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- ItemSeparation of Cellulose fromWastewater and Valorisation via Pyrolysis: A Case Study in the Czech Republic(MDPI, 2024-04-05) Djordjevićová, Denisa; Miino, Marco Carnevale; Raček, Jakub; Chorazy, Tomáš; Hlavínek, Petr; Vranayová, ZuzanaCurrently, the recovery of resources from urban wastewater (WW) represents a priority. On this topic, the potential recovery of cellulose for its subsequent reuse in different sectors is gaining interest. In this work, a large-size conventional wastewater treatment plant (WWTP) was selected as a case study. A preliminary mechanical treatment was used, with the aim of separating, quantifying, and characterizing cellulose in WW. The results suggest that the per-capita production of dry primary cellulosic sludge (D-PCS) is equal to 1.46 ± 0.13 kgD-PCS PE1 y1, with an average calorific value of 21.04 MJ kg1DM. Cellulosic fibres have an average length of >100 µm and a thickness of 2–5 µm. The D-PCS was subsequently treated via medium-temperature pyrolysis; a total of 29.5% of the initial D-PCS was converted into pyrolyzed primary cellulosic sludge (P-PCS) and only 26% into pyrolytic gas. More than 44.5% of the dried cellulose can be converted into pyrolytic oil. Moreover, three different scenarios of recovery have been considered, and the impact of cellulose separation in terms of COD fluxes entering the WWTP and potential energy recovery has been studied. The results suggested that, in this case study, the potential separation of the primary cellulosic sludge from the influent water flux would have no significant impact on COD load entering the biological treatments and biogas production in the anaerobic digestion of the secondary sludge.
- ItemComparison of Trenchless and Excavation Technologies in the Restoration of a Sewage Network and Their Carbon Footprints(MDPI, 2024-01-15) Chorazy, Tomáš; Hlavínek, Petr; Raček, Jakub; Pietrucha-Urbanik, Katarzyna; Tchórzewska-Cieślak, Barbara; Keprdová, Šárka; Dufek, ZdeněkThe restoration of aging sewer networks is a fundamental remediation approach with the aim of renewing or improving existing systems. Remediation methods include repair, renovation, and replacement (renewal). The restoration of a sewer network itself can be performed using either excavation or trenchless technologies. While these technologies offer various advantages, they also present disadvantages. The choice of a restoration technology depends on numerous parameters, including economic factors and local conditions (such as the construction of the existing sewage network, available working space, traffic load, and environmental safety restrictions). In addition to the parameters influencing the choice of restoration technology, recent considerations have been given to constraints related to greenhouse gas emissions and the corresponding carbon footprint. Carbon footprint serves as an indicator of the restoration activity’s dependence on fossil fuels, both during implementation and operation. In the 21st century, concerns regarding carbon footprints have rapidly escalated. The reduction in carbon footprints is a crucial objective from both an economic and an ecological point of view. This article specifically addresses the prospects of monitoring the carbon footprint concerning the partial restoration of a sewer network within the historical core of the city of Brno, located in the Czech Republic.
- ItemEcotoxicity of Wastewater in the Czech Republic(MDPI, 2023-12-08) Bogáňová, Ida Antonie; Hluštík, PetrThe presented article deals with monitoring the ecotoxicity/toxicity of wastewater flowing into selected wastewater treatment plants in the Czech Republic. The sewage treatment plant was in a state of disrepair and was unable to treat the incoming sewage. In this critical period, the parameters – BOD5, CHSKCr, NL, N-NH4, N-inorg, N-total, P-total, RAS and pH were monitored at the inflow to the WWTP. BOD5, CHSKCr, NL, N-NH4, N-NO3, N-NO2, N-inorg, N-total, P-total and RAS were also monitored at the effluent from the wastewater treatment plant. Ecotoxicity (fish, barnacles, algae) and toxicity (Vibrio fischeri) were monitored at the inflow and outflow. The article considers the effects of wastewater ecotoxicity on individual wastewater treatment processes.
- ItemThe use of biochar made from biomass and biosolids as a substrate for green infrastructure: A review(Elsevier, 2023-02-01) Novotný, Michal; Marković, Mihajlo; Raček, Jakub; Šipka, Milan; Chorazy, Tomáš; Tošić, Ivana; Hlavínek, PetrThis paper reviews and summarizes various feedstocks for biochar production, pyrolysis technology and conditions, and physicochemical properties of selected types of biochar. Since biochar has a positive influence on plant growth, fertilizer efficiency, and rainwater capture, showing its use as a stable organic component of the substrate is the main objective of this research paper. Conclusion of the review considers the usage of biochar as a substrate for green infrastructure in pursuance of its characteristics, limiting pollutants concentration, potential benefits and risks for the environment, water sources and occurring climate change. The review is based on the analysis of selected papers on existing research and case studies related to the use of biochar and the evaluation of the impact of biochar on the characteristics of growing medium.
- ItemPreliminary assessment of the technical condition of water supply infrastructures(Elsevier, 2016-06-01) Tuhovčák, Ladislav; Kučera, Tomáš; Sucháček, TomášTo ensure sustainability and reliability of water supply infrastructure, we must apply a basic pre-condition, which is, its continual renewal. For renewal planning, there are many methods, techniques and software tools for decision support, but most of them, in many cases, focus only on water mains. Water supply systems, however, consist of different parts and structures than just water pipes. It is therefore not appropriate to invest in the renewal planning only in relation to one part of the water supply infrastructure. The knowledge of the current technical condition of the water supply infrastructure is crucial to maintain its planned performance and optimise its maintenance and renewal. Effective detailed evaluation of the technical condition requires deployment of specialists, reliable database, considerable amount of time and instrumentation and software. Therefore, it is preferable to perform the first rapid and efficient preliminary identification of problematic areas and elements of water supply systems. This paper presents the methodology and the Technical Energy Audit (TEA Water), the effective preliminary assessment of the technical state of water supply systems (WSS). The paper presents the structure of the proposed technical indicators, the method of their determination and evaluation, including the presentation of case studies of implementing the methodology and software tool in the Czech Republic.