Impact of influent inorganic nitrogen on nitrate removal efficiency of submerged plant microcosms

Author： Weragoda S. K. Tanaka Norio Jinadasa K. B. S. N. Sasaki Yasushi

ISSN： 0275-7540

Source： Chemistry and Ecology, Vol.25, Iss.3, 2009-06, pp. : 179-188

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Abstract

Even though many studies have focused on identifying the effects of NH[image omitted] -N on various aspects of wetland systems, there have been very few attempts to quantify the overall impact of NH[image omitted] -N concentration on NO[image omitted] -N removal efficiency. Consequently, this research was conducted to investigate the effects of influent NH[image omitted] -N (2-10 mgl-1) and NO[image omitted] -N (2-6 mgl-1) concentrations on NO[image omitted] -N removal efficiency and growth inhibition concentrations of Egeria densa Planch. Mass balance for NH[image omitted] -N removal was done to quantify the nitrified NH[image omitted] -N in order to incorporate total NO[image omitted] -N concentration for the non-linear regression analysis. The NO[image omitted] -N and total nitrogen removal efficiencies were significantly varied at three different NO[image omitted] -N concentrations (p<0.05). data="" on="" oxygen="" consumption="" during="" dark="" respiration="" (0.25-0.48 mgl-1 hr-1 g-1="" of="" dry="" weight="" biomass)="" and="" final="" biomass="" (0.17-0.24 g)="" variations="" revealed="" that="" the="" lowest="" growth="" inhibition="" concentration="" of="" nh[image="" omitted] -n="" on="" e.="" densa="" could="" be="" 4 mgl-1.="" non-linear="" regression="" analysis="" established="" a="" positive="" correlation="" (r2="0.97)" between="" influent="" nh[image="" omitted] -n="" concentration="" and="" no[image="" omitted] -n="" removal="" efficiency="" within="" the="" analysed="" range="" of="" nh[image="" omitted] -n="" (0-4 mgl-1).="" results="" suggest="" that="" no[image="" omitted] -n="" removal="" efficiency="" in="" submerged="" plant="" wetland="" systems="" could="" be="" improved="" by="" adding="" sufficient="" amounts="" of="" nh[image="" omitted] -n="" to="" secondary="" treated="" wastewater.="">