title: The problem of dephosphorization using waste recycling.
abstract: The article considers optimizing methods for wastewater treatment systems. Nutrients (nitrogen and phosphorus) are discharged from the river basin of the northwest Russia. Disruption of ecological safety and healthy state of water basins takes place when excess amount of nitrogen and phosphorus is discharged from wastewater. This results in eutrophication that is increased growth of seaweeds and, therefore, in ecological system disruption. The cities of the northwest region are short of funds for renovation of water treatment systems. However, the new solution lies in improvement of biological water treatment system by means of chemical injection. The main research task is implementation of methods for enhanced biological phosphorus removal from domestic sewage. The problem of recycling and ecological safety of rivers within the northwest of Russia and the Baltic Sea is not solved completely. That is why for wastewater dephosphorization, the authors suggest using sulfuric acid production waste at chemical plant "Ammophos," Cherepovets (ferrous sulfate FeSO4·7H2O and phosphogypsum СаSO4·Р2О5), as reagents. The advantage of these reagents is their low cost. The authors show the efficiency of the new optimal reagent's combination. Filtering the wastewater through sand filters after secondary settlers increases the total phosphorus removal efficiency up to 90%. The high effect of all types of phosphorus and total nitrogen removal from wastewater can be resulted from the features of micelle creation during coagulation.
authors.affiliation: Department of Environmental Safety, Saint Petersburg State University of Architecture and Civil Engineering, Vtoraja Krasnoarmejskaja ul. 4, St. Petersburg, 190005, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Smirnova
authors.affiliation: Water Consumption and Ecology Department, Faculty of Engineering Ecology and Municipal Facilities, Saint Petersburg State University of Architecture and Civil Engineering, Vtoraja Krasnoarmejskaja ul. 4, St. Petersburg, 190005, Russia. mikh_alekseev@mail.ru.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Alexeev
mesh_terms: D001454:Baltic States; D002133:Calcium Sulfate; D002947:Cities; D009584:Nitrogen; D010758:Phosphorus; D012426:Russia; D012722:Sewage; D014865:Waste Disposal, Fluid
chemical_list: D012722:Sewage; C077769:phosphogypsum; D010758:Phosphorus; D009584:Nitrogen; D002133:Calcium Sulfate
keywords: Disposal; Environment; Hazards; Pollution; Safety; Sewage treatment; Waste management