Comparative studies on the differently operated trains of the North-Budapest Wastewater Treatment Plant.

In order to reduce the pollution load of the Danube, the North-Budapest Wastewater Treatment Plant has been upgraded to enhanced nitrogen removal by establishing a new activated sludge treatment line and modifying the existing unit for nitrification and denitrification. As both the influent flow rate and the influent chemical oxygen demand (COD), biological oxygen demand (BOD(5)) and total suspended solids (TSS) concentration levels remained far below the design values, setting one fourth of the reactor volume out of operation in the Old Line, and operating the nitrification reactor of the New Line with part-time aeration proved to be possible. Analytical data as well as simulation studies supported the advantage of the intermittent-aeration process in efficient N-removal. However, the lengths of the aerated periods have to be increased with decreasing temperature, and thereby effluent total nitrogen (TN) concentration can increase due to decreasing denitrification efficiency. Potential occurrence of low-dissolved oxygen (DO) bulking should be hindered through applying an efficient anoxic selector system.

Identification and quantification of ibuprofen, naproxen, ketoprofen and diclofenac present in waste-waters, as their trimethylsilyl derivatives, by gas chromatography mass spectrometry.

This paper reports a derivatization, mass fragmentation study relating to the most common, non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, naproxen, ketoprofen and diclofenac, identified and quantified in the aquatic environment. Derivatizations have been performed with four silylation reagents in order to select the most proper one, taking into account analytical and financial points of view, equally. The tested reagents were N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA), N-methyl-N-tert-butyldimethylsilyl-trifluoroacetamide (MTBSTFA) and for this purpose at the first time, hexamethyldisilazan (HMDS)+trifluoroacetic acid (TFAA). Varying derivatization time and temperature, taking into consideration chemical and financial advantages, HMDS+TFAA proved to be the optimum selection. Responses of derivatives have been compared, as a function of the ionization technique (external/internal ionization), as well as on the treatment of compounds' selective fragment ions (SFIs): (i) extracting the corresponding, characteristic m/z masses from TIC elutions and (ii) from SIM elutions, in parallel. Reproducibilities of measurements, expressed in relative standard deviation percentages (R.S.D.%), including the nanogram and the low picogram levels of injected derivatives, provided an average between 0.93 R.S.D.% and 4.11 R.S.D.%. NSAIDs' enrichment was performed with solid-phase extraction (SPE), applying the Oasis HLB (Waters) cartridges: recoveries in the 1-6 microg L(-1) range varied between 84% and 111%, with an average reproducibility of 6.4 R.S.D.%. The utility of the optimized derivatization method is presented, on monthly basis, by the identification and quantitation of the ibuprofen, naproxen, ketoprofen and diclofenac content of the influent and effluent waste-water samples obtained from a Hungarian waste-water treatment plant.

Savings with upgraded performance through improved activated sludge denitrification in the combined activated sludge-biofilter system of the Southpest Wastewater Treatment Plant.

The purpose of the experiments was to increase the rate of activated sludge denitrification in the combined biological treatment system of the Southpest Wastewater Treatment Plant in order to gain savings in cost and energy and improve process efficiency. Initial profile measurements revealed excess denitrification capacity of the preclarified wastewater. As a consequence, flow of nitrification filter effluent recirculated to the anoxic activated sludge basins was increased from 23,000 m3 d(-1) to 42,288 m3 d(-1) at an average preclarified influent flow of 64,843 m3 d(-1), Both simulation studies and microbiological investigations suggested that activated sludge nitrification, achieved despite the low SRT (2-3 days), was initiated by the backseeding from the nitrification filters and facilitated by the decreased oxygen demand of the influent organics used for denitrification. With the improved activated sludge denitrification, methanol demand could be decreased to about half of the initial value. With the increased efficiency of the activated sludge pre-denitrification, plant effluent COD levels decreased from 40-70 mg l(-1) to < 30-45 mg l(-1) due to the decreased likelihood of methanol overdosing in the denitrification filter.