Lütfi Akça

Treatment of wastewater by natural systems

Experimental results from a pilot-scale constructed wetland (CW) treatment plant have been described. The study was conducted at two different systems: continuous and batch. In the continuous system, the treatment yields were monitored in different loading conditions in 1-year period. The pilot plant consists of two serially connected tanks settled up with fillers; Cyperus was used as treatment media and wastewater between the two tanks was recycled periodically. Chemical oxygen demand (COD) and suspended solid (SS) removal efficiencies were obtained as 90% and 95%, respectively. The effluent COD concentration at an average loading of 122 g COD/m2 day was satisfactory for the Turkish Water Pollution Control Regulation. This means that a 0.8 m2 of garden area per person is required. Other removal values for the same conditions were as follows: total Kjeldahl nitrogen (TKN) was 77%, total nitrogen (TN) was 61%, and PO4(3-) -P was 39%. The batch experimental systems consist of 12 pairs of serially connected tanks, with each pair having a surface area of 1 m2. Each set was filled with sewage once a day, and the wastewater between the paired tanks was recycled periodically by the pump. Each pair of tanks was filled with materials such as gravel, peat, and perlite. Seven of them were vegetated with Phragmites, Cyperus, Rush, Iris, Lolium, Canna, and Paspalum, while the other five were not seeded. The best performances were obtained by Iris for COD (% 94), by Canna for ammonia nitrogen (% 98), and by Iris for total nitrogen (% 90) and phosphorus (% 55) removal.

Phosphorus removal and effect of adsorbent type in a constructed wetland system

Abstract This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems of small communities in Turkey. Pilot-scale treatment of a small community’s wastewater was performed over a period of more than 2 y in order to show applicability of these systems. The present study involves removal of phosphorus in horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands operated in series. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system. Wastewater was first introduced into the HFCW and then VFCW before being discharged. VFCW achieved up to 60–90% phosphorus removal whereas HFCW could remove only less than 20%. The effect of type of filling material on adsorption of phosphorus was investigated both in adsorption studies and in ...

Performance of a pilot-scale, three-stage constructed wetland system for domestic wastewater treatment.

This study investigates the effects of season, organic matter loadings, hydraulic conditions, recycling, and rapid drainage on water quality in a pilot‐scale, three‐stage subsurface flow constructed wetland (SSF CW) system. The pilot CW system consisted of a vertical flow‐gravel filtration (v‐GF) wetland in the first stage, a horizontal‐subsurface flow (h‐SSF) bed planted with Iris in the second stage, and a vertical‐subsurface flow (v‐SSF) bed vegetated with Phragmites in the third stage. The objective of this study was to evaluate the potential of these CW systems to remove organic matter from domestic wastewater on a pilot‐scale three‐stage SSF CW system. Comparisons of average influent and effluent concentrations showed that the multistage system could effectively reduce total suspended solids (TSS), biological oxygen demand (BOD) and chemical oxygen demand (COD) levels in effluent by as much as 98% and total organic carbon (TOC) by as much as 79%. Contributions of the first, second and third stages to the overall treatment were approximately 10%, 45% and 45%, respectively. The average TSS, COD, and TOC concentrations were reduced in the entire CW system by 70%, 80% and 90%, respectively. The BOD and TOC removal efficiencies displayed seasonal variations with average removals generally increasing in warmer seasons. Our results also demonstrate that there were strong correlations between removal efficiencies and loading rates. Average removals decreased with an increase in the hydraulic retention time (HRT). The rapid drainage and recycling operation increased the efficiency of BOD removal only.

Determination of degradation of radioactivity and its kinetics in aerobic composting

In this study, the kinetics of disappearance of radioactivity in aerobic composting was investigated. For this purpose, compost materials were prepared by mixing sugar beet wastes, wine factory wastes (grape wastes), straw and biological treatment sludge in different amounts. While alpha-radioactivity was not initially detected in all composting materials, the composting materials had some beta-radioactivity. In the mixtures of sugar beet wastes--straw-biological treatment sludge (1), sugar beet wastes-wine factory wastes (grape wastes)-biological treatment sludge (II) and wine factory wastes (grape wastes)-biological treatment sludge (III), the beta-radioactivity reduced by 82%, 58%, 85% respectively of initial values after 52 d. The beta-radioactivity degradation in the composting process could be represented by first-order kinetics and reaction rate constants of mixtures of I, II and III were k = 0.0693 d(-1) (R2 - 0.84), k = 0.0453 d(-1) (R2 = 0.98), k = 0.0234 d(-1) (R2 = 0.97), respectively.

Pilot-scale anaerobic treatment of domestic wastewater in upflow anaerobic sludge bed and anaerobic baffled reactors at ambient temperatures

Abstract The efficiencies of an upflow anaerobic sludge bed (UASB) reactor and an anaerobic baffled reactor (ABR) were compared for the treatment of domestic wastewater at ambient temperatures. Two pilot-scale anaerobic biological reactors were operated for about two years at ambient conditions at psychrophilic and/or sub-mesophilic temperatures. The average total chemical oxygen demand removal was 56 and 58% in the UASB reactor, whereas it was 41 and 50% in ABR, respectively, in summer and winter periods. The amount of methane gas production was between 0.05 and 0.18 m3 CH4/kg CODremoved in the UASB reactor, although no methane production was observed in the ABR. Temperature was not a limiting factor in anaerobic reactors that were operated at ambient conditions. Because of its higher efficiency, the UASB reactor was recommended over the ABR for the anaerobic treatment of domestic wastewater of the small community investigated within the scope of the study. However, anaerobic treatment of domestic wastew...

Problems related to an existing marine outfall: Marmaris - An example

Abstract Marmaris is a tourist city on the South-west Coast of Turkey. A sewage disposal project for Marmaris with an estimated population of 39.000 (excluding the temporary tourist population) for the year 2012, was completed in 1982. The sewage disposal system consisted of wastewater collection, treatment and deep sea discharge. The length of discharge pipe was determined as 520 m and a diffuser was placed 20 m below the sea level, so that the total coliform concentration at the protection zone boundary could be less than 1000/100 ml. Following the approval of the project, a wastewater collection and marine disposal system was constructed. The material of the discharge pipe was selected as glass reinforced plastic (GRP). The pipe was buried up to a point 10 m below sea level, so that effects of hydrodynamic forces would be minimized. After that point, the pipe was supported at some location by grout bags due to the uneven sea bed. A few years later, it was recognized that the discharge pipe was broken. The fragile GRP material bad fractured as a result of the sliding of some of the supports with resultant free spanning conditions. As a result, the pipe bad broken at one point. Although the breakage was repaired, recent data have shown that the water quality in Marmaris Bay has a tendency to be worsening; consequently, adding biological treatment units to the present system is advisable.

Full-scale hybrid constructed wetlands incorporated with an initial anaerobic stage for domestic wastewater treatment in a drinking water catchment area

AbstractThis study involves sequential treatment of domestic wastewater by anaerobic reactors followed by horizontal (HSSF-CW) and vertical (VSSF-CW) subsurface flow-constructed wetlands. Two full-scale systems constructed in two villages were operated in order to treat domestic wastewaters of about 2,000 and 500 inhabitants. Anaerobic treatment of domestic wastewater served as a pretreatment step before the constructed wetland (CW) systems. Anaerobic pretreatment was performed by an upflow anaerobic sludge bed reactor or an anaerobic baffled reactor. Anaerobically pretreated wastewater was first introduced into parallel HSSF-CWs and then parallel VSSF-CWs before being discharged. Efficient treatment of wastewaters of the two villages was particularly important since they are located in the watershed of a drinking water reservoir. The treatment efficiencies of systems were 88 and 83% for chemical oxygen demand, 89 and 81% for BOD5, 57 and 39% for total nitrogen, 55 and 53% for total phosphorus, 94 and 90%...

Point and Diffuse Sources of Pollution and Surface Water Quality in Marmara Basin of Turkey

Marmara Basin includes the areas in Turkey with the densest industrialization and population. Surface waters are threatened particularly by point sources originating from municipalities and industries, although most of them are discharged to the sea. Therefore quality of existing surface waters and the sources of pollution are of great interest. Watershed protection action plan has recently been prepared for the basin. A detailed study on calculation of pollution loads was one of the most important outputs of the project. For this purpose, pollution loads based on chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN) and total phosphorus (TP) were calculated. Water quality classes of surface waters were determined based on Turkish regulations using the data obtained by State Hydraulic Works (DSI). The relationship between point and diffuse pollution sources and water quality was examined. According to the obtained data most of the creeks around Istanbul are polluted by point sources originating from the highly populated and industrialized city of Istanbul and its suburbs. On the other hand, the creeks which feed Iznik Lake and downstream of Gonen and Biga Creeks are polluted by diffuse sources as well as point sources. Results showed that point-source pollution due to untreated or treated domestic and industrial wastewaters is mainly responsible from pollution in rivers and lakes of the Marmara Basin. Besides in the less populated areas, diffuse-source pollution originating from agriculture and livestock breeding is responsible from deterioration of surface water quality.

Coastal Zone Management Applications in Turkey

Coastal zone management and protection are of utmost importance for countries with coastlines, primarily due to their significant tourism activities. Coastal zones are threatened by pollution from two types of sources, point and non-point. Point source pollution is from domestic and industrial waste, with the former producing a much greater volume during the summer tourist high season. Non-point sources come from agricultural activities, marine transportation, atmospheric deposition, urban run-off, and so forth. Coastal areas are important - 90% of all the countries in the world are coastal countries with 40% of the world’s population living there. If one defines a coastal zone as a 50 m wide strip of coastline, 50% of the world’s population is settled there [1, 2].