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• P transformation was comprehensively investigated during long-term THP-AD process;. • TP in the aqueous phase decreased from 130.61 to 107.01 mg/L after AD process;. • A substantial biodegradation of DON raised the pH of the digestate to 8.3;. • The decreased p was mainly precipitated with mg and Ca, driven by the increased pH. Waste activated sludge (WAS) is a significant phosphorus (P) repository, and there is a growing interest in P recovery from WAS. Typically, the commercial technology for treating WAS involves thermal hydrolysis pretreatment (THP) coupled with anaerobic digestion (AD). However, there is ongoing debate regarding the transformation and distribution of P throughout this process. To address this, a long-term THP-AD process was operated in this study to comprehensively investigate P transformation and distribution. The results revealed that a substantial biodegradation of dissolved organic nitrogen (DON) raised the pH of the digestate to 8.3 during the AD process. This increased pH facilitated the dissolution of Al, leading to a reduction of 6.92 mg/L of NaOH-P. Simultaneously, sulfate reduction contributed to a decrease of 11.04 mg/L of Bipy-P in the solid. However, the reduction of Bipy-P and NaOH-P in the solid did not result in an improved P release to the supernatant. Conversely, a decrease of 23.60 mg/L P in the aqueous phase was observed after anaerobic digestion. The disappeared P was primarily precipitated with Mg and Ca, driven by the increased pH, and it contributed to the increase of HCl-P in the solid from 107.80 to 144.52 mg/L. These findings were further confirmed by results obtained from scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and solid-state 31P nuclear magnetic resonance (NMR) spectroscopy. This study provides valuable insights into the mechanisms of P transformation during THP-AD process that is nearly opposite from conventional AD system. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights • Two processes are used to prepare dialdehyde starch nanoparticles. • Starch nanocrystals showed great stability and dispersibility after oxidation. • The crystallinity and particle size of dialdehyde starch nanoparticles are different. • Starch nanocrystals have great emulsification properties. Abstract Physicochemical and emulsification properties of dialdehyde starch nanocrystals (DASNCs) and dialdehyde starch nanoparticles (DASNPs) were measured in this study. The starch nanocrystals (SNCs), which are prepared by sulfuric acid hydrolysis, were oxidized by sodium periodate to obtain the DASNCs. The DASNPs were prepared by gelatinization and alcohol precipitation of dialdehyde starch. After oxidization by sodium periodate, the SNCs and SNPs became smaller and more suitable for dispersion. X-ray diffraction results showed that the crystal pattern of the SNCs was preserved after oxidation. However, only a single broad peak at the Bragg angle of the DASNPs was observed. The SNCs and DASNCs can form Pickering emulsions, but the emulsions stabilized by the SNPs and DASNPs could be easily broken. The preparation methods for the two kinds of dialdehyde starch nanoparticles are different, so their structures, properties and applications are different. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of solid retention times (SRTs) on hydrogen production via thermophilic alkaline fermentation of waste activated sludge. The reactor was subjected to a SRT from 10 to 6 days during approximately 82 days of operation. The results revealed that SRT had minor influence on hydrolysis and hydrolysis efficiency in different phases were from 48.11% to 50.55%. Nevertheless, the efficiency of acidogenesis process was highly related to SRT and longer SRT could enhance the acidogenesis. On the other hand, acidogenesis efficiency was also related to H 2 partial pressure and high H 2 partial pressure negatively affected the acidogenesis. Thus, the maximum acidification was achieved in phase 1 (21.29%) resulting in the maximum H 2 yield in phase 1 (95.94 mL/g VSS; SRT = 10 days; H 2 partial pressure = 0–18%). Phyla Actinobacteria and Proteobacteria, who are highly related to hydrolytic microbial population, were abundant in all phases that resulted in high hydrolysis extent. H 2 production was attributed to the relative high abundance of Clostridia. Thus, this study suggested that longer SRT and lower H 2 partial pressure was necessary to improve the H 2 yield under alkaline pH condition. [ABSTRACT FROM AUTHOR]

In this study, a thermophilic (65 °C) single-stage wasted activated sludge (WAS) digester was established and the effects of solid retention time (SRT) on the reactor performance were investigated. The result showed that the optimum SRT was 6 days with methane yield of 186.16 mL/g VS. It was found that SRT had little effect on the hydrolysis and volatile solids (VS) destruction, and the high temperature employed seemed sufficient to achieve maximum hydrolysis and VS destruction performance. Longer SRT, however, promoted the release of recalcitrant compounds and impaired acidification, leading to the low methane yield. The microbial community analysis revealed that the dominant pathway for methane production was through syntrophic activity of acetate oxidizing bacteria and hydrogenotrophic methanogens while acetoclastic methanogens were absent in the system. [ABSTRACT FROM AUTHOR]

This study aimed to develop an in-situ sludge pretreatment method by increasing the temperature from thermophilic to extreme thermophilic condition in a single-stage anaerobic digester. The results revealed that a stable performance was obtained within the temperature range of 55–65 °C, and the maximum methane yield of 208.51 ± 13.66 mL/g VS was obtained at 65 °C. Moreover, the maximum extent of hydrolysis (33%) and acidification (27.1%) was also observed at 65 °C. However, further increase of temperature to 70 °C did not improve the organic conversion efficiency. Microbial community analysis revealed that Coprothermobacter , highly related to acetate oxidisers, appeared to be the abundant bacterial group at higher temperature. A progressive shift in methanogenic members from Methanosarcina to Methanothermobacter was observed upon increasing the temperature. This work demonstrated single-stage sludge digestion system can be successfully established at high temperature (65 °C) with stable performance, which can eliminate the need of conventional thermophilic pretreatment step. [ABSTRACT FROM AUTHOR]

Abstract: By hydrolyzing pea hull fibres (PHF) for different times (t) with sulfuric acid, a series of pea hull fibre-derived nanowhisker (PHFNW-t) dispersions was prepared. The PHFNW-t dispersions were then blended with pea starch (PS) to fabricate bionanocomposite films (PS/PHFNW-t). The effect of t on the structure and properties of the PHFNW-t nanowhiskers and those of the corresponding PS/PHFNW-t nanocomposite films were investigated. The length (L), diameter (D) and L/D values of the PHFNW-t ranged from 240 to 400nm, 7 to 12nm, and 32.22 to 36.00, respectively. The PS/PHFNW-t nanocomposite films exhibited higher ultraviolet absorption, transparency, tensile strength, elongation at break, and water-resistance than both the neat PS film and the PS/PHF film (as a control with a t of 0h). The PS/PHFNW-8 film showed the highest transparency, tensile strength, and elongation at break among the PS/PHFNW-t films, due to the high L/D of PHFNW-8. These results revealed that the length of hydrolysis time had a great effect on the structure (including L, D and L/D) of the PHFNW-t nanowhiskers, as well as on the structure and performance of the resulting PS/PHFNW-t films. For preparation of PHFNW-t nanowhiskers and corresponding PS/PHFNW-t films, the most suitable hydrolysis time, in this work, is 8h. [Copyright &y& Elsevier]

Abstract: Pea starch nanocrystals (PSN) dispersion containing nanocrystals in a range of 30–80nm was prepared from native pea starch (NPS) granules by acid hydrolysis. Two series of films were prepared by blending poly(vinyl alcohol) (PVA) with NPS and PSN, respectively. The effects of NPS and PSN on the structure and properties of the resulting films were comparatively investigated by FTIR, XRD, SEM, and testing of light transmittance, tensile, and moisture uptake. The light transmittance (Tr), tensile strength (σ b), and elongation at break (ε b) of the PVA/NPS films were lower than that of PVA film and decreased with an increase in NPS content. However, the PVA/PSN nanocomposite films containing 5 and 10wt% of PSN content exhibited improved physical properties over the PVA film. The PVA/PSN films showed higher Tr, σ b, and ε b, and lower moisture uptake (Mu) than the corresponding PVA/NPS films with the same component ration. For example, the values of Tr, σ b, ε b, and Mu of the PVA/PSN film containing 10wt% of PSN content were 91%, 40MPa, 734% and 71%, respectively; while those of the corresponding PVA/NPS film were 69%, 35MPa, 579% and 73%, respectively. The results revealed that PSN, comparing with NPS, had much smaller sizes and dispersed more homogeneously in PVA matrix, resulting in stronger interactions with PVA. New applications of native pea starch and its nanocrystals as low-cost fillers were explored in this work, and PSN exhibited greater potential than NPS to improve the properties of PVA-based composites. [Copyright &y& Elsevier]

Microporous membranes (CS1-n) were prepared by blending cellulose and soy protein isolate (SPI) in 6 wt.% NaOH/5 wt.% thiourea aqueous solution. The membranes CS1-n were hydrolyzed with 5 wt.% NaOH aqueous solution to obtain membranes CS2-n. The structure and properties of the membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), the flow rate method, and tensile testing. The blend membranes CS1-n exhibited mesh structure woven by SPI and cellulose, and the membranes CS2-n possess microporous structure as a result of the removal of SPI during the NaOH-hydrolysis process. The apparent pore size (2re) measured with SEM, the mean pore size (2rf) obtained by the flow rate method, and the water ultrafiltration rate (UFR) of the CS1-n and CS2-n membranes increased with an increase in SPI content, and are higher than those of the pure cellulose membrane and previous membranes. The values of 2rf (47.7–77.2 nm) and UFR (28–53.5 mL h-1 m-2 mmHg-1) of the microporous membranes CS2-n are higher than those of the corresponding membranes CS1-n, because of removing of most of SPI by NaOH-treatment. The microporous membranes also kept high tensile strength in both dry and wet states. In addition, the membranes CS2-n containing a small amount of SPI are suitable for the culture of Vero cells. Therefore, the membranes could be used as candidates for application in separation technology and biomedical fields. [Copyright &y& Elsevier]

The high food waste content (HFWC) MSW at a landfill has the characteristics of rapid hydrolysis process, large leachate production rate and fast gas generation. The liquid-gas interactions at HFWC-MSW landfills are prominent and complex, and still remain significant challenges. This paper focuses on the liquid-gas interactions of HFWC-MSW observed from a large-scale bioreactor landfill experiment (5 m × 5 m × 7.5 m). Based on the connected and quantitative analyses on the experimental observations, the following findings were obtained: (1) The high leachate level observed at Chinese landfills was attributed to the combined contribution from the great quantity of self-released leachate, waste compression and gas entrapped underwater. The contribution from gas entrapped underwater was estimated to be 21–28% of the total leachate level. (2) The gas entrapped underwater resulted in a reduction of hydraulic conductivity, decreasing by one order with an increase in gas content from 13% to 21%. (3) The “breakthrough value” in the gas accumulation zone was up to 11 kPa greater than the pore liquid pressure. The increase of the breakthrough value was associated with the decrease of void porosity induced by surcharge loading. (4) The self-released leachate from HFWC-MSW was estimated to contribute to over 30% of the leachate production at landfills in Southern China. The drainage of leachate with a high organic loading in the rapid hydrolysis stage would lead to a loss of landfill gas (LFG) potential of 13%. Based on the above findings, an improved method considering the quantity of self-released leachate was proposed for the prediction of leachate production at HFWC-MSW landfills. In addition, a three-dimensional drainage system was proposed to drawdown the high leachate level and hence to improve the slope stability of a landfill, reduce the hydraulic head on a bottom liner and increase the collection efficiency for LFG. [ABSTRACT FROM AUTHOR]