Effects of Ultrasonic and Acid Pretreatment on Food Waste Disintegration and Volatile Fatty Acid Production

This study aims at investigating the effects of ultrasonic and acid pretreatment on food waste( FW)disintegration and volatile fatty acid( VFA) production. Single-factor experiments are carried out to obtain optimal conditions of individual ultrasonic and acid pretreatment,and response surface method( RSM) is applied to optimize the conditions of the combination of ultrasonic and acid( UA) pretreatment. Results show that the optimal acid,ultrasonic and UA pretreatments conditions are individual pH 2,individual ultrasonic energy density of 1. 0 W / mL and the combination of ultrasonic energy density1. 11 W / mL and pH 1. 43,respectively. Correspondingly,the maximum disintegration degrees( DD) of 46. 90%,57. 38% and68. 83%are obtained by acid,ultrasonic and UA pretreatments,respectively. After optimizing pretreatment conditions,batch experiments are operated to produce VFA from raw and pretreated FW under anaerobic fermentation process. Both the maximum VFA production( 976. 17 mg COD / gV S) and VFA / SCOD( 72. 89%) are obtained with ultrasonic pretreatment, followed by UA pretreatment, non-pretreatment and acid pretreatment,respectively. This observation demonstrates that a higher acidity on acid and UA pretreatments inhibits the generation of VFA. Results suggest that ultrasonic pretreatment is preferable to promote the disintegration degree of FW and VFA production.

Biohythane production from two-stage anaerobic digestion of food waste:A review

The biotransformation of food waste(FW)to bioenergy has attracted considerable research attention as a means to address the energy crisis and waste disposal problems.To this end,a promising technique is two-stage anaerobic digestion(TSAD),in which the FW is transformed to biohythane,a gaseous mixture of biomethane and biohydrogen.This review summarises the main characteristics of FW and describes the basic principle of TSAD.Moreover,the factors influencing the TSAD performance are identified,and an overview of the research status;economic aspects;and strategies such as pre-treatment,co-digestion,and regulation of microbial consortia to increase the biohythane yield from TSAD is provided.Additionally,the challenges and future considerations associated with the treatment of FW by TSAD are highlighted.This paper can provide valuable reference for the improvement and widespread implementation of TSAD-based FW treatment.

Enzymatic pretreatment mitigates the dissemination of antibiotic resistance genes via regulating microbial populations and gene expressions during food waste fermentation

Food waste(FW)has been recognized as essential reservoir for resource recovery via anaerobic fermentation,which could also bring the potential risk of antibiotic resistance genes(ARGs)dissemination.Although the structural deficiency of FW could be stimulated by enzymatic pretreatment to enhance fermentation efficiency,the influences of enzymatic pretreatment on ARGs fate and microbial metabolic pathways involved in ARGs dissemination have rarely been reported.This work proved that enzymatic pretreatment could effectively decrease the total abundance of ARGs(reduced by 13.8%-24.5%)during long-term FW fermentation.It was found that enzymatic pretreatment significantly reduced the ARGs belonging to the efflux pump,which might be ascribed to its ability to increase membrane permeability.Furthermore,enzymatic pretreatment was in favor of reducing microbial diversity and various potential ARGs host(e.g.,Methanosarcina,Clostridium,Prevotella,Parabacteroides).Also,this pretreatment remarkably up-regulated the genetic expressions involved in ABC transporter(e.g.,eryF and mntA)and down-regulated the genetic expressions that participated in DNA replication,two-component systems(e.g.,uphA and cckA),and quorum sensing(e.g.,rpfF and lsrG),thereby decreasing ARGs transmission.This study would expand the insight of the influences of pretreatment method on ARGs fate during FW fermentation,and offer practical guidance on the sustainable management of FW.