Sewage sludge biochars management—Ecotoxicity, mobility of heavy metals, and soil microbial biomass

Mierzwa–Hersztek, Monika; Gondek, Krzysztof; Klimkowicz‐Pawlas, Agnieszka; Baran, Agnieszka; Bajda, Tomasz

doi:10.1002/etc.4045

Cited by 63 publications

(18 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The increase in pH was significantly lower than that reported by Jin et al [39], but it has to be pointed out that in the case of Jin et al's research, the process temperature was much higher (400 and 600 • C). The increase in pH value in the present experiment was similar to the result shown by Mierzwa-Hersztek et al [35]. The neutral pH range is desirable, as the mobility of HMs tends to be low [40].…”

Section: Heavy Metal Leachability From Biochars In Relation To Torrefsupporting

confidence: 92%

Is Biochar from the Torrefaction of Sewage Sludge Hazardous Waste?

et al. 2020

View full text Add to dashboard Cite

Improved technologies are needed for sustainable management of sewage sludge (SS). The torrefaction (also known as biomass “roasting”) is considered a pretreatment of SS before use in agriculture. However, it is not known whether the torrefaction has the potential to decrease heavy metals’ (HMs) leachability and the SS toxicity. Thus, the aim of the study was to evaluate the influences of the SS torrefaction parameters (temperature and process time) on HM contents in biochar, HM leachability, and biochar toxicity, and compare them with raw SS. The experiments were designed in 18 combinations (six temperatures, 200, 220, 240, 260, 280, and 300 °C; and three process times—20, 40, 60 min). Standard tests were used to determine HMs content, leachability, and toxicity. Results indicated that the torrefaction did not increase (p < 0.05) the HM content in comparison to the raw SS. The leachability of Zn, Ni, Cu, Cr, and Mn from SS biochars was similar to raw SS. However, the degree of leachability varied significantly (p < 0.05) from as low as 0.1% for Cu to high as 16.7% for Cd. The leachability of Cd (<16.7%) and Pb (<11.9%) from biochars was higher than from raw SS (<6.1% and <2.4%, respectively). The leachability of Cd from SS biochar, in five torrefaction combinations, was higher than the threshold value for hazardous waste. It is recommended that site-specific decisions are made for torrefaction of SS with respect to its HM content, as the resulting biochar could be considered as hazardous waste, depending on the feedstock. Moreover, the biochar produced under the whole range of temperatures during 20 min retention time significantly (p < 0.05) increased the Daphnia magna Straus mobility inhibition by up to 100% in comparison to the biochar obtained during 40 and 60 min torrefaction. Taking into account the increased leachability of specific HMs and D. magna Straus mobility inhibition, biochar should be considered a potentially hazardous material. Future research should focus on biochar dosage as a fertilizer in relation to its toxicity. Additional research is warranted to focus on the optimization of SS torrefaction process parameters affecting the toxicity.

show abstract

Section: Heavy Metal Leachability From Biochars In Relation To Torrefsupporting

confidence: 92%

Is Biochar from the Torrefaction of Sewage Sludge Hazardous Waste?

et al. 2020

View full text Add to dashboard Cite

show abstract

“…For example, poultry litter feedstocks are normally rich in S, Na, and Cl and so are the chars obtained from them ( Cantrell et al, 2012 ; Novak et al, 2013 ). In the case of sewage sludge, there is a wide variation in element content; however, S and Na are abundant and concentrated in derived biochars, as has been reported in other studies ( Lu et al, 2012 ; Song et al, 2014 ; Mierzwa-Hersztek et al, 2017 ).…”

Section: Discussionsupporting

confidence: 63%

Structural and Functional Features of Chars From Different Biomasses as Potential Plant Amendments

et al. 2018

View full text Add to dashboard Cite

Biochars result from the pyrolysis of biomass waste of plant and animal origin. The interest in these materials stems from their potential for improving soil quality due to increased microporosity, carbon pool, water retention, and their active capacity for metal adsorption from soil and irrigation water. Applications in agriculture have been studied under different conditions, but the overall results are still unclear. Char structure, which varies widely according to the pyrolysis process and the nature of feedstock, is thought to be a major factor in the interaction of chars with soil and their metal ion adsorption/chelation properties. Furthermore, biochar nutrients and their elemental content can modify soil fertility. Therefore, the use of biochars in agricultural settings should be examined carefully by conducting experimental trials. Three key problems encountered in the use of biochar involve (i) optimizing pyrolysis for biomass conversion into energy and biochar, (ii) physicochemically characterizing biochar, and (iii) identifying the best possible conditions for biochar use in soil improvement. To investigate these issues, two types of wood pellets, plus digestate and poultry litter, were separately converted into biochar using different technologies: pyrolysis/pyrogasification or catalytic (thermo)reforming. The following physicochemical features for the different biochar batches were measured: pH, conductivity, bulk density, humidity and ash content, particle size, total organic substances, and trace element concentrations. Fine porous structure analysis and total elemental analysis were performed using environmental scanning electron microscopy along with energy-dispersive X-ray spectrometry (EDX). Phytotoxicity tests were performed for each biochar. Finally, we were able to (i) differentiate the biochars according to their physicochemical properties, microstructure, elemental contents, and original raw biomass; (ii) correlate the whole biochar features with their respective optimal concentrations when used as plant fertilizers or soil improvers; and (iii) show that biochars from animal origin were phytotoxic at lower concentrations than those from plant feedstock.

show abstract

“…In the study, Oleszczuk et al [63] reported slightly different relationships-the tested biochars were more toxic to V. fischeri than to L. sativum. Other studies by Mierzwa-Hersztek et al [64] showed that the type of feedstock from which biochars were produced has a significant effect on the toxicity of biochars. According to Ribeiro et al [59], ash amendment and ash + sludge amendment resulted in similar Lolium perenne growth compared to the control.…”

Section: Phytotoxicity Of Biomass Ashmentioning

confidence: 99%

Assessment of energy parameters of biomass and biochars, leachability of heavy metals and phytotoxicity of their ashes

Mierzwa–Hersztek

Gondek

Jewiarz

et al. 2019

J Mater Cycles Waste Manag

Self Cite

104

View full text Add to dashboard Cite

The aim of this study was to determine selected energy parameters, leachability of heavy metals and phytotoxicity of biomass ash for different types of plant biomass (wheat straw, miscanthus straw, bark and sawdust) and poultry manure, as well as biochars produced from them. Based on data from proximate and ultimate analysis of the investigated materials, fuel value index (FVI) was calculated to determine their suitability for energy production. The ashes were analyzed for both chemical composition and leaching behavior. The phytotoxicity test of aqueous ash extracts was performed for Lepidium sativum L. It was found that the calorific value of biochars was higher on average by 36% than the value determined for feedstocks used in the pyrolysis process. The pyrolysis of organic materials resulted in the reduction of the volatile matter content. The gross calorific value was determined in biochars formed from miscanthus straw and sawdust which were 26.6 and 23.4 MJ kg −1 , respectively. Leachability of heavy metals of biomass ash was highly diverse and depended on the analyzed element and the material type. The phytotoxicity analysis showed that, in general, each of the ash extracts tested had a positive effect on the growth of Lepidium sativum L. compared to the control. The use of ash, fertilizer, or sorbents can be an interesting alternative for materials with high ash content. In all these cases, biochars seem to be very attractive materials that can be used not only in energy production. Given the high carbon content of biochar obtained in the pyrolysis process, it has a high-energy potential and can be used as a biofuel.

show abstract

Sewage sludge biochars management—Ecotoxicity, mobility of heavy metals, and soil microbial biomass

Cited by 63 publications

References 43 publications

Is Biochar from the Torrefaction of Sewage Sludge Hazardous Waste?

Is Biochar from the Torrefaction of Sewage Sludge Hazardous Waste?

Structural and Functional Features of Chars From Different Biomasses as Potential Plant Amendments

Assessment of energy parameters of biomass and biochars, leachability of heavy metals and phytotoxicity of their ashes

Contact Info

Product

Resources

About