Dynamic variation in physicochemical properties of activated sludge floc from different WWTPs and its influence on sludge dewaterability and settleability

Zhang, Weijun; Yang, Peng; Xiao, Ping; Xu, Shiwei; Liu, Yuanyuan; Liu, Fei; Wang, Dongsheng

doi:10.1016/j.colsurfa.2014.11.027

Cited by 61 publications

(20 citation statements)

References 26 publications

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“…It was suggested that ferric ions exhibited higher affinity to protein-like substances (Yu et al, 2008). In addition, according to our previous report, protein like substances in SEPS fraction were found to be the main influencing factor of sludge filtration dewatering performance (Zhang et al, 2015c). It is obvious that FeCl 3 conditioning performed better in removal of SEPS due to strong binding strength between ferric ions and protein-like substances, which contributed to improvement of sludge filtration behavior.…”

Section: Fe-sem Analysismentioning

confidence: 93%

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

et al. 2016

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a b s t r a c tThe effects of combined calcium peroxide (CaO 2 ) oxidation with chemical re-flocculation on dewatering performance and physicochemical properties of waste activated sludge was investigated in this study. The evolutions of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was enhanced by calcium peroxide oxidation with the optimal dosage of 20 mg/ gTSS. However, this enhancement was not observed at lower dosages due to the absence of oxidation and the performance deteriorated at higher dosages because of the release of excess EPS, mainly as proteinlike substances. The variation in soluble EPS (SEPS) component can be fitted well with pseudo-zero-order kinetic model under CaO 2 treatment. At the same time, extractable EPS content (SEPS and loosely bound EPS (LB-EPS)) were dramatically increased, indicating sludge flocs were effectively broken and their structure became looser after CaO 2 addition. The sludge floc structure was reconstructed and sludge dewaterability was significantly enhanced using chemical re-flocculation (polyaluminium chloride (PACl), ferric iron (FeCl 3 ) and polyacrylamide (PAM)). The inorganic coagulants performed better in improving sludge filtration dewatering performance and reducing cake moisture content than organic polymer, since they could act as skeleton builders and decrease the sludge compressibility.

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Section: Fe-sem Analysismentioning

confidence: 93%

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

et al. 2016

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“…5 can see that the TB-EPS concentrations conditioned by Al 13 and PAC 2.5 increased again comparing to other aluminum salt coagulants, this also indicated that Al b and Al c showed better performance in compressing EPS structure than Al a , which made SEPS and LB-EPS transfer into TB-EPS, so TP-EPS conditioned by Al 13 and PAC 2.5 increased when SEPS and LB-EPS concentration conditioned by Al 13 and PAC 2.5 decrease, so their TB-EPS concentration was increased. Many studies have demonstrated that sludge filtration property was mainly dependent on properties of SEPS fraction, and the high content of protein in SEPS was always detrimental to sludge filterability (Zhang et al, 2014a(Zhang et al, , 2014b(Zhang et al, , 2015b. In addition, reduction of SEPS concentration contributed to improvement of sludge filterability, it was obvious that PAC with high alkalinity and Al 13 were more effective in removal of SEPS.…”

Section: The Influence Of Hydroxyl Aluminum Conditioning With Differementioning

confidence: 84%

“…This result was in agreement with total EPS content determination. In our previous studies, it was found that sludge dewatering was strongly dependent on concentration of protein-like substances in SEPS (Zhang et al, 2015b), low proteins concentration in SEPS fraction was always related to better dewaterability. This result consisted with sludge dewaterability test.…”

Section: Eps Compositionmentioning

confidence: 99%

Wastewater sludge dewaterability enhancement using hydroxyl aluminum conditioning: Role of aluminum speciation

et al. 2016

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a b s t r a c tChemical conditioning is one of the most important processes for improve the performance of sludge dewatering device. Aluminum salt coagulant has been widely used in wastewater and sludge treatment. It is generally accepted that pre-formed speciation of aluminum salt coagulants (ASC) has an important influence on coagulation/flocculation performance. In this study, the interaction mechanisms between sludge particles and aluminum salt coagulants with different speciation of hydroxy aluminum were investigated by characterizing the changes in morphological and EPS properties. It was found that middle polymer state aluminum (Al b ) and high polymer state aluminum (Al c ) performed better than monomer aluminum and oligomeric state aluminum (Al a ) in reduction of specific resistance to filtration (SRF) and compressibility of wastewater sludge due to their higher charge neutralization and formed more compact flocs. Sludge was significantly acidified after addition Al a , while pH was much more stable under Al b and Al c conditioning due to their hydrolysis stability. The size of sludge flocs conditioned with Al b and Al c was small but flocs structure was denser and more compact, and floc strength is higher, while that formed from Al a is relatively large, but floc structure was loose, floc strength is relatively lower. Scanning environmental microscope analysis revealed that sludge flocs conditioned by Al b and Al c (especially PAC 2.5 and Al 13 ) exhibited obvious botryoidal structure, this is because sludge flocs formed by Al b and Al c were more compact and floc strength is high, it was easy generated plentiful tiny channels for water release. In addition, polymeric aluminum salt coagulant (Al b , Al c ) had better performance in compressing extracellular polymeric substances (EPS) structure and removing sticky protein-like substances from soluble EPS fraction, contributing to improvement of sludge filtration performance. Therefore, this study provides a novel solution for improving sludge dewatering property by controlling aluminum speciation.

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“…(Zhang et al, 2015b). Many studies have demonstrated that sludge filtration property was mainly dependent on properties of soluble EPS fraction, and the high content of protein in soluble EPS was always detrimental to sludge filterability (Zhang et al, 2014b(Zhang et al, , 2015c(Zhang et al, , 2015d. In addition, reduction of soluble EPS concentration contributed to improvement of sludge filterability, it was obvious that TSC 0.5 was more effective in removal of soluble EPS fraction.…”

Section: Fig 4 Effects Of Tscs Dosages On Concentrations Of Differementioning

confidence: 87%

“…Especially, peak B in SEPS and LB-EPS was almost undetectable after TSC 0.5 treatment, revealing that it is very easy to bind with proteinlike substances. In our previous studies, it was found that sludge dewatering was strongly dependent on concentration of proteinlike substances in SEPS (Zhang et al, 2015c(Zhang et al, , 2015d. Therefore, proteins removal was favored for sludge dewatering property improvement under TSCs conditioning.…”

Section: Fig 4 Effects Of Tscs Dosages On Concentrations Of Differementioning

confidence: 99%

Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation

et al. 2017

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a b s t r a c tIn this study, the effects of chemical conditioning using titanium salt coagulants (TSCs) of different hydrolysis speciation in combination with magnetic nano-particles on dewatering performance of waste activated sludge were evaluated by means of specific resistance to filtration (SRF) and capillary suction time (CST). The morphological and extracellular polymeric substances (EPS) properties under chemical conditioning were investigated in detail to understand the reaction mechanisms involved. The results showed that the TSC with basicity of 0.5 performed better in improving sludge dewatering performance than other TSCs. Sludge floc formed by TSC 0.5 treatment was characterized by larger floc size and higher floc strength than that conditioned by other TSCs. EPS compression and densification were the major mechanisms of sludge conditioning, and TSC 0.5 had better performance in compressing EPS structure. In addition, reduction of soluble EPS concentration, especially protein-like substances contributed to improvement of sludge filterability under conditioning. Furthermore, addition of Fe 2 O 3 nanoparticles could further improve dewatering performance and decrease compressibility of sludge system by acting as skeleton builders and enhancing floc strength. The sludge particles aggregation efficiency was effectively improved with addition of nano-Fe 2 O 3 . They also were able to bind with protein-like substance in EPS component, which might contribute to promotion of sludge filterability.

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Dynamic variation in physicochemical properties of activated sludge floc from different WWTPs and its influence on sludge dewaterability and settleability

Cited by 61 publications

References 26 publications

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation

Wastewater sludge dewaterability enhancement using hydroxyl aluminum conditioning: Role of aluminum speciation

Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation

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