In anaerobic digestion processes, pH has a vital role due to the direct impacts on the microbial community. An eco-friendly approach has been applied to control pH in anaerobic bioreactors, using waste-containing fly ash geopolymer spheres (GS) instead of powdered chemical compounds, to promote continuous alkalis leaching. The influence of GS porosity and concentration on the behavior of anaerobic sequential batch reactor treating cheese whey was evaluated. Results showed that the use of GS with the highest concentration and porosity promoted an increase in methane yield up to 30%, compared to the assay with powdered chemical compounds addition. In addition, GS boosted butyric acid production to the detriment of propionic acid, which favored methane production by a factor up to 1.2. This innovative approach indicates that GS addition can regulate pH in anaerobic digesters treating challenging wastewaters and, simultaneously, improve not only its efficiency but also the sustainability of the entire process.
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http://dx.doi.org/10.1007/s00449-021-02522-w | DOI Listing |
Langmuir
November 2024
School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China.
To reuse red mud and slag wastes as raw materials, a green type of porous spherical red mud/slag-based geopolymer (RSG) was synthesized by utilizing suspension curing and foaming techniques. Because methylene blue (MB) and nickel ion (Ni) were common and difficult to treat in wastewater, the adsorption characteristics of MB and Ni, as well as the phase and microstructure of the porous RSG spheres prior to and after adsorption, were thoroughly investigated. The porous RSG spheres showed a stable and mesoporous structure with a BET surface area of 31.
View Article and Find Full Text PDFSci Total Environ
October 2024
Civil and Environmental Engineering Department, The University of Alabama in Huntsville, Huntsville, AL 35899, USA. Electronic address:
The removal of phosphate from agricultural runoff is of great importance to mitigate an overabundance of nutrients discharging into receiving water bodies, which are susceptible to eutrophication. In this study, a La-loaded geopolymer was produced by adding metakaolin within an alkaline medium, consisting of sodium silicate (NaSiO) and sodium hydroxide (NaOH). The ratio of NaSiO:NaOH within the geopolymer slurry was manipulated to evaluate its effect on phosphate adsorption capacity.
View Article and Find Full Text PDFSci Total Environ
August 2024
Dept. of Materials and Ceramic Engineering/CICECO-Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Acid mine drainage (AMD) poses a significant threat to water quality worldwide, being amongst the most problematic environmental concerns of the millennium. This work reports for the first time the remediation of real AMD, from a Portuguese abandoned mine, in fixed bed column using porous red mud/fly ash-based geopolymeric spheres. Porous waste-based spheres (2.
View Article and Find Full Text PDFJ Environ Manage
January 2024
School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China. Electronic address:
Municipal solid waste (MSW) incineration fly ash (FA) is classified as hazardous waste, and strategies for recycling FA have attracted attention. In this study, the porous geopolymer spheres (PGS) were prepared from FA by the foaming-suspension-solidification method, and then the PGS were functionalized with tetraethylenepentamine (TEPA) to capture CO. The results showed that washing pretreatment and the addition of HO foaming agent enhanced the pore volume and specific surface area of PGS.
View Article and Find Full Text PDFEnviron Res
March 2023
School of Metallurgy, Northeastern University, Shenyang, Liaoning, 110819, PR China.
Geopolymer composite spheres derived from potassium-activated graphene-modified slag/fly ash powder were produced in a polyethylene glycol (PEG 400) solvent. The effect of graphene type (graphene oxide (GO) and few-layered graphene (GNP)) on the pore structure and lead ions (Pb) removal performance of the spheres were evaluated. The results showed that the composite spheres modified with GOs (0.
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