Dual-frequency ultrasound (DFUS) has received considerable attention for enhanced inactivation of microbial pathogens for medical treatment, but remains little investigated for water disinfection. This study is focused on inactivation of E. coli and E. faecalis in aqueous solution under dual-frequency ultrasonication at 120 + 1700 kHz using persulfate. Single-frequency ultrasonic inactivation showed the higher efficiency of 1700 kHz, compared to 120 kHz. Under the experimental conditions used, no measurable synergy between two frequencies was observed in the absence of persulfate. A high time-based synergistic effect in terms of total inactivation (5-log) of both bacterial species was achieved by DFUS-activated persulfate with synergistic indices of 1.8–5.0. We assume that this is attributed to increased generation of reactive oxygen species (primarily, sulfate anion (SO₄•⁻) and hydroxyl (•OH) radicals) as a result of enhanced acoustic cavitation. Radical probing and scavenging tests confirmed the generation of radicals and showed a nearly equal contribution of •OH and SO₄•⁻. This method could be an attractive alternative to ultraviolet technology for fast and effective water disinfection.

Relevance. The need to dispose ash and slag waste from CHPP-1 and CHPP-2 in Ulan-Ude, which have a negative impact on the environment. A promising way to eliminate environmental damage is the biological reclamation of ash dumps. Its result is manifested in greening dumps and reducing ash deflation. Aim. To study ash and slag wastes from thermal power plants in Ulan-Ude and establish the possibility of reclamation of ash dumps to reduce the negative impact on the environment. Objects. Ash and slag wastes from the ash dumps of CHPP-1 (ASW-1) and CHPP-2 (ASW-2) in Ulan-Ude. Methods. Chemical, X-ray phase, granulometric, microscopic methods of analysis. Results. The authors have determined chemical, mineralogical and grain compositions of ash and slag wastes from thermal power plants. It was established that they have a high content of silicon, aluminum and a low content of calcium and magnesium. Ash and slag contain vitreous, crystalline and organic components. In the waste, to a greater extent, there is a crystalline phase containing silica, mullite, hematite, magnetite and, to a lesser extent, a glass phase, represented mainly by minerals of the orthoclase group. In terms of granulometric composition, the waste from CHPP-1 is dominated by a finer fraction compared to CHPP-2. Laboratory studies of soil mixtures based on ash and slag waste and local ameliorants (sewage sludge, lignin and chicken manure) were carried out. The optimal ratio of soil components was determined, equal to 4:1:1:1. A beneficial effect of sewage sludge was revealed, as well as a negative effect of high doses of bird droppings on growth and development of plants. Pure ash and slag from CHPP-1 and CHPP-2 without introduction of ameliorants can act as an independent substrate for perennial grasses. Актуальность исследования обусловлена необходимостью утилизации золошлаковых отходов ТЭЦ-1 и ТЭЦ-2 г. Улан-Удэ, которые негативно воздействуют на окружающую среду. Перспективным способом устранения экологического вреда является биологическая рекультивация золоотвалов, результат которой проявляется в озеленении отвалов и снижении дефляции золы. Цель: изучить золошлаковые отходы теплоэлектроцентралей г. Улан-Удэ и установить возможность рекультивации золоотвалов для снижения негативного воздействия на окружающую среду. Объекты: золошлаковые отходы из золоотвалов ТЭЦ-1 (ЗШО-1) и ТЭЦ-2 (ЗШО-2) г. Улан-Удэ. Методы: химический, рентгенофазовый, гранулометрический, микроскопический методы анализа. Результаты. Определен химический, минералогический и зерновой составы золошлаковых отходов теплоэлектроцентралей. Установлено, что они имеют высокое содержание кремния, алюминия и низкое – кальция, магния. Отмечено, что золошлаки содержат стекловидные, кристаллические и органические составляющие. В отходах в большей степени присутствует кристаллическая фаза, содержащая кремнезем, муллит, гематит, магнетит и в меньшей – стеклофаза, представленная в основном минералами группы ортоклаза. По гранулометрическому составу в отходах ТЭЦ-1 преобладает более мелкая фракция по сравнению с ТЭЦ-2. Проведены лабораторные исследования почвенных смесей на основе золошлаковых отходов и местных мелиорантов (осадки сточных вод, лигнин и куриный помет). Определено оптимальное соотношение компонентов почвогрунта, равное 4:1:1:1. Выявлено благоприятное воздействие осадков сточных вод, а также негативное влияние высоких доз птичьего помета на рост и развитие растений. Отмечено, что чистые золошлаки ТЭЦ-1 и ТЭЦ-2 без внесения мелиорантов могут выступать в качестве самостоятельного субстрата для многолетних трав.

The goal of this study is to safely reduce dust emissions from ash dumps and create green landscapes at waste storage sites. The most effective way to achieve this is through revegetation, which allows ash dumps to be transformed into green landscapes. Unlike similar studies, this paper examines the revegetation of a sand-covered ash dump under the extreme conditions of a sharply continental climate. The following perennial plant species were selected: Festuca pratensis, Bromus inermis, and Medicago polymorpha. Laboratory studies revealed that Festuca pratensis was the most adapted to the laboratory conditions in an indoor environment, while Medicago polymorpha showed poor development. The maximum height reached by Festuca pratensis was 0.27 m, Bromus inermis reached 0.23 m, and Medicago polymorpha reached 0.10 m. In the field experiments, over three months of vegetation, maximum plant heights were as follows: Festuca pratensis—0.09 m, Bromus inermis—0.11 m, and Medicago polymorpha—0.30 m. Medicago polymorpha exhibited a higher rate of development compared to the grasses. Thus, revegetating ash dumps from thermal power plants presents a promising solution for creating green spaces, aligning with the principles of sustainable urban development.

The current economic situation and increased attention to environmental protection encourage manufacturers of building materials, in particular ceramic bricks, to look for alternative types of raw materials that make it possible to reduce its cost with good quality of finished products. Mining waste is especially promising, among which peridotites stand out, which have huge reserves and are practically not used. The purpose of the work is to obtain building ceramics with the addition of peridotite and study its mechanical properties.The chemical and mineralogical compositions of raw materials have been determined. Silicon and aluminum oxides account for 78.5% in clay and 61% in peridotites.The latter are characterized by a high content of calcium, magnesium and iron oxides (34.65%). Clay is composed of clay minerals, as well as quartz and feldspar. Tremolite, enstatite and olivine are present in peridotites. The dependence of the mechanical strength of ceramic samples on their firing temperature, the content of the additive and the degree of its grinding has been established. The optimal amount of peridotite is 10%, at which the compressive strength has the maximum value over the entire grinding range of the additive. With an increase in the firing temperature to 1050оC, a slow increase in the strength of the samples occurs. At 1100оC, there is a sharp jump in strength parameters, which increase by 3.6–4.7 times, depending on the granulometric composition of the additive.The main properties of the obtained ceramics were determined. It has been established that peridotites are a promising additive for the production of ordinary bricks with a compressive strength of up to 60 MPa and an average density of up to 2400 kg/m3.