Analysis of the operation of acidifiers after the reconstruction of the block of the Liuberetskie Wastewater Treatment Facilities

Summary

Municipal wastewater in Moscow after primary settling contains insufficient organic matter for the sustainable removal of nitrogen and phosphorus to the standard quality during treatment. Therefore, while designing the reconstruction of the old block of the Liuberetskie Wastewater Treatment Facilities in Moscow, the acidification (prefermentation) method was chosen as the most efficient process solution for enriching wastewater with easily decomposable organic matter (obtaining organic acids during acidic fermentation of raw sludge from primary settling tanks). Upon the completion of the reconstruction of the old LWWTF block at the end of 2021, primary sludge acidifiers were put into operation. Launching acidifiers provided for enriching primary water with easily decomposable organic matter (volatile fatty acids, including acetate) resulting in the improved efficiency of denitrification and biological dephosphorization processes in the aeration tanks. Two or three weeks after the acidifiers had been put into the operation mode, the quality of effluent for nitrogen as nitrates and phosphorus as phosphates was meeting the MPC for fisheries. The process parameters of the acidifiers (hydraulic retention time, residence time for dry matter, the rate of volatile fatty acids formation, the degree of recirculation, the dry matter concentration in the incoming flow) corresponded to those recommended in the literature. Possible situations of abnormal operation of acidifiers have been analyzed and recommendations have been developed to eliminate the causes.

Key words

nitrogen removal , wastewater treatment , acidification , readily available organic matter , prefermentation , phosphorus elimination , process parameters of the acidifiers’ operation

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UDC 628.35:661.63

Belov N. A., Kevbrina M. V., Aseyeva V. G., Gavrilin A. M., Gazizova N. G.

Acidification potential of the incoming wastewater and raw sludge at the Moscow wastewater treatment facilities

Summary

The consistency of biological phosphorus elimination process depends on the readily available organic matter concentration in the incoming wastewater. The concentration of this substance in the wastewater at the Moscow wastewater treatment facilities is not high. Acidification is one of the methods of enhancing readily available organic matter concentration. The production of biologically readily available organic matter (volatile fatty acids) of raw sludge and incoming wastewater at the Kouryanovo Wastewater Treatment Facilities was evaluated in an anaerobic batch-flow reactor at various temperature and time values of prefermentation process. On the basis of the experimental results the techniques of evaluating the availability of the organic compounds for phosphate accumulating bacteria (the technique of evaluating acidification potential) was developed. Acidification potential provides for the assessment of acidification process efficiency for the reduction of phosphate-phosphorus in the effluent.

Key words

acidification , acidification potential , readily available organic matter , prefermentation , phosphorus elimination

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UDC 628.35:004.69

Strelkov A. K., Stepanov S. V., Strelkov D. A., Doubman I. S.

The experience of upgrading wastewater treatment facilities of Zhigulevsk

Summary

The experience of designing, constructing and upgrading wastewater treatment facilities (16,200 m³/day) in Zhigulevsk, Samara Area is described. Prior to the reconstruction the technical condition of the facilities was satisfactory. However, the effluent quality parameters exceeded the maximum permissible levels for BOD, suspended solids, nitrogen compounds, phosphates and oil products. The efficiency of primary settling related to BOD₅ and suspended solids was about 50% resulting in BOD_full: total mineral nitrogen: phosphorus of phosphates ratio changing from 100:12.5:1.7 to 100:21.8:3.16. Despite the deterioration of this primary effluent parameter in the process of nutrients removal it was decided to retain primary settling in the design layout because of the insufficient capacities of the existing aeration tanks. The technology of nitrification-denitrification with anoxic and aerobic zones and chemical phosphorus removal is suggested. The bioreactor capacity was increased 1.5 times by establishing the third process line in addition to the existing ones; besides the construction started from the nitrification-denitrification aeration tank to provide for the sustainable effluent quality for the entire reconstruction period.
For tertiary treatment a filter-bioreactor with a brush head was used. Disinfection is carried out by UV-irradiation in a trough-type unit without changing the gravity effluent flow. The design documentation was approved by the state expertise of the construction projects. By now a considerable part of the facilities has been constructed and put into operation. The successful experience of Zhigulevsk wastewater treatment facilities reconstruction carried out without interruption of wastewater inflow can be overspread among the similar projects in medium-scale cities of the central part of Russia.

Key words

reconstruction , wastewater , biological treatment , nitrification , sewerage treatment facilities , denitrification , phosphorus elimination

UDC 628.2/.4:006.3:349.6
DOI 10.35776/VST.2023.02.02

Danilovich Dmitrii, Frog Dmitrii

The main innovations introduced by Amendment No. 2 to the Code of Practice CP 32.13330.2018 «Sewerage. Pipelines and Wastewater Treatment Plants»

Summary

The main prerequisites for the development of Amendment No. 2 to CP 32.13330.2018, and the tasks facing this work are described. The main innovations introduced by Amendment No. 2 are considered. The principles of synchronization of the system of engineering regulation of wastewater treatment processes with environmental regulation of discharges; clarification of the provisions for determining the estimated wastewater inflows; additions to the subsection on drain stations are described. The main additions and clarifications in terms of wastewater and sludge treatment technologies are described and justified (Chapter 9 of the Code of Practice), namely: updated requirements for intrahour safety factors while calculating channels and flumes; supplemented requirements for reliability in the design of channels of bar screen buildings and the data for calculating the amount of screenings depending on bar spacing; specified conditions for the use of sewage regulators; requirements for the calculation of primary settling tanks, aeration tanks, secondary settling tanks; recommendations for the removal of phosphorus; requirements for the redundancy of sludge dewatering equipment in case of the lack of spare sludge beds; introduced formulas for calculating the pollution of primary effluent; recommendations for sludge acidification from primary settling tanks; requirements for the redundancy of submersible electromechanical equipment of aeration tanks and for the regulation of sludge discharge from secondary settling tanks; detailed recommendations on the use of filtration beds for receiving effluents; the limits of applying mandatory dechlorination while using chlorine and the allowability of using prefabricated units.

Key words

treatment facilities , sewerage , screens , phosphorus elimination , set of rules , dechlorination , primary and secondary settling tanks , pipelines and wastewater treatment plants , municipal (mixed) wastewater , estimated inflow , sewage regulators , drain stations , calculations , aeration tanks , equipment redundancy , sludge acidification , filtration beds , prefabricated units

UDC 628.35:665.666.6
DOI 10.35776/VST.2023.02.06

Kevbrina M. V., Gavrilov Dmitrii, Belov N. A., Agarev Anton

Industrial tests at the Kur’ianovskie Wastewater Treatment Facilities involving the transfer of one primary settling tank into the acidification mode

Summary

In the process of Moscow wastewater treatment primary effluent is lacking enough organic substances for sustainable removal of nitrogen and phosphorus to meet the regulations. One of the methods of enriching wastewater with easily decomposable organic matter is acidification (acid fermentation) of raw sludge. At the Kur’ianovskie Wastewater Treatment Facilities in Moscow industrial testing was conducted at the first new treatment block operating according to the UCT process flow scheme with a design capacity of 600 thousand m³/day on transferring one settling tank into the acidification mode. Of the four settling tanks of the block, raw sludge from the three primary settling tanks operating in the clarification mode was fed to the fourth one operating in the acidification mode. Wastewater flow rate for the acidifier was 30–100% of the flow rate of each of the primary settling tanks, or 11–25% of the water flow rate of the block. The acidified sludge recycling was 100% with respect to the raw sludge flow, or 3% with respect to the mixture of raw sludge and wastewater entering the acidifier. The residence time of the sludge in terms of dry matter (SRT) in the acidifier changed during the experiment from 2 to 3.5 days; the highest treatment efficiency in relation to removing nitrogen and phosphorus compounds was achieved with a residence time of 3.5 days. The hydraulic residence time of wastewater in the settling tank-acidifier (HRT) ranged from 1.9 to 5.5 hours and did not have a noticeable effect on the rate of removing nitrates and phosphorus as phosphates at the next biological stage. The arrangement of the operation of the primary settling tank in the acidification mode showed the presence of the effect of this process that contributed to the additional removal of 3.5 mg/l of nitrogen as nitrate and 0.23 mg/l of phosphorus as phosphate, and provided for the treatment level up to BAT standards. The average concentration of nitrogen as nitrates in the effluent decreased from 11.6 to 8.1 mg/l. For phosphorus as phosphate, before the introduction of acidification at the facilities, the standard effluent quality was provided; however, the enrichment of wastewater in the process of acidification with easily decomposable organic matter contributed to a decrease in the concentration of phosphate phosphorus from 0.35 to 0.12 mg/l. The transfer of one primary settling tank to the acidification mode provided for implementing the acidification process eliminating the construction of acidifiers as separate tanks.

Ключевые слова

nitrogen removal , wastewater treatment , acidification , readily available organic matter , prefermentation , phosphorus elimination , process parameters of the acidifiers’ operation

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