Table 3 Correlation between composition of microbial flocculant with its thermal stability, metal ion dependence and flocculating mechanism

Bacillus agaradhaerens

Ps 65.4%, Pr 4.7%, NA 1.6%

3–63

Ca²⁺-independent

Liu et al. (2015a)

Bacillus aryabhattai

Glycoprotein

40–80

Activated by Ca²⁺

Abd El-Salam et al. (2017)

Bacillus subtilis

Ps 88.3%, Pr 10.1%

10–100

Activated by Ca²⁺

Giri et al. (2015)

Bacillus megaterium

Ps 85.5%, Pr 14.3%

10–120

Ca²⁺-independent

Bridging, charge neutralization

Guo and Chen (2017a)

Rhodococcus erythropolis

Ps 95.6%, Pr 4.4%

10–120

Ca²⁺-independent

Bridging, charge neutralization

Guo et al. (2015c)

Diaphorobacter nitroreducens

Ps 73.9%, Pr 24.1%

20–80

Activated by Ca²⁺, Mg²⁺

Charge neutralization

Zhong et al. (2020)

Klebsiella sp.

Ps 84.6%, Pr 11.1%

30–100

Bridging mechanism

Liu et al. (2013)

Bacillus cereus

Ps

30–100

Sajayan et al. (2017)

Aspergillus flavus

Ps 69.7%, Pr 28.5%

5–45

Cation-independent

Charge neutralization

Aljuboori et al. (2015)

Sphingomonas yabuuchiae

Ps 91%, Pr 9%

20–80

Cation-independent

Tang et al. (2014b)

Paenibacillus jamilae

Ps 89.2%, Pr 6.3%

10–100

Zhong et al. (2018)

Bacillus pumilus

Ps 83.1%, Pr 6%

50–100

Required Ba²⁺

Bridging mechanism

Maliehe et al. (2016)

Chryseobacterium daeguense

Ps 13.1%, Pr 32.4%, NA 6.8%

instability

Cation-independent

Attachment and bridging neutralization

Liu et al. (2015c)

Klebsiella sp.

Ps 84.6%, Pr 6.1%

up to 115

Cation-independent

Bridging mechanism

Yin et al. (2014)

Bacillus marisflavi

Ps 74%, Pr 25%, NA 1%

10–100

Cation-dependent

Bukhari et al. (2020)

Paenibacillus polymyxa

Ps 96.2%

30–110

Enhanced by Ca²⁺

Adsorption, bridging, charge neutralization

Guo et al. (2015a)

Bacillus toyonensis

Ps 77.8%, Pr 11.5%

50–80

Increased by Mn²⁺

Okaiyeto et al. (2015a)

Bacillus amyloliquefaciens

Ps 57.12%

Improved by Ca²⁺

Charge neutralization

Sun et al. (2015b)

Bacillus pumilus

Ps 75.4%, Pr 5.3%, NA 15.4%

up to 100

Enhanced by Ca²⁺, Mg²⁺, Mn²⁺

Makapela et al. (2016)

Klebsiella variicola

Ps 81.8%, Pr 15.9%

20–100

Increased by Ca²⁺, Fe²⁺, Mg²⁺, Mn²⁺

Bridging, charge neutralization

Xia et al. (2018)

Chlamydomonas reinhardtii

Ps 48%, Pr 42%, lipids 8.7%

Enhanced by Ca²⁺

Zhu et al. (2012)

Bacillus megaterium

Ps 78.5%, Pr 9.2%, others 12.3%

20–100

Activated by Ca²⁺, inhibited by Al³⁺, Fe³⁺

Bridging mechanisms

Pu et al. (2020)

Pseudomonas aeruginosa

Ps 89%, Pr 27%

100

Improved by Ca²⁺, K⁺, Na⁺, Zn²⁺, Mg²⁺, Cu²⁺; inhibited by Fe³⁺, Al³⁺

Gomaa (2012)