispersed the external encapsulating components, which originally surrounded microbial cells closely; most of the microbial cells could be deformed but wasn't lysed by cyclic freezing-thawing; DMSO amendment made the outer edge of microbial cells tend to be rough, which may reflect the DMSO-enhanced permeability of cell membrane. The correlative analysis further indicated that the capillary suction time (CST) had the close correlation with particle size/zeta potential (Pearson coefficient>0.85, p-value<0.05), but no strong correlation was identified between CST and slightly reduced bound water contents (Pearson coefficient<0.9, p-value≥0.05). Instead of the cell integrity, the compositional aggregation states dominated the water occurrence states of WAS. Highly-efficient conditioning approaches should rely on the reduction of bio-floc porosity through eliminating solid-liquid interfacial affinity instead of damaging the cell membrane structure.

Effective removal of hydrogen sulfide from landfill gases using a modified iron pentacarbonyl desulfurization agent and the desulfurization mechanism.

High-efficiency desulfurization is key to the recovery and use of landfill gases. In this study, a nano­iron oxide desulfurization agent modified from iron pentacarbonyl was prepared in n-decane (DE) and hexadecane (HE) by ultrasonic disruption without any supporting materials and its hydrogen sulfide removal ability and desulfurization mechanism were studied. The yield of the desulfurization agent was higher when HE was used as the solvent; however, the products generated by both solvents had the same crystal type and similar properties. The efficiency of the desulfurization agent was significantly improved at 150-200 °C, exceeding 90% at 150 °C with single sulfur production. The maximum sulfur adsorption capacity of the desulfurization agent produced after 3 h of DE ultrasonic treatment at 200 °C (DE3) was 492 mg/g (desulfurization efficiency = 97.33%), while that of the agent produced after 3 h of HE ultrasonic treatment at 250 °C (HE3) was 522 mg/g (desulfurization efficiency = 99.30%). The desulfurization reaction involved both chemical adsorption and catalytic decomposition and the catalytic decomposition reaction rate was lower than that of chemical adsorption. Therefore, the more FexSy produced in the chemical adsorption process, the better catalytic performance was.

Influential mechanism of water occurrence states of waste-activated sludge: Potential linkage between water-holding capacity and molecular compositions of EPS.

The water occurrence states in waste-activated sludge (WAS) are crucial to its dewaterability and significantly influenced by the water-retaining capacity of extracellular polymeric substances (EPS) matrix. Accordingly, the non-selective •OH-oxidation processes were widely reported for the sludge dewaterability improvement, just because it can non-selectively destruct complex structure units of EPS, no matter these structure units are crucial to EPS water-holding capacity or not. But these non-selective processes may also require the large consumption of oxidant chemicals, which limits their wide application. This study specifically focused on the •OH-induced variation in molecular compositions of EPS and the corresponding effects on water occurrence states of WAS, which is expected to lay a foundation for optimizing the efficiency of oxidation-based sludge conditioning. Especially, through a novel method based on the equilibrium dialysis with alkaline titration, the typical hydrophilic functional groups of EPS were quantitatively analyzed. The results indicated that the free amino group (-NH2) had the greater impact on the water-holding capacity of EPS than the acidic hydroxyl groups (-OH). Nevertheless, by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), the hydrophilic heteroatom classes (e.g. N:Cw) were found to be less sensitive to the varying oxidant dosage than the molecular saturation degree (e.g. weighted averages of double bond equivalents (DBEw) and aromatic index (AImod,w)). •OH modified the nitrogen-containing or oxygen-containing functional groups, but could not completely remove these hydrophilic functional groups from EPS macromolecules. Therefore, the potential competition for •OH between the hydrophilic functional groups and the unsaturated structure units of EPS was clarified, which guides directions that developing highly-efficient sludge conditioning approaches should be based on the selective removal of hydrophilic functional groups instead of improving •OH production efficiency.

Novel micro-granular sludge process for highly efficient treatment of low-strength and low C/N ratio municipal wastewater.

A novel high-concentration powder bio-carrier (HPB) process was developed for the high-load treatment of low-strength municipal wastewater with low carbon/nitrogen (C/N) ratio (∼3). The powder carrier facilitated the rapid micro-granulation of sludge within 20 days and the average particle size increased rapidly from 47 µm to 210 µm. Accordingly, the concentration of mixed liquid volatile suspended solids (MLVSS) increased from 1.8 g/L to 4.3 g/L, which enabled the HPB process to maintain a short hydraulic retention time (HRT) of 3.6 h. Correspondingly, the high volumetric load of 0.4-1.3 kg chemical oxygen demand (COD)/(m3∙d) and 0.12-0.24 kg total nitrogen (TN)/(m3∙d) could be achieved and twice higher than those of conventional activated sludge process, e.g., anaerobic/anoxic/oxic process. The carrier-induced sludge granulation also significantly optimized the microbial structure, and the high-throughput sequencing revealed the increasing abundances of denitrifying bacteria and anammox bacteria, which was consistent with the nitrogen removal efficiency rising from 44.6% to 77.4%. Accordingly, the enhanced nitrogen removal could be achieved with TN of effluent steadily below 5 mg/L. Especially, the mass balance analysis on carbon and nitrogen further indicated the advantage of newly developed HPB process in carbon source saving for nitrogen removal. All the results are believed to suggest a promising strategy for the highly efficient treatment of low-strength municipal wastewater.

Highly efficient solid-liquid separation of anaerobically digested liquor of food waste: Conditioning approach screening and mechanistic analysis.

Anaerobic digestion is known for its effectiveness and environmental friendliness in treating food waste. However, it produces anaerobically digested liquor (ADL). ADL usually has a high solid content and high concentrations of nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) carried by suspended solids (SS). Thus, when ADL with amounts of SS reaches the subsequent biochemical treatment units, they negatively impact the microbial stability of corresponding processes, causing unstable effluent qualities. For this reason, the solid-liquid separation of ADL acts as a crucial step for the wide application of anaerobic digestion. In this work, the typical sludge conditioning approaches, including flocculation/coagulation, coagulation, oxidation and advanced oxidation processes (AOPs), were systematically screened for their feasibility in enhancing the solid-liquid separation of ADL. The modified Fenton treatment combined with centrifugation was found to be the most effective approach, which realized the removal of 91.36% SS with FeSO4•7 H2O (5.96 g/L) and H2O2 (2.79 g/L) but without pH adjustment of ADL. The mechanism analysis showed that the modified Fenton promoted ADL colloidal aggregates to form looser medium-sized flocs with pores, increased the zeta potential to -17.6 mV, and highly reduced the total interfacial free energy. Also, extracellular polymeric substances (EPS) were released into liquid phase, which further eliminated the water-retaining properties of solid compositions. The analysis of surface chemical composition suggested that the modified Fenton decreased the hydrophilic component from 53.37% to 43.81% and the relative content of protein-N from 45.43% to 23.57%, while increased carbon chain and hydrocarbyl species. Furthermore, principal component analysis (PCA) suggested that SS, zeta potential, Lewis acid-base interfacial free energy, two-dimensional fractal index (2-Df) and C-(N, O) relative content were more sensitive to variations in conditioning approaches than protein-N relative content, and hydroxyl free radical (•OH) played the key role for the modified Fenton to improve SS removal from ADL.

A Phase 2 Study of Camrelizumab for Advanced Hepatocellular Carcinoma: Two-Year Outcomes and Continued Treatment beyond First RECIST-Defined Progression.

INTRODUCTION: In a multicenter, open-label, parallel-group, randomized, phase 2 study for pretreated advanced hepatocellular carcinoma (HCC), camrelizumab showed potent antitumor activity and acceptable safety profile. The aim of this report was to provide long-term data and evaluate potential benefit of treatment with camrelizumab beyond progression. METHODS: From November 15, 2016, to November 16, 2017, 217 patients received camrelizumab 3 mg/kg intravenously every 2 or 3 weeks. Treatment beyond first Response Evaluation Criteria in Solid Tumors (RECIST)-defined progression (TBP) with camrelizumab was allowed. RESULTS: At data cutoff of December 16, 2019 (>2 years after the last patient enrollment; median duration of follow-up, 13.2 months [IQR 5.7-25.8]), 14 (43.8%) of the 32 responses per blinded independent central review were ongoing. The median duration of response was not reached (range 2.5-30.5 + months). The ongoing response rates at 12, 18, and 24 months were 68.3% (95% confidence interval [CI] 47.7-82.2), 59.8% (95% CI 38.8-75.6), and 53.1% (95% CI 31.0-71.0), respectively. The median overall survival (OS) was 14.2 months (95% CI 11.5-16.3). The 18- and 24-month OS rates were 41.3% (95% CI 34.6-47.9) and 33.7% (95% CI 27.3-40.2), respectively. Of the 172 patients who experienced RECIST-defined progression per investigator, 102 received TBP, while 70 did not (non-TBP). The median OS was 16.9 months (95% CI 13.3-22.6) in the TBP group versus 9.4 months (95% CI 5.8-14.8) in the non-TBP group, and the 18- and 24-month OS rates were 47.5% (95% CI 37.3-56.9) versus 33.1% (95% CI 22.3-44.3) and 38.8% (95% CI 29.2-48.4) versus 23.2% (95% CI 13.8-34.1), respectively. No new safety signals of camrelizumab were observed. CONCLUSIONS: With prolonged follow-up, camrelizumab continues to demonstrate the durable response and long survival in pretreated advanced HCC patients with manageable toxicities, especially in those who continued the treatment beyond first RECIST-defined progression.