Gasification of sewage sludge within a circular economy perspective: a Polish case study

Abstract

Sewage sludge (SS) is a by-product of wastewater treatment plant (WWTP) operation. Due to fast rates of urbanization and industrialization, and rapid population growth, the world community faces a serious challenge associated with its disposal. There is an urgent need to explore low cost, energy efficient, and sustainable solutions for the treatment, management, and future utilization of SS. Thermal conversion of SS is considered the most promising alternative for sustainable SS management. Among three main thermochemical processes, it seems that gasification (GAS) of SS has the most advantages. The aim of this paper is a presentation of the gasification process as a sustainable method of SS management that takes into account the idea of a circular economy (CE). Gaseous fuel production, phosphorus recovery potential, and solid adsorbent production during the gasification process are analyzed and discussed. Result of this study shows that the lower heating value (LHV) of the gas from SS GAS process is up to 5 MJ/m3n and it can be effectively utilize in an internal combustion engines. The analysis proved that solid fraction after the SS GAS process can be treated as a valuable phosphorus source and perspective adsorbent materials. The amount of P2O5 in this material was equal to 22.06%. It is similar to natural phosphate rocks (28.05%). The maximum of the adsorption capacity of the phenol was comparable with commercial activated carbon (CAC): 42.22 mg/g for solid fraction after SS GAS and 49.72 mg/g for CAC. Graphical abstract

Scenario Analysis for Selecting Sewage Sludge-to-Energy/Matter Recovery Processes

“…Werle and Sobek defined the StE solutions as a suitable strategy to comply with circular economy goals. Similarly, the gasification was identified as the most proper thermochemical treatment to improve the environmental performance in SS management [16]. Similarly, the Biochar production from SS and microalgae mixtures as well as the consequent energy recoveries due to co-digestion without SS organic wastes are described in [4,17,18].…”

Drivers and Barriers for a Circular Economy (CE) Implementation in Poland—A Case Study of Raw Materials Recovery Sector

“…It is also more and more involved in international collaboration, e.g., by participation in research and development projects (R&D) in the field of new technologies of raw material recovery and waste management (under European Institute of Innovation & Technology; EIT Raw Materials). The raw materials recovery sector has had a significant impact on the innovation (including eco-innovations) [61,62] and competitiveness of the national economy through the development and implementation of innovative technologies for waste management [63][64][65] and recovery of raw materials [66,67]. A growing level of processing of secondary raw materials with the use of more and more innovative processing technologies has been observed [68], which could contribute to the improvement of the level of innovation in the Polish economy [69], although the existing processing capacity of the infrastructure in this scope should be assessed as insufficient.…”

Environmental and exergetic life cycle assessment of incineration- and gasification-based waste to energy systems in China

“…waste was subjected to a "two step" oxidation process. This would enable a better control of homogeneous gas-gas oxidation in the second combustion chamber and allowed the reduction of exhausted flue gas heat loss [37,38], resulting in an increase of the overall efficiency for electricity generation. Therefore, S2 system represented the gasification-based hot syngas direct combustion and steam turbine system (Ga-HSC) as presented in Fig.…”