Перспективи використання гідрофітів для попереднього очищення стічних вод в умовах КП «Житомирводоканал»

Abstract

Обґрунтована можливість використання гідробіонтів видів Eichhornia crassipes (Mart.) Solms і Рistia stratiotes L. в гідрофітному очищенні стічних вод Житомирщини. Використання гідрофітного завантаження за усіма дослідженими варіантами показало позитивну тенденцію щодо поліпшення всіх показників якості води, а ефект очищення від забруднювачів за деякими з них становив понад 80 %. Розроблені склади гідрофітного завантаження показали високу стійкість до підвищених концентрацій забруднювачів у воді, а вивчення стійкості макрофітів у подібних експериментальних умовах дає нові додаткові дані, які дозволяють зіставити різні види рослин щодо їх перспективності для використання з метою очищення і доочищення водних об'єктів.

Обоснована возможность использования гидробионтов видов Eichhornia crassipes (Mart.) Solms и Рistia stratiotes L. в гидрофитной очистке сточных вод Житомирщины (Украина). Использование гидрофитной загрузки по всем исследованным вариантам показало положительную тенденцию по улучшению всех исследованных показателей качества воды, а эффект очистки от загрязнителей по некоторым показателям составил более 80 %. Разработанные составы гидрофитной загрузки показали высокую устойчивость к повышенным концентрациям загрязнителей в воде. Проведенные опыты подтвердили, что изучение устойчивости макрофитов в подобных экспериментальных условиях дает новые дополнительные данные, которые позволяют сопоставить различные виды растений с точки зрения их перспективности для использования в целях очистки и доочистки водных объектов. Исследованые виды гидробионтов: эйхорния и пистия рекомендованы для целей фиторемедиации сточных вод.

The article includes the results of the studies of the effect of water purification using hidrophytic loading, and resistance of macrophytes of Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms species to highly polluted water. The study proved their capacity to treat water and defined the high range resistance to pollution. Biological treatment is the most common way to remove organic matter from urban wastewater. Biological treatment plants constitute about 55 % of the total number of treatment facilities. In recent decades the tendency to changing the qualitative composition of the urban wastewater has been observed due to increased the proportion of nitrogen and phosphorus-containing organic compounds, presence of high concentrations of heavy metals, synthetic surfactants and other substances. Many biological treatment facilities were designed in the 1950s and met the environmental standards of that period, but currently due to technical reasons are not able to ensure the adherence to the present day norms of allowable discharges of pollutants into natural water reservoirs, including biogenic elements. Therefore, the development of the techniques aimed at reducing the content of biogenic elements in the biological treatment of urban wastewater has become an urgent task. According to the literature data, the effective method of biogenic elements removal is the use of higher water plants (HWP). There is evidence of the use of certain hydrophytes in the process of biological treatment of municipal wastewater. Higher water plants significantly affect the chemical properties of water and acts as a biological filter in the process of natural self-purification of water reservoirs. Under the conditions of Polissia region in Ukraine, a number of these plants have been grown for further purifying agricultural and residential wastewater. However, environmental, biological and economic properties of hydrobionts have been insufficiently studied under the conditions of Zhytomyr region. Therefore, the study of hydrophyte application presents a considerable economic interest. The study was aimed at testing the hydrophytic wastewater treatment, defining the water purification effect in model laboratory systems, and identifying the most promising hydrobionts, suitable for these purposes. During the research all the indicators showed improvement. In particular, the water transparence rate before loading into the bioreactor was determined as «muddy». In 10-day period its muddiness decreased and the wastewater was characterized as «slightly muddy». Within next fortnight the study showed further improvement of its quality by this indicator and at the end of the study, the water was characterized as «transparent». The content of suspended particles over the entire period of the research tended to reduce. The amount of suspended particles decreased by approximately one-third in the samples with water plants. The reduction of suspended particles was not recorded in the control sample (within 3 %). Under the conditions of the study, the pH of water during all period of the study amounted to 7.0–7.9. The analysis of nitrogen metabolism was performed taking into consideration possible transformation processes of nitrogen forms, because during the whole research period they tended to vary considerably, which is typical of biological treatment facilities. Obviously, this can be explained by the high content of ammonia nitrogen (0.79–0.83 mg/l) at the beginning of the research and its transformation into nitrite later. The reduction of ammonia content was clearly observed in case of aquatic organism cultivation, during the research period it decreased by one third of the total content, while in the control sample the ammonia content remained practically unchanged. The similar increased nitrate amount in all the samples was observed for about a month; later the content began to reduce, which meant that the oxidized forms were assimilated by the hydrobionts. The appearance of oxidized forms of nitrogen indicates a profound process, as their increase with the overall reduction of BOD suggests that carbonaceous compounds are being oxidized. Phosphate consumption by hydrophytes was quite rapid. The phosphate removal comprised about 80–90 %. In the control sample the phosphates fluctuated slightly and their content decreased by 7 %. COD and BOD rates reduced by approximately half with hydrobiont-containing samples, and in the control sample the reduction was 10 %. Iron content in all samples under hydrophytic wastewater treatment also decreased by half. In the control sample iron concentration changed slightly. In the process of hydrophytic treatment, the decrease of the total mineralization of water was rather slow. At the end of the study the reduction of solids in all samples of hydrophytic treatment was approximately at the same level and amounted to 11–12 %, in the control sample this indicator has changed by only 3 %, which is 7–8 % less than in the samples of hydrophytic treatment. The best treatment for anionic surfactants was observed in the sample with plants of E species – 60 %, in other samples it was 40–44 %. The reduction of this indicator in the control sample was not observed. Water hydrophytic treatment techniques, macrophytes of the Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms cultivation, which are resistant to aggressive pollutants contribute to our knowledge of water plants use in wastewater rehabilitation in Zhytomyr region.