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The effective management of waste-activated sludge (WAS) presents a significant challenge for wastewater treatment plants (WWTPs), primarily due to the sludge's high content of organic matter, pathogens, and hazardous substances such as heavy metals. As urban populations and industrial activities expand, the increasing volume of WAS has intensified the need for sustainable treatment solutions. Conventional approaches, such as landfilling and anaerobic digestion, are frequently ineffective and resource-intensive, particularly when dealing with the protective extracellular polymeric substances (EPS) that render WAS resistant to biodegradation. Thermal pretreatment methods have gained attention due to their ability to enhance the biodegradability of sludge, improve dewaterability, and facilitate resource recovery. These processes function by breaking down complex organic structures within the sludge, thereby increasing its accessibility for subsequent treatments such as anaerobic digestion. The integration of thermal treatment with chemical methods can further optimize the management process, resulting in higher biogas yields, reduced pathogen content, and lower environmental risks. While thermal disintegration is energy-intensive, advancements in energy recovery and process optimization have made it a more viable and environmentally friendly option. This approach offers a pathway to more sustainable and efficient sludge management practices, which align with the goals of reducing waste and complying with stricter environmental regulations. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is an effective technology for the sustainable management of organic agricultural waste, producing both biogas and nutrient-rich digestate. This study aims to review and evaluate different methods for obtaining valuable products from digestate, with a focus on innovative and sustainable approaches. The main objectives are to identify effective technologies for the recovery of nutrients and organic matter, assess their environmental and economic impact and outline the challenges and prospects in this area. The review covers established techniques (with a technology readiness level (TRL) of six to nine, indicating their maturity from pilot to full scale) such as struvite precipitation and ammonia stripping, which are very effective in recovering nitrogen and phosphorus from digestate and converting it into valuable biofertilizers. Struvite, for example, offers an option for slow-release fertilizers that reduces dependence on synthetic fertilizers. A comparative analysis shows that ammonia stripping can efficiently capture nitrogen and produce fertilizer without harming the environment. New methods, such as microalgae cultivation, use digestate as a nutrient source for the production of biofuels and bioplastics, contributing to renewable energy and sustainable material production. The study also examines composting and vermicomposting, where digestate is converted into nutrient-rich soil conditioners that significantly improve soil health and fertility. The production of biochar through pyrolysis is highlighted for its benefits in improving soil properties and sequestering carbon, providing a dual benefit for waste management and climate change mitigation. Membrane technologies, including ultrafiltration (UF) and reverse osmosis (RO), are being investigated for their effectiveness in nutrient recovery, despite challenges such as membrane fouling and high operating costs. The study highlights the potential of these valorization processes to improve the sustainability and economic viability of AD systems and to align with circular economy principles. The results suggest that the continuous optimization of these technologies and the integration of recycling processes are crucial to overcome existing challenges and realize their full potential. [ABSTRACT FROM AUTHOR]

Effective management of recyclable plastic waste is critical for environmental sustainability and economic viability. Blockchain technology has transformative potential in addressing the challenges of plastic waste management. Currently, the inefficiency of plastic recycling systems results in low recycling rates and significant environmental impacts due to poor sorting, contamination, and limited technology application. However, innovations such as chemical recycling, solvent-based techniques, and biotechnology offer promising advances in the management of plastic waste. Blockchain technology provides a transparent, decentralized ledger that enhances traceability and incentives through smart contracts, decentralized applications (DApps), and digital watermarks. These blockchain solutions can improve waste tracking, automate payments, and reward participants who recycle responsibly. Although significant investment in technology and education is required, integrating blockchain with the Internet of Things (IoT) and artificial intelligence (AI)-driven analytics could revolutionize plastic waste management by creating transparent, efficient, and collaborative recycling ecosystems. Blockchain technology has immense potential to redefine the management of plastic waste and promote a sustainable, circular economy. [ABSTRACT FROM AUTHOR]

Celem pracy było wykorzystanie modelu ADM1xp do symulacji procesu kofermentacji kiszonki kukurydzy i obornika bydlęcego. Przydatność modelu oceniano wykorzystując dane z eksperymentu w skali laboratoryjnej. Badania prowadzono przy obciążeniu komory ładunkiem organicznym OLR = 2,1 gVS dm-3·d-1 oraz hydraulicznym czasie zatrzymania wsadu w fermentorze, HRT = 45d. Z powodu dużej liczby parametrów w modelu ADM1xp, zastosowano procedurę, która umożliwia zmniejszenie liczby weryfi kowanych parametrów podczas kalibracji. Najlepsze dopasowanie danych eksperymentalnych do modelowych uzyskano po weryfikacji 9 spośród 105 stechiometrycznych i kinetycznych parametrów. Wartości współczynnika dopasowania (Jc) zmieniały się w zakresie od 0,003 (kwas walerianowy) do 211 (produkcja biogazu).

The aim of this study was to investigate the influence of residual glycerine (5 and 10% w/w) from the biodiesel industry, used as a co-substrate, on biogas production from maize silage. The experiments were conducted in a laboratory-scale, single-stage anaerobic digester at 39ºC and hydraulic retention time (HRT) of 60 d. Addition of 5% residual glycerine caused organic load rate (OLR) to increase to 1.82 compared with 1.31 g organic dry matter (ODM) L-1d-1 for maize silage alone. The specific biogas production rate and biogas yield were 1.34 L L-1d-1 and 0.71 L g ODM-1 respectively, i.e. 86% and 30% higher than for maize alone. Increasing the residual glycerine content to 10% increased OLR (2.01 g ODM L-1d-1), but clearly decreased the specific biogas production rate and biogas yield to 0.50 L L-1d-1 and 0.13 L g ODM-1 respectively. This suggested that 10% glycerine content inhibited methanogenic bacteria and organics conversion into biogas. As a result, there was accumulation of propionic and valeric acids throughout the experiment.