Study of the chemical removal of phosphorus at the municipal wastewater treatment facilities of the Samara urban district

Summary

The parameters of the chemical removal of phosphorus from wastewater in Samara have been determined. The studies were carried out by the method of trial coagulation of raw wastewater, primary effluent and mixed liquor from the aeration tanks. It was found that at the same doses of the chemical, the enhanced removal of phosphorus occurs from the sludge mixture. While using aluminum sulfate, the removal of phosphorus phosphates was enhanced by 0.3–1.6 mg/l more than while adding Aqua-Aurat-30TM aluminum polyoxychloride, depending on the initial concentrations. The concentration of residual aluminum in the effluent while using Aqua-Aurat-30TM was on average 8% lower than while using aluminum sulfate – 0.168–0.221 mg/l versus 0.173–0.274 mg/l. Comparative results of the chemical coagulation with the use of flocculants and without them showed that additional dosing flocculant did not result in an increase in the efficiency of phosphorus removal. It was determined that to achieve above 85% treatment efficiency at a phosphorus-phosphate concentration in the mixed liquor of 3.7–5.2 mg/l, a 1.3–1.8-fold excess of aluminum sulfate was required, and at lower concentrations of 1.23– 1.87 mg/l, this efficiency was achieved only with a 3.1–5-fold excess of the chemical. The research results were used in the project of upgrading a tertiary treatment plant at the Samara wastewater treatment facilities, that provided for the chemical removal of phosphorus in addition to the enhanced process of biological removal of phosphorus. The accepted calculated dose of aluminum sulfate 10 mg/l for a commercial product will reduce the concentration of phosphates after the main stage of biological treatment from 0.53 to 0.2 mg/l.

Key words

wastewater , flocculant , sewerage treatment facilities , aftertreatment , chemical phosphorus removal , coagulants

The experience of the North wastewater treatment plant development and upgrade

Summary

The 25-year experience of operating and developing the North wastewater treatment plant in Saint-Petersburg is described. The stages of upgrading the wastewater treatment plant are presented: the first stage – complying with the Helsinki Recommendations on Baltic Marine Environment Protection (HELCOM) with regard to elimination of nutrients (nitrogen and phosphorus) from wastewater; the second stage – step-by-step 100% treatment of municipal wastewater from the combined sewage system by 2015 to comply with the HELCOM regulatory guidelines; the third stage – reduction of the volume and utilization of wastewater sludge. The improvement of the wastewater treatment plant provided for the upgrade of the facilities and equipment for wastewater mechanical treatment, sludge disposal, pretreatment of sludge mix before dewatering and other measures.

Key words

wastewater , nitri-denitrification , aeration tank , grate , grit chamber , sludge incineration , air blower , chemical phosphorus removal

Project for the reconstruction of the tertiary treatment plant
at the wastewater treatment facilities of the city of Samara

Summary

Design solutions implemented by «Samarskie Kommunal’nye Sistemy» LLC on the reconstruction of the tertiary treatment plant of the Samara wastewater treatment facilities were considered and analyzed. The project provides for the chemical removal of phosphorus in addition to biological dephosphotation and filtration of effluents after biological treatment. The chemical phosphorus removal unit has been constructed as a building with a packaged plant inside for the preparation and dosing of aluminum sulfate solution; this layout provides for reducing the heating and ventilation costs of the chemical treatment facilities. The chemical agent is added at twelve points in the sludge mixture flow at the outlet of each aeration tank. The calculated concentration of phosphorus as phosphate in the effluent is 0.2 mg/l; the annual consumption of marketable coagulant is 1545 tons; the purchase unit cost is 0.15 rubles/m³. Tertiary treatment by filtration has been ensured by the reconstruction of eight circular settling tanks with a diameter of 54 m into settler-filters with floating media. Herewith, no construction of new buildings and utilities is required. The calculated concentration of suspended solids in the effluent is 4 mg/l, BOD_full – 3 mg l. The specific energy consumption for the operation of filters with floating media is
0.57 Wh/m³, the cost of electricity – 0.0022 rubles/m³.

Key words

wastewater , sewerage treatment facilities , aftertreatment , chemical phosphorus removal , filter with floating media

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