This paper analyzesanalyses the effectiveness of three commercial products: aluminum sulfate, aluminum polychloride and polyglutamic acid-based bioflocculant, in water clarification and purification. Poly-g-glutamic acid (PGA), a naturally occurring anionic polymer, is already produced on an industrial scale. A conventional jar test apparatus was used for flocculation experiments. The tests were performed using raw water from the Salto de Pirapora Water Treatment Plant (WTP) in the state of São Paulo, Brazil. The structure and elemental composition of PGA bioflocculant, which was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF) and thermogravimetric analysis (TGA), suggests that it is basically inorganic in nature, with high contents of calcium sulfate (87%) and g-polyglutamic acid (5%), among other chemical compounds. The performance of PGA bioflocculant was superior to that of the other coagulants. In the dry season, 80 mg L À1 of PGa21Ca removed 89.74% of apparent color, and residual turbidity was 5.78 NTU. In the rainy season, 90 mg L À1 of PGa21Ca removed 96.89% of apparent color and residual turbidity was 1.93 NTU.

BACKGROUND Coffee husks (CH) are an abundant lignocellulosic residue that can be converted into biofuels and bioproducts through sustainable and economical processes in a biorefinery approach. For that, steam explosion (SE) pretreatment stands out as a technique to overcome its recalcitrant nature and enable byproduct valorization. In this study, solid and liquid fractions were separated after pretreatment for saccharification and biogas production, respectively. The research relevance relies on the contribution to environment decarbonization and monetization of decarbonization credits (CBIO) generated from the production of renewable fuel from waste biomass under different operational conditions (with and without pretreatment). RESULTS Liquid hydrolysate generated by SE condition at 210 °C and 15 min led to the highest biomethane production (292 NmL CH4 g CODfed−1). Similarly, high‐severity pretreatment also favored the enzymatic hydrolysis yield of the solid fraction (49%). In terms of environment decarbonization, SE promoted not only a lower carbon intensity when compared to the process without any pretreatment (3.8 vs. 6.4 g CO2eq MJ−1), but also increased the monetization of decarbonization credits by 175%, which represented a potential revenue of US $1 481 330. CONCLUSION High temperatures of SE pretreatment of CH at 210 °C were able to promote biogas production and fermentable sugars. In addition, the process reduced carbon emissions and increased the revenue from CBIO commercialization. Therefore, SE proved to be a sustainable and economic alternative for consideration in new green businesses from lignocellulosic residues such as CH. © 2021 Society of Chemical Industry (SCI).

Propriedades floculantes em água artificial do ácido γ-poliglutâmico produzido por Bacillus subtilis em substrato de soja fermentada (natto) Artificial water flocculating properties of γ-polyglutamic acid produced by Bacillus subtilis on fermented soybean substrate (natto)

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