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Biological denitrification and trace pesticide removal in a combined biofilm-electrode reactor/adsorption process has been investigated. In long-term (more than 260 days) continuous experiments, influent and effluent concentrations of nitrate, nitrite, isoprothiolane and gas composition were measured at different electric current and pesticide loading conditions. Experimental results showed that complete and stable denitrification was achieved in BER without accumulation of nitrite and nitrous oxide. Isoprothiolane (IPT) was removed by adsorption onto either granular activated carbon or silicone resin. Removal efficiency of IPT exceeding 97% was achieved and effluent concentration was below the guideline value (40 micrograms/l). Theoretically predicted effluent concentrations were in good agreement with the observed results. From these results, it is concluded that the combined process is applicable to treat nitrate and pesticide contaminated drinking water. Moreover, from comparison with former studies, different possible options to further enhance the decomposition of pesticide were suggested.

in urban and peri-urban areas of Addis Ababa, Ethiopia, with the aim to assess the spatial and temporal aspects of total suspended particulate (TSP) and particulate matter with aerodynamic diameter less than 10 µm (PM10) and their composition in terms of metallic elements. Sixty six filter samples were collected from seven distinct sites using I.O.M. multi fraction dust samplers and fiber glass filter papers. The mass of each particulate matter sample was measured gravimetrically and the composition of PM10 samples was analyzed using ICP-OAES and SEM-EDAX. The concentration of TSP was in the range of 17-556 µg/m 3 and that of PM10 was in the range of 17-285 µg/m 3. The highest TSP and PM10 peak values were observed in February 2008 at two sites, whereas the lowest TSP and PM10 values were observed in June and July 2008 at two sites. The mean TSP concentration surpassed the WHO safe guideline value of 150 µg/m 3 and 79 % of the PM10 values were below the WHO guideline value. The PM10 to TSP mass ratio was in the range 0.26-0.59 and PM10 mass contributed about 39% to the TSP mass. The average element concentration in PM10 filter sample was in the order of Ca > Na > K > Zn > Sb > B > Al > V > Mg > S > Fe. All the analyzed elements contributed about 0.1% to the PM10 mass. SEM-EDAX analysis of PM10 samples showed that Si, Al, Na, Zn, Ba, K and C were the predominant species. Crustal materials contributed 76-95% of the filter mass, and C and Cu represented 5-24%. The size distribution of aerosol particles as derived from SEM analysis was in 0.43-9.3 µm range.

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