scholarly journals Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Influence on Phosphorus Recovery, Yield, and Energy Value of Hydrochar

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 618
Author(s):  
Vicky Shettigondahalli Ekanthalu ◽  
Satyanarayana Narra ◽  
Jan Sprafke ◽  
Michael Nelles
Keyword(s):  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Negative Influence ◽  
Proximate Analysis ◽  
Phosphorus Recovery ◽  
Feed Water ◽  
Temperature Dependent ◽  
Heating Value ◽  
Management Processes ◽  
Sewage Sludge Management

The high moisture content present in sewage sludge hinders the use of sewage sludge in incineration or energy application. This limitation of moisture present in sewage sludge can be obviated by using the hydrothermal carbonization (HTC) process. In sewage sludge management, the HTC process requires less energy compared to other conventional thermo–chemical management processes. The HTC process produces energy-rich hydrochar products and simultaneously enables phosphorus recovery. This study investigates the influence of organic acids, inorganic acid, and alkali as additives on phosphorus transformation, yield, proximate analysis and the heating value of subsequently produced hydrochar. The analysis includes various process temperatures (200 °C, 220 °C, and 240 °C) in the presence of deionized water, acids (0.1 M and 0.25 M; H2SO4, HCOOH, CH3COOH), and alkali (0.1 M and 0.25 M; NaOH) solutions as feed water. The results show that phosphorus leaching into the process-water, hydrochar yield, proximate analysis, and the heating value of produced hydrochar is pH- and temperature-dependent, and particularly significant in the presence of H2SO4. In contrast, utilization of H2SO4 and NaOH as an additive has a negative influence on the heating value of produced hydrochar.

scholarly journals Sewage Sludge Treatment by Hydrothermal Carbonization: Feasibility Study for Sustainable Nutrient Recovery and Fuel Production

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2697
Author(s):  
Gabriel Gerner ◽  
Luca Meyer ◽  
Rahel Wanner ◽  
Thomas Keller ◽  
Rolf Krebs
Keyword(s):  
Liquid Phase ◽  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Economic Feasibility ◽  
Phosphorus Recovery ◽  
High Yield ◽  
Nutrient Recovery ◽  
Waste Biomass ◽  
Sludge Treatment ◽  
Sewage Sludge Treatment

Phosphorus recovery from waste biomass is becoming increasingly important, given that phosphorus is an exhaustible non-renewable resource. For the recovery of plant nutrients and production of climate-neutral fuel from wet waste streams, hydrothermal carbonization (HTC) has been suggested as a promising technology. In this study, digested sewage sludge (DSS) was used as waste material for phosphorus and nitrogen recovery. HTC was conducted at 200 °C for 4 h, followed by phosphorus stripping (PS) or leaching (PL) at room temperature. The results showed that for PS and PL around 84% and 71% of phosphorus, as well as 53% and 54% of nitrogen, respectively, could be recovered in the liquid phase (process water and/or extract). Heavy metals were mainly transferred to the hydrochar and only <1 ppm of Cd and 21–43 ppm of Zn were found to be in the liquid phase of the acid treatments. According to the economic feasibility calculation, the HTC-treatment per dry ton DSS with an industrial-scale plant would cost around 608 USD. Between 349–406 kg of sulfuric acid are required per dry ton DSS to achieve a high yield in phosphorus recovery, which causes additional costs of 96–118 USD. Compared to current sewage sludge treatment costs in Switzerland, which range between 669 USD and 1173 USD, HTC can be an economically feasible process for DSS treatment and nutrient recovery.

scholarly journals Hydrothermal Carbonization as a Strategy for Sewage Sludge Management: Influence of Process Withdrawal Point on Hydrochar Properties

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2890 ◽  
Author(s):  
Fabio Merzari ◽  
Jillian Goldfarb ◽  
Gianni Andreottola ◽  
Tanja Mimmo ◽  
Maurizio Volpe ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Oxygen Demand ◽  
Hydrothermal Carbonization ◽  
Volatile Matter ◽  
Ash Content ◽  
Process Conditions ◽  
Conventional Activated Sludge ◽  
Phosphorous Content ◽  
Sewage Sludge Management ◽  
Ph Decrease

Conventional activated sludge systems, still widely used to treat wastewater, produce large amounts of solid waste that is commonly landfilled or incinerated. This study addresses the potential use of Hydrothermal Carbonization (HTC) to valorize sewage sludge residues examining the properties of hydrochars depending on HTC process conditions and sewage sludge withdrawal point. With increasing HTC severity (process residence time and temperature), solid yield, total Chemical Oxygen Demand (COD) and solid pH decrease while ash content increases. Hydrochars produced from primary (thickened) and secondary (digested and dewatered) sludge show peculiar distinct properties. Hydrochars produced from thickened sludge show good fuel properties in terms of Higher Heating Value (HHV) and reduced ash content. However, relatively high volatile matter and O:C and H:C ratios result in thermal reactivity significantly higher than typical coals. Both series of carbonized secondary sludges show neutral pH, low COD, enhanced phosphorous content and low heavy metals concentration: as a whole, they show properties compatible with their use as soil amendments.

Hydrothermal carbonization of sewage sludge: The effect of feed-water pH on fate and risk of heavy metals in hydrochars

2016 ◽  
Vol 218 ◽  
pp. 183-188 ◽  
Author(s):  
Yunbo Zhai ◽  
Xiangmin Liu ◽  
Yun Zhu ◽  
Chuan Peng ◽  
Tengfei Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Feed Water ◽  
Water Ph

scholarly journals Impact of Pretreatment on Hydrothermally Carbonized Spruce

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2984
Author(s):  
Anna Partridge ◽  
Ekaterina Sermyagina ◽  
Esa Vakkilainen
Keyword(s):  
Treated Wood ◽  
Hydrothermal Carbonization ◽  
Proximate Analysis ◽  
Thermochemical Conversion ◽  
Energy Yield ◽  
Strongly Correlated ◽  
Mass Yield ◽  
Biomass Waste ◽  
Heating Value ◽  
Lignin Extraction

Upgrading biomass waste streams can improve economics in wood industries by adding value to the process. This work considers use of a hydrothermal carbonization (HTC) process for the residual feedstock after lignin and hemicelluloses extraction. Batch experiments were performed at 200–240 °C temperatures and three hours residence time with an 8:1 biomass to water ratio for two feedstocks: Raw spruce and spruce after lignin extraction. The proximate analysis and heating value showed similar results for both feedstocks, indicating that the thermochemical conversion is not impacted by the removal of lignin and hemicelluloses; the pretreatment processing slightly increases the heating value of the treated feedstock, but the HTC conversion process produces a consistent upgrading trend for both the treated and untreated feedstocks. The energy yield was 9.7 percentage points higher for the treated wood on average across the range temperatures due to the higher mass yield in the treated experiments. The energy densification ratio and the mass yield were strongly correlated with reaction temperature, while the energy yield was not. Lignocellulosic composition of the solid HTC product is mainly affected by HTC treatment, the effect of lignin extraction is negligible.

scholarly journals Sustainable Sewage Sludge Management: From Current Practices to Emerging Nutrient Recovery Technologies

2019 ◽  
Vol 11 (12) ◽  
pp. 3435 ◽  
Author(s):  
Sina Shaddel ◽  
Hamidreza Bakhtiary-Davijany ◽  
Christian Kabbe ◽  
Farbod Dadgar ◽  
Stein Østerhus
Keyword(s):  
Sewage Sludge ◽  
Local Economy ◽  
Phosphorus Recovery ◽  
Nutrient Cycle ◽  
Nutrient Recovery ◽  
Key Factors ◽  
Demand And Supply ◽  
The World ◽  
Sewage Sludge Management ◽  
Geographical Context

Nutrient recovery from secondary resources, such as wastewater, has received increasing attention in recent years. Nutrient cycle sustainability and recycling approaches are important measures under development and considerations. This paper aims to present an overview of routes and technologies for nutrient recovery from sewage sludge and measures for improving their sustainability. First, current routes for nutrient recovery from sewage sludge are briefly reviewed. Next, an overview of commercial nutrient recovery technologies, projects, and emerging techniques around the world with the key factors for a successful phosphorus recovery technology is presented. Finally, a proposal for improving the sustainability of these practices is presented. It is concluded that the gap between demand and supply can be a major driver for the shift from ‘removal and treat’ to ‘recovery and reuse’. Moreover, there is not, and will never be, a one-size-fits-all solution. Future strategies and roadmaps need to be adapted to the local economy and geographical context more than ever.

scholarly journals Influence of Post- and Pre-Acid Treatment during Hydrothermal Carbonization of Sewage Sludge on P-Transformation and the Characteristics of Hydrochar

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 151
Author(s):  
Vicky Shettigondahalli Ekanthalu ◽  
Satyanarayana Narra ◽  
Tommy Ender ◽  
Edward Antwi ◽  
Michael Nelles
Keyword(s):  
Liquid Phase ◽  
Sewage Sludge ◽  
Agricultural Land ◽  
Great Influence ◽  
Calorific Value ◽  
Hydrothermal Carbonization ◽  
Proximate Analysis ◽  
Process Conditions ◽  
P Recovery ◽  
P Leaching

Phosphorus (P) recovery from alternative P-rich residues is essential to meet the growing demands of food production globally. Despite sewage sludge being a potential source for P, its direct application on agricultural land is controversial because of the obvious concerns related to heavy metals and organic pollutants. Further, most of the available P recovery and sludge management technologies are cost-intensive as they require mandatory dewatering of sewage sludge. In this regard, hydrothermal carbonization (HTC) has gained great attention as a promising process to effectively treat the wet sewage sludge without it having to be dewatered, and it simultaneously enables the recovery of P. This study was conducted to analyse and compare the influence of acid (H2SO4) addition during and after HTC of sewage sludge on P leaching and the characteristics of hydrochar. The obtained results suggested that despite using the same amount of H2SO4, P leaching from solid to liquid phase was significantly higher when acid was used after the HTC of sewage sludge in comparison with acid utilization during the HTC process. After HTC, the reduction in acid-buffering capacity of sewage sludge and increase in solubility of phosphate precipitating metal ions had a greater influence on the mobilization of P from solid to liquid phase. In contrast, utilization of H2SO4 in different process conditions did not have a great influence on proximate analysis results and calorific value of consequently produced hydrochar.

Enhanced adsorption of orthophosphate and copper onto hydrochar derived from sewage sludge by KOH activation

RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 101827-101834 ◽  
Author(s):  
Ana Spataru ◽  
Rohan Jain ◽  
Jae Wook Chung ◽  
Gabriel Gerner ◽  
Rolf Krebs ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Koh Activation ◽  
Sludge Management ◽  
Effluent Quality ◽  
Sewage Sludge Management ◽  
Enhanced Adsorption

Hydrochar, produced by hydrothermal carbonization of sewage sludge, adsorbs orthophosphate to improve effluent quality, recover & reutilize phosphorous and positively impact sewage sludge management.

A Review on Sewage Sludge Valorization via Hydrothermal Carbonization and Applications for Circular Economy

2021 ◽  
Author(s):  
Dilvin Çebi ◽  
Melih Soner Celiktas ◽  
Hasan Sarptaş
Keyword(s):  
Sewage Sludge ◽  
Circular Economy ◽  
Hydrothermal Carbonization ◽  
Gas Production ◽  
Waste To Energy ◽  
Research Findings ◽  
Process Compliance ◽  
Sewage Sludge Management ◽  
Application Fields ◽  
Network Mapping

Abstract In pursuit of establishing a circular economy, waste-to-energy approach is gaining increasing attention. In this manner valorization of sewage sludge constitutes a critical importance due to generation in high quantities, difficulties in disposal and associating environmental impacts. Hydrothermal carbonization (HTC) is a relatively recent, however acclaimed method for sewage sludge management and valorization due to process compliance with sludge characteristics. In this review, research studies are evaluated under the categorization of application fields of sludge derived HTC products such as solid fuel production, gas production, soil remediation, nutrient recovery, water treatment and energy storage. Research findings are compiled and a network mapping is employed for the visualization of the current situation and correlation in respective fields. The potential of HTC for sewage sludge valorization and future projections concerning available techniques are assessed within the context of circular economy.

scholarly journals Two-in-One Fuel Synthetic Bioethanol-Lignin from Lignocellulose with Sewage Sludge and Its Air Pollutants Reduction Effects

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3072 ◽  
Author(s):  
Ju-Hyoung Park ◽  
Min-Ho Jin ◽  
Young-Joo Lee ◽  
Gyu-Seob Song ◽  
Jong Won Choi ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Flue Gas ◽  
Air Pollutants ◽  
Volatile Matter ◽  
Unburned Carbon ◽  
Heating Value ◽  
Average Value ◽  
Global Issue ◽  
Sewage Sludge Management ◽  
Environmentally Sound

Developing effective, economical, and environmentally sound approaches for sewage sludge management remains an important global issue. In this paper, we propose a bioethanol-lignin (nonfood biomass)-based sewage sludge upgrading process for enhancing the heating value and reducing air pollutants of hybrid sewage sludge fuel (HSF) for the effective management of sewage sludge. Sewage sludge paste with the lignin-CaO solution implies drying at 105 °C accompanied by torrefaction at 250 °C. During torrefaction, moisture and partly volatile matter begin to evaporate, and are almost vaporized out to the surface. In this study, the proposed process enhances the net caloric value (NCV) to 37%. The lignin-embedded HSF shows a two-in-one combustion peak regardless of the mixing ratio, resulting in a 70% reduction of unburned carbon (UBC) emissions, which is one of the particular matter (PM) sources of combustion flue gas. Other air pollutants, such as CO, hydrocarbon, NOx, and SOx, were also reduced by the proposed process. In particular, SOx emission remained at ~1 ppm (average value) regardless of the sulfur content of the fuel.

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