Вестник МГТУ. 2018, том 21, № 1.

Вестник МГТУ. 2018. Т. 21, № 1. С. 80–87. DOI: 10.21443/1560-9278-2018-21-1-80-87 83 Evaluation of EPS flocculating properties has shown the ambiguity of the results of wastewater treatment efficiency (Table 3). Results of the study have indicated that only the bioflocculants obtained due to the EDTA and CH 3 COOH methods purified the wastewater effectively. а b c Fig. 3. Fluorescent staining images of EPS: a – the EDTA method; b – the (NH 2 ) 2 CO method; c – the CH 3 COOH method Рис. 3. Флуоресцентные изображения структуры ВПВ: a – метод EDTA; b – метод (NH 2 ) 2 CO; c – метод CH 3 COOH It should be noted that in the classical case, the reagent treatment of wastewater is mainly aimed at reducing the values of suspended matter and optical density (or turbidity). Reduction of these criteria certainly leads to a decrease in the associated indicators of the content of phosphorus, nitrogen, BOD, COD and other components. For example, wastewater treatment with biofloсculants obtained using the EDTA method is a classic case of reagent treatment with the purification efficiency on the optical density of 27.97 ± 6.1 %, and on the indicator on total suspended solids of 25.78 ± 3.45 %. Bioflocculants obtained with the CH 3 COOH method had the best efficiency of wastewater treatment with respect to the optical density indices – 42.43 ± 6.25 %. It is interesting to note, that in all series of experiments, this type of bioflocculants significantly has reduced the amount of dissolved solids in the wastewater, which is untypical for classical reagents. Thus, the decrease in the content of dissolved solids is 23.35 ± 10.84 %. The result of the purification effectiveness of total suspended solids – 0.1 % – indicates that this type of bioflocculant is poorly "working" with respect to this indicator, which is probably due to the following reasons: either the bioflocculant dose is too small to reduce this indicator, or it is not suitable for this type of wastewater in relation to this indicator. The bioflocculant obtained with the EDTA method purifies wastewater most effectively from total suspended solids. Bioflocculant obtained via the (NH 2 ) 2 CO method, on the contrary, introduces a significant amount of suspended matter to the wastewater. The use of EPS obtained with the technological method (NH 2 ) 2 CO is recognized by the authors as inexpedient for the purification of wastewater from fish processing plants, since all the investigated purification indexes have been unsatisfactory. However, it does not mean that this bioflocculant will not work with other kinds of wastewater, as it happens with most industrial flocculants (and some coagulants) that can "work" only for specific types of wastewater. Table 3. Efficiency of wastewater treatment by EPS Таблица 3. Эффективность очистки сточных вод с помощью биофлокулянтов Constituent Treatment efficiency, % The EDTA method The (NH 2 ) 2 CO method The CH 3 COOH method Total suspended solids 25.78 ± 3.45 0.3 ± 0.24 0.1 ± 0.0 Optical density 27.97 ± 6.1 –0.3 ± 5.19 42.43 ± 6.25 Dissolved solids –3.6 ± 2.7 –4.8 ± 5.6 23.35 ± 10.84