Zero waste processing of wastewater sludge – production of biocoke

Summary

Municipal wastewater sludge has been dominant anthropogenic waste. The problem of its utilization is typical for any city operating a modern system of wastewater treatment. The tasks of optimal sludge utilization have not been solved on the global scale so far. In European practice different, often non-optimal technical solutions depending on the severity of the national environmental standards are applied. In a number of European countries expensive sludge incinerators have been built that provide for thermal utilization of the bulk sludge volume. The generated energy is used in the central heating systems. This technology is considered the most advanced though up to now it has not been supplemented with a cost-efficient and environmentally substantiated technology of processing generated ash. In Russia the bulk of sludge is landfilled; however, the need of developing efficient and environmentally acceptable technology of sludge utilization has become imminent. Pyrolysis is a possible solution of low waste sludge processing with conversion into a useful product – biocoke. The technologies of pyrolysis organic waste processing have a number of advantages over incineration.

Key words

wastewater , sludge , waste utilization , sludge incinerator , pyrolysis , biocoke

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UDC 628.336.3

Butusov M. M., Komarov A. Iu., Pisarenko S. S., Кудерна Mаксимилиан, Pollak Michael

Zero waste processing of wastewater sludge – production of biocoke

Summary

An optimal method of wastewater sludge utilization has not been found so far. An advantageous method of wastewater sludge utilization (both economically and ecologically) can be production of biocoke – material that meets the following criteria: high concentration of pure carbon (more than 15–30%); low hydrogen concentration (H/C less than 0.2); the lack of organic toxicants; high porosity (about 40%); mechanical stability; good sorption properties. Method of production – pyrolysis at 400–900 °С temperature; raw material – organic wastes of different origin (wastewater sludge, agricultural wastes, milling wastes, poultry farm wastes). Biocoke can be used for soil conditioning, reclamation of solid waste landfills, reclamation of technogenic and abandoned territories for planting, mitigation of land erosion and desertization. Compared to other soil media biocoke has an advantage in the possibility of selecting material properties depending on the specific application. AktivIl Company has designed and commissioned a medium-scale multiple-hearth
pyrolysis reactor with a capacity of approximately 300 tons of biocoke annually; sludge from a wastewater treatment plant in one of the Moscow Area cities has been used as a raw material. Biocoke samples produced at different operating modes were analyzed and tested. The first results of the studies showed the possibility of reaching the required parameters of the product. The studies are going on within the frames of some national and international projects.

Key words

wastewater , sludge , waste utilization , pyrolysis , biocoke

DOI 10.35776/VST.2021.07.06
УДК 006.053:628.1/3

Pupyrev E. I., Shiriaevskii Valerii, Gerasimov Vladislav

Pre-project evaluation of the efficiency of water and sludge treatment facilities

Summary

Designing water treatment facilities has a centuries-old history. At present, the world project community has developed practically unified process flow schemes for natural water treatment to the drinking water quality and domestic wastewater treatment. The professional community practices an intensive exchange of ideas, technologies, and industrial products in the field of water purification. Recently, mathematical methods for calculating module structures have been actively developing, methods of digital (computer) design are used. For complex projects, first of all, pre-project work is carried out. Methods for designing water treatment facilities remain inherently heuristic, and a number of design solutions can be proposed for the same problem statement. The digital design environment provides for tackling new problems, first of all, for designing treatment facilities that are optimal not only in terms of the water quality and other technical parameters, but at the same time, if possible, in terms of the economic efficiency. A method is proposed for the development of a pre-design using multivariate mathematical procedures that allow approaching the optimal combination of technical and financial indicators of the future water treatment facility.

Key words

wastewater , anaerobic fermentation , biogas , methane tank , sludge , sludge cake , process flow scheme of wastewater sludge treatment , финансовая модель , Alt-Invest

DOI 10.35776/VST.2021.10.04
UDC 628.336.7

Markelov Aleksei, Shiriaevskii Valerii, Krivoborodov Iurii, Sheremeta Ignat, Nikitin Vasilii

Test results of a pilot plant for vitrification of sludge

Summary

Ekopromtekh R&D Center, LLC (a resident of the Skolkovo Innovation Center, a member of the Moscow Innovation Cluster) has developed an innovative solution to the problem of utilization of sludge generated during wastewater treatment – the sludge vitrification technology. To prove the working efficiency of the technology, its technical feasibility; to determine the environmental indicators and energy characteristics a pilot plant was designed at the existing Shchelkovo interdistrict wastewater treatment facilities with the support of the Skolkovo Foundation in the Moscow Region. In the process of operating the unit, a number of positive effects of the introduction of the technology were revealed. It is shown that vitrification of wastewater sludge rovides for reducing the volume of waste by 25 times (in relation to pre-dewatered sludge), obtaining a safe vitrified material at the outlet for use in construction. To determine the energy characteristics of the process, an integrated experimental-theoretical approach was used including the comparison of the measurement results with the data obtained in the course of CFD modeling and thermophysical calculations. The environmental safety has been confirmed according to the program developed by NII Atmosfera JSC, the measurements were carried out by the Center for Laboratory Analysis and Technical Measurements of the Central Federal District. During the tests, it was proved that, in contrast to incineration, hazardous emissions of superecotoxicants (dioxins/furans) were completely excluded. The measurements were carried out by the Laboratory of Analytical Ecotoxicology of the Institute of Ecology and Evolution named after A. N. Severtsov of the Russian Academy of Sciences. Instead of ash at the outlet the unit produces vitrified granular material that has been assigned V hazard class on the basis of biotesting. The practical value of the vitrified material has been approved: according to the report of the Tsemiskon Testing Center, cement with the addition of glass granulate as an additive corresponds to Portland cement with additives of CEM II/A type, 42.5H strength class. The vitrification technology has been fully developed for wastewater sludge and is ready for scale-up and commercialization.

Key words

sludge , sludge drying , sludge cake , vitrification , vitrified material , zero landfilling , pilot plant , thermal methods of utilization

DOI 10.35776/VST.2021.07.05
UDC 628.336.7

Markelov Aleksei, Shiriaevskii Valerii, Pupyrev E. I., Sheremeta Ignat, Nikitin Vasilii

The technology of wastewater sludge vitrification in comparison with other processing methodsThe technology of wastewater sludge vitrification in comparison with other processing methods

Summary

The experts of Ekopromtekh R & D Centre, LLC have developed an innovative technology for vitrification of wastewater sludge that provides for reducing significantly the volume of wastes and obtaining a safe vitrified material to be used in construction. A comparison of the vitrification technology with other methods of sludge processing is given: depositing, sludge digestion in digesters, drying, pyrolysis, catalytic and classical incineration. In Russia, more than 90% of the generated sludge is landfilled. If this trend persists, an increase in the sludge hauling distance is inevitable. Using unprocessed sludge as fertilizer increases the risk of soil contamination. Financial models of projects that envisage using digesters and selling biogas or electricity do not pay off. In case of using the drying method to obtain fuel from sludge, almost the same amount of thermal energy is consumed as the final product contains. Therefore, the cost of dried sludge as a fuel will not be less than the cost of natural gas, and taking into account other operating costs, including delivery to the consumer, will exceed the cost of gas by 2–3 times. Pyrolysis to obtain marketable products is under development and involves a lot of research. The technology of catalytic incineration of sludge without preliminary drying does not solve the main problems of any incineration process and causes certain difficulties: the risk of emission of superecotoxicants remains; the ash must be disposed of, the autothermal regime is difficult to maintain, the catalyst wears out and requires replacement. The vitrification technology has a number of advantages, it is ready for scaling and industrial implementation.

Key words

wastewater , methane tanks , incineration , sludge , pyrolysis , sludge drying , sludge cake , vitrification , thermal methods , vitrified material , zero landfilling