TY - JOUR
T1 - Recovery of extracellular biopolymers from conventional activated sludge
T2 - Potential, characteristics and limitation
AU - Li, Ji
AU - Hao, Xiaodi
AU - Gan, Wei
AU - van Loosdrecht, Mark C.M.
AU - Wu, Yuanyuan
PY - 2021
Y1 - 2021
N2 - Extracellular polymeric substances (EPS) are biopolymers that can be recovered from excess sludge, which could contribute to a more sustainable wastewater treatment plant (WWTP) operation. An example is alginate like extracellular polymers (ALE) contained in the biopolymers could be a potential resource with a highly-added value. EPS extraction for ALE from aerobic granules sludge (AGS) has already been well studied and applied in the Netherlands. On the other hand, there is little attention to the recovery of biopolymers from conventional activated sludge (CAS). In this study, flocculent sludge from eight CAS-WWTPs in China was collected and their EPS/biopolymers were extracted to investigate their recovery potential, chemical & physical properties and limiting factors. The results revealed that the biopolymers extracted and purified from CAS ranged from 90 to 190 mg/g VSS. The compositional characteristics of the biopolymers were observed by FT-IR, 3D-EEM and UV-Visible spectra, demonstrating some differences in the composition and property of the biopolymers from the different WWTPs. The biopolymers had a similarity of about 60% to a commercial alginate with respect to chemical functional groups and the alginate equivalent was >400 mg/g biopolymers. Moreover, the biopolymers consisted of poly (guluronic acid) blocks (20%-30%) and poly (guluronic acid-mannuronic acid) blocks (8%-28%), and the ionic hydrogel formation tests indicated that condensed beads were immediately formed once the drops of the biopolymers came in contact with CaCl2 solution. These results demonstrated that the biopolymers extracted had a relatively high gel-forming capacity and might also have a potential application as commercial biopolymers. Furthermore, the factors influencing the biopolymers’ formation such as influent substrate, nutrient content and microbial community and the related mechanisms were investigated. Among them, increasing soluble organics (SCOD) content and low nutrient content (C/N/P) in the influent could promote the biopolymers’ formation. Also, different bacteria in BNR processes might have positive or negative effects on the biopolymers’ formation. In conclusion, the diversity and abundance of bacteria were identified to be a crucial and decisive factor controlling biopolymers’ extraction and composition.
AB - Extracellular polymeric substances (EPS) are biopolymers that can be recovered from excess sludge, which could contribute to a more sustainable wastewater treatment plant (WWTP) operation. An example is alginate like extracellular polymers (ALE) contained in the biopolymers could be a potential resource with a highly-added value. EPS extraction for ALE from aerobic granules sludge (AGS) has already been well studied and applied in the Netherlands. On the other hand, there is little attention to the recovery of biopolymers from conventional activated sludge (CAS). In this study, flocculent sludge from eight CAS-WWTPs in China was collected and their EPS/biopolymers were extracted to investigate their recovery potential, chemical & physical properties and limiting factors. The results revealed that the biopolymers extracted and purified from CAS ranged from 90 to 190 mg/g VSS. The compositional characteristics of the biopolymers were observed by FT-IR, 3D-EEM and UV-Visible spectra, demonstrating some differences in the composition and property of the biopolymers from the different WWTPs. The biopolymers had a similarity of about 60% to a commercial alginate with respect to chemical functional groups and the alginate equivalent was >400 mg/g biopolymers. Moreover, the biopolymers consisted of poly (guluronic acid) blocks (20%-30%) and poly (guluronic acid-mannuronic acid) blocks (8%-28%), and the ionic hydrogel formation tests indicated that condensed beads were immediately formed once the drops of the biopolymers came in contact with CaCl2 solution. These results demonstrated that the biopolymers extracted had a relatively high gel-forming capacity and might also have a potential application as commercial biopolymers. Furthermore, the factors influencing the biopolymers’ formation such as influent substrate, nutrient content and microbial community and the related mechanisms were investigated. Among them, increasing soluble organics (SCOD) content and low nutrient content (C/N/P) in the influent could promote the biopolymers’ formation. Also, different bacteria in BNR processes might have positive or negative effects on the biopolymers’ formation. In conclusion, the diversity and abundance of bacteria were identified to be a crucial and decisive factor controlling biopolymers’ extraction and composition.
KW - Alginate like extracellular polymers (ALE)
KW - Conventional activated sludge (CAS)
KW - Extracellular biopolymers
KW - Extraction
KW - Gel-forming capacity
KW - Microbial community
UR - http://www.scopus.com/inward/record.url?scp=85115924040&partnerID=8YFLogxK
U2 - 10.1016/j.watres.2021.117706
DO - 10.1016/j.watres.2021.117706
M3 - Article
AN - SCOPUS:85115924040
SN - 0043-1354
VL - 205
JO - Water Research
JF - Water Research
M1 - 117706
ER -