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UDC 628.336.098.4
Vanyushina A. Ya., Danilovich Dmitrii
Anaerobic digestion – the key technology of municipal wastewater sludge treatment (part 1)
Summary
The technologic options of municipal wastewater sludge treatment are considered with different approach to stabilization of organic matter. The technologic and environmental consequences of raw wastewater sludge landfilling are considered: emission of malodors, dewatered sludge re-thinning that entails re-dewatering are described. 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 decomposition depth. The processes of autothermal thermophilic aerobic digestion and composting that provide for the production of safe and high-quality fertilizer from sludge are considered. It is concluded that the use of these processes is economically limited to the option of land utilization of the entire sludge volume. The issues of domestic approach to digestion that consist in using thermophilic mode with extremely low retention time of sludge in a digester are considered. The largest share of small particles in sludge digested by such technology caused numerous problems with dewatering in 1960–80-ies. The ways of solving these problems at the Kur’ianovo and Liubertsy wastewater treatment facilities in Moscow including the use of advanced dewatering equipment 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, the methods of enhancing the process (thermal hydrolysis, disintegration, ultrasonic, phasing, recycling of digested sludge) are considered. The information on biogas properties is consolidated. (To be continued).
Key words
composting , anaerobic fermentation , sludge , stabilization , thermophilic digestion
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UDC 628.336.098.4
Danilovich Dmitrii, Vanyushina A. Ya.
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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DOI 000000
UDC 628.169
Kofman V. Ya.
Enhancement of biogas generation during anaerobic digestion of excess activated sludge (a review)
Summary
In the process of biological wastewater treatment vast amounts of sludge are generated. Among the methods of sludge handling anaerobic digestion holds a prominent place combining both possible biogas production and prevention of secondary environmental pollution. The rate-limiting stage of anaerobic digestion is hydrolysis. Sludge pretreatment is a common way to increase the rate of hydrolysis and enhance biogas production; developing pretreatment options has been an area of noticeable exploratory activity. Methods of chemical pretreatment (acidic, alkaline, electrochemical oxidation, ozonation, Fenton process, persulfate process, treatment with calcium peroxide), biological pretreatment (two-stage thermophilic/mesophilic process) and physical pretreatment (thermal hydrolysis, microwave treatment, electrokinetic disintegration, ultrasonic treatment, high pressure homogenization) are considered. The patented technologies for pretreatment of wastewater sludge and the main manufacturers of the relative equipment are presented. As an alternative to the traditional anaerobic digestion a microbial electrolysis cell is considered where methane generation during electromethanogenesis occurs in the presence of exoelectrogenic bacteria. A number of wastewater sludge pretreatment technologies are currently available for the implementation on an industrial scale. In this regard, an urgent need in the development of a standardized methodology for analyzing the technical and economic indicators of various anaerobic digestion systems is evident in order to select an optimal option for specific conditions.
Key words
surplus active silt , anaerobic fermentation , thermal hydrolysis , pretreatment , acidic treatment , alkaline treatment , electrochemical treatment , Fenton process , persulfate process , microbial electrolysis cell , electrokinetic disintegration , ultrasonic treatment , homogenization , microwave treatment
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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
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DOI 10.35776/MNP.2019.11.04
UDC 628.336.54
Ponomarenko A. M., Kevbrina M. V., Dorofeev A. G., Nikolaev Yu. A., GRACHEV V. A., KOZLOV M. N., Agarev Anton
Key findings of full-scale tests of a sludge digestion technology
with biomass recycling
Summary
The results of laboratory studies and full-scale tests of the technology of wastewater sludge digestion with biomass recycling are presented. While conducting industrial tests of the technology with biomass recycling an increase in the disintegration of ash-free matter on average up to 56.6% (the value in the control option is 42.2%) was achieved. The disintegration of ash-free matter significantly improved the dewaterability of sludge. The average increase in biogas yield was 3%. During the experiments no negative impact of the sludge recycling technology on the operation of the digester was recorded. The obtained research results allow concluding that the introduction of sludge digestion technology with biomass recycling at the Moscow Wastewater Treatment Facilities is highly promising. Calculations showed that with the introduction of this technology a decrease in the dry matter amount at the outlet of the digesters compared with traditional technology by 9–10% can be expected. The demand for a flocculant for thickening the recycle is minimized by the improved dewaterability of sludge and, thus, the consumption of flocculant during dewatering is reduced.
Key words
anaerobic fermentation , wastewater sludges , sludge thickening , recycle , increase of ash-free matter disintegration
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DOI 10.35776/VST.2022.01.08
UDC 628.355:543.635.355:504.7
Kofman V. Ya.
Upcoming trends of processing waste activated sludge.
Preparation of volatile fatty acids (a review)
Summary
Among the methods of obtaining products with higher added value from waste activated sludge, produced avoiding the emission of greenhouse gases, anaerobic digestion is considered as a viable alternative to biogas production to obtain volatile fatty acids as the final product, that are an intermediate product of methane production in the traditional process. The main factors affecting the production of volatile fatty acids are considered, including pH value, temperature, C/N ratio, process duration, organic matter load of the fermenter, and the presence of microelements. An effective way of increasing the yield of volatile fatty acids is the combined digestion of waste activated sludge and substrates with a high organic carbon concentration (food waste, corn stover, manure, wastewater from dairy and pulp-and-paper production, filtrate from solid waste landfills), as well as pretreatment methods: physical (ultrasonic, microwave, thermal), chemical (alkaline treatment, free nitrous acid, metallic iron, peroxomonosulfate, etc.) and biological (biological surfactants, hydrolytic enzymes, hydrolytic bacteria) ones. The main fields of application of volatile fatty acids are presented including the preparation of medium-chain fatty acids, the production of polyhydroxyalkanoates, protein of single-cell organisms, electricity, hydrogen, as well as the use as a carbon source in the process of biological nitrogen removal.
Key words
surplus active silt , anaerobic fermentation , electric power , volatile fatty acids , polyhydroxyalkanoates , protein of unicellular organisms , medium-chain fatty acids , hydrogen , additional carbon source
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UDC 628.336.6
DOI 10.35776/VST.2024.08.07
Parshikova Marianna, Isakov Vitalii, Nepogodin Aleksandr, Lagutina Elena, Parshikov Stanislav
Improving the efficiency of wastewater sludge treatment process with the use of a biogas unit
Summary
The design of a biogas unit for conducting scientific experiments and training at the basic Department of «Engineering Systems of Housing and Public Utilities» affiliated with MUE «Izhvodokanal» is presented. The results of the experimental studies carried out in 2014 and 2023 focused on producing biogas in a biogas unit are presented. The method for conducting experimental studies is given taking into account the achieved results of the previously conducted experiments focused on producing the maximum volume of generated biogas and potting soil from processed wastewater sludge. The results of other experimental studies during practical training (research work of graduate students) in 2023 are presented. The efficiency of using the biogas unit at the wastewater treatment facilities operated by the water utilities of the Udmurt Republic and enterprises of the agro-industrial complex is stipulated.
Key words
anaerobic fermentation , wastewater sludges , biomass , biogas unit , energy efficient technologies
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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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