SPECIATION OF N AND P THROUGH SOME ANAEROBIC AND AEROBIC STPs

Abstract

Tracing of nitrogen and phosphorus through a treatment plant assists in understanding the mechanisms of transformations of the various forms of nitrogen and phosphorus. The principal forms of nitrogen in wastewater are organic nitrogen, ammonia (NI-14+ or NH3), nitrite (NO2-), and nitrate (NO3-). The usual forms of phosphorus that are found in aqueous solutions include the orthophosphate, polyphosphate, and organic phosphate. In the course of the present study, variations of various forms of nitrogen and phosphorus at different stages of selected treatment processes over a period of five months were studied. Wastewaters were collected from different stages of five UASB (70 ML/d, 56 ML/d, 34 ML/d, 27 ML/d and 38 ML/d) and two (9 ML/d and 32.5 ML/d) oxidation pond based STPs. The samples were analyzed for COD (both filtered and unfiltered), reactive phosphorus, total phosphorus, total hydrolysable phosphate, total kjeldahl nitrogen, ammonical nitrogen, nitrite and nitrate. The different removal efficiencies were observed in UASB and oxidation pond based STPs Removal efficiency in UASB based STPs were observed less because these STPs are based on anaerobic process in which less biomass is formed therefore requiring less nutrients. On the other hand oxidation pond based STPs showed good removal efficiency because these STPs work on aerobic process in which more biomass is formed and hence required more nutrients. The overall removal efficiency of T.P. in UASB based STPs varied between 14.9- 18.5%. Where as removal efficiency of T.P. in oxidation pond based STP varied between 28.07-33.3%. The removal efficiency of TN in UASB based STP varied between 22.4- 28%. Where as removal efficiency of TN in oxidation pond based STP varied between 31.9-33.3%.