Air pollution forecasting in Ankara, Turkey using air pollution index and its relation to assimilative capacity of the atmosphere

A conditional time-averaged gradient (COTAG) system has been developed to provide direct long-term (weekly to monthly) average flux gradient measurements for a range of trace gases, between land and atmosphere. Over daily periods, atmospheric conditions can range from high stability, where the vertical gradients of ambient concentration are enhanced due to very small diffusivity, to highly unstable conditions, in which concentration gradients are small due to the intense turbulent activity of the surface layer. The large vertical gradients generated by high stability would bias the estimate of the actual flux: to avoid this, the COTAG system samples conditionally, within a carefully refined range of stability. A comparison with a continuous flux gradient system suggested that the removal of stable conditions from the sampling period does not substantially modify the evaluation of the long-term fluxes.     

Sea water quality assessment of Prince Islands’ Beaches in Istanbul

In this study, seawater samples were subjected to microbiological and physicochemical analysis (water temperature, pH, Secchi disc depth and ammonia) in the Prince Islands which are located in Marmara Sea, being one of the most popular swimming areas in Istanbul. The monitoring program of the study has been carried out in the summer for 6 weeks at eight stations around the Prince Islands. Measured total coliform values were between 5 ± 2 and 26 ± 55 and faecal coliform values were between 4 ± 2 and 24 ± 50 in the monitoring stations. A statistical study has been conducted to find the relationship between total and faecal coliform concentrations, and t tests were applied. There was no significant difference in each location of the Islands, except one location. The results were evaluated by comparing with national and EU bathing water standards. Results of the study show that deep sea discharges and sea currents contribute dilution of coliform concentration in a positive way, and locations near coastal zones of the islands have acceptable values which are required by the regulations.     

Addressing the operational problems in a composting and recycling plant

The Istanbul composting and recycling plant, constructed in 2001, is one of the few composting plants in Turkey. During test operations of the plant, it was reported that the weight of the oversize materials (OM) above a 80-mm sieve was about 40% of the total incoming waste. They mainly consist of plastic bags that were full of garbage, which resulted in operational problems in the plant. In this paper, the composition of OM was determined and evaluated, particularly to find the economic losses in the plant. It was determined that approximately 58% of the OM transferred to the landfill area due to operational failures and interruptions could be used at the plant with improved operational conditions. Otherwise, the plant would realize an annual economic loss of about 640,800 US$. Compost quality in the plant has been satisfactory, but source separated collection, at least the separation of the wet from the dry fraction, is needed to increase the amount of compost and recovered materials.     

Measurement of black carbon (BC) by an optical method and a thermal-optical method: Intercomparison for four sites

Comparison of black carbon (BC) measurements obtained by two methods was performed for aerosols samples collected on Whatman 41 (W-41) filters, using an optical method (Magee Scientific Optical Transmissometer Model OT-21) and a thermal-optical method (Sunset Laboratory Thermal-optical analyzer). Samples were collected from four sites: Albany (a small urban site, NY), Antalya (coastal site, Turkey), Whiteface Mountain (remote site, NY) and Mayville (rural site, NY). At Albany, comparison between the two methods showed excellent agreement; a least-squares regression line yielded a slope of 1.02, and r² = 0.88. Similar comparisons at Antalya (slope of 1.02, r² = 0.5) and Whiteface Mountain (slope of 0.92 and r² = 0.58) also gave very good relationship. At Mayville, the relationship between the two methods yielded somewhat lower regression: a slope of 0.75, and r² = 0.44. The data from the four locations, when plotted together, yielded an excellent agreement: a slope of 0.91, and r² of 0.84. Based on our measurements, it appears that optical measurement using the OT-21 can be successfully applied to determination of BC in W-41 filters. However, because of the variability in the chemical composition of BC aerosol at different locations, it is suggested that the calibration of OT-21 when using W-41 filters should be performed with a statistically significant numbers of samples for specific sites.     

Effects of leachant temperature and pH on leachability of metals from fly ash. A case study: Can thermal power plant, province of Canakkale, Turkey

Lignite powered electric generation plants result in increasing environmental problems associated with gaseous emissions and the disposal of ash residues. Especially, low quality coals with high ash content cause enormous quantities of both gaseous and solid fly ash emissions. The main problem is related to the disposal of fly ash, which, in many cases, contains heavy metals. It is known that toxic trace metals may leach when fly ash is in contact with water. In this study, fly ash samples obtained from the thermal power plant in the town of Can in Turkey were investigated for leachability of metals under different acidic and temperature conditions. The experimental results show that a decrease in pH of the leachant favors the extraction of metal ions from fly ash. A significant increase in the extraction of arsenic, cadmium, chromium, zinc, lead, mercury, and selenium ions from the ash is attributed to the instability of the mineral phases. These heavy metals concentrations increase with respect to increasing acidic conditions and temperature. Peak concentrations, in general, were found at around 30°C.     

Municipal solid-waste management in Istanbul

Istanbul, with a population of around 13 million people, is located between Europe and Asia and is the biggest city in Turkey. Metropolitan Istanbul produces about 14,000 tons of solid waste per day. The aim of this study was to assess the situation of municipal solid-waste (MSW) management in Istanbul. This was achieved by reviewing the quantity and composition of waste produced in Istanbul. Current requirements and challenges in relation to the optimization of Istanbul’s MSW collection and management system are also discussed, and several suggestions for solving the problems identified are presented. The recovery of solid waste from the landfills, as well as the amounts of landfill-generated biogas and electricity, were evaluated. In recent years, MSW management in Istanbul has improved because of strong governance and institutional involvement. However, efforts directed toward applied research are still required to enable better waste management. These efforts will greatly support decision making on the part of municipal authorities. There remains a great need to reduce the volume of MSW in Istanbul.     

Estimation of Biogas Production Rate in a Thermophilic UASB Reactor Using Artificial Neural Networks

Biogas production rate was modeled and estimated in a thermophilic upflow anaerobic sludge blanket digester. Data set covers a time period of both steady-state conditions and an abnormal operation condition, i.e., organic loading shocks. Multilayer neural networks topology was used as the modeling tool. Half of the experimental data were used for the training of the model and the remaining half were used for the testing stage. Model results were evaluated from the point of view of both steady conditions and abnormal conditions. It was seen from the time series trends of the estimated data that biogas production rates at steady state operation conditions were closely estimated by the model while the results for organic loading shocks were sufficiently followed. Artificial neural network models gave encouraging estimation results for the online control of thermophilic reactors.