Enhancing anaerobic digestion of wild seaweed Gracilaria verrucosa by co-digestion with tofu dregs and washing pre-treatment

Abstract

Marine biomass (such as wild seaweed Gracilaria verrucosa) is highly abundant in Indonesia and has been highlighted as a potential biomass resource for bioenergy production. Furthermore, agro-industrial waste (such as tofu dregs/TD which arises from large scale production in the country) is rich in carbohydrates and proteins, and is therefore considered a viable feedstock for production of high-value added products. This study aimed to investigate the co-digestion of wild seaweed G. verrucosa (WGv) with TD and its impacts on biogas and methane production. The biochemical methane potential (BMP) test was operated for 28 days at temperature of 37 o C. The co-digestion of WGv with TD at 90:10 and 80:20 ratios significantly increased the specific methane potential (SMP), giving an average of 98 LCH4/kgVS and 120 L CH4/kgVS, respectively. Addition of co-digestion substrates promoted co-metabolism in the digesters, increasing the ability of the microorganism to effectively digest the organic matter present in the feedstock's mixture. The washing pre-treatment reduced the concentration of inorganic compounds and salts within the wild seaweed G. verucosa, leading to an improvement in biogas and methane yield. The mass balance illustrated that this process configuration led to a reduction in the quantity of digestate to be managed (i.e. dewatering, transport, and land/soil application). This will subsequently reduce the cost and energy requirements for sludge management, estimated at 37%. Therefore, the co-digestion of WGv with TD and the application of a washing pre-treatment stage prior to AD can positively enhance biogas and methane production. Indepth investigation for optimal valorisation using AD technology is highly essential.

Rearing of black soldier fly larvae (Hermetia illucens) as a tool for managing agricultural byproducts

“…Agricultural production generates a large amount of waste and agricultural byproducts. When these conditions are not well managed, they constitute a real environmental problem (Bolong et al 2016;Suhartini et al 2021;Suhartini et al 2022;Hidayat et al 2022). Good management of these agricultural byproducts can not only reduce their negative effects on the environment but also allow transformations that promote their valorization as an input in agriculture.…”

Turning an invasive alien species into a valuable biomass: Anaerobic digestion of Rugulopteryx okamurae after thermal and new developed low-cost mechanical pretreatments

“…low C/N ratio, which led to ammonium accumulation and the subsequent inhibition of the AD process, and the presence of non-degradable compounds (Saratale et al, 2018). In order to avoid these issues, other alternatives such as anaerobic co-digestion or the treatment of the algal biomass before the AD process have been proposed and evaluated (de la Lama-Calvente et al, 2021;Saratale et al, 2018;Suhartini et al, 2022).…”