Physicochemical and Toxicological Assay of Leachate from Malt Spent Rootlets Biochar

Spirulina-based carbon materials as adsorbents for drinking water taste and odor control: Removal efficiency and assessment of cyto-genotoxic effects

The sensory quality of drinking water, and particularly its taste and odor (T&O) is a key determinant of consumer acceptability, as consumers evaluate water by their senses. Some of the conventional treatment processes to control compounds which impart unpleasant T&O have limitations because of their low efficiency and/or high costs. Therefore, there is a great need to develop an effective process for removing T&O compounds without secondary concerns. The primary objective of this study was to assess for the first time the effectiveness of spirulina-based carbon materials in removing geosmin (GSM) and 2-methylisoborneol (2-MIB) from water, two commonly occurring natural T&O compounds. The efficiency of the materials to remove environmentally relevant concentrations of GSM and 2-MIB (ng L-1) from ultrapure and raw water was investigated using a sensitive headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC/MS) method. Moreover, the genotoxic and cytotoxic effects of the spirulina-based materials were assessed for the first time to evaluate their safety and their potential in the treatment of water for human consumption. Based on the results, spirulina-based materials were found to be promising for drinking water treatment applications, as they did not exert geno-cytotoxic effects on human cells, while presenting high efficiency in removing GSM and 2-MIB from water.

The Effect of Anode Material on the Performance of a Hydrogen Producing Microbial Electrolysis Cell, Operating with Synthetic and Real Wastewaters

The aim of the study was to assess the effect of anode materials, namely a carbon nanotube (CNT)-buckypaper and a commercial carbon paper (CP) on the performance of a two-chamber microbial electrolysis cell (MEC), in terms of hydrogen production and main electrochemical characteristics. The experiments were performed using both acetate-based synthetic wastewater and real wastewater, specifically the effluent of a dark fermentative hydrogenogenic reactor (fermentation effluent), using cheese whey (CW) as substrate. The results showed that CP led to higher hydrogen production efficiency and current density compared to the CNT-buckypaper anode, which was attributed to the better colonization of the CP electrode with electroactive microorganisms, due to the negative effects of CNT-based materials on the bacteria metabolism. By using the fermentation effluent as substrate, a two-stage process is developed, where dark fermentation (DF) of CW for hydrogen production occurs in the first step, while the DF effluent is used as substrate in the MEC, in the second step, to further increase hydrogen production. By coupling DF-MEC, a dual environmental benefit is provided, combining sustainable bioenergy generation together with wastewater treatment, a fact that is also reinforced by the toxicity data of the current study.

Potential hazards of biochar: The negative environmental impacts of biochar applications

Biochar has been widely used as an environmentally friendly material for soil improvement and remediation, water pollution control, greenhouse gas emission reduction, and other purposes because of its characteristics such as a large surface area, porous structure, and abundant surface O-containing functional groups. However, some surface properties (i.e., (i) some surface properties (i.e., organic functional groups and inorganic components), (ii) changes in pH), and (iii) chemical reactions (e.g., aromatic C ring oxidation) that occur between biochar and the application environment may result in the release of harmful components. In this study, biochars with a potential risk to the environment were classified according to their harmful components, surface properties, structure, and particle size, and the potential negative environmental effects of these biochars and the mechanisms inducing these negative effects were reviewed. This article presents a comprehensive overview of the negative environmental impacts of biochar on soil, water, and atmospheric environments. It also summarizes various technical methods of environment-related risk detection and evaluation of biochar application, thereby providing a baseline reference and guiding significance for future biochar selection and toxicity detection, evaluation, and avoidance.

Rootlets, a Malting By-Product with Great Potential

Barley rootlets are the most abundant by-product from the malting industry. Due to the inherent association of the malting industry with brewing and distilling industries, it is also considered a by-product of these industries. Barley rootlets are produced during the germination step of malting. These rootlets are a valuable source of nutrition, with protein and fibre holding a large proportion of their composition. Barley rootlets are generally pelletised and used as animal fodder; however, their usage may not be limited to this. Efforts have been made to utilise barley rootlets as food ingredients, sources of enzymes, antioxidants, raw materials in fermentations, and in biochar production. Conversion of this by-product into other/new applications would reduce waste production from their industry origin and reduce some of the impending environmental concerns associated with by-product production. The current review focuses on providing information on the formation, production, and processing of barley rootlets, while also highlighting the composition, quality, and potential applications of barley rootlets.

In Vivo Genotoxicity of Rice Husk Biochar on Eudrilus eugeniae in Soil

Biochar (char-product), generated by pyrolyzing organic materials, is produced for the intended use of land application to promote carbon sequestration, soil improvement and crop-yield. Despite the benefits biochar applications offers, scientific probing on impacts that may result from amendments with biochar is still fragmented. In this study, impact of biochar on Eudrilus eugeniae DNA was investigated. Rice-husk biochar was applied to soil at rates up to 80% d/w and earthworms were exposed for 35-day. Impact on DNA was measured using electrophoresis-gel-extraction-method. Data obtained showed that biochar application over 25% resulted in decreased survival. Electrophoresis-gel-analysis showed that DNA decreased from 450 to 300 bp in biochar soils (p = 0.002). Biochar rates (5%-25%) induced DNA damage. The DNA showed smeared bands or tail; indicating DNA degradation and/or damage. DNA damage is a clear evidence of negative impact of biochar(s) to soil-biota; suggesting that loading of soil with biochar could have serious consequences on soil-fauna.