Production of Cationic Starch-Based Flocculants and Their Application in Thickening and Dewatering of the Municipal Sewage Sludge.

Polymer flocculants are used to promote solid-liquid separation processes in wastewater treatment technologies, and bio-based flocculants possess many advantages over conventional synthetic polymers. Potato starch microgranules were chemically modified and mechanically sheared to produce modified starch flocculants. The effectiveness of produced cationic starch (CS) and cross-linked cationic starch (CCS) flocculants in the thickening and dewatering of surplus activated sewage sludge was evaluated and compared with that of synthetic cationic flocculants (SCFs) The flocculation efficiency of SCF, CS, and CCS in sludge thickening was determined by measuring the filtration rate of treated surplus activated sludge.

Biodegradation of cross-linked and cationic starches.

The biodegradability and the influence of the degree of substitution of cationic groups or cross-linking level of starch were studied by using enzymatic hydrolysis and two aerobic degradation methods. Cationic starches with a degree of substitution varying from 0 to 0.54 were obtained by modifying native potato starch with 2,3-epoxypropyltrimethylammonium chloride, while cross-linked starches with a degree of cross-linking varying from 0 to 92.