Journal Article

Enhancing methane production using anaerobic co-digestion of waste activated sludge with combined fruit waste and cheese whey

Kuroshkarim, Mohammad, Hallaji, Seyed Mostafa, Moussavi, Seyede Parvin

2019

Overview

Background Recently, it has been indicated that anaerobic co-digestion of waste activated sludge with other waste streams at wastewater treatment plants is a promising strategy for enhancing methane production and materials recovery. The enhanced methane production can be used as a renewable source of energy in wastewater treatment plants. It can also reduce the amount of greenhouse gas emission in landfilling of the waste streams. Results According to the results obtained in this study, anaerobic co-digestion of waste activated sludge with mixed fruit waste and cheese whey improves methane production and the quality of digested sludge in comparison to the anaerobic digestion of waste activated sludge individually. It was indicated that carbon/nitrogen ratio (C/N) in the mixture of waste activated sludge, fruit waste and cheese whey improved considerably, leading to better anaerobic organisms’ activity during digestion. With assessing the activity of protease and cellulase, as the main enzymes hydrolyzing organic matter in anaerobic digestion, it was indicated that co-digestion of waste activated sludge with mixed fruit waste and cheese whey enhances the activity of these enzymes by 22 and 9% respectively. At the end of digestion, the amount of cumulative methane production significantly increased by 31% in the reactor with 85% waste activated sludge and 15% mixed fruit waste and cheese whey, compared to the reactor with 100% waste activated sludge. In addition, chemical oxygen demand (COD) and volatile solid (VS) in digested sludge was improved respectively by 9 and 7% when mixed fruit waste and cheese whey was used. Conclusions This study revealed that mixed fruit waste and cheese whey is potentially applicable to anaerobic digestion of waste activated sludge, as fruit waste and cheese whey have high C/N ratio that enhance low C/N in waste activated sludge and provide a better diet for anaerobic organisms. This is of significant importance because not only could higher amount of renewable energy be generated from the enhanced methane production in wastewater treatment plants, but also capital costs of the companies whose waste streams are being transported to wastewater treatments plants could be reduced considerably.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Activated carbon / Activated sludge / Air pollution / Alkalinity / Alternative energy sources / anaerobes / Anaerobic co-digestion / Anaerobic digestion / Anaerobiosis / Applied Microbiology / Biochemical Engineering / Biogas / Biomaterials / Biomedical Engineering/Biotechnology / Bioreactors / Biotechnology / business enterprises / capital / Capital costs / Carbon / Carbon/nitrogen ratio / Cellulase / Cheese / Cheese - microbiology / Cheese whey / Chemical oxygen demand / Chemistry / Chemistry and Materials Science / Costs / Dairy products / Dairy products industry / diet / endo-1,4-beta-glucanase / energy / enzyme activity / Enzymes / Fruit - enzymology / Fruit - microbiology / Fruit waste / Fruits / Genetic Engineering / Greenhouse effect / Greenhouse gas emissions / Greenhouse gases / Laboratories / Landfills / Materials recovery / Methane / Methane - metabolism / methane production / Methane production, enzymatic activity / Methods / Microorganisms / Municipal solid waste / Nitrogen / Organic chemistry / Organic matter / Plant Breeding/Biotechnology / Proteases / proteinases / Reactors / Renewable energy / Renewable energy sources / Research Article / Sewage - chemistry / Sewage - microbiology / Sewage treatment / Sludge / Sludge digestion / Studies / Waste activated sludge / Waste Disposal, Fluid - methods / Waste management / Waste streams / Waste treatment equipment / Wastewater / Wastewater treatment / Wastewater treatment plants / Water treatment / Water treatment plants / Whey / Whey - enzymology / Whey - microbiology