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The aim of this study was to assess the level of heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination and enrichment in the surface sediments of the Seyhan River, which is the receiving water body of both treated and untreated municipal and industrial effluents as well as agricultural drainage waters generated within Adana, Turkey. Sediment and water samples were taken from six previously determined stations covering the downstream of the Seyhan dam during both wet and dry seasons and the samples were then analyzed for the heavy metals of concern. When both dry and wet seasons were considered, metal concentrations varied significantly within a broad range with Al, For both seasons combined, the enrichment factor (EF) and the geo-accumulation index (I geo ) for the sediments in terms of the specified metals ranged from 0.56 to 10.36 and À2.92 to 1.56, respectively, throughout the lower Seyhan River. The sediment quality guidelines (SQG) of US-EPA suggested the sediments of the Seyhan River demonstrated ''unpolluted to moderate pollution'' of Cu, Pb, and Zn, ''moderate to very strong pollution'' of Cr and Ni. The water quality data, on the other hand, indicated very low levels of these metals suggesting that the metal content in the surface sediments were most probably originating from fine sediments transported along the river route instead of water/wastewater discharges with high metal content.

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for allowing me to take their valuable time. I must thank Dr. Ahmet YUCEER from Cukurova University, Turkey, who has always encouraged me to have a graduate degree in the U.S. Dr. Ertan ARSLANKAYA also deserves thanks for his critique of my work during the experimental stage as well as sharing his expertise in statistical analysis and kinetic modeling. Patrick Brown is also appreciated for his help in laboratory work. Finally, I would like to thank the Higher Education Council of Turkey for making available the Future Faculty Fellowship and Scholarship fund that financed my work at Iowa State University and partial financial support by ISU-IPRT and Fox Engineering and Associates for the full-scale sequencing batch reactor study.

The performance of a membrane bioreactor (MBR) with a tubular ceramic membrane for phenol removal was evaluated under varying hydraulic retention times (HRT) and a fixed sludge residence time (SRT) of 30 days. The tubular ceramic membrane was operated with a mode of 15 minutes of filtration followed by 15 seconds of permeate backwashing at a flux of 250 l m(-2)hr(-1) along with an extended backwashing of 30 seconds every 3 hours of operation, which maintained the transmembrane pressure (TMP) below 100 kPa. Using a simulated municipal wastewater with varying phenol concentrations, the chemical oxygen demand (COD) and phenol removals observed were greater than 88% with excellent suspended solids (SS) removal of 100% at low phenol concentrations (approx. 100 mg l(-1) of phenol). Step increases in phenol concentration showed that inhibition was observed between 600 to 800 mg l(-1) of phenol with decreased sludge production rate, mixed liquor suspended solids (MLSS) concentration, and removal performance. The sludge volume index (SVI) of the biomass increased to about 450 ml g(-1) for a phenol input concentration of 800 mg l(-1). When the phenol concentration was decreased to 100 mg l(-1), the ceramic tubular MBR was found to recover rapidly indicating that the MBR is a robust system retaining most of the biomass. Experimental runs using wastewater containing phenol indicated that the MBR can be operated safely without upsets for concentrations up to 600 mg l(-1) of phenol at 2-4 hours HRT and 30 days SRT.

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