Papers

61,005 results
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Article Tier 2

Wastewater and sludge valorisation: a novel approach for treatment and resource recovery to achieve circular economy concept

This review highlights novel approaches for wastewater and sludge valorisation within a circular economy framework, focusing on recovering value-added products including biopolymers, nutrients, and energy to achieve sustainable development goals and combat water scarcity.

2023 Frontiers in Chemical Engineering 48 citations
Article Tier 2

The presence of microplastics in waste sludges

This Croatian review examines the presence of microplastics in sewage sludge from wastewater treatment plants and their pathways into terrestrial and aquatic environments. The authors discuss alternative sustainable sludge management approaches aligned with circular economy principles.

2023 Repository of Faculty of Chemical Engineering and Technology University of Zagreb
Article Tier 2

Co-Management of Sewage Sludge and Other Organic Wastes: A Scandinavian Case Study

This review analyzes sewage sludge management in Scandinavian countries with a focus on resource recovery through co-digestion with other organic municipal wastes. Researchers found that anaerobic digestion is the dominant treatment approach and that co-management strategies can improve energy yields and nutrient recovery in a circular economy framework.

2021 Energies 29 citations
Article Tier 2

Wastewater Valorization: Practice around the World at Pilot- and Full-Scale

This review summarizes pilot- and full-scale wastewater valorization practices globally, focusing on how water resource recovery facilities recover nutrients, energy, and bio-based materials from sewage and sludge to contribute to a circular economy. The authors identify effective technological strategies that are being implemented or scaled up worldwide.

2021 International Journal of Environmental Research and Public Health 33 citations
Article Tier 2

A systematic overview of current advancements for chemical, material, and energy production using sewage sludge for industrial ecology and sustainability transition

This review examines current advances in recovering chemicals, materials, and energy from sewage sludge, identifying opportunities to convert this waste stream into valuable products while addressing microplastic and contaminant concerns that complicate sludge reuse.

2024 Environmental Sustainability 9 citations
Article Tier 2

Circular Economy in Wastewater Treatment Plant—Water, Energy and Raw Materials Recovery

This review proposes a conceptual framework for future wastewater treatment plants operating as resource recovery facilities within a circular economy, focusing on technologies for recovering water, energy, and raw materials including nutrients and biopolymers.

2023 Energies 51 citations
Article Tier 2

What sewage sludge is and conflicts in Swedish circular economy policymaking

This study analyzes policy conflicts in Sweden around using sewage sludge as agricultural fertilizer within circular economy frameworks, finding that competing framings of sludge as either a valuable nutrient resource or a toxic pollutant (due to microplastics and PFAS) create regulatory deadlock.

2022 Environmental Sociology 26 citations
Article Tier 2

Biorefinery of Sewage Sludge: Overview of Possible Value-Added Products and Applicable Process Technologies

This review examined biorefinery approaches for sewage sludge, evaluating value-added products and applicable process technologies as sustainable alternatives to traditional disposal methods like landfill and incineration.

2023 Water 44 citations
Article Tier 2

Microplastics in Wastewater Sludges : Extraction, Occurrence and Implications for the Circular Economy

This thesis examines microplastic extraction methods, occurrence levels, and circular economy implications for wastewater treatment sludges, including both municipal sewage sludge and industrial sludges from pulp and paper processing.

2025 Trepo - Institutional Repository of Tampere University
Article Tier 2

Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling

Researchers found that primary settling in wastewater treatment removes significant microplastics from sewage, but these particles concentrate in sludge that is often recycled onto agricultural land, creating a pathway back into the environment.

2022 Environmental Pollution 99 citations
Article Tier 2

Standardization: A Necessary Support for the Utilization of Sludge/Biosolids in Agriculture

Not relevant to microplastics — this paper discusses standardization of characterization procedures for sewage sludge and biosolids used in agricultural applications, covering quality, safety, and European regulatory frameworks.

2023 Standards 13 citations
Article Tier 2

Biopolymers in Aerobic Granular Sludge—Their Role in Wastewater Treatment and Possibilities of Re-Use in Line with Circular Economy

This review examines the composition and role of extracellular polymeric substances in aerobic granular sludge, finding that the high alginate content of granules not only improves wastewater treatment performance but also presents opportunities for polymer recovery aligned with circular economy principles.

2021 Energies 27 citations
Article Tier 2

A method for the characterisation of microplastics in sludge

Researchers developed a method for detecting and characterizing microplastics in sewage sludge, which concentrates the majority of microplastics removed during wastewater treatment. This method is important because sludge is widely spread on agricultural land, making it a key pathway for microplastics entering soils.

2019 MethodsX 23 citations
Article Tier 2

The fate of microplastic in sludge management systems

This review assessed the fate of microplastics in sewage sludge management systems, finding that standard stabilization processes including anaerobic digestion and composting do not substantially reduce MP concentrations. Land application of MP-rich sludge was identified as a major pathway for plastic particles entering agricultural soils, with the review calling for alternative sludge disposal strategies aligned with circular economy principles.

2022 The Science of The Total Environment 62 citations
Article Tier 2

Combined application of analytical techniques for microplastic determination to achieve comprehensive results for sewage sludge samples

Researchers combined multiple analytical techniques for comprehensive microplastic determination in sewage sludge samples, addressing the challenge that more than 90% of microplastics entering wastewater treatment plants are retained in sludge and require robust multi-method characterization.

2024 Zenodo (CERN European Organization for Nuclear Research)
Article Tier 2

Seasonal Variation, Distribution and Characteristics of Microplastic in Sewage Sludge

Researchers investigated seasonal variation in microplastic concentration, distribution, and characteristics within sewage sludge at wastewater treatment plants, examining how precipitation patterns and sludge treatment processes influence microplastic retention and the pathways by which sludge-borne microplastics enter agricultural soils upon land application.

2022 Zenodo (CERN European Organization for Nuclear Research)
Article Tier 2

Recovery of Cellulose, Extracellular Polymeric Substances and Microplastics from Sewage Sludge: A Review

This review examines the technical feasibility and circular economy potential of recovering cellulose, extracellular polymeric substances, and microplastics from sewage sludge, finding that while biopolymer recovery offers significant value, microplastics remain a persistent polymeric pollutant whose removal and valorization pathways are underexplored compared to nutrient recovery.

2022 Energies 16 citations
Article Tier 2

Parametric study of coagulant recovery from water treatment sludge towards water circular economy

Researchers investigated coagulant recovery from water treatment sludge at two treatment plants using sulfuric acid acidification at variable normalities, characterizing recovered coagulants by SEM and FTIR and testing their turbidity removal performance. The study aimed to establish optimal acidification conditions for a circular economy approach to coagulant reuse in surface water treatment.

2023 Water Science & Technology 5 citations
Article Tier 2

Circular Economy in Wastewater Management—The Potential of Source-Separating Sanitation in Rural and Peri-Urban Areas of Northern Finland and Sweden

Researchers evaluated regional-scale source-separation sanitation scenarios in sparsely populated northern Finland and Sweden, finding that black water separation and urine diversion can substantially improve nutrient recovery compared to conventional wastewater treatment, particularly in rural and peri-urban areas.

2022 Frontiers in Environmental Science 24 citations
Systematic Review Tier 1

Assessing metal contamination and speciation in sewage sludge: implications for soil application and environmental risk

This systematic review estimated that global sewage sludge production could triple to 160 million tons if all wastewater were treated to EU standards, and found that metals in sludge applied to farmland are predominantly in less bioavailable forms. The research is relevant to microplastics because sewage sludge is a major pathway for microplastic contamination of agricultural soils, carrying both metal and plastic pollutants to farmland.

2023 Reviews in Environmental Science and Bio/Technology 110 citations
Article Tier 2

Microplastics in sewage sludge from the wastewater treatment plants in China

Researchers analyzed microplastics in sewage sludge from wastewater treatment plants across China, finding high concentrations of microplastics — predominantly fibers and fragments — raising concerns about their spread when sludge is applied to agricultural land.

2018 Water Research 1001 citations
Article Tier 2

Fate of microplastics in a centralized biogas plant treating mainly sewage sludge

Researchers tracked the fate of microplastics through a centralized biogas plant treating sewage sludge, examining how anaerobic digestion and subsequent dewatering partition microplastics between solid and liquid digestate fractions. The study informs efforts to develop safer digestate-based recycled fertilizers that minimize microplastic introduction to agricultural soils, where 20-55% of microplastics entering wastewater treatment plants are estimated to end up in sludge.

2025 Journal of Environmental Management
Article Tier 2

Sewage Sludge in Agricultural Lands. The Legislative Framework in EU-28

This review examines the legislative framework across EU member states for using sewage sludge as agricultural fertilizer. While sludge provides valuable nutrients and organic matter, researchers found it can also contain contaminants including microplastics, heavy metals, and pathogens. The study highlights the need for updated regulations that account for emerging pollutants like microplastics to better protect soil health and food safety.

2024 Preprints.org 5 citations
Article Tier 2

Land Application of Biosolids in Europe: Possibilities, Con-Straints and Future Perspectives

This review examines how sewage sludge, or biosolids, is used as agricultural fertilizer across European countries and the regulations governing this practice. While biosolids provide valuable nutrients like phosphorus, the study highlights concerns about contaminants including microplastics, pharmaceuticals, and heavy metals that could enter soil and food chains through land application.

2021 Water 119 citations