Abstract—This study investigates the adsorption characteristics of sawdust for removing nutrients (e.g., NH 3 -N, NO 3 -N, and NO 2 -N) from stormwater. A series of laboratory batch experiments was performed and the effects of different parameters on nutrient adsorption were observed. The parameters of concern include: initial concentration (0.5-5mg/L) and dosage (2-20mg of dry sawdust). Results revealed that the maximum removal was obtained at lower initial concentration. An increase of adsorbent dosage increased the percent removal of NH 3 -N, NO 3 -N, and NO 2 -N. The maximum removal of NO 3 -N, and NO 2 -N was found 100%, while NH 3 -N removal was found 55%. The sorption of sawdust was characterized by Langmuir and Freundlich isotherm and the results show that the correlation coefficient of applicability (R 2 ) of Freundlich model (R 2 = 0.8324, 0.9856, and 0.9231 for NH 3 -N, NO 3 -N and NO 2 -N respectively) fits better than Langmuir (R 2 = 0.7963, 0.9751, and 0.8049 for NH 3 -N, NO 3 -N and NO 2 -N respectively). Index term—Adsorption, equilibrium isotherm, nutrients removal, sawdust. I. INTRODUCTION Ammonia (NH 4 +), nitrate (NO 3 -), and nitrite (NO 2 -) are inorganic nitrogen commonly found in urban stormwater runoff [1]. These compounds are normally resulted from auto emissions, fluid leaks from vehicles, home use fertilizer and pesticides, refuse, and pet feces. These pollutants in stormwater have adverse effects on groundwater quality especially in urban areas [2] which is also responsible for eutrophication problem in receiving water [3]. These nutrients have harmful effects on human health and overall ecosystem. Although nitrate is fairly non-toxic, but when it transform to nitrite, which combines with hemoglobin in the blood to form methemoglobin, it might have risk in infant’s body called methemoglobinemia also known as “blue-baby syndrome” a situation of oxygen deficiency [4]. There is incidental confirmation linking nitrite in leading to cancer risk [5]. Thus, the maximum contaminant levels of NO 3 - –N and NO 2 - –N are set as 10 mg/L and 1mg/L for drinking water respectively [6]. Bioretention systems are commonly used for removing the inorganic nitrogen from stormwater [7-10]. The use of different sorption media in this system is the most daunting task to select. Using renewable resources for contaminant removal through adsorption is becoming more cost-effective method. Some materials have been tested for this purpose, such as sepiolite [11], bittern [12], clinoptilolite [13-14], Manuscript received January 29, 2012; revised March 7, 2012. K. D. Harmayani is PhD candidate at Civil Engineering, Curtin University, Western Australia (e-mail: kadekdia@ student.curtin.edu.au). A. H. M. F. Anwar is Senior lecturer at Civil Engineering, Curtin University, Western Australia (e-mail: F.Anwar@curtin.edu.au). hardwood mulch [15], and sawdust [16-18]. All researchers were mixing sawdust with other green sorption media. Xuan (2010) studied a mix of selected media consisted of 68% fine sand, 25% tire crumbs, and 7% of sawdust. They used less than 10% of sawdust in their adsorption media for supporting denitrification. If part of the medium becomes anaerobic, in that case, sawdust acts as an electron donor. They investigated that 96 % of nitrates were removed during 24 hours of shaking time which followed by 24 hours of anaerobic period [17]. Whereas Hossain [18] mixed 50% sand, 20% limestone, 15% sawdust, and 15% tire crumb in their experiments. They concluded that the filter media mixture was efficient and effective for the removal of nitrate and nitrite at lower concentration. The highest removal efficiency was reached at 95.36% with 0.5 mg/L influent of nitrate after 5 hours of hydraulic retention time. Nitrite was reached 98.72% removal efficiency with 2.5 mg/L of nitrite and 100% removal efficiency for ammonia with both waste load concentration of 0.5 and 2.5 mg/L after 1 and 1.5 hours hydraulic retention time [18]. Kim [16] selected the different material as potential electron donors to treat stormwater. They performed three sets of experiments: (i) Set 1 consisted of alfalfa, newspaper, and leaf mulch compost, (ii) Set 2 consisted of sawdust, wood chips, and wheat straw, and (iii) Set 3 consisted of small sulfur-limestone, large sulfur-limestone, and large sulfur only particles. They found that in experimental set 1, 100 % nitrate removal was observed in the alfalfa and newspaper column. In set 2, the sawdust, wheat straw, and wood chips columns were achieved greater than 95% nitrate removal. The small sulfur-limestone column, in set 3, was attained 91% nitrate removal. Based on these results, they chose newspaper, wood chips, and small sulfur-limestone as the best electron donor for their further experiments. In experimental set 2, because of wood chips showed better removal of nitrate along the column length (data not shown), they opted wood chips rather than sawdust [16]. There is a very limited literature explaining the mechanism of adsorption on sawdust solely in stormwater. Since sawdust is abundant, inexpensive and unused resources from agricultural byproduct, the use of this material would be beneficial for both the environment and wood agriculture: polluted streams would be cleaned and a new market would be opened for the sawdust. Sawdust from radiata pine contains cellulose, lignin, and tannins or other phenolic compounds which are active ion exchange compounds [19]. The main objective of this study is to investigate the removal efficiency and modes of surface coverage of sawdust for the removal of inorganic nitrogen from synthetic stormwater and to examine the adsorption isotherm models which best describe the experimental data. K. D. Harmayani and A. H. M. F. Anwar International Journal of Environmental Science and Development, Vol. 3, No. 2, April 2012 114 Adsorption of Nutrients from Stormwater Using Sawdust