Biochemical methane potential trial of terrestrial weeds: Evolution of mono digestion and co-digestion on biogas production

Abstract

Parthenium hysterophorus, Lantana camaraandAgeratum conyzoidesare considered among the world’s top twenty notorious terrestrial weeds due to their reproduction potential and hazardous nature. They can grow within a few weeks and cover entire agricultural land (Parthenium hysterophorus), forest land(Lantana camara)and native vegetation (Ageratum conyzoides).These terrestrial weeds are difficult to manage as they re-grow miraculously even after being completely obliterated. The availability ofParthenium hysterophorus,Lantana camaraandAgeratum conyzoidesin abundance make them attractive feedstock for anaerobic digestion process. Anaerobic co-digestion ofParthenium hysterophorus,Lantana camaraandAgeratum conyzoideswere performed using cow dung as inoculum and food waste as co-substrate and compared with their anaerobic mono-digestion process. The mono-digestion process resulted in lower biogas yield due to the accumulation of toxic inhibitors. Co-digestion studies are essential to balance nutrients and dilute toxic inhibitors. Different food/microorganisms (F/M) ratios (0.5, 1.0, 1.5. 2.0, 2.5 and 3.0) were optimized for the comparison of mono-digestion and co-digestion ofParthenium hysterophorus,Lantana camaraandAgeratum conyzoidesthrough1L biochemical methane potential batch assays. Due to co-digestion with food waste, biogas yields forParthenium hysterophorus, Lantana camaraandAgeratum conyzoidesincreased by 17.86%, 10.5% and 15.17% respectively. The reactors were scaled up to 20L capacity to evaluate the spike in biogas yield for the weeds through a daily-fed two-stage anaerobic digester and the enhancement of biogas through anaerobic co-digestion process forParthenium hysterophorus,Lantana camaraandAgeratum conyzoideswere examined to be82.9%, 73.3% and 83.01% respectively compared to the mono-digestion process. Operation of a two-stage anaerobic digester showed successful augmentation of biogas production from these noxious terrestrial weeds through the anaerobic co-digestion process with food waste.