No abstract

No abstract

<p>In the last years, global focus has been directing towards the circular economy model. In this framework materials that had so far been regarded as waste, are now considered as valuable resources for both energy and added-value materials recovery. In this context, more and more valorization methods and technologies are being developed for waste valorization, with biomass materials of municipal and agroindustrial origin constituting ideal options, due to both composition and availability.</p><p>Biochar generation from waste biomass is a method with high potential for effectively valorizing such residual resources, by providing not only a waste management option, but also multiple agronomic and environmental benefits. In fact, biochar materials are characterized by high versatility as far as their applications are concerned. Due to their wide variety of properties, biochars can be used in various applications, such the use as an adsorbent for contaminant removal from water or wastewater, or the use as an amendment for improving soil characteristics and remediating contaminated sites.</p><p>In the present study, six different waste biomass feedstocks, specifically three of municipal origin, namely two types of sewage sludge and the organic fraction of municipal solid waste, and three of agroindustrial origin, namely grape pomace, rice husks and exhausted olive pomace, were used to generate biochar through pyrolysis at two different temperatures, i.e. 400 and 600 °C. The resulting carbonaceous materials were then characterized through a series of analyses. Based on both physical and chemical biochar properties, it was able to evaluate their potential use in different applications, for agronomic or environmental purposes.</p>

This study focused on the valorization of different types of waste biomass through biochar production at two pyrolysis temperatures (400 and 600°C). The different feedstocks being used included three materials of municipal origin, specifically two types of sewage sludge and the organic fraction of municipal solid waste, and three materials of agroindustrial origin, specifically grape pomace, rice husks and exhausted olive pomace. The scope of the research was to characterize the resulting materials, in order to evaluate their possible uses in agronomic and environmental applications. Biochar characterization included the determination of several physical and chemical parameters, while germination assays were also carried out. Under the investigated conditions, both pyrolysis temperature and feedstock type appeared to significantly affect biochar characteristics, leading to the production of versatile materials, with many different possible uses. Specifically, results implied that biochars of both municipal and agroindustrial origin have the potential to effectively be used in applications including the improvement of soil characteristics, carbon sequestration, the removal of organic and inorganic contaminants from aqueous media, and the remediation of contaminated soil, with the degree of suitability of each material to each specific use being estimated to differ depending on its particular characteristics. For this reason, with these characteristics in mind, before proceeding to larger scale applications a cautious selection of materials should be conducted.

<p>The objective of this study was to produce regular and Graphene Oxide (GO) coated biochar adsorbents, using two types of biomass as feedstock, i.e. Rice Husks (RH) and Sewage Sludge (SS), in two pyrolytic temperatures (400°C and 600°C). The produced adsorbents were thoroughly characterized in terms of physicochemical properties, where biochars produced from RH at 600°C showed the most favourable results. Specifically, the S<sub>BET</sub> values of these samples were up to four times higher compared to biochars produced at 400°C and up to thirteen times higher, compared to the respective SS biochars. Moreover, the metal content of the samples was determined, in order to assess their safety, where all values were under the limits set by the European Union. Finally, biochars were tested as adsorbents for the removal of six organic micro-pollutants, i.e. 2,4-Dichlorophenol (2,4D), Bisphenol A (BPA), Androsterone (ADT), Norethindrone (NOR), Estrone (E1) and Ethinyl Estradiol (EE2), from table water and wastewater, in low (realistic) initial concentrations. The pollutants were successfully adsorbed by biochar, in rates of 40%-97.5% for the RH biochars and 10%-97.5% for the RH biochars, in 1h. GO-enriched RH biochars produced at 600°C were the most effective adsorbents, removing the pollutants in rates higher than 70%, in just 10min of adsorption time.</p>