Using Black Liquor from the Soda Pulping Process for Protein Production by Candida utilis

Abstract

Black liquor produced from pulping with a high value of chemical oxygen demand (COD) and biological oxygen demand (BOD) is highly harmful if discharged into the environment directly. One possible way to decrease the damage to the soil and water is to reuse the organic substances contained in it to cultivate yeasts for producing single-cell proteins (SCP) while reducing the COD. With this in mind, this study is devoted to treatment technology and the comprehensive utilization of black liquor. Various parameters were evaluated, and the COD of black liquor, initial pH, and nitrogen sources had significant influences on biomass and crude protein production. The research resulted in the maximum values of COD removal rate and crude protein production with 78.78 ±3.21% and 1.18 ±0.02 g/L achieved, respectively, under the optimized condition of black liquor concentration (60%), the recruitment of urea (0.5 g/L), initial pH (6.0), temperature (34 °C), shaking speed (180 rpm), and incubation time (36 h). Furthermore, this study provided a potential viable treatment of black liquor and revealed a feasible way to make full use of black liquor for the economical production of SCP.

Press water from the mechanical drying of Douglas-fir wood chips has multiple beneficial effects on lignocellulolytic fungi

“…The optimization of wood chip drying by mechanical dewatering in conventional sawmills could lead to higher energy efficiency and reduced fuel consumption [ 54 ]. However, the COD values of the resulting PW are comparable with effluents seen in the pulp and paper industry (thermo-mechanical pulp processing effluents and black liquor), which cause considerable operating costs due to the requirement of wastewater treatment [ 55 – 59 ]. Therefore, the treatment of large PW volumes could similarly become a financial burden.…”

Growth-Promoting Effects of Press Water from the Mechanical Drying of Douglas-Fir Wood Chips on Lignocellulolytic Fungi

“…Thus, this seemingly small improvement could have considerable effects on the entire sawmilling process [48]. The COD values of the PW are comparable with e uents seen in the pulp and paper industry (thermo-mechanical pulp processing e uents and black liquor), which cause considerable operating costs due to the requirement of wastewater treatment [49][50][51][52][53]. Therefore, the discharge and treatment of large PW volumes could require more energy than the energy saved by the mechanical drying compared to the conventional thermal drying, hence becoming a nancial burden [18].…”

Agroindustrial Byproducts for the Generation of Biobased Products: Alternatives for Sustainable Biorefineries

“…Wastewater from the pulping process is another residue that can be used for the production of SCP by yeasts. Hu et al (2015) evaluated the use of black liquor (a lignin fraction obtained from alkali pretreatment of lignocellulosic biomass after the pulping process) for the production of SCP of C. utilis, obtaining 12.6 g/L of biomass and 39.82% total amino acid content. Furthermore, bamboo wastewater from bamboo pulping and papermaking was used for SCP production by C. utilis, achieving 19.17 g/L of yeast biomass (Li et al, 2009).…”

“…Furthermore, bamboo wastewater from bamboo pulping and papermaking was used for SCP production by C. utilis, achieving 19.17 g/L of yeast biomass (Li et al, 2009). Wastewater might be considered as a good carbon and nitrogen source for yeast growth (Hu et al, 2015), in addition to providing an alternative treatment for this type of industrial residue.…”