초록
<P><B>Abstract</B></P> <P>The potential of waste activated sludge (WAS) as acidogenic fermentation feedstock for biohydrogen (H<SUB>2</SUB>) and short chain carboxylic acids (SCA) production was studied. Primarily, WAS was subjected to pretreatment using physical, chemical and physicochemical methods to accelerate the SCOD solubilization. Alkaline-catalyzed physiochemical pretreatment of WAS resulted in higher degree of solubilization (DOS) (1% NaOH (v/v): DOS: 40.9%, SCOD: 14.6 g/l) followed by acid (1% H<SUB>2</SUB>SO<SUB>4</SUB> (v/v): DOS: 36.4%, SCOD: 8.84 g/l). The organic-rich hydrolysate (alkaline-catalyzed) was acidogenically fermented for the production of H<SUB>2</SUB> and SCA at varying initial pH conditions (6, 7 and 10) against the untreated WAS as a control. Acidogenic fermentation of pretreated WAS at pH-10 resulted in higher H<SUB>2</SUB> (29%) and SCA production (4.9 g/l) followed by pH-6 (23%; 3.6 g/l), pH-7 (10%; 1.2 g/l) and control (5%; 0.3 g/l), respectively. SCA distribution profiles were also varied as a function of pH and retention time. Maximum SCA concentration in pH-10 system owed the highest acidification (37.9%) followed by pH-6 (25.5%), pH-7 (8.0%) and control (1.91%). The outcome of the study infers the potential of WAS as a resource for various biobased products synthesis in the framework of biorefinery. Hydrogen is a green fuel and SCA are considered as building blocks for various high-value products synthesis, production of which using WAS addresses the sustainability to current wastewater treatment units.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Alkaline-catalyzed physiochemical pretreatment of WAS resulted high SCOD. </LI> <LI> Acidogenesis of pretreated WAS depicted high H<SUB>2</SUB> and SCA production than untreated. </LI> <LI> Biosystem pH condition played critical role in the SCA production and distribution. </LI> <LI> Study confers the potential of WAS for waste derived biorefinery. </LI> </UL> </P>