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The effects of marble processing wastewater physicochemical treatment sludge (K1) on polypropylene (PP) waste pyrolysis were investigated by lab-scale batch pyrolysis system. PP-K1 proportions and pyrolysis temperature were studied as variables and both were found to have influences onto pyrolysis char, oil/tar, gas fractions distribution, as well as pyrolysis char characteristics (determined via SEM, EDX, FTIR, TGA and XRD analyses). The influence of K1 could be related to its high mineral composition (CaCO3, CaMg(CO3)2 and (Mg0.03Ca0.97)(CO3)) which also detected in the char products. K1 acts as catalyst and remained unchanged in thermochemical reactions below 700°C. The main thermal degradation of PP occurs around 400–470°C, although it starts at about 300–350°C, whereas, K1 resulted in more thermal degradation at 300°C pyrolysis. As K1 dose increased, pyrolysis chars became more thermally stable with the pyrolysis temperature. Diverse types of chars in terms of porosity, thermal strength and chemical structure were produced with PP + K1 as compared to the PP chars. For example, with 10%–20% K1 doses, the chars are in aromatic structure while chars become aliphatic when K1 dosage increased to 30% or above. The structural diversity made these chars new products that can be used as raw material for subsequent purposes. This study provided a basis for the chars' physical and chemical properties which are needed for further research to develop new generation evaluation areas for them. Therefore, a new symbiotic upcycling approach has been presented for PP wastes and marble processing wastewater treatment sludge. [ABSTRACT FROM AUTHOR]

This research presented, for the first time, the results of the successful application of the waste press sludges, WSLP (plant for lacquer and paint) and WSEP (powdery enamel plant), from a wastewater treatment plant generated during heating device production in the construction industry. The results of WSEP characterization and its influence on cement paste, mortar, and concrete properties showed that this material could be used as a cement replacement (with a maximum replacement amount of 20%) in producing mortar and concrete. Although waste WSLP sludge does not possess pozzolanic properties and does not meet the criteria prescribed by the standards for application in mortar and concrete due to its chemical inertness and fineness, as well as its extended setting time, it can be used as a replacement for stone filler or other powdered mineral admixture in the production of self-compacting concrete (SCC) in amounts up to 100%, with a maximum quantity of up to 100 kg/m3. The obtained results indicate that with the appropriate conversion, waste sludges, despite representing hazardous waste, can be used as safe products in the construction industry; i.e., the waste material can become a useful and valuable raw material by applying (respecting) all of the principles of the green economy. [ABSTRACT FROM AUTHOR]

In order to promote the yield and calorific value of combustible gas products in the pyrolysis, a CaO-based biochar (CSC) derived from waste crab shell was used as a low-cost sorption-enhanced catalyst to enhance oil-fried sludge (OS) pyrolysis. The effects of CSC addition and pyrolysis temperature on OS pyrolysis characteristics were analyzed in detail. The results indicated that adding CSC significantly enhanced OS pyrolysis and produced more combustible gas products with CO2 removal. At 700 °C, adding CSC promoted the combustible gas yields and greatly reduced CO2 by 96.9 %. And the corresponding LHV of pyrolysis gas products increased by 26.8 % and reached up to 33.7 MJ/N m3. Additionally, TG-FTIR analysis revealed that adding CSC reduced the formation temperature of CH4. Importantly, although there was only 35.5 wt% of Ca in CSC, CSC exhibited almost the same sorption-catalysis-enhanced effects compared to pure CaO. These findings suggest that biochar derived from crab shell has the potential to replace CaO for enhancing sludge pyrolysis into value-added fuel products. [ABSTRACT FROM AUTHOR]

The addition of various environmental contaminants in water resources has demanded high efficiency from water treatment plants in achieving the expected levels of water potability. Moreover, sewage treatment plants have sought to reduce the organic, inorganic, and microbiological pollutant load of effluents before their disposal into water. However, during these processes, by-products called water treatment sludge and sewage sludge are generated. Water treatment sludge is basically composed of sand, clay, silt, a small amount of organic matter, microorganisms, and metals. While sewage sludge is rich in organic matter, macronutrients and micronutrients, besides pathogenic microorganisms, and toxic contaminants. Studies have demonstrated their high toxicity to different animals and plants. Among the ways to detoxify these residues, biostimulation, bioaugmentation, monitored natural attenuation, and composting stand out. The main reuse of these two residues includes soil conditioners and materials for civil construction. Moreover, water treatment sludge can be used for aluminum and iron recovery, and sewage sludge for biogas and bio-oil production. Thus, in view of the growing production and the real need to propose safety measures for the sustainable management of these wastes, this review intends to reflect on the dangers of their inappropriate disposal on environmental health and to divulge ecotoxicological information on these wastes, as well as the reuse potential of both sludges. An active search was performed on the Google Scholar, Springer, National Center for Biotechnology Information, and Scientific Electronic Library Online platforms, where a literature review was carried out on articles published between 1990 and 2022. [ABSTRACT FROM AUTHOR]

Due to the high cost and limited sources of cerium coagulants, it is extremely important to take measures to recycle this raw material. This paper presents the new possibility of recovering cerium(III) chloride, cerium(III) sulphate, cerium(IV) sulphate, and potentially phosphate from sewage sludge (101.5 g/kg Ce and 22.2 g/kg total P) through a brewery wastewater treatment process using recycled CeCl3 as a coagulant. In order to recover the Ce and P, the sludge was subjected to extraction using an HCl solution. Optimal process conditions were determined by means of central composite design and response surface methodology (CCD/RSM) for three input parameters (HCl mass, reaction time, and extractant volume). Under optimal conditions (0.35 g HCl per 1 g of sludge, 40 min reaction time, extractant volume of 25 mL per 1 g of sludge), the highest efficiency obtained was 99.6% and 97.5% for Ce and P, respectively. Cerium(III) oxalate as Ce2(C2O4)3∙10H2O was precipitated from the obtained solution using H2C2O4 (99.97%) and decomposed into CeO2 (at 350 °C), which was afterwards subjected to a reaction with HCl (30%, m/m) and H2O2 (30%, m/m), which led to the crystallisation of CeCl3∙7H2O with a purity of 98.6% and a yield of 97.0%. The obtained CeO2 was also subjected to a reaction with H2SO4 (96%, m/m) and H2O2 (30%, m/m), which produced Ce2(SO4)3 with a yield of 97.4%. The CeO2 was also subjected to a reaction with only H2SO4 (96%, m/m), which produced Ce(SO4)2 with a yield of 98.3%. The filtrate obtained after filtering the Ce2(C2O4)3∙10H2O contained 570 mg/L of P, which enabled its use as a source of phosphorus compounds. The presented processes of Ce and potentially P recovery from sewage sludge originating from brewery wastewater contribute to the idea of a circular economy. [ABSTRACT FROM AUTHOR]

Modified sludge biochar, recognized for its notable economic and environmental benefits, demonstrates potential as an effective catalyst for peroxydisulfate (PDS) activation. Nevertheless, the specific mechanisms underlying its catalytic performance require more comprehensive investigation. In this study, a modified biochar (TSBC) doped with oxygen (O) and nitrogen (N) atoms was synthesized from sewage sludge and tannin extract, which significantly enhanced the activation of PDS for the degradation of sulfamethoxazole (SMX). The TSBC/PDS system demonstrated robust performance for SMX degradation, achieving over 90% efficiency over a wide pH range (3–10). Subsequent quenching experiments demonstrated that TSBC predominantly catalyzed PDS to generate O 2 1 , which effectively degraded SMX via a non-radical pathway. The O- and N-containing functional groups in TSBC were identified as the primary catalytic sites. Besides, density functional theory (DFT) calculations revealed that the incorporation of graphitic N significantly improved the adsorption capacity of PDS on the TSBC surface. Furthermore, based on the identification of intermediates and theoretical calculations, SMX was degraded mainly by two different pathways: S-N cleavage and O 2 1 oxidation. This study offers a foundational framework for the targeted modification of sludge biochar, thereby expanding its applications. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Investigaciones Agroindustriales is the property of Revista Colombiana de Investigaciones Agroindustriales del Centro Agropecuario Sena Buga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, the interest of the scientific community has become focused on the integration of circular economy principles by eliminating end-of-life concepts and forming zero-waste strategies. The present paper suggests the possible application of innovative, eco-friendly, cost-effective, and highly efficient ceramic materials with the partial implementation of aluminosilicate-based waste in the form of wastewater sludge in advanced technology solutions. The specific objective was to demonstrate the effective utilization of the investigated waste in the production of refractory adhesives and/or sealants for Intermediate-Temperature Solid-Oxide Fuel Cells (IT-SOFCs). Different physical–mechanical and chemical properties were determined along with the performance of leaching tests, the thermal cycling procedure, and leakage tests in a single cell. Based on the maintenance of mechanical integrity after thermal cycling and satisfying crystal and microstructural stability after high-temperature treatment, it was concluded that the investigated materials may be considered promising candidates for application as heat-resistant adhesives for connecting components in heating systems. However, they were not found to be applicable as sealants for IT-SOFCs in raw form according to the failure of testing in a single cell. Still, requirements for this purpose could be met after certain modifications of the composition and synthesis methodology, which presents the major initiative for our further research in this field. [ABSTRACT FROM AUTHOR]

The paper presents the results of laboratory studies on the removal of phosphate in a wastewater treatment plant by adding sludge formed at the water treatment plant (water treatment sludge—WTS) in the city of Astana (Kazakhstan). Raw WTS from the sludge drying beds was used in the study, and the content of chemical compounds present in the dry sludge residue was determined, yielding 10.8–14.6% aluminum oxide (Al2O3) and 4.58–5.31% iron oxide (Fe2O3). The sludge moisture ranged from 90.5 to 95.6%, and the ash content ranged from 51.3 to 63.9%. The raw sludge from the WTP was added to the wastewater collected before the sand trap and after biological treatment. On the basis of the obtained test results, it was found that the effect of phosphate removal depended primarily on the sludge dose and was above 90% when adding 50 mL of sludge to 1 L of sewage. To a lesser extent, the effect of phosphate removal was dependent on the contact time of the sludge with the wastewater and the place where the wastewater sample was taken. [ABSTRACT FROM AUTHOR]

In thus study, municipal sludge was treated by wet oxidation coupled with alkali hydrolysis for recycling as a carbon source for biological denitrification and struvite crystallization. The effects of the reaction variables on the soluble chemical oxygen demand (SCOD) yield were investigated. To obtain the optimal reaction conditions for the SCOD yield, a response surface method was used, and a quadratic regression equation model was established. The optimal reaction conditions were as follows: H2O2 dosage: 5.9 g, reaction time: 30 min, reaction temperature: 214°C, and NaOH dosage: 2.7 g. A SCOD yield of 58% was obtained, which is consistent with the predicted value. The results indicate that an alkaline hydrolytic solution can be effectively used as a carbon source for biological denitrification. When the ratio of C/N = 6, the highest denitrification rate of 0.51 mg/(g·h) was obtained. Struvite crystallization was used to recover phosphorus from the alkaline solution. The ratio of Mg/P and pH significantly affected struvite production. The analytical results from scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy indicated that struvite was the main substance in the crystallization production. The results of this study demonstrate the feasibility of reusing sewage sludge as a carbon source and struvite. [ABSTRACT FROM AUTHOR]

Recovering and recycling nitrogen available in waste streams would reduce the demand for conventional fossil-based fertilizers and contribute toward food security. Based on life cycle assessment (LCA), this study aimed to evaluate the environmental performance of nitrogen recovery for fertilizer purposes from sewage sludge treatment in a municipal wastewater treatment plant (WWTP). Utilizing either air stripping or pyrolysis-derived biochar adsorbent, nitrogen was recovered from ammonium-rich reject streams generated during mechanical dewatering and thermal drying of anaerobically digested sewage sludge. A wide range of results was obtained between different scenarios and different impact categories. Biochar-based nitrogen recovery showed the lowest global warming potential with net negative GHG (greenhouse gas) emissions of −22.5 kt CO2,eq/FU (functional unit). Ammonia capture through air stripping caused a total GHG emission of 2 kt CO2,eq/FU; while in the base case scenario without nitrogen recovery, a slightly lower GHG emission of 0.2 kt CO2,eq/FU was obtained. This study contributes an analysis promoting the multifunctional nature of wastewater systems with integrated resource recovery for potential environmental and health benefits. [ABSTRACT FROM AUTHOR]

The treatment and disposal of sewage sludge is one of the most important and critical problems of wastewater treatment plants. 8.7 million tonnes of dry matter of sewage sludge were produced annually in the European Union in the year 2020. Due to the fact that sewage sludge contains a large number of substances that are not beneficial for human health, the conditions for sludge management will be significantly tightened in the EU countries. One option for sludge liquidation is the production of biofuel in a form of granules or pellets from sewage sludge enriched by waste celluloses. The achieved results show that the resulting quality of such alternative biofuel is fully comparable to conventional fossil fuels. The economic analysis is based on the simulation of cash flows associated with the implementation of the project over the lifetime and the calculation of levelised cost (LCOE). Results shows (under the current economic situation) that solar dryer technology ensures the lowest LCOE at the level of 26 EUR/GJ in fuel. If the LCOE of the alternative biofuel includes the price of the saved emission allowance and the future costs of sewage sludge disposal, the resulting price is directly competitive with lignite. The results thus clearly show that there is an ecological and economically competitive substitute for solid fossil fuels, which may be an important step for the future use of local combustion sources such as district heating plants. [ABSTRACT FROM AUTHOR]

Waste heat recovery is a key problem to be solved for metallurgical slag. Furthermore, the heat source is a current bottleneck for sewage sludge gasification technology. At present, there is no complete process system for the thermochemical conversion of sludge driven by metallurgical slag waste heat. To recover the waste heat of slag, a granulation and waste heat recovery system using the sewage sludge gasification reaction is proposed in this paper. The sludge gasification kinetics were analyzed using thermogravimetry (TG). The active catalytic components in both Cu and Ni slag were determined using X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the metallurgical slag could improve the decomposition rate of the sludge gasification reaction. The main catalytic components were Fe3O4 and CaO for Cu slag and Ni slag, respectively. The conversion ratio was increased by 7.8% and 11.8%, while the activation energy decreased from 21.09 kJ/mol to 17.36 kJ/mol and 17.30 kJ/mol, respectively, when Cu slag and Ni slag were added. After oxidative modification, the catalytic function was enhanced for Cu slag, whereas it was weakened for Ni slag. [ABSTRACT FROM AUTHOR]

Sludge pyrolysis has sparked the interest of researchers because of its capability to dispose of hazardous residues while producing valuable bioproducts. Numerous expensive and laborious experiments are conducted to understand sludge pyrolysis. Machine learning technology can eliminate the need for experimental measurements by systematically learning relationships between variables from historical data. This research aimed to propose a machine learning model to characterize sludge pyrolysis products. A comprehensive database covering various sludge types and pyrolysis reaction conditions was constructed from experimental data. The k-nearest neighbor algorithm was used to reconstruct the missing inputs of sludge composition. The principal component analysis method was then used to decrease dataset dimensionality and acquire relevant information. The obtained scores were normalized and introduced into three machine learning models. The input variables were the chemical properties of sludge and reaction conditions. The response parameters were the distribution and composition of pyrolysis products. Based on descriptive data analysis, the optimum bio-oil yield was obtained at temperatures between 500 and 600 °C. At higher temperatures (700–800 °C), a transition was observed in the product distribution towards more syngas. The random forest regression model showed the highest accuracy among the applied models, with a correlation coefficient higher than 0.813 and a relative mean squared error lower than 12.51. The SHAP analysis using the random forest algorithm was successfully conducted to understand the importance of input variables on output responses. The five top significant features affecting bio-oil yield were ash content, fixed carbon content, operating temperature, and volatile matter content. [Display omitted] • Machine learning technology was used to characterize wastewater sludge pyrolysis. • Random forest regression could predict the product distribution of sludge pyrolysis. • The best model estimated the process with a correlation coefficient higher than 0.813. • The importance of inputs on outputs was investigated by the random forest algorithm. • An easy-to-use software interface was developed for future research applications. [ABSTRACT FROM AUTHOR]

Water treatment plants are responsible for ensuring the quality and distribution of drinking water. The most commonly employed treatment method is the conventional type, which generates a significant amount of waste known as sludge. As chemicals are used throughout the treatment to remove impurities from the water, the sludge may contain toxic substances in its composition and, therefore, must receive an environmentally appropriate final disposition. This study aimed to assess, through respirometry, the biodegradability of water treatment sludge when applied to soil, associated or not with biostimulating material (sewage sludge), focusing on its use in agriculture. Before and after biodegradation, physical–chemical, microbiological, and phytotoxic potential characterization of the different treatments containing soil, water treatment sludge, and sewage sludge was also carried out. The chemical/biochemical oxygen demand ratio indicated the presence of less biodegradable compounds in the water treatment sludge compared to sewage sludge. The respirometry test revealed that the samples containing sewage sludge presented the highest CO2 production and biodegradation efficiency. The sample soil, sewage sludge, and 5% water treatment sludge showed the best result for these parameters. None of the treatments performed was considered phytotoxic, exhibiting germination percentages superior to 70%. The sample containing the highest concentration of water treatment sludge associated with sewage sludge presented a statistically significant increase in root growth after biodegradation. Thus, the addition of sewage sludge led to an increase in the agronomic potential of the mixture. Therefore, water treatment sludge as a soil conditioner seems to be a promising alternative for its recycling. [ABSTRACT FROM AUTHOR]

Slow pyrolysis experiments were performed at 500 °C on Russian feedstock (hydrolysis lignin, peat, mixed sewage sludge, and pine and spruce woods, for comparison). The pyrolysis products were analyzed through gas chromatography, and more than 130 components were identified and grouped according to their chemical family. A qualitative analysis of the pyrolysis products showed that the highest amount of molecules (more than 40%) released during the pyrolysis of hydrolysis lignin belongs to the phenol chemical family. They result from the lignin degradation. The peat pyrolysis led to a large amount (more than 50%) of sugars. The molecules detected during the pyrolysis of the mixed sewage sludge are similar to that of the spruce sample and almost the same as that of the pine sample, because the selected sewage sludge is a mixture of municipal and industrial waste from pulp and paper industry. Comparisons between the data obtained for these Russian feedstock and that of the literature concerning quite similar materials exhibit differences which may be the consequence of the feedstock and of the experimental conditions. [ABSTRACT FROM AUTHOR]

In this study, pyrolysis of municipal sewage sludge samples from different sources including cattle and chicken manure as well as brook mud, was investigated using a thermogravimetric analysis coupled with a Fourier transform infrared spectrometer (TG-FTIR) at different heating rates (25, 50 and 100 °C/min). In order to determine the kinetic parameters, Arrhenius, model-free Kissinger–Akira–Sunose (KAS), as well as Friedman and Flynn–Wall–Ozawa (FWO) methods were compared. The thermogravimetric results revealed that pyrolysis involved different stages, and that the main decomposition reactions took place in the range of 200–600 °C. In this range, decomposition of biodegradable components (e.g., lipids and polysaccharides), proteins and carbohydrates occurred; meanwhile, there were samples (e.g., cattle manure, brook mud) in which the decomposition step could be observed even at temperatures above 700 °C. According to the Arrhenius method, the activation energies of the first decomposition stage were between 25.6 and 85.4 kJ/mol, while the activation energies of the second and third stages were in the ranges of 11.4–36.3 kJ/mol and 20.2–135 kJ/mol, respectively. The activation energies were also calculated by the KAS, Friedman and FWO methods, which were in the range of 100–300 kJ/mol for municipal sewage sludge or distillery sludge, and ranged between 9.6 and 240 kJ/mol for cattle manure, chicken manure and brook mud samples. [ABSTRACT FROM AUTHOR]

Low-temperature transformation of technogenic waste, and water treatment sludge and fly ash of thermal power plants in particular, into long-acting fertilizers is a promising way to reduce their negative impact on the environment. We developed technology of waste utilization that includes determining the composition of the raw material mixture, mixing, granulation and drying of the fertilizer granules. It was stated that the components of the fertilizer should be mixed in the following ratio (wt.%): fly ash 4h6; CaO 20-25; zeolite clinoptiolite 15-20; sludge of water treatment of municipal sewage 50-55; and urea -- the remainder. During the mixing of the components and their granulation some physical and chemical processes take place and heat releases; therefore to ensure the required moisture of the granules, they were dried at the temperature of 30-40°C. The obtained porous granules of fertilizer contain (wt.%): total nitrogen 5.1-5.2; total potassium 0.34-0.35; total calcium 21.7; and ammonium nitrogen 0.6-0.7. Zeolite as an adsorbent promotes the gradual release of ammonium from fertilizer into the soil. The results of fertilizer testing showed that sunflower biomass was increased by 7-10% in case of using the fertilizer as compared with the soil without it. [ABSTRACT FROM AUTHOR]

The aim of the work was to assess the efficiency of ozonation and ozonation in combination with H2O2 in jet loop reactor to increase biotreatability of persistent veterinary antibiotic Tiamulin. The efficiency of oxidative processes was monitored by combined approach based on determination of efficiency of wastewater treatment and impact to waste sludge stabilization. Degradation of Tiamulin in model wastewater (100 mg L−1) during oxidation was followed by COD and DOC measurements while changes in biodegradability were determined by respirometric measurements. Biogas production potential was also determined to identify problems related to anaerobic digestion of waste sludge resulted in treatment of Tiamulin-contaminated wastewater. At ozone dose of 69 gozone gCOD−1 and 220 gozone gDOC−1removal for COD and DOC was 26% and 17%, respectively. Better biotreatability was confirmed by respirometric testing. H2O2 addition did not improve removal efficiency (11–13%). The second stage of nitrification was suppressed by the addition of Tiamulin and ozonation again recovered N - NO 3 − formation. O3/H2O2 treated sample reduced the nitrification, especially formation of N - NO 2 − in the first phase of the process. Simultaneously, quadratic model was developed to describe the relationship between oxygen uptake rate and changes in ammonium nitrogen concentration due to the oxidative treatment. The positive impact of ozone was also confirmed by ozonation of Tiamulin-contaminated (400 mg L−1) waste sludge where biogas production potential was increased for 6-times. Combination of approaches confirmed, that O3 effectively increase the treatability of Tiamulin in wastewater and sludge while addition of the hydrogen peroxide generally did not improve the performance of the processes. [ABSTRACT FROM AUTHOR]

Application of water treatment residuals (WTR) and biosolids (BS) might ameliorate fragile soils. However, studies integrating impacts of waste preparation methods such as liming and grinding associated with co‐application approaches for soil conditioning are lacking. The present study aimed to evaluate the feasibility of agricultural use of WTR as well as their co‐application with BS to ameliorate a sandy soil through assessing impacts on selected soil quality indicators and on nutrient and potentially toxic element concentration in plant tissue in addition to the biomass yield of annual crops. The following treatments were evaluated: non‐amended soil (control); drying plus grinding and liming WTR; WTR co‐application with BS at 3:1 ratio; and a soil amendment commercially available in Brazil. All treatments were soil incorporated in the 0.0–0.2 m layer at 30 Mg ha−1 dose (dry mass). Selected soil physical, hydraulic, and chemical parameters were determined. Furthermore, nutrients and potentially toxic elements concentration in plant tissue as well as the agronomic performance of maize and ryegrass were measured. The co‐application of WTR and BS increased the soil content of P, Zn, and Cu in the 0.0–0.1 m layer. The concentration of these nutrients also was greater in ryegrass tissue and promoted the biomass yield in 51%. WTR did not increase contaminants and did not decrease the P content in soil and in plant tissue, independently of drying plus grinding and liming. Considering the conditions investigated in our study, WTR/BS co‐application was environmentally safe and effective in ameliorating soil quality. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Chemical & Petroleum Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • Synthesis of ecological-nanohydroxylapatite (ECO-NHAp) made from Fine–grained calcareous sludge waste. • The obtained materials were found to be effective adsorbents for Cd2+ metal ions from water. • The adsorption revealed Langmuir isotherms reaction. • More than 99% heavy metal pollutants removal using ECO-NHAp. This paper reports on the hydrothermal synthesis of ecological-nanohydroxyapatite (ECO-NHAp) using Ca extracted from fine-grained calcareous sludge via acid dissolution for use as an adsorbent in the removal of Cd2+ from wastewater. The ECO-NHAp was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller surface analysis, and nuclear magnetic resonance spectrometry. Batch adsorption experiments were performed to investigate the effects of contact time and initial Cd2+ concentration on adsorption efficiency. Kinetics and adsorption behavior were examined using Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, and Sips isotherms. Overall, the Cd2+ adsorption capacity of ECO-NHAp was good (35.09 mg/g) and Langmuir isotherms indicated monolayer adsorption. After controlling for entropy, we found the changes in enthalpy and entropy were positive, while the Gibbs energy was negative. The proposed ECO-NHAp synthesized using raw materials from fine-grained calcareous sludge could be used as a rapid adsorbent for metal ion extraction. [ABSTRACT FROM AUTHOR]

Keywords: Costs; Wastes; Sludge; Water Systems; Wastewater Treatment; Streams; Liability; Coagulation; Lime; Softening; Biosolids EN Costs Wastes Sludge Water Systems Wastewater Treatment Streams Liability Coagulation Lime Softening Biosolids 6 7 2 11/03/23 20231101 NES 231101 The US Environmental Protection Agency (EPA) is preparing to advance several actions that could have costly implications for drinking water and wastewater treatment facilities with waste residual streams containing per- and polyfluoroalkyl substances (PFAS). The listing of PFAS as hazardous constituents is a first step toward listing wastes containing PFAS as hazardous wastes, which triggers more controlled waste management requirements (e.g., documentation and reporting, transportation, disposal practices). While EPA has not yet initiated a rulemaking to list PFAS-containing wastes as RCRA hazardous wastes, the listing of PFAS as hazardous constituents is a first step that puts the process in motion. [Extracted from the article]

As a key step in disposal and reutilization, sludge dewatering is very difficult, since extracellular polymers substances (EPS) binds the water, and compressible organic matter deforms and causes water filtration channels to collapse. Sludge dewaterability was demonstrated to enhance by carbonaceous skeleton (CSkel)-assisted thermal hydrolysis in our previously study. This work further investigated the assisting role of different types of CSkel in EPS decomposition during sludge thermal hydrolysis stage and channels reformation during press filtration stage. Two major types of CSkel, lignocellulosic waste (waste sawdust, waste straw, processing by-product) and protein-rich waste (shrimp shells, jatropha oil cake), were selected. The experimental results showed that in the thermal hydrolysis stage, the decomposition of lignocellulosic waste would increase fatty acids production by 28%, resulting in an acidic environment that reduced the total amount of three hydrophilic amino acids, i.e., glycine, serine and threonine. These promoted the release of water from the sludge. In the press filtration stage, average pore size of sludge was reduced by approximately 87% and nanoscale holes began to appear and increase. Assisting of CSkel rebuilt the filtration channels which brought good connectivity between the pores in sludge cake. Lignocellulosic waste proved significantly more effective than protein-rich waste in achieving a water removal rate of 88.63% under 1 MPa. This study provided a basis for selecting suitable CSkel to optimize sludge dewatering for subsequent utilization. [Display omitted] • After thermal hydrolysis assisted by lignocellulosic waste, the water removal rate of the sludge can be increased to 88.63% at 1 MPa, outperforming protein-rich waste in this respect. • In thermal hydrolysis stage, the decomposition of lignocellulosic waste promoted the production of fatty acids and amino acids, creating an acidic environment. • In an acidic environment, cell rupture was facilitated and the production of hydrophilic amino acids was inhibited, both of which favored water release. • With the assistance of CSkel, the average pore size of the sludge cake reduced by 87% and interconnected micro-/nano-pores served as rigid channels for water removal from sludge during press filtration. [ABSTRACT FROM AUTHOR]

Sludge-derived carbons were prepared by hydrothermal carbonization and pyrolysis-activation. In this work, the physiochemical properties and electrochemical performance of these carbons were compared in detail. The structure of pyrochar (PC) has been fully developed that layered porous skeleton was formed during activation process. Thus, obtained the pyrolysis-activated carbon (PAC) had excellent specific surface area (463.2 m2/g) and pore volume (0.36 m3/g), which were higher than these of hydrothermal carbonization-activated carbon (HCAC-300) (364.1 m2/g, 0.18 m3/g). Due to the high nitrogen content of sludge, there were abundant N functional groups (N-5, N-6, N-Q) on the surface of PAC and HCAC. The self-doping of nitrogen was beneficial for improving the carrier concentration and charge transport capacity of carbons, and forming the pseudocapacitance via the redox reaction. Owing to the remarkable physiochemical properties, PAC exhibited highest specific capacitance of 114.7 F/g at 1 A/g, which led to a large amount of charge storage and rapid diffusion of electrons/ions. However, hydrothermal carbonization performed a high economic advantage in disposing the high-humidity feedstock such as sludge. Therefore, the exploration on improving the pore structure in hydrothermal carbonization process thus obtaining high performance carbon material would be of significance and of prospects. [Display omitted] • N was successfully self-doped into the sludge-derived carbons. • N-6, N-5 and N-Q were the main forms of N in the sludge-derived carbons. • The self-doping of N was beneficial for forming the pseudocapacitance. • Layered porous skeleton was formed during activation process. • PAC behaved excellent specific surface area and pore volume than HCAC. [ABSTRACT FROM AUTHOR]

The content of fine sand (< 200 μm) in primary sludge is relatively high in Chongqing sewage treatment plant owing to the part of rainwater will be mixed with sand and discharged into the municipal pipe network. Due to the insufficient separation of the sand, different obstacles to subsequent treatment processes may increase equipment wear, reduce effective volume of the tank, or shorten the cleaning cycle. There is a common use of grit chamber for the separation. Nevertheless, the use of hydrocyclone shows an outstanding performance in cost effectiveness and ease operation. The primary sludge in a sewage plant in Chongqing was monitored, and the average concentration of total suspend solids (TSS), total sand content, and volatile suspended solid (VSS) were 40.25 g/L, 17.51 g/L, and 13.41 g/L, respectively. The size of sand in the sludge was small, and the sand below 30 μm accounted for about 70% of the total sand. It formed flocs with organic matter and was removed in subsequent process units. While the size between 30–200 μm, called fine sand, was the main separation object, accounted for about 28.5%. According to XRF and XRD analysis, the sludge composition was mainly composed of quartz (SiO2), plagioclase (Na(AlSi3O8)), and calcite (CaCO3), which were similar to the main mineral composition of surface sediments and mountain rocks in the main urban area of Chongqing. A single-factor experiment on two types (FX100 and FX50) of hydrocylones was conducted to determine their abilities concerning the separation of fine sand and enrichment of organic matters from primary sludge. FX100 and FX50 showed best performance in the case of P = 0.17 Mpa, underflow diameter (Du) = 18 mm and P = 0.20 Mpa, Du = 6 mm, respectively. The removal efficiency of fine sand by hydrocyclone FX50 was 71.39%. While, it had poor performance on organic matter enrichment and the removal efficiency of which was 17.38%. By contrast, the removal rate by FX100 reached 61.89% for fine sand and only 6.89% for organic matters detached. The superimposition effect did not appear in the serial experiments on hydrocylone FX100 and FX50, but the power is 3.5 times of that of single-stage hydrocylone FX100. Comprehensive consideration of the processing capacity per unit time and operating power, the hydrocylone FX100 was more suitable for actual operation. [ABSTRACT FROM AUTHOR]

Drinking water treatment sludge (DWTS) was used for the preparation of ceramic microfiltration membrane. The DWTS powder was firstly characterized to determine its chemical and mineralogical composition, and to understand its thermal behavior. DWTS powder was mixed with clay as binder and starch as porosity agent, then pressed to shape flat membrane, and sintered at different temperatures from 950 to 1150 °C. The optimal sintering temperature (1050 °C) provides ceramic membrane with a porosity of 46.7%, a pore size of 0.92 μm, a mechanical strength of 14.5 MPa and a permeability of 724.5 L/h.m2.bar. This membrane was successfully used to clarify a synthetic baking powder suspension and an textile effluent. DWTS-based membrane was able to remove completely the turbidity from feeds, to reduce significantly the chemical oxygen demand (COD), and to discolor completely textile wastewater. Furthermore, four empirical models were applied to describe the fouling mechanism occurred during filtration experiments. [ABSTRACT FROM AUTHOR]

Two lysimeter experiments were conducted to evaluate the impacts of biosolids and drinking water treatment residual nanoparticles (nWTRs) on phosphorus and aluminum phytoavailability and yield of corn plants. Two consecutive experiments were conducted with different application rates of biosolids (0% and 3%) and nWTRs (0%, 0.1%, 0.2%, and 0.3%). The results revealed that the total biomass production (grain plus stover) increased significantly (p <.05) as a result of nWTRs application at 0.1% rate. Application of nWTRs to biosolids-treated soil slightly decreased yield at 0.2% and 0.3% application rates. The best combination ratio between nWTRs and biosolids at which high corn yield is 0.1% nWTRs to 3% biosolids. Application of 3% biosolids significantly increased bioavailable P in the studied soil, but application of 0.3% nWTRs significantly decreased the bioavailable P concentrations in soil in the two seasons of cultivation. Application of nWTRs at 0.1% and 0.2% rates decreased soil pH in the soil treated with 3% biosolids in first and second seasons of cultivation in comparison with control treatment. The application of nWTRs greatly and significantly (p <.05) increased the water-holding capacity of studied soil treated with and without biosolids. [ABSTRACT FROM AUTHOR]

Phosphorus recovery from wastewater is a focus area in Denmark; the aim is to recover at least 80% of the phosphorus. In order to extract phosphorus, surplus sludge from wastewater treatment plants was acidified (pH 2–4) to increase the dissolved phosphorus concentration, which then can be precipitated and recovered. Pilot-scale acidification and dewatering tests were done using sludge from three different wastewater treatment plants: plant (1) digested primary and secondary sludge, plant (2) digested primary sludge, and plant (3) non-digested sludge. Treatment of digested sludge gave the highest phosphorus release, but the acid consumption was high due to carbon dioxide stripping. The dry matter content of the acidified dewatered sludge was high (20–40%), but the dry matter content in the filtrate increased with decreasing pH. Approximately half of the dry matter content in the filtrate could be removed by introducing an additional separation step. The optimal pH for phosphorus extraction was 3, where up to 68% of the phosphorus was dissolved. Part of the released orthophosphate was lost with the filter cake but still, 60% of the total phosphorus content in the sludge ends up in the filtrate. [ABSTRACT FROM AUTHOR]

Here, we investigate how to improve the energetic potential of different sludge and scum from water and sewage treatment plants through co-combustion of their blends. We collected samples in Curitiba, Brazil, from: (a) anaerobic sewage treatment sludge; (b) aerobic sewage treatment sludge; (c) sewage treatment scum; (d) drinking water treatment sludge. We characterized the samples in terms of their energetic potential—by thermal analysis—and chemical composition—by scanning electron microscopy and X-ray diffractometry. The aerobic treatment sewage sludge and sewage treatment sludge had the highest useful heating value (9.47 MJ kg−1), whereas pure drinking water treatment sludge had the lowest one (4.62 MJ kg−1), which was increased upon blending with anaerobic sewage treatment sludge (7.29 MJ kg−1). Sewage treatment scum and aerobic treatment sewage sludge were mainly composed by quartz and gypsum, and both the blends and pure samples had the same crystalline structure. In conclusion, mixing aerobic/anaerobic sludges and sewage treatment sludge/drinking water treatment sludge improved their energetic potential compared to the pure samples. Thus, blending is a promising alternative to manage water and sewage by-products in a circular economy perspective. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anaerobic digestion is a technology known for its potential in terms of methane production. During the digestion process, multiple metabolites of high value are synthesized. However, recent works have demonstrated the high robustness and resilience of the involved microbiomes; these attributes make it difficult to manipulate them in such a way that a specific metabolite is predominantly produced. Therefore, an exact understanding of the manipulability of anaerobic microbiomes may open up a treasure box for bio-based industries. In the present work, the effect of nalidixic acid, γ-aminobutyric acid (GABA), and sodium phosphate on the microbiome of digested sewage sludge from a water treatment plant fed with glucose was investigated. Despite of the induced process perturbations, high stability was observed at the phylum level. However, strong variations were observed at the genus level, especially for the genera Trichococcus, Candidatus Caldatribacterium , and Phascolarctobacterium. Ecological interactions were analyzed based on the Lotka–Volterra model for Trichococcus , Rikenellaceae DMER64 , Sedimentibacter , Candidatus Cloacimonas , Smithella, Cloacimonadaceae W5 and Longilinea. These genera dynamically shifted among positive, negative or no correlation, depending on the applied stressor, which indicates a surprisingly dynamic behavior. Globally, the presented work suggests a massive resilience and stability of the methanogenic communities coupled with a surprising flexibility of the particular microbial key players involved in the process. [ABSTRACT FROM AUTHOR]

The character of water production in Yuanba gas field became increasingly obvious, and deep analysis of the sludge source with study on the countermeasures of sludge reduction would become of great importance in high efficiency developing the gas field. Taking the sulphur-bearing waste water and residual liquid after pigging in Yuanba gas field as study objects, this paper optimized drug selection, reaction time, reaction conditions and reagent proportioning, meanwhile, for the goal of sludge reduction, the sludge pressure filtration equipment and rational allocation of sludge ratio was also optimized, considering the low desulfurization rate and high yield mud during the wastewater treatment. Experimental results show the mud in Yuanba gas field comes from the sulphur-bearing waste water after treatment and the residual liquid after pigging, The rate of water content of the sludge from the sulphurbearing waste water could reduce to less than 30% by preliminary desulfured with vaporizing extract process deeply desulfurization with ZnCL and filter pressing by filter frame sequently. The residual liquid after pigging can be emulsified in alkaline environment with compound demulsifier named EEA, which can be mixed with common mud producing from the sulphur bearing waste water in a ratio below l : 2, In this way, the rate of water content of the oily sludge could be remained at 30% -33% after filter pressing by filter frame. The study in this paper can provide experimental demonstration and on site guidance for sewage treatment and sludge reduction re search in Y uanba gas field [ABSTRACT FROM AUTHOR]

• WTS waste used as raw material to the production of new SCM. • WTS waste processed by flash calcination and electrical muffle furnace. • Different temperature and residence time investigated. • Characterization performed to verify the potential pozzolanic activity. • Calcined WTS shows great potential to the production of a new SCM. This paper investigates the potential of using calcined water treatment sludge to the development of supplementary cementitious material. Sludge samples have been collected in the drying beds of a water treatment plant located in Southern Brazil and calcined in the laboratory. Chemical and mineralogical characterization has been performed through energy dispersive X-ray spectrometry, thermogravimetric analysis, and X-ray diffraction with crystalline phases quantified by Rietveld refinement. Morphological analysis has been supported by scanning electron microscope images. Physical characterization has been carried out through specific surface area, particle size distribution, and pozzolanic activity performance with Portland cement. Results have shown that the water treatment sludge is a non-hazardous and non-inert waste without environmental restrictions for use in construction. Considering technical, environmental and economic aspects related to energy consumption, sludge samples calcined at 600 °C for 1 h present the most promising results regarding the production of supplementary cementitious material equivalent to a normal pozzolan, while highly active pozzolan requires 750 °C for 1 h. Calcined water treatment sludge showed great technical and environmental potential to be used as an alternative source of supplementary cementitious material in the near future. [ABSTRACT FROM AUTHOR]

• Material and C/N flows of sludge are statistically studied with 139 relevant datasets. • Different technologies convert 0˜75% of total solid into dissolved organic carbons. • Potential carbon consumption by the yielded soluble TN and TP must be considered. • Thermal and mechanical pretreatments statistically dissolved the most nitrogen. • Alkali/thermal treatment achieved the highest effective carbon source on average. Sewage sludge can serve as a carbon source for denitrification after pretreatment and hydrolysis. However, existing technologies have various technical routes and performances for carbon recovery and nitrogen release. To evaluate the abilities of different technologies to recover carbon sources, material and elemental flow analyses were performed by parameterising and balancing the sludge compositions and conversion coefficients based on 139 datasets. Technological routes with alkali/thermal and alkali/H 2 O 2 /microwave treatments statistically achieved the highest yields of volatile soluble solids, and those with thermal and mechanical treatments dissolved the most nitrogen during pretreatment. The technological route with alkali/thermal treatment achieved the highest effective carbon source of 191 g/kg of initial total solid on average when the potential carbon consumption by the yielded soluble total nitrogen and phosphorus was subtracted. This study provides important statistical evidence for the development and comparison of alternative technologies for recovering carbon sources from sludge for denitrification. [Display omitted] [ABSTRACT FROM AUTHOR]

The main source of usable water supply in Poland is surface water. The most frequently used methods of surface water treatment are coagulation and filtration processes. During these processes post-coagulation sludge is generated, which is the main waste produced in water treatment plants. This sludge is characterized by an amorphous structure with a strongly developed specific surface, similar to sewage sludge. Dried and crushed post-coagulation sludge was used in the studies as an adsorbent of two acid dyes: Acid Red 18 (AR 18) and Acid Green 16 (AG 16). The most favourable pH of process and contact time as well as sorption isotherm were established. For both dyes the most favourable pH value was equal 2. The tests showed that in the case of AR 18 (180 min) a longer contact time was necessary to reach the equilibrium than for AG 16 (120 min). Moreover, based on the different isotherm two-parameter models, the sorption capacity, type of sorption and energy of sorption were calculated based on linear and non-linear regression. The tests showed that in the case of dye AG 16 monolayer sorption occurred - the analysis showed better fitting the results to Langmuir model. Moreover, for both dyes, physical adsorption took place - it was indicated by the values of parameter 1/n (computed from the Freundlich model). [ABSTRACT FROM AUTHOR]

The study was designed to demonstrate the effect of water treatment residual naoparticles amendments for 0.3% biosolids treated calcareous and sandy soils on Cu, Pb, and Ni fractions change and release during 60 days incubation period; included five wetting drying cycles regime. The redistribution of studied metals fractions for control soil (0%WTR) depended on soil and metal type. There was a pronounced decrease in metal-residual fraction at the end of the incubation period (60 days); while other fractions were occupied with these residual fraction- released metals. Application of nWTR to both soils substantially reduced the non-residual fractions (NORS) of Cu and Ni and simultaneously increased residual (RS) both metals fractions. Furthermore, both Pboxides and RS fractions were increased as a result of nWTR addition. The metals forms transformation for nWTR amended soils as the incubation time prolonged from 30 to 60 days was studied. The Cu-forms transformation remained relatively unaltered with slightly increase of RS Cu versus decrease of exchangeable and carbonate Cu. With respect to Pb and Ni, residual fraction was increased significantly and this increase was arisen from either the decrease of all fractions of Ni- NORS or Pb-organic fraction. The amount of desorbed Cu, Pb, and Ni from both soils using DTPA extraction was significantly decreased after application of nWTR within the five wetting drying cycles. All the kinetic data were well expressed using both intraparticle diffusion and Elovich models due to the high coefficient of determination (R2) and low standard error (SE) values. The final results indicate the ability of nWTR to reduce heavy metals mobility in biosolid treated calcareous and sandy soils. [ABSTRACT FROM AUTHOR]

This study analyses the partition of 131I in organic, inorganic and residual fractions from secondary and digested sludge. Due to the microbiological process in the aeration tank, it was found that the secondary sludge sample had the highest 131I content associated with the organic fraction. In the digested sludge, the organic fraction was smaller due to the anaerobic digestion of part of the organic matter. In this case, 131I was also distributed into the inorganic and residual fractions. Based on this second result, the potential volatilization of 131I in the anaerobic digester has been assessed. The results showed that this radionuclide was not present in air samples, and therefore the potential exposure through inhalation would be negligible for WWTP workers. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Environmental Protection is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presently, the highest level of waste generation is characterized by ferrous metallurgy enterprises, the large-tonnage wastes of which are slags of various industries. Taking into account the negative impact of slags on the environment, the limited opportunities for expanding dump volumes, as well as the depletion of sources of raw mineral raw materials, the aim of research was to develop an alternative method for the utilization of steel-smelting slags of the mining and metallurgical complex. Tthe steel smelting slag of the Novolipetsk metallurgical plant and the sewage sludge of the city water treatment station in Lipetsk were selected as the materials for the study. In the laboratory, the chemical composition of the waste was determined by means of a complex of modern analytical methods, including atomic emission spectrometry with inductively coupled plasma, X-ray fluorescence spectrometry, and atomic absorption spectrometry with electrothermal atomization. The results of the analysis enabled to assess the possibility of sharing waste as a soil additive to improve the quality of the soil. Then, under laboratory conditions, the grass mixture was grown on model soil samples with a soil additive consisting of the investigated waste with a different mass ratio. On the basis of the obtained data on seed germination, the growth of the aerial part of the biomass, the height of the leaves, and also the content of the accumulated metals in the plants, a formulation of an organomineral additive was proposed for poor soils of disturbed lands. [ABSTRACT FROM AUTHOR]

A simulation model for water treatment plant sludge management was proposed, based on the system dynamics approach. This model can be extended to the sludge management of a sanitation system (WTP + WWTP). The model is useful for the selection of the best destination for the sludge generated in treatment plants based on the various changes that a decision can have throughout the operation of the sanitation system. The applicability of the proposed model was tested in a case study of WTPs 3 and 4 and the Anhumas Wastewater Treatment Plant located in Campinas, the main city of the Piracicaba, Capivari and Jundiaí river basin, an important area of water resource management in Brazil. The developed model can be used by treatment plants to: select the best final destination option according to treatment technologies; select the best location for final disposal, considering transport, disposal and storage costs; verify the influence on treatment costs to adapt to a pre-defined final destination for joint management; or compare beneficial disposal costs with landfill disposal costs. The model was developed to allow for gradual increase in acceptance of the residue over time. By establishing this variable, slightly lower final costs were observed in the scenario of sending the sludge with aluminum coagulant to ceramic industries, compared to sending it to landfill, in the case study used for model development. Despite the interesting results, these values should be considered only indicative. Therefore, it can be stated that the major challenge to using the SD model is the accurate and appropriate data collection for correct simulation, as well as its historical series, for accurate evaluation of the viability of the model. The proposed simulation methods showed greater sensitivity to treatment costs, highlighting the importance of beneficial use of the proposed sludge to the technologies employed for water and sludge treatment. [Display omitted] • The model was tested in a large WTP in Brazil which meets 75% of the water demand of a population of over 1.2 million people. • The model can be extended to a sanitation system (WTP + WWTP). • Sludge destination option for the red ceramics industry using PAC coagulation was the most economical for the case study. [ABSTRACT FROM AUTHOR]

Kitchen wastewater can be transformed into a valuable resource through anaerobic fermentation. However, the efficiency of this process is hindered by various factors including salt inhibition and nutrient imbalance. In this study, we examined the effects of co-fermentation with sludge and membrane filtration on the anaerobic fermentation of kitchen wastewater. Our findings indicate that co-fermentation with sludge resulted in a 4-fold increase in fermentation rate and a 2-fold increase in short-chain fatty acids (SCFAs) production. This suggests that the addition of sludge helped to alleviate salt and acid inhibition through ammonia buffering and elemental balancing. The membrane filtration retained 60% of soluble carbohydrates and 15% of proteins in the reactor for further fermentation and recovered nearly 100% of NH 4 + and SCFAs in the filtrate, which helped to alleviate acid and ammonia inhibition. The combined fermentation system significantly increased the richness and diversity of microorganisms, particularly caproiciproducens and Clostridium_sensu_stricto_12. The membrane flux remained stable and at a relatively high level, indicating that the combined process may be economically feasible. However, scaling up the co-anaerobic fermentation of kitchen wastewater and sludge in a membrane reactor is necessary for further economic evaluation in the future. [Display omitted] • Systematic study on co-fermentation of sludge and kitchen waste for SCFAs harvest. • Co-fermentation with sludge mitigates salt inhibition and acid inhibition. • Membrane retention rates of carbohydrates and proteins were 60% and 15%. • No retention of NH 4 + and SCFAs by membrane alleviate dual inhibitions. • Richness and diversity of microorganisms was increased by co-fermentation. [ABSTRACT FROM AUTHOR]