Anna Jasińska

The increasing focus on sustainability and the circular economy has brought waste-to-energy technologies to the forefront of renewable energy research. However, the environmental impacts and management of contaminants associated with these technologies remain critical issues. This article comprehensively reviews the environmental impacts of converting sewage sludge into energy and fertilizers, focusing on managing potential contaminants and assessing the implications and ecological risks. It also highlights the latest trends in waste-to-energy technologies, waste-to-soil amendment, and their integration into circular economy frameworks. The discussion encompasses challenges and opportunities in optimizing these processes in wastewater treatment plants to minimize pollutants and enhance sustainability. Addressing these challenges is essential for ensuring the long-term viability and acceptance of waste-to-energy solutions, making this topic highly relevant and timely.

The European Union’s energy policy favors increasing the share of renewable energy in total energy production. In this context, the co-digestion of various waste streams seems an interesting option. This study aimed to determine the effect of selected pretreatment methods on the efficiency and kinetics of the co-digestion process of poultry manure with sewage sludge and organic waste. This research was carried out in four stages: (1) the selection of the third component of the co-digestion mixture; (2) the determination of the most favorable inoculum-to-substrate ratio for the co-digestion mixture; (3) the selection of the most favorable pretreatment parameters based on changes in volatile fatty acids, ammonium nitrogen, extracellular polymers substances (EPS) and non-purgeable organic carbon (NPOC); and (4) the evaluation of anaerobic co-digestion based on the result of the BMP tests and kinetic studies. All the pretreatment methods increased the degree of organic matter liquefaction as measured by the NPOC changes. Waste with a high fat content showed the highest methane potential. The addition of grease trap sludge to feedstock increased methane yield from 320 mL/g VS_add to 340 mL/g VS_add. An optimal inoculum-to-substrate ratio was 2. The pretreatment methods, especially the thermochemical one with NaOH, increased the liquefaction of organic matter and the methane yield, which increased from 340 mL/g VS_add to 501 mL/g VS_add (trial with 4.5 g/L NaoH).

Anaerobic digestion is a well-known and long-used biological method for stabilizing organic materials. Among the benefits of this process in waste management are the reduction of greenhouse gases, the production of alternative energy, and the acquisition of valuable digestate that can be used in the form of biogas, thereby closing the cycle of elements in nature. For some materials, such as manure, which is heterogeneous in terms of morphology and chemical composition, digestion of a single substrate may not be very efficient. Therefore, more and more studies on the co-digestion process are appearing in the literature. This solution allows higher biogas production and the possibility of processing several wastes simultaneously. The prospect of the future effective application of anaerobic co-digestion depends on regulations, work regime, and access to raw materials. Therefore, there is a need to systematize the available knowledge and results, as well as to identify the possibilities and limitations of the discussed process, which is undertaken in this paper.

The area of degraded sites in the world is constantly expanding and has been a serious environmental problem for years. Such terrains are not only polluted, but also due to erosion, devoid of plant cover and organic matter. The degradation trends can be reversed by supporting remediation/reclamation processes. One of the possibilities is the introduction of biodegradable waste/biowaste substrates into the soil. The additives can be the waste itself or preformed substrates, such composts, mineral-organic fertilizers or biochar. In EU countries average value of compost used for land restoration and landfill cover was equal 4.9%. The transformation of waste in valuable products require the fulfillment of a number of conditions (waste quality, process conditions, law, local circumstances). Application on degraded land surface bio-based waste substrates has several advantages: increase soil organic matter (SOM) and nutrient content, biodiversity and activity of microbial soil communities and change of several others physical and chemical factors including degradation/immobilization of contaminants. The additives improve the water ratio and availability to plants and restore aboveground ecosystem. Due to organic additives degraded terrains are able to sequestrate carbon and climate mitigate. However, we identified some challenges. The application of waste to soil must comply with the legal requirements and meet the end of use criteria. Moreover, shorter or long-term use of bio-waste based substrate lead to even greater soil chemical or microbial contamination. Among pollutants, “emerging contaminants” appear more frequently, such microplastics, nanoparticles or active compounds of pharmaceuticals. That is why a holistic approach is necessary for use the bio-waste based substrate for rehabilitation of soil degraded ecosystems.

Central obesity is a risk factor for GERD, Barrett's esophagus and esophageal adeno-carcinoma. Recent studies have suggested that adipocytokines are the possible link between adiposity and Barrett's carcinogenesis. To determine the adiponectin, resistin and leptin concentration as well as the central adiposity parameters in BE patients with and without intestinal metaplasia (IM) in comparison to GERD and healthy controls. Total of 77 patients (30 patients with GERD, 26 BE with IM and 21 BE without IM) and 30 healthy controls were investigated for the central obesity parameters. Serum levels of adipocytokines were measured with ELISA. The serum concentration of adiponectin was significantly lower in BE compared to those in GERD and to controls (p<0.001). Levels of leptin was slightly higher in BE than in GERD and controls (NS). Level of resistin was significantly higher in GERD compared to both control and BE patients (p<0.001). Waist circumference, WHR and WTR were significantly higher in BE patients compared to GERD (p<0.001) and to control group (p<0.001). Features of central obesity rather than BMI are associated with BE development. Adipokines may be important at the early step of BE development, before the IM occurrence.