2010 journal article

Stable thermophilic anaerobic digestion of dissolved air flotation (DAF) sludge by co-digestion with swine manure

BIORESOURCE TECHNOLOGY, 101(9), 3020–3024.

By: K. Creamer*, Y. Chen*, C. Williams n & J. Cheng n 

co-author countries: United States of America πŸ‡ΊπŸ‡Έ
author keywords: Anaerobic digestion; Manure; Thermophilic; Dissolved air flotation
MeSH headings : Air; Anaerobiosis; Animals; Biodegradation, Environmental; Bioreactors / microbiology; Environmental Restoration and Remediation / methods; Manure / analysis; Methane / analysis; Sewage / microbiology; Solubility; Swine; Temperature
Source: Web Of Science
Added: August 6, 2018

Environmentally sound treatment of by-products in a value-adding process is an ongoing challenge in animal agriculture. The sludge produced as a result of the dissolved air flotation (DAF) wastewater treatment process in swine processing facilities is one such low-value residue. The objective of this study was to determine the fundamental performance parameters for thermophilic anaerobic digestion of DAF sludge. Testing in a semi-continuous stirred tank reactor and in batch reactors was conducted to determine the kinetics of degradation and biogas yield. Stable operation could not be achieved using pure DAF sludge as a substrate, possibly due to inhibition by long-chain fatty acids or to nutrient deficiencies. However, in a 1:1 ratio (w/w, dry basis) with swine manure, operation was both stable and productive. In the semi-continuous stirred reactor at 54.5 degrees Celsius, a hydraulic residence time of 10 days, and an organic loading rate of 4.68 gVS/day/L, the methane production rate was 2.19 L/L/day and the specific methane production rate was 0.47 L/gVS (fed). Maximum specific methanogenic activity (SMA) in batch testing was 0.15 mmoles CH(4) h(-1) gVS(-1) at a substrate concentration of 6.9 gVS L(-1). Higher substrate concentrations cause an initial lag in methane production, possibly due to long-chain fatty acid or nitrogen inhibition.