Co-Digestion of Cattle Slurry and Waste Milk under Shock Loading Conditions

Abstract

Anaerobic digestion of cattle slurry has become a well established practice. In recent years disposal of waste milk in the UK has been the cause of many pollution incidents. This paper describes the co-digestion of cattle slurry and waste milk under shock loading conditions in 1 dm3 laboratory digesters. Methane concentration in the biogas of all digesters receiving waste milk additions initially dropped, but quickly recovered to above previous levels. The methane production rate (dm3 methane day~1) was most elevated in those digesters receiving the greatest loading of waste milk ; however, initial depression of biogas methane concentration was also greatest in this system.

Performance and Stability of Two‐Stage Anaerobic Digestion

“…Many parameters have been suggested for monitoring digester performance, each intended to measure an imbalance between hydrolysis/fermentation and methanogenesis after a digester upset has occurred or is occurring. These parameters include gas‐phase methane and carbon dioxide concentration ( Callag han et al, 1997 ), gas production or methane production rates ( Chynoweth et al, 1994 ), pH ( Killilea et al, 2000 ), alkalinity ( Denac et al, 1988 ; Hawkes et al, 1992 ), gas‐phase hydrogen concentration ( Cord‐Ruwisch et al, 1997 ; Weiland and Rozzi, 1991 ), and VFA concentrations ( Ahring et al, 1995 ; Graef and Andrews, 1974 ). These parameters do not provide insight to the metabolic state and capacity of the methanogenic population or an acceptable solids loading rate to maintain a stable operation.…”

Anaerobic co-digestion of a simulated organic fraction of municipal solid wastes and fats of animal and vegetable origin

“…In anaerobic digestion, co-digestion is the term used to describe the combined treatment of several wastes with complementary characteristics, being one of the main advantages of the anaerobic technology. There is abundant literature about the utilization of co-digestion, such as co-digestion of organic fraction of municipal solid wastes and agricultural residues [5,6], organic solid wastes and sewage sludge [7] or more specific wastes [8].…”

Methane production from thermophilic co‐digestion of dairy manure and waste milk obtained from therapeutically treated cows

“…The conversion of butyric acid to acetic acid causes the observed rise in carbon dioxide concentration of the biogas (Callaghan et al . ). However, increasing methane concentrations were observed in all the digesters after 2 days with highest values observing in SM and SMWM10 of both treatments.…”

“…Nevertheless, Callaghan et al . () have reported that the addition of waste milk to a batch anaerobic digestion of cattle manure produced elevated methane production levels, with the highest methane production being observed in digesters receiving the highest loading of milk. This observation also tallied with the current experiment as the maximum waste milk percentage that has been included into the digesters under shock loading conditions was ca.…”

“…Different manure: waste milk ratios were tested with different organic loading rates at 55°C to investigate bio-hydrogen production and observed reduced methane concentration in produced gas with increasing the concentration of waste milk as a co-substrate. Nevertheless, Callaghan et al (1997) have reported that the addition of waste milk to a batch anaerobic digestion of cattle manure produced elevated methane production levels, with the highest methane production being observed in digesters receiving the highest loading of milk. This observation also tallied with the current experiment as the maximum waste milk percentage that has been included into the digesters under shock loading conditions was ca.…”