INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 2, No 1, Copyright 2010 All rights reserved Integrated Publishing Association

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1 INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 2, No 1, 2011 Copyright 2010 All rights reserved Integrated Publishing Association Research article ISSN Cost effective method for ammoniacal Nitrogen removal using SBR coupled photobioreactor Sudarsan.J.S 1, Renganathan.K 2, Ann christy 3 1- Assistant professor School of civil engineering, SRM University, Chennai 2- M.Tech Environmental engineering student, SRM University, Chennai 3- M.Tech Environmental engineering student, North Maharashtra University,Maharastra sudarsanjss@yahoo.com doi: /ijes ABSTRACT Nutrient compounds such as ammoniacal nitrogen (NH4-N), nitrite and nitrate, often present in different types of waters and wastewaters, can find their way to lakes, rivers and drinking water reservoirs. Wastewater NH4-N is becoming more important in the alleviation of environmental problems including eutrophication, corrosion and fouling. A pilot plant was designed to study the removal of ammoniacal nitrogen using biological system. The nitrification process was carried out in a sequential batch reactor and removal of nitrate from the system generated during the oxidation of ammoniacal nitrogen was carried out in a photobioreactor using algae. On average 95% ammoniacal nitrogen removal was achieved by the sequential batch reactor and 98% nitrate removal was achieved using photobioreactor. Keywords: Nutrient compounds, Eutropication, Sequential Batch Reactor, Photobioreactor, Ammoniacal nitrogen. 1. Introduction Water is a precious natural resource, and due to this realization it has become a prevalent source of concern; more attention is placed on its maintenance and purification. The rapid development and industrialization coupled with an increased awareness about the need for a clean environment have forced industrialists, environmentalists and governments to look for cheap, efficient and long lasting solutions to waste water treatment and recycling of nitrogen and phosphorus. In recent years, wastewater NH4-N is becoming more important in the alleviation of environmental problems including eutrophication, corrosion and fouling. NH4- N removal is one of the fundamental aims in wastewater treatment. It can be carried out by biological, physical, chemical or a combination of these methods like adsorption, chemical precipitation, membrane filtration, reverse osmosis, ion exchange, air stripping, breakpoint chlorination and biological -nitrification and denitrification.nitrification defines the aerobic mediated step which describes the transformation of ammonia into nitrite through the activity of ammonium-oxidizing bacteria. These are aerobic metabolic reactions which do not require organic substances as electron donors. The nitrate so formed in the system can further be removed either by the process of denitrification or by algal uptake. Denitrification is a process in which nitrogen oxides (nitrites or nitrates) are reduced to nitrogen gas by replacing oxygen as the terminal electron acceptors during the anaerobic oxidation by several types of electron donors, like, organic matter.in a photobioreactor, the algae while growing will take up nitrate as a nutrient from waste water for their cell synthesis and consequently removes nitrate from the waste water. Due to these reasons the photobioreactor seems to be an interesting method for nitrate removal.along with nitrate removal they offer a potential Received on July, 2011Published on September

2 valuable biomass which can be harvested and can be used for several other purposes like generation of biofuel, fertilizer etc. 2. Objectives 1. To determine the ammoniacal nitrogen removal rate using sequential batch reactor. 2. To determine the nitrate removal efficiency using photobioreactor. 3. Material and Methods 3.1 Design of Pilot-scale Sequential Batch Reactor (SBR) A bench scale sequential batch reactor was designed to carry out the process of nitrification. A rectangular tank with a storage volume of 3 L was used for the installation of the SBR System. The reactor was equipped with a submersible aerator, a submersible pump and an agitation system 5.The period of filling, reaction, settling and withdrawing were varied from 0.25 h (filling), 2-7 h (reaction), h (settling) and 0.25 h (decanting). The effluents from SBR were subjected to hourly measurements of ammoniacal nitrogen, and nitrate nitrogen. During nitrification, the ph of the SBR was controlled at higher than 7.5 by the addition of NaHCO Design of Photobioreactor Photobioreactor was designed for the removal of nitrate nitrogen formed during the oxidation of ammoniacal nitrogen by the activity nitrifying bacteria (nitrification).the nitrate nitrogen removal in the Photobioreactor was performed by algae. The Photobioreactor consists of a glass column 45cm length, 30 cm width and 10cm depth. This column was partitioned using baffles made of glass to increase the surface area for attachment. The Photobioreactor was inoculated with algal culture, the reactor was illuminated using a cool white fluorescent lamp and reactor was maintained at room temperature. Gentle mixing and agitation was provided using an air compressor attached to the reactor. The effluents of Photobioreactor were tested for presence of nitrate after every two hour. 3.3 Chemical Analysis Nitrate (NO3 -) was determined by Sodium Salicylate method by reading the absorbance at 415nm using Spectrophotometer, Ammoniacal nitrogen (NH4-N) using the automatic titrator (Mettler Toledo DL 53).The effluents from SBR were subjected to hourly measurements of ammoniacal nitrogen, and nitrate. While the effluents of Photobioreactor were tested for presence of nitrate after every two hour. 3.4 Experimental Procedure The Sequencing batch reactor was filled with the synthetic wastewater laden with ammoniacal nitrogen, inoculated with a culture of nitrifying organisms and was operated batchwise with aeration and mixing.the process of nitrification was carried out by the microorganisms in the SBR and resulted in oxidation of ammoniacal nitrogen and generation of nitrate. After sedimenting the organisms for 1 hour, the supernatant was removed and fed to the Photobioreactor which was inoculated with algae. The algae present in the 69

3 Nitrate concentration (mg/l) NH4-N concentration (mg/l) Cost effective method for ammoniacal Nitrogen removal using SBR coupled photobioreactor Photobioreactor consumed the nitrate present in the effluent water for their growth and in turn resulted in appreciable reduction of nitrate in the effluent water. 4 Results and discussion Ammoniacal nitrogen removal rate have been determined using Sequencing batch reactor (SBR).The influent ammoniacal nitrogen concentration in stage 1 was 600 mg/l.the concentration of NH4-N in the influent (600 mg/l) decreased progressively to 252 mg/l in the effluent in 300 minutes. The ammoniacal nitrogen concentration was brought within the limit within 480 minutes of bacterial activity (the prescribed CPCB limit for ammoniacal nitrogen is 50 mg/l). In 540 minutes the concentration of ammoniacal nitrogen was reduced to a range of 28 mg/l.the graph obtained is shown in figure 1. NH 4 -N Removal rate in SBR Time in hours Figure 1: Ammoniacal nitrogen removal rate in SBR 4.2. Nitrate removal rate obtained using Photobioreactor (PBR) The nitrate nitrogen concentration in stage 1 was 500 mg/l.the concentration of NO3-N (500 mg/l) decreased progressively to 263 mg/l in 2 hrs. The presence of NO3-N in the effluent, indicate that more retention time was required to achieve complete removal of NO3 -N. The nitrate nitrogen concentration was brought within the limit after 26 hours (the prescribed CPCB limit for nitrate-nitrogen is 10 mg/l).complete removal happened in 28 hours, the concentration of ammoniacal nitrogen was reduced to a range of 3.56 mg/l.the result is shown in figure 2. Nitrate Removal Rate in PBR Time in hours Figure 2: Ammoniacal nitrogen removal rate in PBR 70

4 5. Conclusion It was demonstrated that the SBR coupled with photobioreactor is an appropriate treatment system to perform the removal of ammoniacal nitrogen in wastewater. The microalgae present in the photobioreactor utilize the free CO2 present in the atmosphere for its photosynthetic activity. The effluent treatment by physic-chemical methods is energy and cost intensive, often resulting in secondary pollutants.sbr coupled photobioreactor proved to be the best alternative for the removal of ammoniacal nitrogen in the waste water. Complete nitrification can be achieved in the SBR after within a period of 9-10 hours provided optimum ph is maintained, and the effluent water will be free of ammonia but rich in nitrate. Complete nitrate removal can be achieved within a period of hours when a photobioreactor is used hence the effluent water will be free of nitrate and suitable for the discharge into the river. The harvested algal culture can be used for production of extracellular compounds, chemicals, animal feed, and therapeutics. 6. References 1. Carrera J, Vicent T. and Lafuente J, (2004), Effect of influent COD/N ratio on biological nitrogen removal (BNR) from high-strength ammonium industrial wastewater. Process Biochemistry, 39(12), pp Degen J, Uebele A., Retze A.,(2001), A novel airlift photobioreactor with baffles fro improved light utilization through flashing light effect. J. Biotechnology, 92, pp Gali. A., Dosta S., Lopez P. and Alvarez M., (2008), SBR technology for high ammonium loading rates. Water science and technology, (2), pp Gibbs B., Newland M. and Cord-Ruwisch R.,(2005),Long-term aeration management for improved N-removal via SND in a sequencing batch reactor, Water Research, 39 (15),pp Harker M., Tsavalos A.J. and Young A.J., (1996), Autotrophic growth and carotenoid production of Haematococcus pluvialis in a 30 liter airlift photobioreactor. J. Ferment. Bioeng, 82, pp Koops H.P. and Pommerening-Roser A., (2002), Distribution and ecophysiology of the nitrifying bacteria emphasizing cultured species. FEMS. Microbial Ecology, (37), pp Metcalf.and Eddy, (1991), Wastewater Engineering: Treatment, Disposal, Reuse. New York: 2 nd Ed, (1), McGraw-Hill Inc.,pp Mahvi A.H., (2008), Sequencing Batch Reactor: a promising technology in wastewater treatment, Journal of Environmental Health Science and Engineering., 5(2), pp Ogbonna J.C., Soejima.T. and Tanaka, H, (1998), Development of efficient large scale photo bioreactors. In: Zaborosky, O.R. (Ed.), Biohydrogen.Plenum Press, New York, (2), pp

5 10. Wilderer et al, Wilderer P.A. and Goronszy, M.C., (2001), Sequencing batch reactor technology. IWA Scientific and Technical Report, UK,No