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Date submitted2024-03-29
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Date accepted2024-06-03
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Date published2024-07-04
Potential use of water treatment sludge for the reclamation of small-capacity sludge collectors
- Authors:
- Olga M. Guman
- Irina A. Antonova
In small settlements, collectors for the sludge produced during water treatment processes are small-sized and located in the vicinity of drinking water storage reservoirs or in coastal areas. Sludge removal is not economical. Besides, the relief depressions formed after sludge disposal are required to be reclaimed. In ore mining regions, where the main settlements of the Urals are located, sludge produced in water treatment has high contents of heavy metals typical of ore mining provinces. Consequently, places of sludge accumulation are potential sources of water pollution. The article discusses the possibility to mix sludge with slaked lime and local overburden with the help of special equipment. So far water treatment sludge in the region has been used to reclaim the surface of solid waste landfills by creating anaerobic conditions for waste decomposition. When placed inside the embankment dams as an independent object, sludge needs to be improved for the increase of its bearing capacity and the ability to bind heavy metals. The article aims at the substantiation of the composition and properties of the reclamation material made of the water treatment sludge mixed with local overburden and slaked lime (technosoil). For this reason the paper describes the composition of the sludge in a sludge collector, the composition and properties of the overburden rocks as a component of the mixtures with water treatment sludge, the composition and properties of the mixtures of water treatment sludge with overburden rocks and Ca(OH)2 as a component dewatering sludge and neutralizing toxicants. Furthermore, the research work provides the technology created for the optimal processing of the water treatment sludge in the process of the reclamation of a sludge collector. The research results and the experience obtained in reclamation of disturbed lands in the region have confirmed the possible use of technosoil for the reclamation of small-capacity sludge collectors. The analysis of the chemical composition and physical and mechanical properties of the mixtures under study has shown that the most economical and environmentally sound reclamation material is a mixture of water treatment sludge, loose overburden dump soils and Ca(OH)2 in a ratio of 60 : 30 : 10 %.
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Date submitted2024-04-22
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Date accepted2024-06-13
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Date published2024-07-04
Comprehensive utilization of urban wastewater sludge with production of technogenic soil
The article presents the analysis of the existing approach to wastewater sludge treatment and justifies the selection of the most promising management technology that allows maximum use of wastewater sludge resource po-tential. To obtain a useful product (biocompost) suitable for use as part of technogenic soil, experimental studies of aerobic stabilization of organic matter of dehydrated urban wastewater sludge with the addition of other waste by using passive composting technology were carried out. The technology is included in the list of best available technologies (BAT). The selection of the most optimal components for the mixture was based on the results of determining the C and N content, humidity and pH of the components used that ensured the composting of organic waste. The results of laboratory studies of the obtained biocompost according to the main agrochemical and sanitary-epidemiological indicators are presented. Testing was carried out according to the criterion of toxicity of the biocompost’s aqueous extract. The assessment of the technogenic soil was performed when using biocompost in its composition for compliance with existing hygienic requirements for soil quality in the Russian Federation. Based on the results of the vegetation experiment, optimal formulations of the technogenic soil were determined, i.e., the ratio of biocompost and sand, under which the most favorable conditions for plant growth are observed according to a combination of factors such as the number of germinated seeds, the maximum height of plants and the amount of biomass. The conducted research makes it possible to increase the proportion of recycled urban wastewater sludge in the future to obtain soils characterized by a high degree of nutrient availability for plants and potentially suitable for use in landscaping, the biological stage of reclamation of technogenically disturbed lands, as well as for growing herbaceous plants in open and protected soil.
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Date submitted2018-05-14
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Date accepted2018-07-15
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Date published2018-10-24
Experience of Integrated use of gold-bearing raw material in the production of precious metals
- Authors:
- V. V. Zhmurova
- N. V. Nemchinova
With the depletion of rich gold-bearing ores, the processing started to use polymetallic ores, which, in addition to precious metals, contain other elements that could be valuable after recovery. The problem of using such ores is extremely difficult because of the high cost of recovery of associated valuable components. The paper presents the results of studies on the integrated use of extracted gold-bearing raw materials based on the example of the Berezitovoye deposit (Amurskaya oblast), they have low content of precious metals and many heavy non-ferrous metals (copper, lead). Experimental work was carried out to obtain copper by the method of cementation from solutions formed after the leaching of the impurities of gold-containing cathode deposits with hydrochloric acid. The cementing metal was iron turnings (waste products of the turning shop of the enterprise). Next, it was proposed to use cemented copper as a collector during re-melting of slags – wastes of processing of low-grade polymetallic ores containing precious metals. The authors obtained ingots of alloyed gold with gold weight fraction of 16 %, which meets the requirements of TU 117-2-7-75 on the content of non-ferrous metals. During hydrochloric acid treatment of cathodic deposits silver partially passed into the solution, it was recovered together with cemented copper and, in subsequent melting, passed into alloyed gold. Thus, the method proposed by the authors helps to reduce the content of precious metals in the «incomplete production cycle» of the gold recovery factory. The opportunity of selling the cementation copper at the enterprises specializing on manufacturing of jewels is shown; the expected economic effect at the same time amounted to more than 1.8 million rubles.