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The global shift towards sustainable waste management has led to an intensified exploration of co-digestion and co-treatment of sewage and organic waste using anaerobic reactors. This review advocates for an integrated approach where organic waste is treated along with the sewage stream, as a promising solution to collect, treat, and dispose of organic waste, thereby reducing the environmental and economic burden on municipalities. Various efforts, ranging from laboratory to full-scale studies, have been undertaken to assess the feasibility and impacts of co-digestion or co-management of sewage and organic waste, using technologies such as up-flow anaerobic sludge blankets or anaerobic membrane bioreactors. However, there has been no consensus on a standardized definition of co-digestion, nor a comprehensive understanding of its impacts. In this paper, we present a comprehensive review of the state-of-the-art in liquid anaerobic co-digestion systems, which typically operate at 1.1% total solids. The research aims to investigate how the integration of organic waste into mainstream anaerobic-based sewage treatment plants has the potential to enhance the sustainability of both sewage and organic waste management. In addition, utilizing the surplus capacity of existing anaerobic reactors leads to significant increases in methane production ranging from 190 to 388% (v/v). However, it should be noted that certain challenges may arise, such as the necessity for the development of tailored strategies and regulatory frameworks to enhance co-digestion practices and address the inherent challenges., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Controlling CaCO 3 precipitation within anaerobic granular sludge (AnGS) is crucial for the anaerobic treatment of paper recycling wastewater. A viable strategy was proposed to control calcification by adjusting a mild acidic condition in an anaerobic reactor without hindering organic degradation. The results indicated that lowering the bulk pH (6.5 to 6.8) reduced calcium precipitation by 60.1 % in calcium-rich influent (Ca 2+ 1200 mg/L) and eradicated CaCO 3 deposition on AnGS. Extracellular polymeric substances (EPS) have proven to be crucial participants in Ca 2+ migration. The acidic solution weakens the interactions between EPS and Ca 2+ and then diminishes the EPS adsorption capacity and affinity for Ca 2+ . The mild acidic environment goes beyond reducing CaCO 3 formation in wastewater. EPS protonation reduced the probability of Ca 2+ adhering to the AnGS surface, which halted calcium transportation from bulk liquid to granule. This work offers a feasible strategy to prevent AnGS calcification in high-calcium wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Although anaerobic reactors are an excellent alternative in the treatment of domestic effluents, they have the disadvantage of requiring post-treatment. Many technologies have been studied and, recently, rapid filtration systems have been presented as a viable alternative for post-treatment. This work compared post-treatment techniques for anaerobic upflow sludge blanket (UASB) reactors by rapid filtration systems (double filtration (DF); triple filtration with clinoptilolite (TFc); and triple filtration with activated carbon (TFac)) to conventional systems (facultative pond (FP); biological filter (BF); biological filter with recirculation and decantation (BFD)), verifying their potential for improvement of the final effluent quality. The UASB effluent post-treatments by FP, BF, BFD, DF, TFc, and TFac were evaluated. The removal of turbidity in both BFD and FP post-treatments was below 75%. The DF, TFc, and TFac treatments showed over 99% removal of the same parameters. COD removal in the FP, BF, and BFD post-treatments was over 10%, while in the DF, TFc, and TFac treatments, it was over 80%. The greatest total phosphorus removal was observed in TFc and TFac, whose values were over 99%. The best removal of ammoniacal nitrogen, 99% was observed in the TFc treatment. Regarding Al, Cd, Cr, Cu, Mn, Ni, Pb, and Zn removal, all rapid filtration systems showed better performance when compared to conventional systems. The DF, TFc, and TFac systems showed over 90% removal of most metals evaluated, while the FP and BF treatments presented values below 50% for most metals, and in the BFD system, the removal values were below 80% for most metals. The results indicate that rapid filtration systems were better at removing all evaluated parameters when compared to conventional systems., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A commonly indicated drawback of anaerobic wastewater treatment is the low effectiveness of phosphorus removal. One possibility to eliminate this disadvantage is the implementation of active fillings that contain admixtures of metals, minerals, or other elements contributing to wastewater treatment intensification. The aim of the research was to present an active filling produced via microcellular extrusion technology, and to determine its properties and performance in anaerobic wastewater treatment. The influence of copper and iron admixtures on the properties of the obtained porous extrudate in terms of its functional properties was also examined. The Barus effect increased with the highest content of the blowing agent in the material from 110 ± 12 to 134 ± 14. The addition of metal powders caused an increase in the extrudate density. The modification of PVC resulted in the highest porosity, amounting to 47.0% ± 3.2%, and caused the tensile strength to decrease by about 50%. The determined values ranged from 211.8 ± 18.3 MPa to 97.1 ± 10.0 MPa. The use of the filling in anaerobic rectors promoted COD removal, intensified biogas production, and eliminated phosphorus with an efficiency of 64.4% to 90.7%, depending on the type of wastewater and applied technological parameters.

Quality of the granular sludge developed during the start-up of anaerobic up-flow sludge bed reactors is of crucial importance to ensure the process feasibility of treating industrial wastewater such as those containing solvents. In this study, the microbial granule formation from suspended-growth biomass was investigated in two chitosan-assisted reactors. These reactors operated mimicking industrial sites working with night closures treating a mixture of ethanol, ethyl acetate, and 1-ethoxy-2-propanol. Each reactor operated under different hydrodynamic regimes typical from UASB (R1: <0.15 m h -1 ) and EGSB (R2: 3 m h -1 ). High soluble COD removal efficiencies (>90%) accompanied by rapid formation of robust anaerobic granules were achieved at both up-flow velocity levels. After three weeks from the start-up, mean size diameters of 475 µm and 354 µm were achieved for R1 and R2, respectively. The performance of the process was found to be stable for the whole operational period of 106 days treating intermittent OLR up to 13 kg COD m -3 d -1 . A memory dose of chitosan at day 42 was beneficial to guarantee good quality of the granules by offsetting the negative impact of intermittent water supply on the granular size. Methanocorpusculum was identified as the dominant archaea at both up-flow velocities. Acetobacterium , Geobacter and Desulfovibrio bacteria were also abundant, demonstrating its role on the degradation of light-oxygenated solvents.