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.

scholarly journals Influence of Hydrothermal Carbonization on Composition, Formation and Elimination of Biphenyls, Dioxins and Furans in Sewage Sludge

Energies ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 1582 ◽  
Author(s):  
Heiner Brookman ◽  
Fabian Gievers ◽  
Volker Zelinski ◽  
Jan Ohlert ◽  
Achim Loewen
Keyword(s):  
Sewage Sludge ◽  
Organic Pollutants ◽  
Total Concentration ◽  
Hydrothermal Carbonization ◽  
Process Conditions ◽  
Limit Values ◽  
Composition Formation ◽  
Input Material ◽  
Dioxins And Furans ◽  
Toxicity Equivalent

In many areas of application, the influence of hydrothermal carbonization (HTC) on the composition of organic pollutants is still unexplored. In this study, sewage sludge (SS) was carbonized and the input as well as the hydrochar were examined for the organic pollutants: polychlorinated biphenyls (PCB), polychlorinated dibenzo-dioxins (PCDDs), and polychlorinated dibenzo-furans (PCDFs). The process temperatures of carbonization were 200 °C, 220 °C, and 240 °C and the holding time was 5 h for all tests. The total concentration of PCBs was relatively stable for all temperatures, whereas the toxicity equivalent (WHO-TEQ) at 200 °C and 220 °C increases compared to the input material. The strongest impact on toxicity was observed for PCDDs where concentrations were reduced for higher temperatures, whereas the toxicity increases by more than 16 times for temperatures of 240 °C. The concentrations and toxicity of PCDFs were reduced for all carbonization temperatures. In hydrochar from HTC at 240 °C, the limit values for the application of SS in German agriculture have been exceeded. The results indicate that the process conditions for HTC should be controlled also for SS with average contamination if the hydrochar is to be used as material, especially in agriculture.

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.

scholarly journals Sewage Sludge Valorization via Hydrothermal Carbonization: Optimizing Dewaterability and Phosphorus Release

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4417
Author(s):  
Taina Lühmann ◽  
Benjamin Wirth
Keyword(s):  
Sewage Sludge ◽  
Scale Up ◽  
Reaction Times ◽  
Hydrothermal Carbonization ◽  
Phosphorus Release ◽  
Process Conditions ◽  
The European Union ◽  
Relevant Effect ◽  
Input Material ◽  
Initial Ph

As the use of sewage sludge as a fertilizer in agriculture is increasingly restricted in the European Union, other ways to utilize this waste stream need to be developed. Sewage sludge is an ideal input material for the process of hydrothermal carbonization, as it can convert wet biomass into a solid energy carrier with increased mechanical dewaterability. Digested sewage sludge was hydrothermally carbonized at 160–200 °C for 30–60 min with initial pH levels of 1.93–8.08 to determine optimal reaction conditions for enhanced dewaterability and phosphorus release into the liquid phase. Design of experiments was used to develop response surface models, which can be applied to optimize the process conditions. For optimal dewaterability and phosphorus release, low initial pH values (pH 1.93) and mild temperatures around 170 °C are favorable. Because holding time had no statistically relevant effect, a dependency of reaction time was investigated. Though it did not yield substantially different results, it could be included in investigations of short reaction times prospectively. Low reaction temperatures and short holding times are desirable considering economic reasons for scale-up, while the high acid consumption necessary to achieve these results is unfavorable.

scholarly journals Hydrothermal Carbonization of Fruit Wastes: A Promising Technique for Generating Hydrochar

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2022 ◽  
Author(s):  
Bide Zhang ◽  
Mohammad Heidari ◽  
Bharat Regmi ◽  
Shakirudeen Salaudeen ◽  
Precious Arku ◽  
...  
Keyword(s):  
Value Added ◽  
Hydrothermal Carbonization ◽  
Volatile Matter ◽  
Ash Content ◽  
Operating Conditions ◽  
Grape Pomace ◽  
Heating Value ◽  
Wet Biomass ◽  
Fruit Wastes ◽  
Value Added Products

Hydrothermal carbonization (HTC) is a useful method to convert wet biomass to value-added products. Fruit waste generated in juice industries is a huge source of moist feedstock for such conversion to produce hydrochar. This paper deals with four types of fruit wastes as feedstocks for HTC; namely, rotten apple (RA), apple chip pomace (ACP), apple juice pomace (AJP), and grape pomace (GP). The operating conditions for HTC processing were 190 °C, 225 °C, and 260 °C for 15 min. For all samples, higher heating value and fixed carbon increased, while volatile matter and oxygen content decreased after HTC. Except for ACP, the ash content of all samples increased after 225 °C. For RA, AJP, and GP, the possible explanation for increased ash content above 225 °C is that the hydrochar increases in porosity after 230 °C. It was observed that an increase in HTC temperature resulted in an increase in the mass yield for RA and GP, which is in contrast with increasing HTC temperature for lignocellulose biomass. Other characterization tests like thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) also showed that the HTC process can be successfully used to convert fruit wastes into valuable products.

scholarly journals Phosphorus recovery from sewage sludge hydrochar: process optimization by response surface methodology

2020 ◽  
Vol 82 (11) ◽  
pp. 2331-2343
Author(s):  
Andrea Luca Tasca ◽  
Gemma Mannarino ◽  
Riccardo Gori ◽  
Sandra Vitolo ◽  
Monica Puccini
Keyword(s):  
Response Surface Methodology ◽  
Sewage Sludge ◽  
Response Surface ◽  
Hydrothermal Carbonization ◽  
Extraction Yield ◽  
Ash Content ◽  
Phosphorus Recovery ◽  
3 Dimensional ◽  
Solid Liquid ◽  
Influence Of Ph

Abstract Hydrothermal carbonization can play an innovative role in sewage sludge (SS) treatment and valorization, as well as in phosphorus recovery. In this study, leaching tests using nitric acid were performed on hydrochar from SS and the influence of pH (1–3.5), leaching time (30–240 min), and solid/liquid (S/L) ratio (5–20 wt%) was analyzed and optimized according to the Design of Experiments method, under the Response Surface Methodology approach. The highest phosphorus extraction yield (59.57%) was achieved at the lowest pH and the lowest S/L ratio, while an increase in temperature from 20 to 60 °C negatively affected the phosphorus recovery. Quadratic models, with the addition of semi-cubic terms, were found to best represent both phosphorus yield and ash content of the hydrochar after leaching. As observed by 3-dimensional surface responses, phosphorus yield increases as the pH decreases. The pH is the factor that most influences this response, while time has little influence. At pH 1, the yield increases as the S/L ratio decreases, while the S/L ratio only slightly affects the response at pH 3.5. At an S/L ratio of 12.5%, multi-objective optimization indicates that pH 1 and a leaching time of 135 min are the parameters that allow both maximum phosphorus yield and minimum ash content.

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