The circular economy concept in the municipal wastewater and sewage sludge management – site-specific cases from Poland

Abstract

Introduction of the circular economy package as a result of the necessity to protect natural resources has also forced a new approach for effective wastewater and biowaste treatment and management. Wastewater treatment plants (WWTPs) have become crucial elements of regional bioeconomy - mainly through energy (waste to energy) and matter (nutrients-energy-water) recovery as an element of sustainable development of a smart city. In Poland in 2019 operated 3278 municipal wastewater treatment plants. To achieve specific effluent goals for BOD, nitrogen and phosphorus, different adaptations and modifications have been made. Modernization of technological lines of wastewater treatment has led to a significant improvement in the quality of treated sewage, at the largest WWTPs in Warsaw, Cracow or Gdansk. Eleven WWTPs produce approx. 34% of the total volume of approx. 337 GWh of electricity from biogas in Poland. The potential of producing electricity from biogas in WWTPs in Poland can be estimated at approx. 700–850 GWh per year. According to the data of the Statistics Poland in 2019 in Poland approx. 25% of sewage sludge was used directly in agriculture and for land reclamation. Simultaneously more than 100 WWTPs produce compost at high quality. However only few produce organic/organic-mineral fertilizers, mainly with addition of calcium.

Research on the toxic effects of polyacrylamide and cadmium on plants during soil utilization of municipal sludge

“…Rich in nutrients and organic matter, sludge serves as an excellent source of plant nutrients. It offers significant benefits, such as improving soil structure and enhancing its water‐holding capacity, making it an outstanding natural fertilizer (Kacprzak, 2023; Tabra et al, 2020). Most metals in sludge are stable, but heavy metals are biotoxic to plants (Wei et al, 2020).…”