Rapid population growth and urbanization have resulted in a multi-fold increase in water consumption over the last few decades, resulting in the generation of large amounts of sewage and sewage sludge that impose severe environmental burdens if not handled properly. Sludge management itself accounts for up to 50% of the total operating costs of wastewater treatment plants (WWTPs). Conventional sludge management practices such as incineration, landfilling, and ocean disposal have been deemed difficult in light of today’s stringent environmental legislation and compliance standards. As a result, progress has been made toward developing more sustainable approaches for sludge management. This study reviews recent advancements in sewage sludge management techniques that not only ensure the safe disposal of sewage sludge but also focus on utilizing the potential of sewage sludge as feedstock for energy and resource recovery. Energy could be recovered by subjecting the pre-treated sludge to controlled anaerobic digestion (AD) to produce biogas or by utilizing the lipid content of the sewage sludge through esterification or direct sludge pyrolysis to produce biodiesel/bio-oil. Heavy metals such as Ag, Au, Cu, Fe, Ga, Cr, and others, as well as nutrients such as N, P, K, Mg, S, and others, could also be recovered. If energy and resource recovery from sewage sludge is practiced on a global scale, it could significantly contribute to global greenhouse gas (GHG) emission reduction. This review discusses the commercially developed and still-under-research technologies for energy and other resource recovery of sewage sludge. Additionally, techniques, along with their limitations and potential measures to improve their yields, are also discussed.

Sludge management is an integral process of an effluent treatment plant (ETP). This study aimed at using the electro-Fenton (EF) process for pretreatment of a cattle-based slaughterhouse ETP sludge to enhance biogas production from anaerobic digestion. EF-oxidation experiments were conducted in 0.5 L beakers with mild-steel electrodes, to study the effect of factors, viz., H₂O₂ concentration, current density and reaction time on soluble chemical oxygen demand (sCOD) concentration, soluble extracellular polymeric substances (sEPS) concentration and volatile suspended solids (VSS) removal efficiency. This was followed by the quantification of biogas production from the raw and pretreated sludge in anaerobic digestion (AD). Experimental conditions for the EF process were optimized using response surface methodology (RSM). At optimized experimental conditions, EF pretreatment resulted in an increase in sCOD and sEPS concentrations, from 0.91 g/L to 6.1 g/L and 0.18 g/L to 1.4 g/L, respectively. VSS removal efficiency was 68.1%. Batch anaerobic digestion studies demonstrated an enhancement in the specific biogas yield, from 110 NmL/g-VS to 460 NmL/g-VS.

The present study evaluated the performance of a 330 L on-site pilot-scale aerobic granular sludge sequencing batch reactor (AGS-SBR) in removing COD, total nitrogen (TN), and phosphorus (P... The graphical abstract titled “Aerobic Granular Sludge – Sequencing Batch Reactor” summarizes the treatment of high-strength slaughterhouse wastewater using an aerobic granular sludge SBR system. T... Practical ApplicationsSlaughterhouse wastewater is complex and produced in large volumes, containing high levels of organics and nutrients that are difficult to treat using conventional methods. In...

Phosphorus, an essential nutrient and a finite resource, poses significant environmental challenges when discharged into water bodies from industrial wastewater, contributing to eutrophication and ecosystem degradation. Concurrently, its recovery offers a sustainable pathway to address resource scarcity. This review critically evaluates recent progress in phosphorus removal and recovery technologies, emphasizing five widely recognized approaches: (i) biological processes, such as aerobic granular sludge and enhanced biological phosphorus removal (EBPR); (ii) chemical precipitation using agents like lime and metal salts; (iii) struvite crystallization; (iv) electrocoagulation (EC) and (v) Bioelectrochemical Systems (BES) for phosphorus recovery. The assessment focuses on these methods’ efficiency, feasibility, and sustainability, highlighting their strengths and limitations. These strategies can foster environmentally sustainable wastewater treatment, mitigate eutrophication risks, and reduce dependence on finite phosphate resources.