Phosphorus release from sediments of a deep wastewater stabilization pond

The fractional composition and potential mobility of particulate phosphorus was investigated in sediment from a deep wastewater stabilization pond. Th e predominant phosphorus fractions were Fe- and At-bound P (NaOH-RP) and Re sidual-P (consisting mainly of organic P), which amounted to 35 and 34% of total phosphorus, respectively. A laboratory study was conducted to determi ne the influence of various environmental parameters (pH, redox conditions, biological activity and temperature) on phosphorus release from lagoon sed iment. Phosphorus release was observed under both anaerobic and aerobic con ditions. Anaerobic release was about 1.4-5 times greater than aerobic relea se. Phosphorus release was redox-sensitive and favoured by high pH values, up to 17.4% of total phosphorus being liberated anaerobically and at high p H. Biological activity favoured phosphorus release. since the amount releas ed under non-sterile conditions exceeded that observed under sterile condit ions. Sediment phosphorus was fractionated before and after the release experimen ts. The NaOH-RP fraction was sensitive to pH and redox environmental change s, and was readily released under reduced conditions and at high pH. The mo bility of the Residual-P fraction was enhanced in incubations involving bio logical activity due to the decomposition of the organic matter in the sedi ments, and NaOH-nRP (organic phosphorus) decreased by up to 45% during the incubation of non-sterile suspensions.