Nitrogen removal during secondary treatment by aquatic systems

Abstract

Within the context of this study, two lab-scale aquatic plant reactors consisting of duckweed (Lemna minor) ponds, were investigated for the removal of nitrogen forms during the secondary treatment of domestic wastewater. TKN, NH3-N and NO3-N parameters have been measured in both reactors for hydraulic retention times ranging from 3.3 days to 23 days and at various distances from the inlet of reactors. The results were evaluated for hydraulic retention times, hydraulic loading rates and mass loading rates. It was concluded that hydraulic and mass loading parameters were more meaningful than hydraulic retention time. Optimum nitrogen removal values of hydraulic loading rate and mass loading rate were found to be 1.2 cm/day and 90-160 mg TKN/m2-day, respectively. At the higher and lower loading rates, nitrogen removal efficiency was lower than those at optimum conditions. Effluent TKN concentration was around 2.5 to 3.0 mg/l while NH3-N concentration was almost zero at these loading conditions. On the other hand, effluent NO3-N concentrations changed between 7 mg/l to 11 mg/l. When investigating the longitudinal profile, values were reduced rapidly along the reactors. It was concluded that most of the nitrogen conversion occurred at the beginning of the reactor.

Natural Treatment and Onsite Processes

“…Additional experiments are needed locally to validate the model. Two lab-scale duckweed (Lemna minor) ponds were evaluated for nitrogen removal during secondary treatment of domestic wastewater with hydraulic retention times ranging from 3.3 to 23 days (Nalbur et al, 2003). Operational parameters evaluated were hydraulic retention time, hydraulic loading rate, and mass loading rate.…”

Comprehensive Analysis on Elements, Energy Recovery, and Oil Compositions of Biomass Deoxy-liquefaction

“…As for the aquatic plants, the research was much more concerned about their purification capability for domestic sewage and trade effluent than their conversion for energy generation. − Actually, aquatic plants were lignocellulose’s biomass and should also be good candidates for deoxy-liquefaction oil production because of its no fertilization and herbicide requirements, its strong adaptability in harsh climate conditions, and its growth in water and muck with high output. An application of deoxy-liquefaction on aquatic plants conversion (water hyacinth) was proposed for the first time by Lu et al The characteristics of the raw material were given in Table and Figure .…”

Greenhouse gas emissions from ecotechnologies for wastewater treatment

“…Wastewater treatment by two types of WSPs, AFP and DBP, has been studied for the removal of carbon, nitrogen, bacteria and viruses Nalbur et al, 2003;Awuah et al, 2004;Zimmo et al, 2004a;El-Shafai et al, 2007;Johnson and Mara, 2007). However, only a few studies have considered GHG emissions from AFPs and DBPs (Van der Steen et al, 2003a;.…”