| Abstract [eng] |
Generally, synthetic flocculants are used for water treatment, sewage treatment and destabilization of other disperse systems. They are not biodegradable or their degradation products are toxic, and after separation processes, the processing of such waste may be more complicated. Starch, which is biodegradable, its degradation products are environmentally friendly, and is derived from renewable sources, is an excellent source of effective flocculants that can be a suitable alternative to synthetic flocculants usually used in the industry. The aim of the work was to develop an effective biodegradable modified starch flocculant with quaternary ammonium groups which would be suitable for removing negatively charged pollutants and for thickening the municipal sewage sludge. In the work a novel hydromechanical method for obtaining starch flocculants was proposed and the conditions of obtaining an efficient and biodegradable optimal structure ionogenic starch flocculant were selected. The dependence of biodegradability on the degree of substitution of cationic starch derivatives was determined. According to the model systems and municipal wastewater destabilization studies, the flocculation mechanism of new modified starch derivatives was proposed. It was determined that the sheared cross-linked cationic starch derivative is the most suitable for thickening municipal sewage sludge; the floccules resistant to mechanical stress are obtained when using this derivative. A technological scheme for the production of modified starch flocculant was invented. According to this scheme, a prototype of cross-linked cationic starch flocculant was produced in the pilot of equipment and tested in the water treatment company of Lithuania. |
