Journal of Hazardous Materials 189 (2011) 577–585 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Removal of phosphorus from aqueous solution by Posidonia oceanica fibers using continuous stirring tank reactor Mohamed Ali Wahab a,∗ , Rafik Ben Hassine b , Salah Jellali a a University of Carthage, Water Research and Technologies Centre (CERTE), Wastewater Treatment and Recycling Laboratory, B.P. 273, 8020 Soliman, Tunisia b International Environmental Green Technology (IGET), Tunisia article info Article history: Received 9 September 2010 Received in revised form 22 February 2011 Accepted 23 February 2011 Available online 2 March 2011 Keywords: Adsorption CSTR Phosphorus removal Tertiary treatment Posidonia oceanica fibers (POF) abstract The present study aims to develop a new potentially low-cost, sustainable treatment approach to soluble inorganic phosphorus removal from synthetic solutions and secondary wastewater effluents in which a plant waste (Posidonia oceanica fiber: POF) is used for further agronomic benefit. Dynamic flow tests using a continuous stirred tank reactor (CSTR) were carried out to study the effect of initial concentration of phosphorus, amount of adsorbent, feeding flow rate and anions competition. The experimental results showed that the removal efficiency of phosphorus from synthetic solutions is about 80% for 10 g L -1 of POF. In addition, the variation of the initial concentration of phosphorus from 8 to 50 mg L -1 increased the adsorption capacity from 0.99 to 3.03 mg g -1 . The use of secondary treated wastewater showed the pres- ence of competition phenomenon between phosphorus and sulphate which could be overcoming with increasing the sorptive surface area and providing more adsorption sites when increasing the adsorbent dosage of POF. Compared with columns studies, this novel CSTR system showed more advantages for the removal of soluble phosphorus as a tertiary treatment of urban secondary effluents with more adsorption efficiency and capacity, in addition to the prospect use of saturated POF with nutriment as fertilizer and compost. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The release of phosphorus from municipal wastewater efflu- ents into the environment is one major cause of eutrophication in receiving water bodies [1,2]. Phosphorus removal in conventional small-scale wastewater treatment systems is a critical issue that has not yet been sufficiently solved. In general, primary and sec- ondary treatment is effective in removing particulate phosphorus. However, phosphorus in the secondary effluents is mostly soluble and is consumed for phytoplankton growth causing eutrophica- tion in surface water bodies [3]. Consequently, tertiary treatment of secondary municipal effluents to remove soluble phosphorus has become increasingly necessary to meet environmental regulations worldwide. There are a wide range of technologies available to remove phosphorus from wastewaters, such as chemical precipitation, biological treatment, constructed wetlands, and a number of wastewater-and-sludge-based methods [4,5], which typically require considerable capital investment and maintenance costs for infrastructure and reagents. Among all the approaches proposed, ∗ Corresponding author. Tel.: +216 79325044; fax: +216 79325802. E-mail addresses: waheb med@yahoo.fr (M.A. Wahab), salah.jallali@certe.rnrt.tn (S. Jellali). adsorption is one of the most popular methods and is currently con- sidered as an effective, efficient, and economic method for water purification. The assessment of a solid–liquid adsorption system is usually based on two types of investigations: batch adsorption and dynamic adsorption studies. Batch mode, which is usually lim- ited to the treatment of small quantities of wastewater, is useful in providing information about effectiveness of sorbate–sorbent system. However, due to its very low scale and its static flow con- ditions, the data obtained under batch conditions are generally not applicable to most real treatment systems. In the practical opera- tion of full-scale adsorption processes, continuous-flow fixed bed columns are often used. Fixed bed columns are known to be effi- cient in the removal of both biological oxygen demand (BOD 5 ) and total suspended solids (TSS) from wastewater. However, nitrogen (N) and phosphorus (P) removal is known to be somewhat prob- lematic [6,7]. Indeed, clogging was a big issue when using reactive media in filtration systems. This was mainly associated to the use of fine media size, to biofilm development caused by large amount of TSS and chemical oxygen demand (COD) in the supplied effluent, and in a minor extent, to carbon dioxide (CO 2 ) capture and precip- itation under calcium carbonate (CaCO 3 ) inside media, and to the flow rate. To overcome the clogging phenomenon, several solutions have been proposed including the use of prefilter to remove sus- pended solids and organic carbon [8], and the use of larger sized media (more than 5 mm medium diameter, e.g. [9]). However, all 0304-3894/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2011.02.079