Showing papers on "Enhanced biological phosphorus removal published in 1971"

Phosphorus availability and nitrogenase activity in aquatic blue‐green algae

Abstract: SUMMARY Metabolically active phosphorus-starved cultures of blue-green algae assimilate 32P rapidly in the light and in the dark. The uptake of phosphorus results in a rapid (within 15 min) stimulation in acetylene reduction by Anabaena cylindrica, A. flosaquae, Anabacnopsis circuiaris and Chlorogloea fritschii, with a response being obtained to less than 5 μg/1 of phosphorus. Uptake of phosphorus also causes a rapid increase in respiration in the dark but not in photo respiration, and the size of the cellular ATP pool and the 14CO2 fixation rate both increase more slowly. The metabolism of phosphorus-sufficient cells, which assimilate phosphorus more slowly, shows little response when phosphorus is provided. Excess phosphorus is stored in the vegetative cells of blue-green algae as polyphosphate bodies which may form within 60 min of adding phosphorus to phosphorusstarved cells and which serve as a source of phosphorus for the algae when exogenous phosphorus is limiting. Preliminary results from Scottish waters suggest that urban effluents are important sources of available-phosphorus for algal growth and that the levels entering fresh waters from agricultural land are, per unit volume, lower. In both types of water the levels of available-phosphorus are rather similar to the levels of orthophosphate-phosphorus present. Most detergents tested serve as a source of phosphorus for nitrogen-fixing blue-green algae and cause a rapid stimulation in reduction when added to phosphorus-starved cultures. Of the detergents assayed, the biological types were richest in available phosphorus. The addition of detergents may result in a rapid increase in number of polyphosphate bodies present in the algae. Detergents in general also contain an inhibitor of algal metabolism. Whether a stimu-lation or an inhibition occurs depends on the quantities of detergent added and on whether or not the alga is phosphorus-deficient.

Sewage treatment process

Abstract: A continuous sewage treatment process for upgrading the quality of sewage plant effluent by converting sewage sludges to active substances and returning these active substances to the sewage system whereby removal of dissolved contaminants occurs by the addition of the active substances.

Anaerobic Digestion of Sludges Containing Iron Phosphates

Abstract: The phosphorus removals can be enhanced by precipitating bulk of the phosphorus with cation addition to the existing plants without costly alterations Ferrous-iron was used to precipitate bulk of the phosphorus from raw waste water in the form of primary sludge and in aeration tanks in the form of waste activated sludge The digestibility and the fate of phosphorus during the anaerobic digestion of such sludges was evaluated in bench scale studies and compared with those of corresponding control sludges containing very little or no iron precipitated phosphorus The presence of iron in the sludge up to about 5% iron on the dry solids basis did not upset or affect the performance of the gas mixed digestion units A significant release of phosphorus occurred on the anaerobic digestion of waste activated sludge containing high amounts of ferrous-iron precipitated phosphorus, while a significant uptake of phosphorus was observed on the digestion of primary sludge containing ferrous-iron precipitated phosphorus

Internal precipitation of phosphate from activated sludge

Abstract: THERE IS DISCLOSED AN ACTIVATED SLUDGE SEWAGE TREATMENT PROCESS IN WHICH INFLUENT SEWAGE MATERIAL IS MIXED WITH ACTIVATED SLUDGE CONTAINING PRECIPITATED PHOSPHATE PARTICLES TO PROVIDE A MIXED LIQUOR. THE MIXED LIQUOR IS AERATED TO CAUSE THE MICRO-ORGANISMS PRESENT IN THE SLUDGE TO TAKE UP PHOSPHATE. PHOSPHATE-ENRICH SLUDGE IS SEPARATED FROM THE MIXED LIQUOR TO PROVIDE A SUBSTANTIALLY PHOSPHATE-FREE EFFUENT. THE PHOSPHATE-ENRICHED SLUDGE IS TREATED TO CAUSE THE MICRO-ORGANISMS IN THE SLUDGE TO RELEASE PHOSPHATE TO THE LIQUID PHASE AND A PHOSPHTE PRECIPITANT IS ADDED TO PRECIPITATE THE WATER SOLUBLE PHOSPHATE CONTENT. THE SLUDGE CONTAINING THE PRECIPITATED PHOSPHATE PARTICLES IS RECYCLED FOR MIXING WITH INFLUENT SEWAGE MATERIAL.