Methanogenesis of raw cheese whey: pH and substrate–inoculum ratio evaluation at mesophyll temperature range

Abstract

BACKGROUND Cheese whey is a byproduct of the dairy industry, which is characterized by its high organic matter content, so its valorization by anaerobic digestion (AD) requires a pretreatment or a dilution that allows high values of degradability. However, this increases the cost and duration of whey treatment. In this paper, a study on the viability of anaerobic treatment of a type of crude whey is presented. For it, the effect of pH, substrate–inoculum ratio (S:I) and its interaction during mesophilic AD of raw cheese whey were evaluated. The interactions of the parameters were analyzed by response surface analysis. RESULTS The results showed that in the mesophilic temperature range, the pH most suitable for AD of whey is slightly alkaline (pH = 8). Production and methane yield were improved, increasing the proportion of raw whey, which means that it is possible to operate with high organic loading rate, maintaining adequate operation conditions (pH = 8, T = 40 °C). The best performance of the digester reached 7.1 LCH4 Lwhey−1, and a specific methanogenic activity of 1.15 gCOD gTVSi−1 day−1. CONCLUSION It is possible to use raw cheese whey to produce methane. The alkaline pH and high S:I ratio improved the methane yield and promote methanogenic activity. Intermediate compounds (volatile fatty acids, NH3 and/or H2S) accumulated during the AD operation, which could have influenced the reactor performance; hence, further study is advisable to elucidate their effect on the global process. © 2020 Society of Chemical Industry

Assessment of Single- vs. Two-Stage Process for the Anaerobic Digestion of Liquid Cow Manure and Cheese Whey

“…The fact that alkalinity levels should remain high enough in order to avoid any destabilization and/or acidification by VFAs accumulation should be taken into consideration. Both substrates' characteristics are in accordance with the values that have been published in previous studies [30][31][32].…”

Optimización De Las Variables Del Proceso De Digestión Anaerobia De Lactosuero en La Producción De Biogás

“…Valores inferiores a 6.7 pueden inducir considerable supresión del metabolismo en el proceso de digestión anaerobia, causando efectos negativos en la producción de biogás. Flores et al (2020) reportaron que con un rango de pH de 7.0 a 8.0 en el proceso de digestión anaerobia del lactosuero se obtuvo la máxima producción de biogás y rendimiento de metano. El efecto negativo de valores de pH superiores a 8.0 en la producción de biogás y el rendimiento de metano puede obedecer a que favorecen la formación de subproductos metabólicos que tienen un efecto antagónico en la etapa de metanogénesis (Rajagopal et al 2013) En el cuadro I se comparan los valores máximos de producción de biogás y rendimiento de metano obtenidos a partir de condiciones óptimas con los reportados en otros estudios que usaron lactosuero como sustrato.…”

Anaerobic co-digestion of dairy raw by-products and Ulva sp. macroalgae: effect of organic and inorganic additives

“…During the anaerobic digestion of raw byproducts, it is necessary to add a buffering medium, since the rapid degradation of the soluble compounds causes the pH drop and could compromise the digester stability [30]. Co-digestion of a mixture containing dairy effluents is often responsible of the production of VFA.…”