Tannic acid (TA), a phenolic compound, may be considered as a sludge conditioning agent on account of its ability to precipitate protein. In this study, the effectiveness of TA conditioning on ...enhancing waste activated sludge (WAS) dewatering was investigated at various pH values. The results indicated that with the conditioning of 0.15 mmol TA per gram of total solid (TS), the WAS dewaterability was affected distinctly by the pH regulation. The reductions of 86.8% capillary suction time (CST), 96.3% specific resistance of filtration (SRF), and 23.6% water content (Wc) of dewatered sludge cake were achieved at an optimal pH value of 4.0. Meanwhile, obvious alterations were observed in some aspects like supernatant viscosity, zeta potential, particle size and extracellular polymeric substances (EPS) polymers. Correlation analysis indicated that the proteins in slime EPS and loosely bound EPS dominantly governed sludge dewaterability. Fluorescence quenching analysis indicated that in the range of acidity, the increase of pH value afforded more binding sites of sludge EPS for TA. However, the removal of EPS protein depended on the combined effect of TA conditioning and pH regulation. The findings provided a novel approach and explanation of WAS dewaterability enhancement using organic additive conditioning and pH regulation.
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•Tannic acid conditioning altered sludge properties obviously.•High correlation between extracellular protein and sludge dewaterability.•The pH value affected binding sites of sludge EPS available for tannic acid.•Combined effect of tannic acid and pH conditioning contributed to protein removal.
•Sludge enhanced dewatering technologies are comprehensively reviewed.•Mechanisms of different sludge enhanced dewatering technologies are discussed.•Process adaptability of different sludge ...conditioning methods are analysed.•Sludge electro-dewatering and its coupled processes are discussed.•Sludge enhanced dewatering technology and its coupled processes are prospected.
Sludge is an inevitable by product of sewage treatment, and it includes pathogens, heavy metals, organic pollutants and other toxic substances. The components of sludge are complex and variable with extracellular polymeric substances (EPS) being one. EPS are highly hydrophilic and compressible, and make sludge dewatering difficult. Therefore, the development of efficient sludge-dewatering technology is an important means of mitigating rapid sludge growth. At present, the main methods used for sludge deep-dewatering technology are chemical preconditioning with high-pressure filtration and electrical mechanical dewatering. The selection of chemical preconditioning directly determines the final efficiency of the sludge-dewatering process. In this paper, we conduct a comprehensive review of the problems related to sludge dewatering and systematically summarise the impact of different chemical conditioning technologies on the efficiency of sludge dewatering. Furthermore, the characteristics of different enhanced dewatering technologies are evaluated and analysed for their adaptability and final disposal methods. We believe that this review can clarify the chemical conditioner mechanism to improve sludge dewatering, provide reference debugging information for the sludge-dewatering process and promote the development of efficient and environmentally friendly sludge-dewatering technology.
Adsorption is an effective and reliable method to recover phosphorus (P) from sewages. Extracellular polymeric substances (EPS) and agarose are common polysaccharides bioresources, and their ...carboxylic and phenolic hydroxyl groups can directly adsorb P via ion exchange and hydrogen bonding mechanisms. Here, we designed EPS-based and Fe-modified hydrogels (agarose (AG)- and agarose-humic (AH)- based hydrogels) for P recovery. The results showed that AG and AH hydrogels could adsorb 33.9 and 67.7 mg P g−1, respectively. Both as-developed hydrogels showed > 75% of the maximal adsorption capacity in the tested pH conditions (3−10). Coexisting anions (i.e., SO42-, NO3-, and CO32-) did not significantly affect the adsorption performance, except for CO32- which inhibited the process. Intraparticle diffusion controlled the adsorption process. After adsorption, large amounts of FePO4 and Fe2(HPO4)3 were generated in the hydrogels, confirming that ligand exchange was the major driving force.
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•EPS-based hydrogels are made from agarose and humic acid.•EPS-based hydrogel appeared to have excellent phosphorus adsorption performance.•Ligand exchange is the major driving force for hydrogels to trap phosphate.
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•The Na+ + Lysozyme pretreatment increased the yield of SCFAs in WAS by 7.6 times.•A synergistic effect was occurred between Na+ and lysozyme in promoting cell lysis.•Na+ + Lysozyme ...pretreatment significantly shortened the hydrolysis and acidification reaction times.•87% of the carbon source recovery in the liquid phase can be achieved after PAC conditioning.
Augmentation of the anaerobic treatment efficiency of waste activated sludge (WAS) to achieve better resource utilization is an effective approach for reducing carbon emissions and minimizing solid waste generation. However, resource recovery from WAS is often limited by the insufficient release and hydrolysis of organic matters within microbial cells. To overcome these issues, a novel Na+ and lysozyme co-pretreatment method has been used in this study to accelerate the production of short-chain fatty acids (SCFAs) by promoting cell lysis. Experimental results have revealed that the maximal SCFAs production of 302.8 ± 47.8 mg COD/g VSS is achieved with 10 % w/w lysozyme and 0.34 mol/L Na+ co-pretreatment on day 2, which is 7.6-fold higher than that of the control. Mechanism exploration has also exposed that Na+ and lysozyme exhibit a pronounced synergistic effect in cell lysis, where 1 + 1 > 2. The maximum sludge disintegration degree (DDM) and SCFAs conversion efficiency have been achieved by combined pretreatment, reaching 68.5 % and 74 %, respectively. The structure of extracellular polymeric substance (EPS) including protein content and looseness are also modified by Na+ or Na+ + Lysozyme pretreatment, which further confirm the impact of Na+ on the permeability of EPS. The carbon sources generated through Na+ and lysozyme pretreated WAS can be efficiently recovered through PAC conditioning, with a high recovery rate of 87 %. The Na+ and lysozyme reagents implemented in the present study are all non-toxic and cost-effective, thereby promising a green and efficient solution for the carbon recovery and separation from the WAS.
•Exergy analysis of diesel engine fuelled with various SBE biodiesel–diesel blends containing EPS.•Profound effect of engine speed and load on exergetic performance parameters of diesel ...engine.•Selection of B5 containing 50g EPS/L biodiesel as the best mixture.•Potential application of the applied framework for optimizing sustainability index of IC engines.
Exergy analysis of a DI diesel engine running on several biodiesel/diesel blends (B5) containing various quantities of expanded polystyrene (EPS) was carried out. Neat diesel and B5 were also investigated during the engine tests. The biodiesel used was produced using waste oil extracted from spend bleaching earth (SBE). The experiments were conducted to assess the effects of fuel type, engine speed, and load on thermal efficiency, exergetic parameters, and sustainability index of the diesel engine. The obtained results revealed that the exergetic parameters strongly depended on the engine speed and load. Generally, increasing engine speed remarkably decreased the exergy efficiency and sustainability index of the diesel engine. However, increasing engine load initially enhanced the exergy efficiency and sustainability index, while its further augmentation did not profoundly affect these parameters. The maximum exergy efficiency and sustainability index of the diesel engine (i.e. 40.21% and 1.67, respectively) were achieved using B5 containing 50g EPS/L biodiesel. Generally, the approach presented herein could be a promising strategy for energy recovery from polymer waste, emissions reduction, and performance improvement. The findings of the present study also confirmed that exergy analysis could be employed to minimize the irreversibility and losses occurring in modern engines and to enhance the sustainability index of combustion processes.
Summary
Members of the Arabidopsis thaliana TCP transcription factor (TF) family affect plant growth and development. We systematically quantified the effect of mutagenizing single or multiple TCP ...TFs and how altered vegetative growth or branching influences final seed yield. We monitored rosette growth over time and branching patterns and seed yield characteristics at the end of the lifecycle. Subsequently, an approach was developed to disentangle vegetative growth and to determine possible effects on seed yield. Analysis of growth parameters showed all investigated tcp mutants to be affected in certain growth aspects compared with wild‐type plants, highlighting the importance of TCP TFs in plant development. Furthermore, we found evidence that all class II TCPs are involved in axillary branch outgrowth, either as inhibitors (BRANCHED‐like genes) or enhancers (JAW‐ and TCP5‐like genes). Comprehensive phenotyping of plants mutant for single or multiple TCP TFs reveals that the proposed opposite functions of class I and class II TCPs in plant growth needs revision and shows complex interactions between closely related TCP genes instead of full genetic redundancy. In various instances, the alterations in vegetative growth or in branching patterns result into negative trade‐off effects on seed yield that were missed in previous studies, showing the importance of comprehensive and quantitative phenotyping.
Significance Statement
This study shows the importance of the TCP transcription factor family during Arabidopsis growth and development, coupled to yield and plant architecture. It was found that all class II TCPs are involved in axillary bud outgrowth and that the proposed opposite functioning of class I and class II TCPs requires revision.
Enhanced biological phosphorus removal (EBPR) process is known to mainly rely on the ability of phosphorus-accumulating organisms to take up, transform and store excess amount of phosphorus (P) ...inside the cells. However, recent studies have revealed considerable accumulation of P also in the extracellular polymeric substances (EPS) of sludge, implying a non-negligible role of EPS in P removal by EBPR sludge. However, the contribution of EPS to P uptake and the forms of accumulated extracellular P vary substantially in different studies, and the underlying mechanism of P transformation and transportation in EPS remains poorly understood. This review provides a new recognition into the P removal process in EBPR system by incorporating the role of EPS. It overviews on the characteristics of P accumulation in EPS, explores the mechanism of P transformation and transportation in EBPR sludge and EPS, summarizes the main influential factors for the P-accumulation properties of EPS, and discusses the remaining knowledge gaps and needed future efforts that may lead to better understanding and use of such an EPS role for maximizing P recovery from wastewater.
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•An updated overview on the characteristics of P accumulation in EPS is provided.•Mechanisms of P transformation and transportation in sludge and EPS are explored.•Main influential factors on the P-accumulation properties of EPS are analyzed.•Remaining knowledge gaps and needed future efforts are highlighted.
Species distribution models (SDMs) are widely used to predict the occurrence of species. Because SDMs generally use presence-only data, validation of the predicted distribution and assessing model ...accuracy is challenging. Model performance depends on both sample size and species' prevalence, being the fraction of the study area occupied by the species. Here, we present a novel method using simulated species to identify the minimum number of records required to generate accurate SDMs for taxa of different pre-defined prevalence classes. We quantified model performance as a function of sample size and prevalence and found model performance to increase with increasing sample size under constant prevalence, and to decrease with increasing prevalence under constant sample size. The area under the curve (AUC) is commonly used as a measure of model performance. However, when applied to presence-only data it is prevalence-dependent and hence not an accurate performance index. Testing the AUC of an SDM for significant deviation from random performance provides a good alternative. We assessed the minimum number of records required to obtain good model performance for species of different prevalence classes in a virtual study area and in a real African study area. The lower limit depends on the species' prevalence with absolute minimum sample sizes as low as 3 for narrow-ranged and 13 for widespread species for our virtual study area which represents an ideal, balanced, orthogonal world. The lower limit of 3, however, is flawed by statistical artefacts related to modelling species with a prevalence below 0.1. In our African study area lower limits are higher, ranging from 14 for narrow-ranged to 25 for widespread species. We advocate identifying the minimum sample size for any species distribution modelling by applying the novel method presented here, which is applicable to any taxonomic clade or group, study area or climate scenario.
This article explains how a type 2 fuzzy logic controller can improve the torque of a 3-phase Permanent Magnet Synchronous Motor (PMSM) in an electric power steering system. The goal is to ensure ...effective electric power steering under various road conditions and speeds. The implementation of type-2 FLS involves fuzzification, inference, and output processing. Type-reduction methods are more advanced than type-1 defuzzification methods, handling more rule uncertainties. While computationally demanding, a simple type-reduction computation process is outlined for interval type-2 fuzzy sets. The type 2 fuzzy logic controller algorithm manages the PMSM motor using Field-Oriented Control (FOC), adjusting the motor voltage based on torque, speed, and steering angle sensor inputs. The study's results provide a solid basis for future research on designing and controlling electric power steering systems with precision and efficiency. This research sets the stage for improved electric power steering systems, contributing to the development of intelligent automotive technologies.
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•High active NH2-MIL-101(Fe)@EPS photocatalysts were facile prepared.•EPS-embedding strategy accelerated the separation of electron-hole pairs.•Photocatalysis promoted the nitrate ...byproduct reduction in the anammox process.•EPS accelerated the electron derived from photocatalyst transferring to bacteria.•Increased abundance of flavin and complex III accelerated electron transfer.
Anaerobic ammonium oxidation (anammox) is an efficient nitrogen removal process; however, nitrate byproducts hampered its development. In this study, extracellular polymeric substances (EPS) were embedded into NH2-MIL-101(Fe), creating NH2-MIL-101(Fe)@EPS to reduce nitrate. Results revealed that chemical nitrate reduction efficiency of NH2-MIL-101(Fe)@EPS surpassed that of NH2-MIL-101(Fe) by 17.3 %. After adding 0.5 g/L NH2-MIL-101(Fe)@EPS within the anammox process, nitrate removal efficiency reached63.9 %, consequently elevating the total nitrogen removal efficiency to 92.4 %. 16S rRNA sequencing results elucidated the predominant role of Candidatus Brocadia within NH2-MIL-101(Fe)@EPS-anammox system. Concurrently, sufficient photogenerated electrons were transferred to microorganisms, promoting the growth of Desnitratisoma and OLB17. Additionally, photogenerated electrons activated flavin and Complex III, thereby up-regulating crucial genes involved in intra/extracellular electron transfer. Subsequently, denitrification and dissimilatory nitrate reduction to ammonium were activated to reduce nitrate. In summary, this study achieved a notable rate of photocatalytic nitrate reduction within anammox process through the NH2-MIL-101(Fe)@EPS photocatalysts.
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