Rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H2O2 pretreatment

Abstract

a b s t r a c tThe rheological behavior of sludge is of serious concern in anaerobic digestion. This study investigated the rheological properties of sewage sludge during enhanced anaerobic digestion with microwave-H 2 O 2 pretreatment (MW-H 2 O 2 ). The results showed that MW-H 2 O 2 pretreatment resulted in the improvement of sludge flowability and weakening of its viscoelastic properties. Further positive effects on the rheological properties of digested sludge during anaerobic digestion were observed. The flowability was improved with a low level of apparent viscosity. The decrease of the consistency index and increase of the flow behavior index indicated that the strength of the inner structures and non-Newtonian flow characteristics of digested sludge weakened. Both the storage modulus (G 0 ) and loss modulus (G 00 ) decreased, indicating that the viscoelastic behavior became weak. These effects were possibly attributed to the changes of the digested sludge micro-structures, such as extracellular polymeric substances (EPS). This study concluded that anaerobic digestion for treating sewage sludge combined with pretreatment is a more favorable option than single anaerobic digestion from the perspective of rheology.

Profiles and drivers of antibiotic resistance genes distribution in one-stage and two-stage sludge anaerobic digestion based on microwave-H2O2 pretreatment

“…The detailed MW-H 2 O 2 pre-treatment process was described elsewhere (Liu et al, 2015a). Briefly, NaOH solution at 5 M was firstly added to adjust pH of the raw sludge to 10.0, and then the sludge was heated to 80°C by microwave irradiation for inhibiting activity of catalase which is present in aerobic living cells to avoid the decomposition of H 2 O 2 by the catalase that exists in the sludge (Liu et al, 2016a;Wang et al, 2009). After that, H 2 O 2 (30%, w/w) was added at a dosage of 0.2 g H 2 O 2 / g TS as suggested previously (Wang et al, 2009).…”

Enhancing sludge biodegradability through free nitrous acid pre-treatment at low exposure time

“…It is well known that methane production (MP) from waste activated sludge (WAS) is often limited by the slow fermentation rates (hydrolysis and acidification) and its poor biochemical methane potential (BMP) [1][2][3][4][5][6][7][8][9][10]. To overcome this, recent research has been focusing on developing a novel, attractive and economic pre-treatment for WAS based on free nitrous acid (FNA) [6,7,[11][12][13][14].…”

Synergy of combined free nitrous acid and Fenton technology in enhancing anaerobic digestion of actual sewage waste activated sludge

“…Anaerobic digestion of waste activated sludge is often restricted by poor biochemical methane potential, low biodegradability and slow fermentation process 7 . In order to address these issues, various strategies have been employed in recent studies.…”