Effective Removal of Cryptosporidium by a Novel Bioflocculant

Extracellular biopolymer produced from Klebsiella terrigena was found to have excellent flocculating ability over a wide range of colloid particles (0.5 to 25μ). The biopolymer was thermostable, with an optimum temperature for flocculation of 30°C. Analysis with Fourier transform infrared spectrophotometry (FT‐IR) shows that the biopolymer mainly possesses hydroxyl, carboxyl, and methoxyl groups, with neutral sugar and uronic acid as its major and minor components, and the structure of a polysaccharide. The average molecular weight of the biopolymer was greater than 2 × 10 3 kilodalton (KDa), as determined by gel permeation chromatography. Scanning electron microscopy indicated a porous morphology of the biopolymer. At a dosage of 2 mg/L, the purified biopolymer could remove 62.3% of Cryptosporidium oocysts (1 × 10 6 ) spiked in tap water samples. Calcium (5mM) was required for effective removal. The removal efficiency of Cryptosporidium oocysts by the biopolymer remained unaltered over a pH range of 6 to 8. The results of this study indicates a possible utility of the Klebsiella terrigena biopolymer as an alternative to typically used chemical flocculants for removal of Cryptosporidium oocysts from water.