Pyrolysis of Municipal Sewage Sludge to Investigate Char and Phosphorous Yield together with Heavy-Metal Removal—Experimental and by Thermodynamic Calculations

Vali, Naeimeh; Åmand, Lars-Erik; Combres, Aurélie; Richards, Tobias; Pettersson, Anita

doi:10.3390/en14051477

Cited by 13 publications

(17 citation statements)

References 36 publications

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“…Based on these results, it appears that there is the potential to use pyrolysis as an effective means of recovering and reusing both the energy and phosphorus present in SS [89]. Vali et al [142] showed that over 90% of the phosphorus contained in SS was retained in the char after pyrolysis at temperatures up to 850 • C, while higher temperature led to the formation of gaseous P compounds. At the same time, the concentration of HMs in the char decreased significantly (except Cu and Zn), as most of them were volatilized in the gas phase or solubilized into the aqueous phase.…”

Section: Pyrolysis and Gasificationmentioning

confidence: 99%

Exploiting the Nutrient Potential of Anaerobically Digested Sewage Sludge: A Review

et al. 2021

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The world is currently witnessing a rapid increase in sewage sludge (SS) production, due to the increased demand for wastewater treatment. Therefore, SS management is crucial for the economic and environmental sustainability of wastewater treatment plants. The recovery of nutrients from SS has been identified as a fundamental step to enable the transition from a linear to a circular economy, turning SS into an economic and sustainable source of materials. SS is often treated via anaerobic digestion, to pursue energy recovery via biogas generation. Anaerobically digested sewage sludge (ADS) is a valuable source of organic matter and nutrients, and significant advances have been made in recent years in methods and technologies for nutrient recovery from ADS. The purpose of this study is to provide a comprehensive overview, describing the advantages and drawbacks of the available and emerging technologies for recovery of nitrogen (N), phosphorus (P), and potassium (K) from ADS. This work critically reviews the established and novel technologies, which are classified by their ability to recover a specific nutrient (ammonia stripping) or to allow the simultaneous recovery of multiple elements (struvite precipitation, ion exchange, membrane technologies, and thermal treatments). This study compares the described technologies in terms of nutrient recovery efficiency, capital, and operational costs, as well as their feasibility for full-scale application, revealing the current state of the art and future perspectives on this topic.

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Section: Pyrolysis and Gasificationmentioning

confidence: 99%

Exploiting the Nutrient Potential of Anaerobically Digested Sewage Sludge: A Review

et al. 2021

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“…e effect of pyrolysis temperature on the concentration of trace metals in the biochars was the main focus of research on the production and characterization of biochars [11]. However, the toxicity of the produced biochar is still unclear [41]. In this study, a phytotoxicity test is used as an effective and a low-cost equipment to identify the toxic effects of the produced biochars on root elongation inhibition (REI) of lettuce seeds (Figure 2).…”

Section: Effect Of Pyrolysis Temperature On Trace Metal Concentration and Biochar Toxicitymentioning

confidence: 99%

“…Recently, it was demonstrated that SS pyrolysis can cause the thermal breakdown of pathogens and some toxic organic compounds [38,39], required for possible land application [40,41]. Consequently, biochar derived from SS can have a significant impact on the physical, chemical, and biological properties of depleted soils without posing a risk of contamination [42,43].…”

Section: Introductionmentioning

confidence: 99%

Biochar Derived from Domestic Sewage Sludge: Influence of Temperature Pyrolysis on Biochars’ Chemical Properties and Phytotoxicity

Zoghlami

Hechmi

Weghlani

et al. 2021

Journal of Chemistry

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The pyrolytic conversion of domestic sewage sludge (SS) into biochar is a promising method to reduce its large volume and recycle its high-value fuel gas as renewable energy and the use of its chemicals as soil fertilizers. Even though the effects of pyrolysis temperature on energy recovery have been extensively studied, little information has been found on nutrient recovery and biochar’s phytotoxicity before its reuse as a soil amendment. This study aims to investigate the ideal pyrolysis temperature that guarantees higher fertility levels as well as meeting quality standards for land disposal. Accordingly, air-dried domestic sewage sludge has been pyrolyzed at 260°C (PSS1), at 420°C (PSS2), and at 610°C (PSS3) with a residence time of 20, 40, and 60 minutes, respectively. The raw sewage sludge and the produced biochars have been analyzed to determine their volatile organic matter (VOM), mineral content (MC), nutrients’ level (total nitrogen TN, available phosphorus P, and potassium K), alkalinity (pH), and salinity (electrical conductivity EC and Na). The toxic effect of biochars derived from SS has been evaluated through the analysis of trace metals (Pb, Cr, Cd, Cu, and Zn) and their toxicity by measuring root elongation inhibition (REI). As expected, pyrolysis temperature has a significant impact on the biochars’ characteristics. This has been justified by higher VOM, TN, and P in the sewage sludge (SS) and the biochar (PSS1) produced at low temperature (260°C). However, higher pH, EC, Na, and K have been found in the biochars (PSS2 and PSS3) produced at higher temperature (420 and 610°C). The effect of pyrolysis temperature on trace metals concentrations has shown different patterns from one element to another, which indicates lower levels in the biochar (PSS2) produced at 420°C. As a result, the lowest REI has been observed in PSS2 compared to that in SS, PSS1, and PSS3, which highlights that 420°C is the ideal pyrolysis temperature for the safe reuse of SS as a soil amendment.

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“…Depending on conditions of pyrolysis and type of SS [15], biochars obtained from SS pyrolysis are highly macroporous, with the small volumes of the meso-and micro-pores [19] among others, e.g., wood-derived biochar. However, one should bear in mind that the pyrolysis conditions regulate the availability and toxicity of emerging contaminants [20,21]. For instance, it has been reported that, pyrolysis at lower temperature of 300 °C resulted in the significant reduction in DTPA (diethylenetriaminepentaacetic acid)-extractable metals in the SS-derived biochar [14].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, increased temperature led to increased content of stable aromatic carbon, ash, some macro-(Ca, Mg, P, and K) and micronutrients (Cu and Zn) and increased alkali reaction [20]. Nevertheless, a suitable temperature of the SS pyrolysis can be used to transform bioavailable heavy metals into less soluble forms [21,23].…”

Section: Introductionmentioning

confidence: 99%

Microwave pyrolyzed sewage sludge: influence on soil microbiology, nutrient status, and plant biomass

Lónová

Holátko

Hammerschmiedt

et al. 2022

Chem. Biol. Technol. Agric.

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Background Sewage sludge (SS) has been considered a potent source of soil nutrients. However, its direct application to agricultural soils have been discouraged owing to its toxic nature. Therefore, conversion and modification of SS to decrease its toxicity has resulted in advanced methods. Co-pyrolysis of SS with other amendments is an ideal treatment resulting in an environmentally safe and nutrient rich final products with additional properties to sequester carbon. In the present study, a novel biochar was produced through the microwave pyrolysis of SS mixed with zeolite and sawdust. The pyrolysis product was thus characterized for elemental composition, polycyclic aromatic hydrocarbons, via Fourier Transform Infrared Spectroscopy (FTIR), and for its effects on soil microbial characteristics, soil health and plant biomass after soil application. Results Results revealed that, the SS modification resulted in stable product with higher nutrients which further depend on the type and ratio of feedstock used. Its application to soil significantly improved soil chemical and microbiological properties and altered lettuce biomass. Conclusions We concluded that sawdust feedstock promoted nutrient availability in the resulting biochar and induced higher activity of nutrient mineralizing enzymes, whereas zeolite slowed down the release of nutrients from soil and putatively immobilized enzymes. This joint effect of sewage sludge biochar, sawdust and zeolite benefited the plant acquisition of nutrients in comparison with the microbial nutrient uptake. We thus conclude that microwave pyrolyzed SS could be used as a soil enhancer. Graphical Abstract

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Pyrolysis of Municipal Sewage Sludge to Investigate Char and Phosphorous Yield together with Heavy-Metal Removal—Experimental and by Thermodynamic Calculations

Cited by 13 publications

References 36 publications

Exploiting the Nutrient Potential of Anaerobically Digested Sewage Sludge: A Review

Exploiting the Nutrient Potential of Anaerobically Digested Sewage Sludge: A Review

Biochar Derived from Domestic Sewage Sludge: Influence of Temperature Pyrolysis on Biochars’ Chemical Properties and Phytotoxicity

Microwave pyrolyzed sewage sludge: influence on soil microbiology, nutrient status, and plant biomass

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