Comparison of Novel Biochars and Steam Activated Carbon from Mixed Conifer Mill Residues

There is increasing demand in environmental remediation and other sectors for specialized sorbents made from renewable materials rather than hard coals and minerals. The proliferation of new pyrolysis technologies to produce bio-based energy, fuels, chemicals, and bioproducts from biomass has left significant gaps in our understanding of how the various carbonaceous materials produced by these systems respond to processes intended to improve their adsorption properties and commercial value. This study used conventional steam activation in an industrial rotary calciner to produce activated carbon (AC) from softwood biochars made by three novel pyrolysis systems. Steam was injected across four heating zones ranging from 816 °C to 927 °C during paired trials conducted at calciner retention times of 45 min and 60 min. The surface area of the three biochars increased from 2.0, 177.3, and 289.1 m2 g−1 to 868.4, 1092.9, and 744.8 m2 g−1, respectively. AC iodine number ranged from 951 to 1218 mg g−1, comparing favorably to commercial AC produced from bituminous coal and coconut shell. The results of this study can be used to operationalize steam activation as a post-processing treatment for biochar and to expand markets for biochar as a precursor in the manufacture of specialized industrial sorbents.

Comparative Study of the Properties of Wood Flour and Wood Pellets Manufactured from Secondary Processing Mill Residues

The generation of secondary processing mill residues from wood processing facilities is extensive in the United States. Wood flour can be manufactured utilizing these residues and an important application of wood flour is as a filler in the wood–plastic composites (WPCs). Scientific research on wood flour production from mill residues is limited. One of the greatest costs involved in the supply chain of WPCs manufacturing is the transportation cost. Wood flour, constrained by low bulk densities, is commonly transported by truck trailers without attaining allowable weight limits. Because of this, shipping costs often exceed the material costs, consequently increasing raw material costs for WPC manufacturers and the price of finished products. A bulk density study of wood flour (190–220 kg/m3) and wood pellets (700–750 kg/m3) shows that a tractor-trailer can carry more than three times the weight of pellets compared to flour. Thus, this study focuses on exploring the utilization of mill residues from four wood species in Maine to produce raw materials for manufacturing WPCs. Two types of raw materials for the manufacture of WPCs, i.e., wood flour and wood pellets, were produced and a study of their properties was performed. At the species level, red maple 40-mesh wood flour had the highest bulk density and lowest moisture content. Spruce-fir wood flour particles were the finest (dgw of 0.18 mm). For all species, the 18–40 wood flour mesh size possessed the highest aspect ratio. Similarly, on average, wood pellets manufactured from 40-mesh particles had a lower moisture content, higher bulk density, and better durability than the pellets from unsieved wood flour. Red maple pellets had the lowest moisture content (0.12%) and the highest bulk density (738 kg/m3). The results concluded that the processing of residues into wood flour and then into pellets reduced the moisture content by 76.8% and increased the bulk density by 747%. These material property parameters are an important attempt to provide information that can facilitate the more cost-efficient transport of wood residue feedstocks over longer distances.

Removal of Diclofenac in Wastewater Using Biosorption and Advanced Oxidation Techniques: Comparative Results

Wastewater treatment is a topic of primary interest with regard to the environment. Diclofenac is a common analgesic drug often detected in wastewater and surface water. In this paper, three commonly available agrifood waste types (artichoke agrowaste, olive-mill residues, and citrus waste) were reused as sorbents of diclofenac present in aqueous effluents. Citrus-waste biomass for a dose of 2 g·L−1 allowed for removing 99.7% of diclofenac present in the initial sample, with a sorption capacity of 9 mg of adsorbed diclofenac for each gram of used biomass. The respective values obtained for olive-mill residues and artichoke agrowaste were around 4.15 mg·g−1. Advanced oxidation processes with UV/H2O2 and UV/HOCl were shown to be effective treatments for the elimination of diclofenac. A significant reduction in chemical oxygen demand (COD; 40–48%) was also achieved with these oxidation treatments. Despite the lesser effectiveness of the sorption process, it should be considered that the reuse and valorization of these lignocellulosic agrifood residues would facilitate the fostering of a circular economy.

Opuntia ficus-indica L. Mill Residues—Properties and Application Possibilities in Food Supplements

Recently, industry has been focusing on the development of new products made from food by-products in order to reduce and take advantage of food wastes. The objective of this study was to evaluate tablet formulations developed by mixing two commercial excipients, microcrystalline cellulose (M) and α-lactose-monohydrate (L), added with powder from residues (mesocarp and pericarp) of green and red (G and R) cactus pear fruit (Opuntia ficus-indica L. Mill), having the following formulations: green with microcrystalline cellulose (GM), green with lactose (GL), red with microcrystalline cellulose (RM), and red with lactose (RL). The results showed lower disintegration times for the tablets with microcrystalline cellulose. The fiber functional properties presented good values for lipid and water holding capacity. There was a higher total phenolic content (TPC) in formulations with green cactus pear residue powder with microcrystalline cellulose and lactose (GM and GL, respectively), but the DPPH and ferric reducing/antioxidant power (FRAP) values were higher in the formulations with red cactus pear residues (RM and RL), while ABTS values were similar among all formulations. In conclusion, tablets made from Opuntia residues are proposed as a product of interest for the food supplement industry because of the good quality parameters and the functional and antioxidant properties that they provide.

Biogeochemical characterization of soils affected by more than 100 years of lead mining activity.

<p>Mining has an adverse effect on soil quality as it is a source of heavy metal environmental pollution with direct consequences on its ecosystem services, especially those related to microbial activity. The magnitude and diversity of the impact produced by pollution is linked to the complexity and diversity of mining processes that share the same mining area. The soil will be modified, not only in the physicochemical characteristics but also physical alterations of varied typology will occur. All these changes and alterations related to mining activity are accompanied by changes in the composition, diversity and activity of soil microorganisms..<br>A study was carried out on a mine site showing variable degrees of contaminations with metals, to estimate the impact of mining works on the geochemistry of soils, and the activity and diversity of soil microorganisms.  The aim is to characterize the level of disturbance on the “soil health” due to the presence of different metals, related physicochemical factors, and typology of the wastes affecting the soil. Besides, the process of bacterial colonization of the wastes has been also subject of interest to our work.<br>The selected study area was originally a lead-silver mine. Later, a mineral treatment plant was established in the area in order to recover Zn from the primary gangue dumps. In addition spills of olive mill residues were later deposited in the area. Four composite samples from the five distinct sites differing in their characteristics were selected: tailings, dumps, olive mill residues, contaminated soil and reference soil. A range of various analyses was done on these samples including pH, electrical conductivity, organic matter, multi-elemental contents, enzymatic activity and bacterial biodiversity (16S rRNA amplicon sequencing).<br>Selected sampling sites have contrasted physicochemical characteristics: acidic pH was observed in dumps (3.8 in average) and neutral in tailings and soils (~6); highest conductivity was recorded in dumps (2282 microS cm-1 in average) and lowest in soils (62 microS cm-1 in average); the highest organic matter value was measured in soils amended with olive mill residues (60% in average). Heavy metals were detected in higher concentrations in dumps and olive mill residues than in tailings or soils. It is noteworthy in dump samples the maximum concentrations of metals reach 6.8% with significant amounts of Zn, Cu, Sb, Hg, Ni, Co and Mn. Highest enzymatic activities were measured in contaminated and non-contaminated soils, while lowest values were obtained in dumps and tailings soils, in accordance with the concentration of metal measured in the matrix. Next generation sequencing analysis of 16S rRNA amplicon lead to the discrimination on the different sites sampled according to bacterial composition and diversity. Most abundant bacterial phyla were Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Gemmatimonadetes, Bacteriodetes, TM7, Firmicutes, Cyanobacteria and Verrucomicrobia.<br>As a conclusion, we have found evidences of the intense affection of the metal pollution to the microbiological biodiversity, particularly that related with the presence of high Pb concentrations.</p>