Showing papers on "Enhanced biological phosphorus removal published in 1979"

Removal of phosphorus from sewage

Abstract: PURPOSE: To activate the phosphorus metabolism of microorganisms and to remove phosphorus from sewage at a high efficieny, by mixing the sewage with a recycled sludge, adding Na 2 S to the mixture, and then subjecting the mixture to an anaerobic treatment followed by an aeration treatment. CONSTITUTION: A sewage 1 to be treated is mixed with a recycled sludge 2 in the anaerobic treatment vessel 3, to which is added Na 2 9 and maintained in the vessel 3 for a predetermined period. The addition of Na 2 S enhances the anaerobic character of the vessel 3, which is detected by measuring an oxidation reduction potential in the vessel 3. The Na 2 S is added at such a rate that the oxidation-reduction potential is maintained at lower than +100mV. After the anaerobic treatment in the vessel 3, the solution mixture is carried to an aeration vessel 4 and subjected there to a usual aeration treatment using activated sludge. The oxidation- reduction potential in the vessel 3 is usually +250mV or more, under which microorganisms absorb phosphorus and accumulate therein. Therefore, after the separation of solid from the aerated solution in the precipitating vessel 5, the phosphorus content of the treated solution 6 is extremely lowered, while a large amount of phosphorus is accumulated in the excessive sludge 8 and discharged outside the system. The recycled sludge 2 is recycled to the vessel 3 and treated again. COPYRIGHT: (C)1981,JPO&Japio

Kinetics of phosphorus transformations in aerobic and anaerobic environments

Abstract: In the activated sludge treatment of sewage phosphorus accumulation by certain aerobic organisms occurs initially at a rapid rate followed by much slower uptake. The inclusion of an anaerobic zone in the plant configuration position prior to the aeration basin is a prerequisite and the conditions prevailing in this basin are shown to influence the mass of phosphorus removed during the rapid accumulation period. The design of three new 150 000 m 3 /d plants in Johannesburg incorporating a degree of flexibility whereby conditions in the anaerobic zone can be altered to improve and/or maintain good phosphorus removal, is discussed.

Decontamination of water containing organics and phosphorus

Abstract: PURPOSE: To separate organics and phosphorus from water at a high efficiency, by charging an activated sludge to water containing organics and phosphours, and subjecting the water to an aerobic treatment followed by an anaerobic treatment to separate phosphorus as a culcium compound. CONSTITUTION: Raw water 6 is introduced with a returned sludge 7 to an aeration vessel 1, and subhected there to an aeration treatment, by which organics are decomposed by bacteria and phosphorus is absorbed by the bacteria. The treated solution is separated to a solid part and a liquid part in a precipitation vessel 2. An extracted sludge 9 is carried to a phosphorus discharging vessel 3, where a solution is kept at pH about 6W9 and agitated slowly in an anaerobic atmosphere. The bacteria consume phosphorus contained therein and discharge phosphate ions. The phosphate ions are separated as precipitations by the addition of a calcium compound 11. The treated solution is separated to a solid part and a liquid part in a separation vessel 4. The sludge 7 is returned to the aeration vessel 1. The liquid part 13 is carried into a precipitation vessel 5 where the liquid part comes in to contact with crystal seeds containing calcium phosphate in the presence of calcium ions to separate the phosphate ions. COPYRIGHT: (C)1981,JPO&Japio

The Technological Conditions for the Development of Acinetobacter for Phosphorus Removal

Abstract: A simplified suspended growth integrated system with an anaerobic zone in front of the aerobic one was used for the development of the bacterium Acinetobacter for phosphorus removal. The pilot plant experimental equipment was built at the Prague municipal works. The tests were carried out on a comparative basis, the control system was operated as a completely mixed activated sludge process. In the integrated system a to phosphate removal of 80 to 86% was achieved only in a biological way. In the control system, there was no development of Acinetobacter and the biological phosphate removal was only 5%. To rise it to the extent comparative with the integrated system, high doses of ferric chloride for a simultaneous precipitation of phosphate were required. The results obtained showed that the strictly biological process in the integrated system could meet normal practice requirements, even though it is not able to compete with the simultaneous phosphate precipitation using high coagulant dosages as for as the attainable efficiency and higher values of the sludge index are concerned.