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The significant production of sewage sludge by wastewater treatment plants on a global scale and the lack of correspondence between housing development and the expansion of sanitation infrastructure indicate a genuine concern regarding environmental preservation. This study addresses the crucial issue of effective sewage sludge management and its environmental impact. In the context of searching for new drying methods that optimize energy use and effectively stabilize sewage sludge, this work investigated the drying behavior of sewage sludge from treatment plants in two northern Moroccan cities using a prototype of an indirect forced convection solar dryer. The drying experiments enabled the determination of drying kinetics as well as highlighted the influence of temperature and humidity on the drying rate. The characteristic drying curve (CDC) and its mathematical expression were determined using Van Meel’s formalism. Thermal diffusivity of wastewater sludge during drying was also investigated. Using Fick’s diffusion model, diffusion coefficients ranged between 0.59 × 10-9 m²/s and 1.43 × 10-9 m²/s, demonstrating an increase in effective diffusivity with rising temperature. The Arrhenius equation provided activation energy values of 16.80 kJ/mol for Oujda samples and 19.72 kJ/mol for Nador samples, indicating the effect of temperature on effective diffusivity. A new equation based on the Midilli-Kucuk model was proposed to predict the drying behavior under untested aerothermal conditions, considering drying temperature and the initial dryness. This study offers a comprehensive analysis of the drying kinetics and effective diffusivity of sewage sludge, providing valuable insights for designing large dryers for sludge management in WWTPs. This approach presents an optimal solution for drying and stabilizing sludge, contributing to environmental preservation efforts. [ABSTRACT FROM AUTHOR]

AbstractSludge flocs encapsulate a significant amount of bound water, resulting in poor dewatering efficiency. To address this issue, the addition of alum (KAl(SO4)2·12H2O) has emerged as an effective strategy for enhancing sludge dewatering performance. This research specifically investigates the effects of various alum dosages on the dewatering characteristics of sludge. The introduction of alum alters internal temperature, pH levels, and intracellular osmotic pressure, which facilitates the release of trapped water within the flocs. Additionally, alum accelerates sludge sedimentation and promotes the agglomeration of smaller particles into larger ones, further improving dewatering efficiency. However, determining the optimal alum dosage for sludge conditioning is essential, as excessive amounts can lead to a decrease in dewatering performance. [ABSTRACT FROM AUTHOR]

Dewatered sludge (DS) is a sewage sludge with a unique property due to extracellular polymeric substances (EPSs) and polymer flocculants. These components form a stable 3D polymer network to increase dewatering efficiency, leaving behind valuable materials such as lipids. This article explored the influences of DS particle size on lipid yield and the effects of extraction on the chemical, morphological, and thermal properties of the residual dewatered sludge (RDS). Lipid yields with unimodal distribution were observed across the particle size ranges (<0.5, 0.5–1.0, 1.0–2.0, 2.0–4.0, and 4.0 mm). The highest lipid yield of 1.95% was extracted from 1.0–2.0 mm after 4 h at 70 °C and 0.1 g/mL sludge-to-solvent ratio. Efficiency was influenced by the DS's morphology, facilitating solvent infiltration and pore diffusion. The extraction process reduced water and organic fractions, resulting in higher thermal stability. Bibliometric analysis of "extraction*" and "sewage sludge" shows increasing research interest from 1973 to 2024. Five research clusters were observed: heavy metal speciation and stabilization, sludge and its bioavailability, extraction techniques and resource recovery, contaminants remediation, as well as phosphorus recovery and agricultural applications. These clusters highlight the diverse approaches to researching DS and RDS while promoting sustainable waste management. [ABSTRACT FROM AUTHOR]

There is carried out a quantitative assessment of the changes in the circulating water composition under the influence of its conditioning method in a circulating water supply system of the Balkhash Concentrator Plant. Research objects are circulating water model mixtures which are reuse in copper ores flotation after clarification in a tailings dam. They are obtained in a laboratory because of modelling the mixing and storage conditions of enrichment tailings from the Balkhash Concentrator Plant and acid effluents neutralization sludge from the Balkhash Copper Smelter Plant with industrial effluents from other enterprises in Balkhash region. There is considers two schemes for conditioning of recycle water in the process water supply system: by mixing clarified water obtained during the combined or separate waste storage (enrichment tailings and acid effluents neutralization sludge). Studies have shown that after mixing these flows in the tail collector and their combined storage in the tailings dam chemical and physico-chemical processes occur that contribute to the removal of several pollutants (copper, arsenic, iron, zinc, cadmium, and nickel) from circulating water, which can be explained by the binding of cations these elements into insoluble compounds. Based on the results obtained, it is recommended to use a combined waste storage technology for the circulating water conditioning. [ABSTRACT FROM AUTHOR]

• CaO has the best performance in the 8-dimensional comparison of 6 conditioners. • Fe/Ca-based conditioners increased 7.5 ∼ 14.8 % char-N and reduced 1.5 ∼ 7 % gas-N. • Fe promoted volatile amine-N cyclization, while Ca promoted it dehydrogenation. • Cl promoted haloalkanes & NO x precursors formation via electrophilic substitution. The nitrogen transformation during sludge pyrolysis is affected by the dewater conditioner. However, the comparative analysis of the conditioner under identical pyrolysis conditions has been previously absent. In this study, Ca-, Fe- and Al-based conditioners were selected as the representatives. A comprehensive evaluation considering the cost of the conditioners and the product characteristics was conducted. Additionally, the in-situ fixation mechanism of the conditioner on nitrogen-containing gas was concurrently revealed. Among the six conditioners, CaO and AlCl 3 were identified as the top performers, ranking first and second, respectively. Furthermore, Fe/Ca-based conditioners reduced NH 3 and HCN release by 1.5 ∼ 5.53 % and 0 ∼ 1.55 %, respectively, by facilitating the conversion of amine-N to a more stable form in condensable fraction. Fe promoted volatile amine-N cyclization, while Ca encouraged its dehydrogenation. Both Fe/Ca-based conditioners increased 7.5 ∼ 14.8 % nitrogen retention in char, by inhibiting the decomposition of protein-N. Al-based conditioners had little effect on NH 3 and HCN, but contributed to 2.3 ∼ 2.8 % production of stabilized nitrogen in char. The introduction of Cl in Fe/Ca/Al chloride conditioners would promote the decomposition of inorganic ammonium salts to produce NH 3 at 30 ∼ 185 °C. And Cl also reacted with volatiles through electrophilic substitution reaction, leading to the formation of halogenated hydrocarbons in condensable fraction and the release of more NH 3 , HCN, and HNCO at 30 ∼ 465 °C. The findings of this study provide a detailed comparative analysis of various conditioners under uniform conditions and reveal the in-situ fixation mechanism of nitrogen-containing gas. This will provide guidance for the sludge conditioning-dewatering-drying integrated treatment and disposal. [ABSTRACT FROM AUTHOR]

In wastewater treatment by the activated sludge (AS) process, settleability and dewaterability of AS are key issues that are directly related to the treated water quality and sludge treatment costs. Several studies investigated the relationship between the shape of AS flocs and their settling/dewatering property. To quantify the floc morphology, it is imperative to attach a camera to a microscope or move the stage manually. Hence, labour and equipment costs may increase. In this study, by combining a digital microscope and an automatic stage, more than 100 magnified floc images were rapidly obtained from one AS sample dropped on a slide glass, and shape parameters were collectively calculated using an analysis software. During 1-year monitoring of four wastewater treatment plants in Sapporo City (Hokkaido, Japan), the morphological parameters and extracellular polymeric substances (EPS) quantity/quality of AS were analyzed on the basis of their correlation to the time to filtration (TTF) and sludge volume index (SVI), which are indicators for describing the dewatering and settling properties of AS, respectively. In one plant, larger, denser, and smoother flocs tended to contain less EPS and exhibited better sludge dewaterability. In another plant, larger, denser, and smoother flocs were considered to contribute to better settlement. Especially, an equivalent high-density floc diameter and the ratio of mixed liquor suspended solids (MLSS) concentration to the total floc area were commonly suggested to explain AS dewaterability and settleability. [ABSTRACT FROM AUTHOR]

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As an industrial waste residue, Electrolytic Manganese Residue (EMR) can greatly promote sludge dewatering and further particle-size optimization can significantly strengthen sludge dewaterability. In this study, the effects of ammonium sulfate, calcium sulphate dihydrate, and manganese carbonate in EMR on sludge dewatering performance were investigated using the response surface optimization method. It was found that the optimized ratio of three components in EMR was 1.0:1.6:2.2 based on capillary suction time (CST), specific resistance of filtration (SRF), and zeta potential of dewatered sludge. The composition ratio of particle-size optimized EMR was modified based on the above optimization, resulting in a significant increase in sludge dewatering performance (CST and SRF reduced by 8.7% and 11.2%, respectively). Compared with those in original sludge, the content of bound extracellular polymeric substances in the conditioned sludge with optimized ratio was drastically reduced while that of soluble extracellular polymeric substances was slightly increased, which was in accordance with the decline of fluorescence intensity. These findings indicated the disintegration of extracellular polymeric substances, the enhancement of hydrophobicity, and dewatering properties of the sludge. In summary, optimized EMR can effectively intensify the dewaterability of sludge, providing a competitive solution for dewatering and further disposal of sludge. [ABSTRACT FROM AUTHOR]

The activated sludge process plays a crucial role in modern wastewater treatment plants. During the treatment of daily sewage, a large amount of residual sludge is generated, which, if improperly managed, can pose burdens on the environment and human health. Additionally, the highly hydrated colloidal structure of biopolymers limits the rate and degree of dewatering, making mechanical dewatering challenging. This study investigates the impact and mechanism of microwave irradiation (MW) in conjunction with peracetic acid (PAA) on the dewatering efficiency of sludge. Sludge dewatering effectiveness was assessed through capillary suction time (CST) and specific resistance to filtration (SRF). Examination of the impact of MW-PAA treatment on sludge dewatering performance involved assessing the levels of extracellular polymeric substances (EPS), employing three-dimensional excitation-emission matrix (3D-EEM), Fourier transform–infrared spectroscopy (FT-IR), and scanning electron microscopy. Findings reveal that optimal dewatering performance, with respective reductions of 91.22% for SRF and 84.22% for CST, was attained under the following conditions: microwave power of 600 W, reaction time of 120 s, and PAA dosage of 0.25 g/g MLSS. Additionally, alterations in both sludge EPS composition and floc morphology pre- and post-MW-PAA treatment underwent examination. The findings demonstrate that microwaves additionally boost the breakdown of PAA into •OH radicals, suggesting a synergistic effect upon combining MW-PAA treatment. These pertinent research findings offer insights into employing MW-PAA technology for residual sludge treatment. [ABSTRACT FROM AUTHOR]

The aerobic granular sludge(AGS) technology draw scientific researchers attention, and more and more scientific research focuses on it, due to its superior advantages, such as good settling performance, high biological phase, high toxicity resistance and multiple biological effects. With the rapid development of AGS technology, a considerable amount of residual AGS will be produced, and dehydration is the biggest bottleneck of sludge reduction. This study investigated the dewatering process and method of residual AGS cultured by continuous flow experiment. Experiments were conducted using centrifugal dewatering technology with a dosing scheme to analyze the granular sludge dewatering process, and investigate the release process of EPS component in AGS dewatering. Our results implied the specific resistance of AGS has a very low value ((1.82 ± 0.03) x 109m/kg) and it was not obvious for the conditioning effect of chemical conditioner on AGS dewatering. However, the moisture content can be reduced to 63.5% after dewatering with the presence of inorganic substances. The addition of drinking water treatment plant sludge (Alum sludge) can improve the efficiency of the dewatering of AGS. A possible dewatering process of AGS dewatering was proposed which was divided into two stages: First, a considerable amount of free water in the sludge was quickly removed under the action of gravity without pressure filtration. Second, the bound water release required cooperation between applying centrifugal or pressing force to grind granular cells and separate protein-like substances with the inorganic matter inside the granular sludge. The possible mechanism of AGS dewatering and hypothesis dewatering process are useful to optimize the AGS dewatering process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mineral-activated perxymonosulfate (PMS) shows dewaterability and triclosan removal. • Iron-rich minerals are more economical than traditional sources of Fe2+. • Rheological test demonstrates that siderite/PMS can promote sludge fragmentation. • Siderite could release Fe2+ more sustainably to persistently produce free radicals. High water and pharmaceutical and care products (PPCPs) bounded in sludge flocs limit its utilization and disposal. The advanced oxidation process of perxymonosulfate (PMS) catalyzed by iron salts has been widely used in sludge conditioning. In this study, two iron-rich minerals pyrite and siderite were proposed to enhance sludge dewatering performance and remove the target contaminant of triclosan (TCS). The permanent release of Fe2+ in the activation of PMS made siderite more effective in enhancing sludge dewater with capillary suction time (CST) diminishing by 60.5 %, specific resistance to filtration (SRF) decreasing by 79.2 %, and bound water content (BWC) dropping from 37.1 % to 2.6 % at siderite/PMS dosages of 0.36/0.20 mmol/g-TSS after 20 min of pretreatment. Pyrite/PMS performed slightly inferior under the same conditions and the corresponding CST and SRF decreased by 51.5 % and 71.8 % while the BWC only declined to 17.8 %. Rheological characterization was employed to elucidate the changes in sludge dewatering performance, with siderite/PMS treated sludge showing a 48.3 % reduction in thixotropy, higher than 28.4 % of pyrite/PMS. Oscillation and creep tests further demonstrated the significantly weakened viscoelastic behavior of the sludge by siderite/PMS pretreatment. For TCS mineralization removal, siderite/PMS achieved a high removal efficiency of 43.9 %, in comparison with 39.9 % for pyrite/PMS. The reduction in the sludge solids phase contributed the most to the TCS removal. Free radical quenching assays and EPR spectroscopy showed that both siderite/PMS and pyrite/PMS produced SO 4 -· and ·OH, with the latter acting as the major radicals. Besides, the dosage of free radicals generated from siderite/PMS exhibited a lower time-dependence, which also allowed it to outperform in destroying EPS matrix, neutralizing the negative Zeta potential of sludge flocs, and mineralizing macromolecular organic matter. [ABSTRACT FROM AUTHOR]

The treatment of sewage sludge has become a global concern. Large amounts of sewage sludge can be disposed of by burning coal-mixed sludge. Thermogravimetric analysis and lab-scale combustion experiments in a drop tube furnace were utilized to study the combustion characteristics, pollutant emissions, and heavy metal migration during the co-combustion of coal and sewage sludge. The results showed that the blended fuels with a sewage sludge content less than 10 weight percent exhibited coal-like combustion characteristics. Additionally, the additional sewage sludge favored the ignition performance of blended fuels. When sewage sludge was added, the SO2 emissions rose to 76 mg/Nm3 under the 10% sludge condition—nearly three times higher than that of coal alone. While NOx emissions stayed mostly unchanged, HCl and HF emissions were very low. Meanwhile, Cr, Cu, and Ni migrated to the bottom ash, and their concentrations were all reduced with an increase in sewage sludge. Pb, Cd, Cr, Cu, Ni, and Hg migrated to the flue gas, mostly in the form of gaseous components. The results provide crucial information in the co-combustion of sewage sludge and coal, with implications in the development and improvement of large-scale, harmless, and resource-recovering techniques for waste sludge. [ABSTRACT FROM AUTHOR]

High volume and water content makes anaerobic digestate management difficult. Environmental drawbacks and limited resource recovery are associated with traditional polymer conditioning methods. The method of polymer conditioning incurs high operating costs, affects the environment, and pollutes water. Therefore, modifying traditional polymer conditioning of mesophilic digestate (MD) is necessary to address environmental concerns and promote resource recovery. This study explored alternative chemical conditioning agents, including metal coagulant ferric chloride (FeCl3) and oxidant hydrogen peroxide (H2O2), to enhance the dewatering efficiency of MD with pH adjustment while comparing the corresponding results without pH adjustments. The goal was to determine the best chemical dose combination that minimizes polymer consumption while maximizing volume reduction. After adjusting MD's pH [ Ca(OH)2 ] to 8.0 and treating it with 2.1 kg/t dry solids (DS) polymer, 2.1 kg/t DS FeCl3 , and 600 mg/L H2O2 , significant improvements in MD dewaterability were observed, including a 96% increase in capillary suction time and 40% increase in cake solid. In addition to dewatering, improving phosphorus recovery in the digestate was investigated. The same chemical conditioning resulted in 98% elimination of P from centrate and recovered in the sludge cake. The study emphasizes the necessity of pH adjustment and choosing suitable conditioning chemicals to improve dewatering performance while considering P release implications. By reducing polymer usage and incorporating FeCl3 and H2O2 , significant improvements can be achieved in dewatering performance and P removal from MD centrate while better managing digestate. The conditioning process consists of a novel chemical combination of cationic polymer, FeCl3 , and H2O2 at an adjusted pH that would enhance the post-treatment efficiency of municipal anaerobic digestates with improved dewatering efficiency, reduced odor, improved pathogen elimination, and resource recovery. The research suggested that switching toward a two-staged temperature phased anaerobic digestion process would significantly enhance resource recovery and yield class A biosolids. Complying with class A biosolids regulations allows for broadening its practical application and increasing its market value. Contributing to the economic viability of the wastewater treatment plants (WWTPs). Research findings suggest that WWTPs can reduce polymer consumption by 40%, substantially reducing their operational costs and improving their efficiency. Improved cake solid content and reduced volume result in lowered storage and transportation costs. As a result of nutrient and resource recovery from digestate, biosolids are more economically valuable and align with sustainability goals by minimizing waste and conserving resources. In this research, odor reduction is improved by 91%, improving the quality of WWTP environments. This research provides cost-effective and environmentally friendly wastewater treatment solutions that address nutrient imbalance, pathogen contamination, and odors. [ABSTRACT FROM AUTHOR]

Coastal cities in the Amazon lack basic infrastructure to treat and finally discharge urban domestic sewage. Implementing sub-river outfalls and waste-treatment pre-conditioning that significantly reduce pollution impact would be a sustainable alternative to cope with such an issue. The aim of the present research is to analyze the technical, economic and environmental feasibility of alternative projects applied to domestic waste's proper destination in the coastal zone of Amapá State (ZCEA), Brazil. Infrastructure basic sizing and the current treatment provided to domestic waste discharged in Amazonas River, in natura, were taken into consideration for study conduction. Research methodology was applied as follows: (a) pre-sizing the main infrastructure elements of sub-river outfalls (EM); (b) assessing the reduction of impacts on quality of water in the metropolitan seashore of Macapá and Santana cities; (c) economic assessment based on the alternative implementation of underwater outfalls in Macapá's Northern and Central zones, where one finds Amazonas River's high self-depuration ability and regular bathymetry. Technical feasibility, mainly in Fazendinha and Santana cities, was not satisfactory due to topobathymetric unevenness and traffic jam in Santana Channel's waterway. We have concluded that the self-depuration and sanitary features in Amazonas River's assessed stretches are a sustainable, effective and competitive technology extremely favorable for the implementation of sub-river outfalls, given its simplicity and, most of all, adjustment to the regional socioeconomic reality. [ABSTRACT FROM AUTHOR]

The awareness of the concept of the "Circular Economy" is motivating scientists to convert drinking water treatment plant by-products, which are based on aluminum waste, into a valorized material for wastewater treatment. Alum sludge from a local waterworks plant in Egypt was collected and dewatered using chitosan-coated magnetic nanoparticles. The role of the conditioned sludge in wastewater treatment was then examined. Chitosan (Ch) augmented with magnetite nanoparticles (MNs), labeled as ChMNs, was prepared by means of a simple co-precipitation route with mixing ratios of 1:1, 2:1, and 3:1 of chitosan and magnetite nanoparticles to form the ChMN catalyst. The ChMNs were shown to beneficially enhance alum sludge conditioning and dewaterability. The conditioned and dried aluminum-based sludge (AS) loaded with ChMNs was then used as a source of Fenton's catalyst for Synozol Red-KHL textile dyeing wastewater. The characteristics of the AS-ChMN sample were investigated using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of the AS-ChMN composite was assessed by examining its diffuse reflectance spectra (DRS). Response surface methodological analysis was applied to optimize the operational parameters in order to reduce the use of chemicals and improve dye oxidation to form a complete (99%) dye oxidation strategy. The experiments demonstrated that the optimal operating parameters included doses of 1.5 g/L and 420 mg/L for AS-ChMNs and hydrogen peroxide, respectively, as a source of Fenton's reaction at a working pH of 3.5. Kinetic and thermodynamic analyses for potential full-scale applications were conducted, showing the reaction to be exothermic and spontaneous in nature and following second-order reaction kinetics. Hence, the novelty of this work lies in the introduction of conditioned and dewatered alum sludge waste as a photocatalyst for textile dye effluent oxidation, which could be considered a "win–win" strategy. [ABSTRACT FROM AUTHOR]

Nine biochars were produced by co-pyrolysis of sawdust and biological sludge following the "design of experiment" approach. Two kinds of sludge (both deriving from the treatment of mixed industrial-municipal wastewater) and two types of woody waste were selected as categorical predicting variables, while contact time, pyrolysis temperature, and sludge percentage were used as quantitative variables. Biochars were analysed for their product characteristics and environmental compatibility based on the European Standards (EN 12915–1:2009) for materials intended for water treatment (i.e. ash content, water leachable polycyclic aromatic hydrocarbons (PAHs) and elements), as well as for specific surface area (SSA), using them as response variables of a multivariate partial least square multiple regression, whose results provided interesting insights on the relationships between pyrolysis conditions and biochar characteristics. Biochars produced with sludge and/or providing the highest SSA values (258–370 m2 g−1) were selected to undergo a sustainable chemical treatment using a by-product of the gasification of woody biomass, complying in all cases with European Standards and achieving therefore the end-of-waste status for sewage sludge. The biochar deriving from the highest percentage of sludge (30% by weight) and with the highest SSA (390 m2 g−1) was thermally activated achieving SSA of 460 m2 g−1 and then tested for the sorption of direct yellow 50 and methylene blue in ultrapure water and real wastewater, compared to a commercial activated carbon (AC). The biochar showed Langmuir sorption maxima (Qm) 2–9 times lower than AC, thus highlighting promising sorption performances. Qm for methylene blue in wastewater (28 mg‧g−1) was confirmed by column breakthrough experiments. [ABSTRACT FROM AUTHOR]

To reduce the volume of landfill sludge, a more environmentally friendly technology is used to study the effects of different freeze–thaw–vacuum pretreatment modes. In addition to the cumulative effect of cooling time within different temperature bands, we analyse the temperature difference loss rate of shallow sludge over the period of cooling. During the annular freezing process, the mechanism of ice front formation is revealed by exploring the energy transfer process of landfill sludge. When repeated freeze–thaw–vacuums are performed, the pretreatment modes of a single pre-freeze–thaw and two consecutive pre-freeze–thaws are compared. The superiority of two modes is discussed in the light of local differences in dewatering performance and overall settlement trend characteristics. Furthermore, the final micromorphological structure indicates that the repeated freeze–thaw–vacuum pretreatment mode of sludge is affected by its depth to a certain extent. It is found that factors such as sludge depth and radial water migration have a significant impact on the time accumulative effect and energy transfer of frozen sludge. The sludge treatment mode of two consecutive pre-freeze–thaws has a better effect on the overall dewatering and reduction. [ABSTRACT FROM AUTHOR]

Dewatering is a crucial stage in the treatment of sludge since it directly increases capacity and lowers the cost of subsequent handling. Enhanced dewatering of printing and dyeing sludge was experimentally investigated with combined conditioners of sludge-derived biochar and ferric chloride (FeCl3) in this study. Results showed that the optimal conditioner dosages were: FeCl3 of 3% dry sludge (DS) and biochar of 60% DS. Compared with raw sludge, the sludge specific resistance to filtration (SRF) decreased by 77.14%, and the moisture content of sludge decreased from 85.38% to 67.08%. In addition, the chemical oxygen demand (COD), turbidity and chromaticity of supernatant decreased by 32.50%, 89.20% and 77.50%, respectively. It was found that the synergistic effect existed between the two conditioners. The possible mechanism was that FeCl3 aggregated small sludge particles to form large flocs and improved the dewatering performance of sludge, while biochar helped to build an incompressible and permeable sludge cake to further improve the sludge dewaterability due to its relatively hydrophobicity and large specific surface area. Therefore, combined addition of FeCl3 and biochar might be a promising conditioning method to enhance textile sludge dewaterability. [ABSTRACT FROM AUTHOR]

Significant co-conditioning of aluminum-based sludge using alternative conditioner (natural biopolymer-magnetite/H2O2) as a Fenton conditioner for improving the sludge dewaterability is investigated in the current study. Firstly, natural biopolymer/magnetite (NBP-M) were prepared in various ratios and the samples labeled as (NBP-M-(1:1); NBP-M-(1:3) and NBP-M-(2:1). Focuses were placed on factors influencing such novel Fenton conditioner. Capillary suction time (CST) was utilized to assess sludge dewaterability. Experiments have exhibited that significant development of alum sludge dewaterability could be attained at minimum reaction time and using low concentrations of the applied catalyst, i.e. natural biopolymer/magnetite and H2O2. It was found that sludge conditioning and dewaterability became better with increasing both reagents concentrations. A Box–Behnken experimental design based on the response surface methodology was investigated to explore the optimum of the influencing variables, i.e. catalyst (NBP-M) concentration, H2O2 loading and pH. The optimized values for NBP-M, H2O2, and pH are 46 and 380 mg/L, respectively at pH 3.0, at which the CST reduction efficiency of 58 ± 3% can be attained, this approved with that predicted by an established polynomial model in the current investigation. [ABSTRACT FROM AUTHOR]

In recent years, the production of municipal sludge has gradually increased, and finding suitable sludge treatment and disposal technologies is an urgent problem that needs to be solved. Bio-drying of sludge is a relatively efficient and convenient drying method, but currently, there are still problems with unstable drying effects and high moisture content of dried products, which limits the subsequent utilization of bio-drying products. This article uses a thermal assisted bio-drying device that simulates carbonization waste heat reflux, and uses corncob, straw, sawdust, and rice husk as conditioners to carry out bio-drying of dehydrated sludge. The influence of the types and ratios of conditioner under thermal assistance on the bio-drying of dehydrated sludge is explored. The results showed that the moisture removal efficiency of the corncob and straw groups was better, and their material moisture content could be reduced to below 10% within 24 h. The lower calorific value of straw-sludge drying products was the highest, at 11,608.8 kJ/kg. The best conditioner under the conditions of this experiment was straw, and the drying effect was best when the mass ratio of dehydrated sludge to straw was 4:1. The research results contribute to promoting the development of sludge bio-drying technology. [ABSTRACT FROM AUTHOR]

Municipal sludge generated from wastewater treatment plants can cause a serious environmental and economic burden. A novel hybrid conditioning strategy was developed to enhance the dewatering performance of sludge, employing 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim][CF3SO3]) treatment combined with H2SO4 acidification. Following conditioning, the capillary suction time ( CST normalized ), the specific resistance of filtration (SRF), and moisture content of the treated sludge were decreased to 1.99 ± 0.24 (s·L/g TSS), 1.33 ± 0.05 (1012 m/kg), and 72.01 ± 0.94%, respectively. The results were superior to those achieved with sludge treated solely by H2SO4 acidification or [C4mim][CF3SO3] alone. The biomacromolecules within the sludge flocs were dissolved by [C4mim][CF3SO3], while simultaneously, the microorganisms were inactivated. Consequently, the colloidal-like structures of the sludge flocs were destroyed. Additionally, the ionizable functional groups of the biomacromolecules were instantly protonated by the introduced H+ ions, and their negative charges were neutralized during the H2SO4 acidification process. The presence of H+ ions promoted the weakening of electrostatic repulsion between the sludge flocs. As a result, an enhancement of sludge dewaterability was obtained after treatment with [C4mim][CF3SO3] and H2SO4 acidification. The finding of the intensification mechanism of sludge dewaterability brought by hybrid treatment of acidification and [C4mim][CF3SO3] provides novel insights into the field of sludge disposal. [ABSTRACT FROM AUTHOR]

The sedimentation, consolidation and desiccation behaviour of sub-aerially deposited tailings in tailings storage facilities, despite occurring simultaneously and being essential to maximise tailings dry density and dewatering efficiency, are usually analysed in laboratories using distinctive testing equipment, which is unable to reveal their interactions. A large instrumented column was constructed to test the three processes of tailings in a single apparatus, capable of monitoring the changes in the hydrological parameters of coal tailings with depth and surface settlement under natural weather conditions. The column was initially filled with coal tailings slurry and exposed to natural weather for two years, during which five wetting–drying periods were identified. The monitored results indicate that exposing the slurry tailings for one month would lead to the formation of an unsaturated tailings layer with a thickness of 150 mm, likely representing the optimised tailings deposition cycle and thickness, respectively, under the given tailings characteristics and semi-arid climates. Settlement mainly occurred after major rainfall events due to the collapse of cracks and cavities formed during the preceding desiccation. The maximum thickness of the unsaturated tailings increased over the first four periods as the predominant desiccation and settlement strengthened the evaporative capillary forces, despite it decreasing greatly in the last period due to insufficient desiccation. An empirical model was proposed to consecutively estimate the surface moisture content of deformable tailings and validated by achieving a good agreement in the water mass estimated by two methods during wetting–drying cycles. [ABSTRACT FROM AUTHOR]

This work explores the effects of the temperature (250, 280, 310°C), time (20, 40, 60 min), sewage sludge mixing ratio (25, 50, 75%) on the solid fuel quality and yield of the biochar produced from sewage sludge blended with pine sawdust. The optimal conditions for the torrefaction of sewage sludge and pine sawdust were investigated by the response surface methodology. Mathematical models were developed on the weight yield, high heating value and ash content and experimental data were examined through analysis of variance. The results depicted that the effects of temperature and mixing ratio were more considerable than residence time for the three response variables. The optimum point for weight yield, HHV, ash were predicted to be 60.82%, 21.58 MJ kg-1 and 18.78% at 310°C, 20 min and sewage sludge mixing ratio of 25%, respectively. The experimental results show that the average values of the experiments were 56.4%, 22.9 MJ kg-1, and 21% for weight yield, HHV and ash content, respectively. [ABSTRACT FROM AUTHOR]

This article explores the use of microbial methods to remove heavy metals from industrial effluent in the pharmaceutical industry. The effluent contains metallic cations that can contaminate the soil and food chain. Traditional treatments for metal-containing waste have limitations, so researchers are investigating alternative biological methods involving bacteria and bio surfactants. The article also presents a study on the effects of microbial treated and untreated tannery effluent on the growth of green gram. The study concludes that bacteria are effective in removing heavy metals from pharmaceutical effluent. [Extracted from the article]

To simultaneously solve problems in an eco-friendly manner, introducing a waste residual as a sustainable conditioner to aid alum sludge dewatering is suggested as a cradle-to-cradle form of waste management. In this regard, the superiority of deep dewatering alum sludge with a powdered wood chip composite residual as a novel conditioner was explored, whereby traditional conventional conditioners, i.e., polyelectrolytes and lime, were substituted with powdered wood chips. Initially, Fe3O4 was prepared at the nanoscale using a simple co-precipitation route. Next, wooden waste was chemically and thermally treated to attain cellulosic fine powder. Subsequently, the resultant wood powder and Fe3O4 nanoparticles were mixed at 50 wt % to attain a wood powder augmented with iron, and this conditioner was labeled nano-iron-cellulose (nIC-Conditioner). This material (nIC-Conditioner) was mixed with hydrogen peroxide to represent a dual oxidation and skeleton builder conditioning substance. Characterization of the resultant conditioner was carried out using transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) transmittance spectrum analysis. The feasibility of the experimental results revealed that the moisture content in the sludge cake was lower after conditioning, and the capillary suction time (CST) was reduced to 78% compared to that of raw alum sludge after 5 min of dewatering time. Moreover, the optimal system parameters, including nIC-Conditioner and H2O2 concentrations, as well as the working pH, were optimized, and optimal values were recorded at 1 g/L and 200 mg/L for nIC-Conditioner and H2O2, respectively, with a pH of 6.5. Additionally, scanning electron microscope (SEM) analyses of the sludge prior to and after conditioning were conducted to verify the change in sludge molecules due to this conditioning technique. The results of this study confirm the sustainability of an alum sludge and waste management facility. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on the redesign of a dewatering process in a polymer sludge wastewater treatment plant. The study focuses on addressing the challenges posed by high levels of organic pollutants in the sludge, with the aim of enhancing dewaterability, reducing odors, and minimizing suspended solids. Initially, a vacuum belt filter was utilized, but it proved inadequate in removing sufficient water, resulting in substantial annual disposal costs. To address this issue, a filter press system was proposed, which significantly improved the dewatering process, producing a dryer cake with a solid content of 35%, compared to 19% achieved by the vacuum belt filter. Performance evaluation of the processes was conducted based on concentration of solids and capture efficiency, demonstrating the superiority of the filter press method. Furthermore, the filtrate obtained through the filter press met local discharge regulations, eliminating the need for additional treatment before disposal. The implementation of the filter press not only improved the dewatering process and ensured compliance with discharge standards but also resulted in substantial cost savings of up to 50% per year. The payback period for the current system was determined to be 1.5 years, highlighting the economic advantages of the filter press. Overall, the findings of this study emphasize the practical advantages of the filter press in handling sludge cakes and filtrate for disposal, making it a favorable choice for dewatering polymer sludge and other wastewater treatment plants. [ABSTRACT FROM AUTHOR]

• Entotechnologies involve insects to upcycle organic waste. • Frass is an animal manure produced by insects. • 2–4 tonnes of frass are co-generated for each tonne of edible insect produced. • Frass has fertilizing, plant protection and soil health promoting properties. • Frass regulation is developing in Canada, USA and Europe. A range of issues related to sustainability in the agrifood industry have spurred interest in mass production of insects as human food and animal feed alternatives. This rapidly evolving sector addresses several challenges, including the management of food waste or agrifood by-products and the production of alternative animal proteins demonstrating low environmental impacts that improve sector circularity. The mass production of insects on agrifood processing wastes or by-products represents an opportunity to address these challenges. While the production of insects offers prospects for sustainable protein production, a major side stream is the production of frass or larval excrement including uneaten feed and chitin-rich exuviae (derived from multiple larval moults). The production of each tonne of edible insects generates 2 to 4 tonnes of frass with an interesting potential in agriculture versus traditional organic amendments (compost, manure, biochar). This review aims to demonstrate the characteristics of frass, its common harvest and conditioning methods, its optimal application rates for planting crops, the mechanisms by which it can protect plants against biotic and abiotic stresses and demystify the risks and potential associated with its application in agriculture. The characteristics of frass are compared with those of conventional fertilizers or other. This report also compiles the Canadian, US and European regulatory frameworks as a novel plant fertilizer and aims to pave the way for future research necessary for its valorization in plant production. [ABSTRACT FROM AUTHOR]

Utilizing waste, such as sewage sludge, into biochar fits the circular economy concept. It maximizes the reuse and recycling of waste materials in the wastewater treatment plant. The experiments were conducted to assess: (1) the impact of the temperature on the properties of biochar from sewage sludge (400 °C, 500 °C, 600 °C, 700 °C); (2) how the physical activation (CO2, hot water) or chemical modification using (MgCl2, KOH) could affect the removal of ammonia nitrogen and phosphorus from filtrate collected from sludge dewatering filter belts or synthetic solution, wherein the concentration of ammonium nitrogen and phosphorus were similar to the filtrate. Based on the Brunner–Emmett–Teller (BET) surface and the type and concentration of surface functional groups for the second stage, biochar was selected and produced at 500 °C. The modification of biochar had a statistically significant effect on removing nitrogen and phosphorus from the media. The best results were obtained for biochar modified with potassium hydroxide. For this trial, 15%/17% (filtrate/synthetic model solution) and 72%/86% nitrogen and phosphorus removal, respectively, were achieved. [ABSTRACT FROM AUTHOR]

Humic substances (HSs) present in water and wastewater cause fouling of anion exchange resins (AERs), which mainly results in reducing the ion exchange capacity (IEC). In this paper, an attempt was made to investigate fouling of two polystyrene and one polyacrylic AER using water from the Oder River, treated wastewater after the ultrafiltration process (UFTW) and digester reject water from sludge dewatering at the Janówek Wastewater Treatment Plant (WWTP) in Wrocław. HSs contained in digester reject water were characterised by the lowest aromaticity and molecular weights (MWs), the highest proportion of hydrophilic fraction and the highest amount of oxygenated functional groups. The Fourier-transform infrared (FTIR) analyses made it possible to identify chemical bonds characteristic of HSs and determine the mechanism of their retention on the surface of AER beads. The conducted experiments brought unexpected results, as the IEC increased with the amount of organic matter in the feed. Presumably, the humic substances accumulated on the beads and in the porosity of the anion exchangers themselves participated in the ion exchange process. [ABSTRACT FROM AUTHOR]

The use of aluminium (Al) salts, particularly alum, in coagulation is a widespread and conventional treatment method for eliminating pollutants, including phosphorus (P) which can cause eutrophication, from wastewater. However, a significant challenge of this process is the substantial amount of sludge generated, necessitating proper disposal. Historically, land disposal has been a common practice, but it poses potential issues for plant life on these lands. Despite the associated drawbacks, sludge contains elevated concentrations of vital plant nutrients like P and nitrogen, presenting an opportunity for beneficial use in agriculture. Given the imminent scarcity of P fertilizers due to the eventual depletion of high-grade P ores, this review explores the potential advantages and challenges of utilizing Al sludge as a P source for plants and proposes measures for its beneficial application. One primary concern with land application of Al sludge is its high levels of soluble Al, known to be toxic to plants, particularly in acidic soils. Another issue arises from the elevated Al concentration is P fixation and subsequently reducing P uptake by plants. To address these issues, soil treatment options such as lime, gypsum, and organic matter can be employed. Additionally, modifying the coagulation process by substituting part of the Al salts with cationic organic polymers proves effective in reducing the Al content of the sludge. The gradual release of P from sludge into the soil over time proves beneficial for plants with extended growth periods. [ABSTRACT FROM AUTHOR]

The mining industry is confronted with substantial challenges in achieving environmental sustainability, particularly regarding water usage, waste management, and dam safety. The increasing global demand for minerals has led to increased mining activities, resulting in significant environmental consequences. By 2025, an estimated 19 billion tons of solid tailings are projected to accumulate worldwide, exacerbating concerns over their management. Tailings storage facilities represent the largest water sinks within mining operations. The mismanagement of water content in tailings can compromise their stability, leading to potential dam failures and environmental catastrophes. In response to these pressing challenges, the mining industry is increasingly turning to innovative solutions such as tailings dewatering and water reuse/recycling strategies to promote sustainable development. This review paper aims to (I) redefine the role of mine tailings and explore their physical, chemical, and mineralogical characteristics; (II) discuss environmental concerns associated with conventional disposal methods; (III) explore recent advancements in dewatering techniques, assessing their potential for water recovery, technical and economic constraints, and sustainability considerations; (IV) and present challenges encountered in water treatment and recycling within the mining industry, highlighting areas for future research and potential obstacles in maximizing the value of mine tailings while minimizing their environmental impact. [ABSTRACT FROM AUTHOR]

This research was carried out to evaluate the effects of different dosages (1.85–4.44 g kg−1 Ts−1) of three cationic polyelectrolytes with charge densities (CD) of 20%, 40%, and 60% on the dewatering properties of an aerobically digested sludge. The sludge was collected from the sludge processing line in a wastewater treatment plant in the city of Mashhad, Iran (MWWTP). To assess the sludge dewatering properties, parameters such as specific resistance to filtration, sludge cluster geometry, filtration rate, and filtrate turbidity and volume were measured. The experimental results were then compared with the effects of a reference polyelectrolyte that was used in the conditioning of the sludge in that treatment plant. The results indicated that the sludge samples treated with the polyelectrolyte of the highest CD matched better dewatering performance than the samples conditioned with the other two polyelectrolytes. This polyelectrolyte (60%CD) presented its best effects at the dosage of 4.07 g kg−1 Ts−1. With this dosage, its performance was similar to the performance of the reference polyelectrolyte at the dosage of 4.44 g kg−1 Ts−1. [ABSTRACT FROM AUTHOR]

The advanced anaerobic digestion process enhances sludge resource utilization. However, thermal hydrolysis pretreatment of anaerobically digested sludge reduces dewatering efficiency due to excessive organic matter decomposition. This necessitates significant time and effort for sludge conditioning in wastewater treatment plants. Using conditioning agents can achieve high dewatering efficiency. This study investigates how the order of adding coagulants and flocculants impacts the dewatering performance of digested sludge. The results indicate that, compared to the flocculation–coagulation process with the same dosage, the coagulation–flocculation process leads to a 15–20% increase in the average particle size of digested sludge. The content of polysaccharides and proteins in S-EPS decreases by 28.8–30.8% and 10.1–11.3%, respectively. The filter cake solids content increases by 8.5%, and there is an increase in surface water channels within the flocs. This is because initially adding coagulants efficiently adsorbs small particles, forming larger aggregates that settle effectively. This promotes the breakdown of extracellular polymeric substances, releasing more bound water. Adding flocculants later bridges the aggregates, further enhancing settling and filtration performance, thereby improving sludge dewatering efficiency. These research findings contribute to a better understanding of the mechanisms of coagulant and flocculant co-conditioning for digested sludge and provide recommendations for optimizing sludge conditioning steps. [ABSTRACT FROM AUTHOR]

Due to its environmental benefits, CO2 shows great potential in refrigeration systems. However, a basic CO2 transcritical (BCT) refrigeration system used for airconditioning in buildings might generate massive indirect carbon emissions for its low COP. In this study, a novel CO2 transcritical/two-stage absorption (CTTA) hybrid refrigeration system is broadly investigated, and both energy efficiency and life cycle climate performance (LCCP) are specifically engaged. The theoretical model shows that optimal parameters for the generator inlet temperature (TG2), intermediate temperature (Tm), and discharge pressure (Pc), exist to achieve maximum COPtol. Using the LCCP method, the carbon emissions of the CTTA system are compared to six typical refrigeration systems by using refrigerants, including R134a, R1234yf and R1234ze(E) etc. The LCCP value of the CTTA system is 3768 kg CO2e/kW, which is 53.6% less than the BCT system and equivalent to the R134a system. Moreover, its LCCP value could be 3.4% less than the R1234ze(E) system if the COP of the CO2 subsystem is further improved. In summary, the CTTA system achieves ultra-low carbon emissions, which provides a potential alternative to air conditioning systems in buildings that can be considered alongside R1234yf and R1234ze(E) systems. [ABSTRACT FROM AUTHOR]

In the effort to identify sustainable sludge management options, pilot-scale sludge treatment reed beds (STRBs) were tested and assessed in the Sultanate of Oman in the first integrated experimental study of this nature-based solution in the Middle East region. A total of 18 pilot STRB units were established and monitored for almost 2 years; half were planted with native Phragmites australis reed species, and half served as unplanted control units. Employing a randomized complete block design, the study examined varying sludge loading rates (SLR) of 75, 100, and 125 kg/m2/year. Results underscored the effectiveness of STRBs in reducing the sludge volume, with observed reductions reaching 98.0% of the applied sludge volume, particularly prominent in the SLR75 units. During the final resting phase, the STRBs showed slightly higher concentrations of total Kjeldahl nitrogen (TKN) and total phosphorus (TP) compared to the unplanted beds, while maintaining concentrations lower than those of the applied activated sludge. Furthermore, heavy metal concentrations were consistently diminished in the STRBs compared to the unplanted beds, aligning with the established national and international standards for sludge reuse in agricultural contexts. The results of this study provide the first valuable insight into the potential of STRBs as an effective, sustainable, and climatically suitable approach for sludge dewatering. Specifically, an SLR of 100 kg/m2/year is proposed as an optimum loading rate for the hot and arid Middle East climate. This study advances our understanding of STRBs as a pivotal component in the realm of arid-region sludge treatment, shedding light on their capacity to facilitate enhanced dewatering, mineralization, and nutrient removal, thereby contributing to the broader discourse on sustainable waste management practices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sludge dewatering extent was enhanced after Fe 3 O 4 -activated H 2 O 2 treatment. • Enhanced mechanism of sludge dewatering by Fe 3 O 4 -activated H 2 O 2 was unveiled. • Fe 3 O 4 -activated H 2 O 2 disrupted sludge EPS and released intracellular water. • Fe 3 O 4 as skeleton builder enhanced sludge floc strength and formed new channels. Homogeneous Fenton (Fe2+/H 2 O 2) serves as a high-efficiency conditioning method for sludge dewatering due to the generation of strong oxidizing hydroxyl radicals (OH). However, high dose of ferric salts produces iron-rich dewatered sludge and decrease sludge organic matters, which will not be conducive to the subsequent disposal and reutilization. Considering advantages of Fe 3 O 4 as heterogeneous Fenton catalyst, Fe 3 O 4 -activated H 2 O 2 (Fe 3 O 4 + H 2 O 2) in this study was adopted to improve sludge deep-dewatering. Reduction efficiency of the bound water (71.3 %) after Fe 3 O 4 + H 2 O 2 treatment (after a reaction time of 30 min) were much higher than those in the Fe2++H 2 O 2 treatment. Especially, the moisture content of treated sludge cake by Fe 3 O 4 + H 2 O 2 remarkably decreased from 86.4 % to 61.3 %. Improvement mechanism of sludge dewatering after Fe 3 O 4 + H 2 O 2 treatment mainly included electrostatic neutralization, reactive radical oxidation, and skeleton building by analysis of contribution factors. The generation of H+ in acidification could neutralize the negatively charged compounds to promote sludge hydrophobicity. Meanwhile reactive radicals generated from Fe 3 O 4 + H 2 O 2 destroyed sludge extracellular polymeric substances and cell structure to release intracellular water. Furthermore, Fe 3 O 4 as a skeleton builder could reconstruct destructive sludge flocs and form new dewatering channels. Finally, low Fe leaching content and recoverability of Fe 3 O 4 effectively will decrease environmental implication. [ABSTRACT FROM AUTHOR]

The process of removing water from sewage sludge is particularly important due to its high content in the raw sludge. This translates into problems with the transport and storage of sediments. Additionally, high water content reduces the calorific value of the sludge. The methods for selecting the appropriate parameters for sewage sludge conditioning and filtration, based on the experimental data presented in this work, may allow for the optimization of sludge dewatering lines in small and large sewage treatment plants. The optimization of the dewatering process has a significant impact on the environmental and economic benefits, which consequently results in a decrease in the power costs of the devices used, flocculants, and sludge processing, and, above all, it contributes to the reduction in the negative impact on the environment. The use of mineral substances in the preparation of sewage sludge improves the effects of its dewatering in the pressure filtration process, as expressed in the obtained values of the final hydration and process efficiency. The use of polyelectrolytes alone significantly improves the effects of sewage sludge dewatering. In this work, the polyelectrolytes were supported by the addition of cement or zeolite. The conditioning of sewage sludge in combined methods using C-494 polyelectrolyte and minerals made it possible to reduce the compressibility coefficient to the range of 0.24–0.47 and, at the same time, to achieve the best results of sludge dewatering in the filtration process. The lowest hydration of 74.9% was achieved when polyelectrolyte and cement were added to the sludge, and this hydration was 6.5 percentage points lower compared to that of the non-filtered sludge. [ABSTRACT FROM AUTHOR]

Sludge biochar supported Fe(II) (Fe(II)-SBC) was successfully prepared using waste activated sludge as peroxydisulfate (PDS) activator to condition sludge for deep dewatering. The experimental results showed that Fe(II)-SBC with FeO on it could effectively active PDS to produce ${\rm SO}_4^{-\cdot }$ SO 4 − ⋅ and ${\rm HO}\cdot$ HO ⋅. The radicals could destroy the structure of sludge cells and extracellular polymeric substance (EPS), transformed the hydrophilic and tightly bound EPS into soluble-EPS, degrade partial proteins and polysaccharides and released bound water. The negatively charged groups on sludge floc were dripped off by ${\rm SO}_4^{-\cdot }$ SO 4 − ⋅ / $\; {\rm HO}\cdot$ HO ⋅ or neutralized with Fe2+, Fe3+, H+, or Fe(II)-SBC, leading to an increase in zeta potential to −2.24 mV and sludge destabilization. The residual Fe(II)-SBC served as a skeleton builder that decreased the compression coefficient of the sludge cake to 0.75. Under the combined functions, the CST and SRF were reduced by 70% and 82.7%, respectively, and Wc was reduced to 72.4%. The byproducts of Fe3+ and SO42- finally remained in sludge cake in the form of NaFeSi2O6 and CaSO4. [ABSTRACT FROM AUTHOR]

In the past, due to improper sludge treatment technology and the absence of treatment standards, some municipal sludge was simply dewatered and then sent to landfills, occupying a significant amount of land and posing a serious threat of secondary pollution. To free up land in the landfill area for the expansion of a large-scale wastewater treatment plant (WWTP) in Shanghai, in this study, we conducted comprehensive pilot research on the entire chain of landfill sludge reprocessing and resource utilization. Both the combination of polyferric silicate sulfate (PFSS) and polyetheramine (PEA) and the combination of polyaluminum silicate (PAS) and polyetheramine (PEA) were used for sludge conditioning before dewatering, resulting in dewatered sludge with approximately 60% moisture content. The combined process involved coagulation and sedimentation, flocculation, and oxidation to treat the leachate generated during dewatering. The treatment process successfully met the specified water pollutant discharge concentration limits for the leachate, with the concentration of ammonia nitrogen in the effluent as low as 15.6 mg/L. Co-incineration in a power plant and modification were applied to stabilize and harmlessly dispose of the dewatered sludge. The coal-generating system ran stably, and no obvious problems were observed in the blending process. In the modification experiment, adding 5% to 7% of the solidifying agent increased the sludge bearing ratio by 53% and 57%, respectively. This process effectively reduced levels of fecal coliforms and heavy metals in the sludge but had a less noticeable effect on organic matter content. The modified sludge proved suitable for use as backfill material in construction areas without requirements for organic matter. The results of this study provide valuable insights for a completed full-scale landfill sludge reclamation and land resource release project. [ABSTRACT FROM AUTHOR]

Municipal wastewater treatment plants (WWTPs) are exposed to high concentrations of micropollutants that can impact conventional activated sludge treatment. The consequences of this include failure to meet discharge standards and the disintegration of flocs, leading to poor sludge settleability. This lab-scale study focuses on the influence of doxycycline, an antibiotic widely used against human and animal diseases, on protozoa, metazoa, and bacterial communities under sludge growing conditions. Doxycycline was added to the mixed liquor of a communal WWTP up to 0, 100, 200, and 400 mg of doxycycline L−1 and incubated in batch conditions for 23 days. The regular addition of nutrient and carbon sources was preformed every 2 days to prevent sludge starvation. Sludge growth, conductivity, and settleability were measured and compared to sludge microbial community structure, determined by microscopic observations and high-throughput 16S rDNA sequencing. The high doxycycline concentration negatively impacted settleability and correlated with a decrease in bacterial diversity and floc disintegration. The addition of doxycycline promoted the enrichment of Proteobacteria Brevundimonas sp., Luteibacter anthropi, and the Bacteroidetes Chryseobacterium massoliae. These species are known to be resistant to a wide spectrum of antibiotics, including tetracyclines. A study of a larger scale may be conducted based on this study' results. [ABSTRACT FROM AUTHOR]

A nonlinear model is proposed to predict the effect of filter medium resistance on the filter cake compression and dewatering at constant pressure. This model is based on the Darcy-Terzaghi-Shirato filtration-compression equations presented in material coordinates and modified to consider the power-law pressure dependence of the specific cake resistance α. Above mentioned model is extended to consider the filter medium resistance R m introducing the number of Biot, Bi = α av W R m .Local profiles of compressive pressure and filter cake characteristics, as well as consolidation ratio and cake dryness, are simulated and compared for different moderately and highly compressible filter cakes (silica, activated sludge, Baker's yeast, and CaCO 3) based on the analytical and numerical solutions of the model. It is shown that the behavior of cake compression and dewatering significantly depends on the filter medium resistance R m , especially at the small numbers of Bi ≤ 1. • Impact of medium resistance on filter cake compression is modelled considering pressure dependencies of cake characteristics. • Behavior of cake dewatering significantly depends on the filter medium resistance, especially at the small numbers of Bi ≤ 1. • Consolidation ratio and cake dryness attained at the same compression time are lower for smaller numbers of Bi. [ABSTRACT FROM AUTHOR]

A reasonable strategy for the development of sludge conditioning methods prior to dewatering appears to be the use of substances that allow the safe management of dewatered sludge. It is also justified to use mineral or organic conditioners instead of synthetic chemicals, e.g., polyelectrolytes, or to try to use other substances, e.g., waste. The properties of iron coagulant (PIX 113) combined with perlite and cellulose can be an environmentally safe method of sludge conditioning. The tests were carried out in accordance with European standards on the efficiency of mechanical dewatering of sewage sludge. The most advantageous method of sludge conditioning was the dosing of the iron coagulant PIX 113. The use of at least a coagulant dose of 0.40 g/g DS enabled the achievement of minimum sludge dewatering parameters, i.e., specific resistance of filtration (SRF) < 5.0 E12 m/kg and final hydration of filtration cake (FH) < 80%. The use of cellulose and perlite as stand-alone conditioners or in combination with PIX 113 resulted in a deterioration of the sludge dewaterability and the quality of the filtrate. It is assumed that the further development of environmentally friendly conditioning methods requires the use of easy-to-use, non-toxic and biodegradable substances. It is important to select conditioners which, in practically acceptable doses, can improve the conditioning effect or show a synergistic effect in combination with previously used conditioners. [ABSTRACT FROM AUTHOR]

The efficient utilization of low-cost carbon feedstocks, such as municipal solid waste (MSW), in biorefineries has become increasingly important for reducing GHG emissions and meeting the growing demand for renewable energy sources. However, MSW as a feedstock presents several challenges, including high moisture content, compositional variability, particle size and shape, density, and ash content. To address these challenges, the potential of mechanical dewatering and high-moisture pelleting processes for densifying MSW fractions, such as paper, cardboard, thin plastic, and thick plastic, into low-cost carbon feedstocks with improved handling and conversion properties were investigated. The effect of these preprocessing technologies on the critical quality attributes (CQAs) of the resulting pellets, including bulk density, durability, and size uniformity, were evaluated. The results showed that with these preprocessing technologies, the paper and cardboard fractions could be pelleted at moisture contents over 40% (w.b.) while achieving >99% durability and >300 kg/m3, while the high moisture plastic fractions were not suitable for pelleting. The thick plastic fraction processed in a screw press was shown to remove up to 30% of the moisture content in a single pass. These findings suggest that these mechanical preprocessing technologies can improve the physical properties of low-cost municipal solid waste fractions for biofuels production. [ABSTRACT FROM AUTHOR]

• Pioneering application of Mn2+-based catalytic ozonation conditioning to in-situ sludge reduction. • Doubled the MLSS reduction rate in sludge and a 19% decrease in observed sludge yield. • Significant increase in peak dehydrogenase activity from 143.83 to 176.41 mg TF/g TSS·hr. • An 18% promotion in the maximum utilization of carbon sources by microorganisms. • Enhancement of sludge reduction and solubilization dominated by Defluviicoccus and Ferruginibacter. To improve the sludge conditioning efficiency without increasing the ozone dose, an in-situ sludge reduction process based on Mn2+-catalytic ozonation conditioning was proposed. Using ozone conditioning alone as a control, a lab-scale sequencing batch reactor coupled with ozonated sludge recycle was evaluated for its operating performance at an ozone dose of 75 mg O 3 /g VSS and 1.5 mmol/L Mn2+ addition. The results showed a 39.4% reduction in MLSS and an observed sludge yield of 0.236 kg MLSS/kg COD for the O 3 +Mn2+ group compared to the O 3 group (15.3% and 0.292 kg MLSS/kg COD), accompanied by better COD, NH 4 +-N, TN and TP removal, improved effluent SS and limited impact on excess sludge properties. Subsequently, activity tests, BIOLOG ECO microplates and 16S rRNA sequencing were applied to elucidate the changing mechanisms of Mn2+-catalytic ozonation related to microbial action: (1) Dehydrogenase activity reached a higher peak. (2) Microbial utilization of total carbon sources had an elevated effect, up to approximately 18%, and metabolic levels of six carbon sources were also increased, especially for sugars and amino acids most pronounced. (3) The abundance of Defluviicoccus under the phylum Proteobacteria was enhanced to 12.0% and dominated in the sludge, they had strong hydrolytic activity and metabolic capacity. Denitrifying bacteria of the genus Ferruginibacter also showed an abundance of 7.6%, they contributed to the solubilization and reduction of sludge biomass. These results could guide researchers to further reduce ozonation conditioning costs, improve sludge management and provide theoretical support. [Display omitted] [ABSTRACT FROM AUTHOR]

The dewatering of substrates is one of the key tasks in the handling of material flows in a circular economy. Besides belt filters, sedimenters, and decanters, screw presses are frequently used to reduce the water content of substrates. However, screw presses available on the market are usually designed for high throughputs (>5 m3/h). The dewatering of smaller feed rates (<1 m3/h), however, requires more compact solutions. For this reason, a compact screw press (short screw length), which is normally used in agriculture for cow manure dewatering, was investigated in this work, as there exist no publications on this type of compact screw press. A mobile test setup was developed and loaded with different material such as digested sludge from a wastewater treatment plant, commercially available potting soil, wood shavings, and biological waste. The dry matter content of the feed material, the feed material itself, the screw rotational speed, and the weight setting (pressure) at the back plate were varied, and the effects on the dewatering result were recorded. A significant influence on the dewatering result was found for the weight setting, the type of substrate (particle size), and the dry substance content of the feed material. The tests confirmed that the compact screw press separator is suitable for the dewatering of wood shavings and biological waste (with an increase in dry matter percentage of up to 7.7%). The direct dewatering of potting soil and digested sludge is not possible and can only be implemented by using structural support material. This study fills the gap between published work on large screw presses and potentially new application fields of compact screw press manure separators, which, until now, have only been used in agriculture. [ABSTRACT FROM AUTHOR]

At present, the treatment method for urban sludge is mainly sludge landfill, which requires the water content of sludge to be less than 60%. Therefore, many researchers have proposed different methods to reduce sludge water content. Freeze–thaw (F/T) and chemical conditioning of sludge, combined with vacuum pressure and vertically inserted drainage board, has been proven to be an effective method to reduce the moisture content of landfill sludge (LS). Based on the consolidation theory of radial drainage, the characteristics of LS in the process of vacuum preloading were studied. A method of instantaneous multistage loading was proposed. The concept of free drainage stage before consolidation drainage is proposed, and the correction of the consolidation coefficient is introduced. Finally, the rationality of the theory was verified by experimental data. The results showed that the consolidation theory is rational for deep dewatering of LS in the vacuum preloading method. The difference between sludge dewatering after F/T pretreatment and chemical pretreatment was mainly reflected in the consolidation coefficient and the free drainage stage. The sludge after F/T pretreatment has higher permeability, more water precipitation, and low moisture content after vacuum preloading. [ABSTRACT FROM AUTHOR]

The volume of sewage sludge generated continues to increase, leading to harmful secondary pollution and highlighting the pressing need for sewage sludge reduction. Sewage sludge drying is a well-established method for treating municipal sewage sludge. This study systematically reviews the latest research on the formation and control of gaseous pollutants during sewage sludge thermal drying. First, this paper comprehensively introduces sewage sludge drying, covering its principles, heat sources, and the inevitable generation of waste gas during the drying process of sewage sludge rich in organic matter. Subsequently, it summarizes the methods for detecting sewage sludge drying exhaust gas and outlines the emission characteristics of such exhaust gas. The three main types of dry exhaust gases discussed include volatile nitrogen-containing compounds, represented by ammonia (NH3); volatile sulfur-containing compounds, represented by hydrogen sulfide (H2S); and the benzene series (BTEX). Finally, based on current technical capabilities, this paper proposes two methods for controlling pollution from sewage sludge drying exhaust gas: suppressing pollutant release during the drying process and treating exhaust gas at the end of drying. Inhibition of pollutant release during the drying process primarily involves reducing the types and quantities of pollutants released by adjusting the sewage sludge drying temperature and time, employing sewage sludge conditioning, and implementing others. Drying back-end exhaust gas treatment removes contaminants from the drying exhaust gas through processes like condensation, adsorption, absorption, biodegradation and other methods. This work offers a fresh perspective on understanding how various factors in the sewage sludge drying process influence the characteristics of dried exhaust gas emissions and the overall control of sewage sludge exhaust gas emissions. [ABSTRACT FROM AUTHOR]

A large amount of sediment is dredged from surface water bodies such as rivers, lakes, and oceans every year around the world. It should be further disposed of or recycled. Dewatering is an essential step before the treatment and recycling of dredged sediment. At present, flocculation is one of the most used techniques for dewatering of dredged sediment. This article provides a comprehensive review on the status of dewatering of dredged sediment in water bodies by flocculation processes, with emphasis on the self-flocculation process of dredged sediment and the effects of adding different flocculants. The important influencing factors for the self-flocculation process of dredged sediment were summarized, and the corresponding mechanisms were discussed. The mainly used flocculants for the flocculation process and their influencing mechanisms for the properties of the flocs were also reviewed. In addition, the effect of the flocculants on the migration of contaminants in dredged sediment was assessed. This review can provide reference and guidance for future studies and the real projects on dewatering of dredged sediment by flocculation processes. [ABSTRACT FROM AUTHOR]

The sludge treatment reed bed is a sustainable sewage sludge management technology that offers promising sludge dewatering and stabilisation, due to its low energy and labour requirements, and minimal operating and maintenance costs. Despite numerous existing studies and increasing applications of sludge treatment reed bed in both developed and developing countries, the lack of standard system configurations and operating regimes led to several operational problems, including bed clogging and poor dewatering and mineralisation efficiency. Sludge dewatering and stabilisation in STBRs are complex processes governed by system- and operation-related factors such as the substrate media, macrophytes, loading regime, sludge characteristics, and climate conditions. Rather than the complex experimental study, process-based modelling has become a promising approach to investigating the influence of specific factors on the efficiency of sludge dewatering and stabilisation. This paper presents an overview of the critical system and operating parameters in sludge treatment reed beds and a summary of the interactions between the factors. Then, a framework of process-based modelling is proposed, which provides a useful platform to study the interactions of operating parameters and other factors in the complex processes of sludge dewatering and stabilisation, which supports the system design and optimisation of sludge treatment reed beds. [ABSTRACT FROM AUTHOR]