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The synergistic effect of heteroatoms is a viable method to enhance the adsorption performance of heavy metal onto carbon-based materials. However, the high cost, complex operation and a lot of pollution from the synthesis process have limited its development. Herein, a facile two-step pyrolysis method is used to prepare in situ N and S doped porous biochar from paper mill sludge for the removal of Cr(VI) from aqueous environment. The NSC-450 sample prepared under the optimum conditions has a large specific surface area of 3336.7 m 2 g -1 , an average pore size of 2.56 nm and a total pore volume of 2.10 cm 3 g -1 , manifesting the excellent adsorption capacity of 356.25 mg g -1 for Cr(VI). The adsorption of Cr(VI) by NSC-450 is consistent with the Langmuir isotherm and pseudo-second-order model, suggesting a spontaneous and endothermic chemisorption process. The analysis results show that the NH, graphitic nitrogen and thiophene structures have a positive effect on converting a large amount of Cr(VI) to Cr(III) by synergistic reduction, indicating obviously facilitating Cr(VI) removal compared to other sites. Therefore, in this material, the strong adsorption mechanism is mainly reductive complexation. Moreover, the effects of real water quality, anions, cations and fulvic acid on the adsorption behavior of Cr(VI) onto the NSC-450 were further investigated. The results demonstrate that the chromium removal rate remains above 82% even in actual electroplating wastewater, suggesting NSC-450 has great practical application prospect. This work offered a feasible method for high-value utilization of sludge, but also provided a novel perspective for the future design of heteroatom-doped carbon materials for promoting to eliminate hexavalent chromium from water environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Given the high content of Ca 2+ in waste paper recycling wastewater, the anaerobic granular sludge (AnGS) undergoes calcification during wastewater treatment and affects the treatment efficiency. To restore the activity of calcified AnGS and improve the performance of AnGS, four types of N-acyl-homoserine lactones (AHLs) were added to the AnGS system while papermaking wastewater treatment. The addition of N-butyryl-DL-homoserine lactone(C4-HSL) and N-octanoyl-DL-homoserine lactone (C8-HSL) had an inhibitory affect the COD removal efficiency and SMA of sludge at the inception. The addition of N-hexanoyl-L-homoserine lactone (C6-HSL) has no obvious effect on the COD removal efficiency, but can improve the SMA of sludge more obviously. The addition of N-(β-ketocaproyl)-DL-homoserine lactone (3O-C6-HSL) can increased COD removal efficiency and promoted SMA together obviously. The addition of C6-HSL and 3O-C6-HSL can increase volatile suspended solid (VSS)/total suspended solid (TSS), and regulate extracellular polymeric substance (EPS) secretion in AnGS. Analysis of microbial sequencing revealed changes in the microbial community structure following AHL addition, which enhanced the methane metabolism pathway in sludge. The addition of C6-HSL, C8-HSL, and 3O-C6-HSL increased Methanosaeta population, thus increasing the aceticlastic pathway in sludge. Thus, exogenous AHLs can play an important role in regulating microbial community structure, and in improving the performance of AnGS., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

This paper reported a new method for the determination of the water distribution in sludge. It was based on a multiple headspace extraction (MHE) procedure to step-wise remove the water vapor from a closed vial containing a sludge sample, followed by a gas chromatographic measurement (GC). By plotting the GC signal of water vapor vs. the headspace extraction number, three different trend lines from the profile can be observed. From which two transition points can be determined and thus the stages for the free water, capillary water, and adsorption water release can be divided. Based on the sum of GC peak areas ate each stage, the content of these water types in the sludge can be calculated through a method calibration. The results showed that the MHE-GC method has a better measurement repeatability (RSD < 18.6%) and sensitivity (limit of quantitation = 0.028%) than the thermal drying method (used as a reference method). There was also a good agreement between the MHE-GC and the reference method on the free water and capillary water analysis. Moreover, the results on the adsorption water and bound water testing by the present method is more justifiable than the reference method., Competing Interests: Declaration of Competing Interest No conflict of interest exists in the submission of this manuscript, and the manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2020. Published by Elsevier B.V.)

This paper describes a headspace gas chromatographic (HS-GC) method for the in-situ determination of the observed yield coefficient (Y obs ) of aerobic activated sludge from domestic wastewater treatment plants. It is based on the measurement of oxygen and carbon dioxide in samples that have been incubated in headspace vials for relatively short periods of time. The method has good precision (the relative standard deviation < 5.46%) and accuracy (the relative differences < 9.23% when compared with the data from the reference method). The new method is much simpler and more efficient than the reference methods and should greatly facilitate the testing in aerobic activated sludge related applications, such as system design, operation and management., (Copyright © 2019. Published by Elsevier B.V.)

Column-type combined reactors were designed to cultivate micro-aerobic pentachlorophenol (PCP) degrading granular sludge under oxygen-limited conditions (0.1-0.2 mgL(-1)) over 39-day experimental period. Micro-aerobic granular had both anaerobic activity (SMA: 2.34 mMCH4/hg VSS) and aerobic activity (SOUR: 2.21 mMO2/hg VSS). Metabolite analysis results revealed that PCP was sequentially dechlorinated to TCP, DCP, and eventually to MCP. Methanogens were not directly involved in the dechlorination of PCP, but might played a vital role in stabilizing the overall structure of the granule sludge. For Eubacteria, the Shannon Index (2.09 in inoculated granular sludge) increased both in micro-aerobic granular sludge (2.61) and PCP-degradation granular sludge (2.55). However, for Archaea, it decreased from 2.53 to 1.85 and 1.84, respectively. Although the Shannon Index demonstrated slight difference between micro-aerobic granular sludge and PCP-degradation granular sludge, the Principal Component Analysis (PCA) indicated obvious variance of the microbial composition, revealing significant effect of micro-aerobic condition and PCP on microbial community. Furthermore, nucleotide sequencing indicated that the main microorganisms for PCP degradation might be related to Actinobacterium and Sphingomonas. These results provided insights into situ bioremediation of environments contaminated by PCP and had practical implications for the strategies of PCP degradation., (Copyright © 2014 Elsevier B.V. All rights reserved.)