Okan Tarık Komesli

Removal of endocrine disrupting compounds in a lab-scale anaerobic/aerobic sequencing batch reactor unit

The fate and removal of six selected endocrine disrupting compounds in a lab-scale anaerobic/aerobic (A/O) sequencing batch reactor (SBR), operating at 5 days, solids retention time (SRT) were investigated. A carbamazepine (CBZ), acetaminophen (ATP), diltiazem (DTZ), butyl benzyl phthalate (BBP), estrone and progesterone mix was spiked as model endocrine disrupting compounds (EDC) into domestic wastewater obtained from a nearby sewage treatment plant. The influent, effluent and sludge samples from the SBR unit were analysed by using an LC/MS/MS instrument equipped with electrospray ionization. More than 80% removal was observed for all the EDCs tested. It was found that biodegradation is the most important mechanism for BBP, ATP and progesterone. Biodegradation constants were calculated according to the simplified Monod model for these compounds. The DTZ seemed to have lower rate of biodegradation. The CBZ appeared totally resistant to biodegradation. However, it presented a high rate of sorption onto the sludge and was thereby treated. This contradicts with the literature studies.

Intermittent Ozone Application in Aerobic Sludge Digestion

Excess biological sludge, WAS, produced during activated sludge process is a growing problem for the utilities owing to the stringent regulations now imposed worldwide. One method of handling the excess sludge is to digest it, to reduce its amount and to stabilize it. Aerobic digestion is particularly suitable for nutrient treating plants as sludge should not be exposed to anaerobiosis since this will lead to release of accumulated phosphorus. A novel and patented ozone-assisted aerobic sludge digestion process (PCT/TR2010/000213) is shown to appreciably shorten the 15–30-day aerobic digestion period and the extent of solids destroyed. WAS samples were ozonated for different periods in Erlenmeyer flasks, once a day, on each of four consecutive days. Flasks were continuously aerated between ozone applications. The MLVSS, MLSS, COD and OUR parameters were measured routinely during the course of four days of digestion in order to optimize the process. As a result 22.6%, 40%, 75% and 84% MLVSS reductions were obtained at total ozone applications of 0.42, 0.64, 0.85 and 1.27 mg O3 g−1 MLSS, at the end of the fourth day. Hence, it became possible to save on contact time as well as achieving a bio-solids digestion far exceeding the standard aerobic process, which is 40–50% in 15–30 days, at the expense of a minimum of ozone dose. The developed process is deemed superior over side-stream ozonation where ozone is applied to the return activated sludge, RAS, line; in that it does not cause any reduction in active biomass amount maintained in the aeration tank. Conversely, reduction in active biomass concentration results in reduced treatment efficiency.

Prolonged reuse of domestic wastewater after membrane bioreactor treatment

AbstractIn this study, experience in a nine-year operation of a full-scale 2000 PE vacuum rotating membrane bioreactor having a submerged flat-type membrane module having pore size of 0.038 μm and a total surface area of 540 m2 is discussed. The plant was designed to treat and reuse raw wastewater collected from dormitories and the academic village at METU campus. Throughout the study, 99.99% BOD5 and above 95% COD removals were achieved most of the time. Moreover, turbidity was consistently measured below 1 NTU and around 6–7 log coliform removals were achieved with less than 1 coliform/100 mL in the effluents most of the time, except for the leakage from the bearings. During the study, energy consumption by the plant was also analyzed by routinely measuring energy consumption in different parts of the plant. Consumption was analyzed in two parts. Energy consumed by the blower supplying aeration to the biological treatment tank was monitored separately from the rest of the plant. Except for the periods w...

Investigation of sludge viscosity and its effects on the performance of a vacuum rotation membrane bioreactor

Sludge characteristics of a full-scale vacuum rotation membrane (VRM) bioreactor having plate-type membranes with 0.038 μm nominal pore size and 540 m2 surface area were investigated. The VRM plant is composed of an aeration tank and a filtration chamber. The sludge floc size distribution, as determined microscopically, was mainly between 0 and 100 μm in the filter chamber with very little difference in size distribution between summer (20–25°C) and winter (10–15°C) seasons. Small floc size encountered in the filtration chamber was evident due to excessive shear administered by the rotation action and vigorous agitation by the scouring air. The mixed liquor suspended solids (MLSS) was variable between 5.23 and 14.10 g/L in the VRM tank and sludge behaved plastic. Viscosity ranged between 2.39 and 30 cP in the VRM tank in relation with MLSS concentration and temperature. Above 20 cP inter-plate spaces rapidly clogged leading to major clean-up.

Accurate determination of pesticides, hormones and endocrine disruptor compounds in complex environmental samples using matrix dilution and matrix matching with dispersive liquid–liquid microextraction

Abstract Quantitative determination of contaminants in environmental samples is usually hampered by low analyte recovery which results from the complex nature of the sample matrix. This study presents the application of a developed dispersive liquid–liquid microextraction method for the determination of 12 analytes in environmental samples including sea water, fresh water (lake, well and tap water), brackish water and soil samples. Matrix matched standards were used to compensate for the low analyte recovery recorded by the conventional calibration method. The effect of matrix dilution on analyte recovery was also tested. All matrix matched and matrix diluted spiked recoveries were done concurrently with calibration standards prepared in deionized water. Percent recoveries recorded for the analytes according to deionized water calibration standards ranged between 66 and 137%. Matrix matching and matrix dilution yielded close to 100% recovery results, but the later lowered the detection limit according to the dilution factor.

Effect of permeate flux in a membrane SBR (MSBR) treating the liquid fraction of manure

In this study, a lab-scale membrane sequencing batch reactor (MSBR) was applied for the treatment of synthetic wastewater simulating the liquid fraction of manure. The system performance was tested at 3 different hydraulic retention times (HRTs: 12.8h, 10.4h and 9.2h) to examine nutrients and organic matter removal. A submerged flat-type ultrafiltration membrane unit was applied as a policing step in order to improve the SBR’s effluent characteristics. The membrane module operated at 16, 20 and 25 L/m∙h flux during the three examined periods. The efficiency of the MSBR for organic content removal was demonstrated with a chemical oxygen demand (COD) effluent concentration ranging from 77 to 204 mg/L that is below the Turkish limits for discharge to the environment. Additionally, the integrated system effectively removed NH4-N achieving 99.8% nitrification and more than 86% denitrification at an HRT=12.8 h with less than 1 mg/L NH4-N concentration in the effluent. The decrease of the HRT in periods 2 and 3 reduced the NH4-N removal efficiency to 93% and 81% and the denitrification performance to 74% and 56%, respectively. However, the NH4-N effluent concentration was within the limits for discharge set by the Turkish legislation. The phosphates (PO4-P) efficiency was 80%, 60% and 39% for periods 1, 2 and 3, respectively. The membranes enhanced nutrients and COD removal; the impact was higher in the case of phosphates with 10% of PO4-P being removed in the membrane chamber in period 1.