Anaerobic digestion – the key technology of municipal wastewater sludge treatment (part 2)

Summary

The technologic options of municipal wastewater sludge treatment are reviewed with different approaches to stabilization of organic matter. The technologic and environmental consequences of raw wastewater sludge landfilling are described. Aerobic sludge stabilization processes are considered. It is concluded that their use is restricted to the options when land utilization of the entire sludge volume is possible. It is shown that traditional aerobic stabilization that was widely used last century does not meet the present day requirements both to power consumption and organics decomposition depth. The aspects of the domestic approach to digestion that consist in using thermophilic mode with extremely low retention time of sludge in a digester are considered. The ways of solving these problems at the Kouryanovo and Lyubertsy wastewater treatment facilities in Moscow are described. It is concluded that in the XXI century anaerobic digestion of wastewater sludge in digesters does not have any other comparable alternative for large and mid-sized wastewater treatment facilities. The main trends in using digestion process, digester design, methods of enhancing the process are considered. The information on biogas properties is consolidated and various options of its utilization are reviewed. Process flow schemes with the use of digesting and combining with other sludge treatment processes (drying, incineration), methods of digested sludge utilization are considered. The information on environmental aspects of digestion – reducing greenhouse gas emissions and carbon footprint – is given. The technologies of purification of return flows of digested sludge dewatering are described. The advanced sludge treatment flow scheme based on digestion and recommended for large-scale facilities is given.

Key words

anaerobic fermentation , sludge , nitrogen , phosphorous , return flows , methane tank , stabilization , biogas utilization , energy budget

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UDC 628.32.004.69

Bagaev Iurii, Veshkurtsev V. M., Gundyreva Tat’iana, Khutornyuk G. N.

Modernization of Sewerage Treatment Facilities

Summary

The basic technical decisions and a description of the new equipment introduced at sewerage treatment facilities of the city of Novosibirsk are presented. It is told about the methods used when repairing pipelines and capacitive facilities. Modernization is carried out at all stages of treatment: at the main pumping station, mechanical and biological treatment facilities, sludge treatment facilities. Measures carried out make it possible to improve the quality of wastewater treatment, to reduce the discharge of polluting substances into the Ob. Modernization of the operating treatment facilities owing to the use of up-to-date equipment made it possible to improve the reliability of operation of the complex as a whole, to reduce the volume of sludge intended to further utilization, to reduce the negative influence on the environment and improve the city ecology.

Key words

sedimentation tank , modernization , intensification , centrifuge , filter-press , sewerage treatment facilities , grate , grit chamber , methane tank , sludge dewatering , thickener

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UDC 628.336.515

KOZLOV M. N., Kevbrina M. V., Kolbasov G. A., Agarev Anton, Shashkina P. S.

The key results of the full-scale studies of sludge digestion technology with biomass recycle

Summary

For a number of years the specialists of R&D Centre of «Mosvodokanal» JSC have been developing and testing in a lab environment the technologies that can enhance the process of wastewater sludge digestion within the existing capacity of the treatment facilities. As a result a method was chosen which provided for thickening a part of sludge with subsequent thickened sludge returning back into the digester. The important advantage of this method is the possibility of increasing sludge retention time as dry matter without increasing the hydraulic retention time with simultaneous biomass retaining. Therefore, the required decomposition rate is provided in smaller size reactors. In the course of studying the process solutions on wastewater sludge digestion optimization the method of biomass recycle showed itself as the most economically viable. During the full-scale studies of the recycle option the decomposition of the ash-free basis increased in average to 56.6% (42.2% reference value) which was confirmed by the significant improvement of sludge dewatering properties. The average biogas yield increased by 3%. In the course of the experimental studies no adverse effects of the sludge recycling technology on the digester performance were observed. The results obtained during the full-scale studies evidence the long-term benefits of introducing the technology of wastewater sludge digestion with biomass recycle at the Moscow wastewater treatment facilities.

Key words

anaerobic fermentation , methane tank , decomposition of organic matter , biomass , sludge thickening , recycle

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

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UDC 628.336.5.004.18

Rublevskaya O. N., Melnik E. A.

Tackling the problem of energy saving in the Saint-Petersburg wastewater system

Summary

The technologies of primary and secondary sludge treatment at the Saint-Petersburg wastewater treatment facilities are considered. The technologies of thermal hydrolysis and thermophilic and mesophilic digestion were suggested by European companies PWT (Germany), Veolia (OTV, France) and Cambi (Norway). Implementing the project of using the energy potential of wastewater sludge will allow Saint-Petersburg Vodokanal PUE to gain unique experience of systematic approach to the solution of sludge utilization problem.

Key words

sludge , fermentation , biogas , methane tank , mesophilic process , thermophilic process , thermal hydrolysis

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