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

For citation: Kevbrina M. V., Gavrilov D. V., Belov N. A., Agarev A. M. Industrial tests at the Kur’ianovskie Wastewater Treatment Facilities involving the transfer of one primary settling tank into the acidification mode. Vodosnabzhenie i Sanitarnaia Tekhnika, 2023, no. 2, pp. 46–52. DOI: 10.35776/VST.2023.02.06. (In Russian).

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