Lutfi AKCA - Academia.edu (original) (raw)

Papers by Lutfi AKCA

İTÜDERGİSİ/d, Feb 5, 2011

+-N ve NO 3-N arıtma verimleri sırayla; %73 ve %57, %37 ve %58 olarak bulunmuştur. Nitrifikasyon ... more +-N ve NO 3-N arıtma verimleri sırayla; %73 ve %57, %37 ve %58 olarak bulunmuştur. Nitrifikasyon hız sabitleri 0.898 gün-1 (YAAS), 0.541 gün-1 (SYAS) ve denitrifikasyon hız sabitleri 0.486 gün-1 (YAAS), 0.502 gün-1 (SYAS) olarak bulunmuştur. Çalışma sonunda elde edilen verilerle birinci dereceden piston akım modeline ve çoklu regresyon ilişkilerine dayanılarak tahmini çıkış değerleri elde edilmiştir. Sonuç olarak çıkış konsantrasyonlarının tahmininde çoklu regresyon modelle daha iyi sonuçlar alınmıştır.

Water Science and Technology, 2004

Within the context of this study, two lab-scale aquatic plant reactors consisting of duckweed (Le... more Within the context of this study, two lab-scale aquatic plant reactors consisting of duckweed (Lemna minor) ponds, were investigated for the removal of nitrogen forms during the secondary treatment of domestic wastewater. TKN, NH3-N and NO3-N parameters have been measured in both reactors for hydraulic retention times ranging from 3.3 days to 23 days and at various distances from the inlet of reactors. The results were evaluated for hydraulic retention times, hydraulic loading rates and mass loading rates. It was concluded that hydraulic and mass loading parameters were more meaningful than hydraulic retention time. Optimum nitrogen removal values of hydraulic loading rate and mass loading rate were found to be 1.2 cm/day and 90-160 mg TKN/m2-day, respectively. At the higher and lower loading rates, nitrogen removal efficiency was lower than those at optimum conditions. Effluent TKN concentration was around 2.5 to 3.0 mg/l while NH3-N concentration was almost zero at these loading c...

Water Science and Technology, 2005

The main concern of this paper was to predict the sludge quantities generated from 18 wastewater ... more The main concern of this paper was to predict the sludge quantities generated from 18 wastewater treatment plants, which were stated to be established in the “Istanbul Water Supply, Sewerage and Drainage, Sewage Treatment and Disposal Master Plan”, 10 of which are in operation at present. Besides this, obtaining the required data to compare various treatment schemes was another goal of the study. Especially, the estimation of the sludge quantity in the case of enhanced primary sedimentation was of importance. Wastewater sludge management strategies were discussed in order to develop suggestions for Istanbul Metropolitan city. Within this context, the wastewater treatment facilities, mentioned in the Master Plan that had been completed by 2000, were evaluated in terms of sludge production rates, locations and technical and management aspects. Disposal alternatives of the wastewater treatment sludge were also evaluated in this study. Using of the dewatered sludge as a landfill cover m...

İTÜDERGİSİ/e, 2010

Günümüzde kesintisiz ve sağlıklı içmesuyu temini ile toplam su kalitesi yönetimi öncelikli bir mü... more Günümüzde kesintisiz ve sağlıklı içmesuyu temini ile toplam su kalitesi yönetimi öncelikli bir mühendislik uygulaması olarak karşımıza çıkmaktadır. İçmesuyu kalitesi yönetimi için içmesuyu kaynağından tüketicilerin musluğuna kadar bütün süreçlerin bir bütün halinde ele alınması gerekmektedir. Tüm süreçleri yerinde ve bileşenleri ile birlikte izleyebilmek konumsal çalışmayı da beraberinde getirmektedir. Su kalitesi ile ilgili üretilen kararların bilimsel, gerektiğinde yasal olarak savunulabilen, kamuoyu incelemesine açık, iyi belgelenmiş ve kaliteli verilere dayanması büyük önem taşımaktadır. Bu sebeple Coğrafi Bilgi Sistemi(CBS) tabanlı bir karar destek sistemi oluşturularak "Su Kalitesi İzleme Bilgi Sistemi" tasarlanmıştır. "İçmesuyu Kalitesi Yönetim Ana Planı" çerçevesinde oluşturulan Coğrafi Bilgi Sistemi tabanlı izleme sistemi ile sorgulama, bilgiye ulaşma, şebeke analizi, eğilim analizleri, karar-üretme, modelleme, tematik(konulu) harita üretimi, senaryo üretimi ve yönetimi gibi çalışmalar için oldukça güçlü ve fonksiyonel bir yapı oluşturulmuştur. Ortaya konulan genel sistemin uygulaması, İstanbul içmesuyu sistemi ele alınarak yapılmıştır. Su kalitesi ölçümlerinin sürekli olarak yapıldığı arıtma tesisleri çıkışı, depo giriş ve çıkışları ile şebekede belirlenen kritik noktaların izlenmesi amacıyla bir coğrafi bilgi sistemi tasarlanmış, bu sistemin karar destek aracı olarak kullanılması ve yapılan analizler sonucu işletmenin iyileştirilmesi için içmesuyu havzasının kontrolü ve korunması, arıtma tesislerinin optimizasyonu, ana isale hatlarının periyodik temizliği ve deşarjı, depoların periyodik dezenfeksiyonu ve dış etkilere karşı korunması, dağıtım şebekesinde boru sonu ve ölü noktaların azaltılması, şebekelerdeki kritik noktalardan periyodik deşarjların yapılması, içmesuyu sisteminde çalışanların ve kamuoyunun bilinçlendirilmesi/bilgilendirilmesi gibi alınabilecek önlemler ve öneriler ortaya konulmuştur.

Water Science and Technology, 1995

İTÜDERGİSİ/e, 2010

Atıksulardan azotlu bileşiklerin gideriminde kullanılan konvansiyonel biyolojik ve kimyasal arıtm... more Atıksulardan azotlu bileşiklerin gideriminde kullanılan konvansiyonel biyolojik ve kimyasal arıtma yöntemlerinin, yapay sulak alanlar ile kıyaslandığında kontrolü ve işletilmesi yüksek maliyetli, proses olarak daha hassas sistemler oldukları görülmektedir. Ardışık yüzeyaltı akışlı sistemlerin azotlu bileşiklerin gideriminde uygulama alanı bulmasında doğal sistemlerin kontrollü birer modifikasyonu olması, bu sistemlerin işletme ve bakım maliyetlerinin düşük olması ve sistemin doğal çevreyle uyumlu olması önemli hususlardır. Bu çalışmada, geri devirli ardışık yüzeyaltı akışlı sistemin, nitrat geri devrinin yapıldığı anoksik/oksik (A/O) aktif çamur sistemlerine benzer şekilde çalıştırılarak azot giderimi sağlanabileceği gösterilmiştir. Geri devirli sistemde sistem performansı incelenmiştir. Bu amaçla anaerobik ön arıtmadan geçirilmiş ve anaerobik ön arıtmasız evsel atık...

Water Science and Technology, 2000

In accordance with the development of tourism, sea pollution has become the major problem of the ... more In accordance with the development of tourism, sea pollution has become the major problem of the coastal zones. In order to realize sustainable touristic activities in Turkey, it is very important to treat wastewater and preserve the environmental quality. It is roughly estimated that there are around 2000 small treatment plants in Turkey. However, it is necessary to construct 10,000 more wastewater treatment plants to solve the wastewater problems in small settlements. In this study, performances of small treatment systems were investigated. Two types of the treatment plants were of concern. The first one is a continuous system based on fixed bed activated sludge process, whereas the second system is based on batch activated sludge process. 96 treatment plants have been investigated in this study. The wastewater characteristic is determined as strong domestic wastewater. It has been observed that the effluent quality of the batch activated sludge and aerated biofilter systems meet ...

Water Science and Technology, 2005

In this study, nitrogen removal was investigated in pilot-scale subsurface flow (SSF) and in free... more In this study, nitrogen removal was investigated in pilot-scale subsurface flow (SSF) and in free water surface flow (FWS) constructed wetlands installed in the campus of TUBITAK-Marmara Research Center, Gebze, near Istanbul, Turkey. The main purposes of this study are to apply constructed wetlands for the protection of water reservoirs and to reuse wastewater. Experiments were carried out at continuous flow reactors. The effects of the type of plants on the removal were investigated by using emergent (Canna, Cyperus, Typhia spp., Phragmites spp., Juncus, Poaceae, Paspalum and Iris.), submerged (Elodea, Egeria) and floating (Pistia, Salvina and Lemna) marsh plants at different conditions. During the study period HLRs were 30, 50, 70, 80 and 120 L m2 d−1 respectively. The average annual NH4-N, NO3-N, organic N and TN treatment efficiencies in SSF and FWS wetlands are 81% and 68%, 37% and 49%, 75% and 68%, 47% and 53%, respectively. Nitrification, denitrification and ammonification ra...

Water Science and Technology, 2006

With the aim of protecting drinking water sources in rural regions, pilot-scale subsurface water ... more With the aim of protecting drinking water sources in rural regions, pilot-scale subsurface water flow (SSF) and free water surface flow (FWS) constructed wetland systems were evaluated for removal efficiencies of nitrogenous pollutants in tertiary stage treated wastewaters (effluent from the Paşaköy biological nutrient removal plant). Five different hydraulic application rates and emergent (Canna, Cyperus, Typhia sp., Phragmites sp., Juncus, Poaceae, Paspalum and Iris) and floating (Pistia, Salvina and Lemna) plant species were assayed. The average annual NH4-N, NO3-N and organic-N treatment efficiencies were 81, 40 and 74% in SSFs and 76, 59 and 75% in FWSs, respectively. Two types of the models (first-order plug flow and multiple regression) were tried to estimate the system performances. Nitrification, denitrification and ammonification rate constants (k20) values in SSF and FWS systems were 0.898 d−1 and 0.541 d−1, 0.486 d−1 and 0.502 d−1, 0.986 d−1 and 0.908, respectively. Resu...

Water Science and Technology, 2011

This research project aimed to determine the technologically feasible and applicable wastewater t... more This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. 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 (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, avera...

21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, May 27-June 1, 2012, Bari, Italy, 2012

Marmara Basin includes the areas in Turkey with the densest industrialization and population. Sur... more 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.

Transboundary Water Resources in the Balkans, 2000

... the findings of the feasibility report dated October 1992, the first three high priority area... more ... the findings of the feasibility report dated October 1992, the first three high priority areas were Marmaris, Kusadasi/Davutlar and ... THE PROBLEM OF SUMMER HOUSES (SECONDARY VACATION HOMES) Owners of summerhouses, holiday resorts and other tourist hotels in the ...

Water Science and Technology, 1999

Turkey is a developing country where industrial and urban developments mostly occur in coastal ar... more Turkey is a developing country where industrial and urban developments mostly occur in coastal areas. Besides the present pollution loads, newly developed tourist areas and industries, through increased input of wastes, further stress the coasts of Turkey. In this study, the state of sewerage systems, treatment plants and sea outfalls in Turkish coasts were investigated. The pollution problems should be considered differently from region to region. Development of coastal areas appeared to be partially tourist and partially industrial in nature. Because of this fact, problems from different coastal areas were discussed in different projects and solutions were recommended.

Ecological Engineering, 2012

Pilot-scale treatment of a small community's domestic wastewater was performed over a period of m... more Pilot-scale treatment of a small community's domestic wastewater was performed over a period of more than 2 years. The study involves removal of nitrogen in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. Anaerobically pretreated wastewater was first introduced into HFCW and then VFCW before being discharged. HFCW supported denitrification in addition to removal of organic matter whereas VFCW obtained nitrification. Effective parameters such as temperature and effluent recirculation rate were tested in the system. Lower effluent concentrations were obtained with a 100% recirculation ratio compared to nonrecirculation. On the other hand, nitrification was found to be significantly higher in summer compared to winter. The pilot-scale system achieved the project goals by obtaining 98% total Kjeldahl nitrogen (TKN) and 79% total nitrogen (TN) removal during operation with recirculation. The study points out a novelty that the discharge limits could be achieved for nitrogen by the application of recirculation in a hybrid constructed wetland. The study shows that a hybrid constructed wetland system with recirculation is an effective method to obtain low nitrogen concentrations in downstream of anaerobic pretreatment of domestic wastewaters of small communities, particularly in the warm climate of the Mediterranean Region.

Water Research, 1993

Abstract An optimization model of the activated sludge wastewater treatment systems was presented... more Abstract An optimization model of the activated sludge wastewater treatment systems was presented. Such a system was relatively complex, containing a series of unit processes, each designed to achieve a specific goal. The design basis of each unit in the system, which consists of primary settling, aeration and secondary settling tanks was given. The model was run at the varying dissolved oxygen concentration. A relationship was developed between sludge volume index and sludge age using data from literature. The relationships between sludge volume index and coefficients of solids flux model, V 0 and n , were also found separately. An optimum design model was developed for the system. In the optimization model, relationships mentioned above were considered. The model was solved by using the Box-Complex Algorithm. The results obtained from the model were discussed.

Desalination and Water Treatment, 2015

This study involves sequential treatment of domestic wastewater by anaerobic reactors followed by... more This 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 BOD 5 , 57 and 39% for total nitrogen, 55 and 53% for total phosphorus, 94 and 90% for total suspended solids removal on average, respectively, in Balcik and Orucoglu villages. The effluent concentrations met the discharge limits. The study showed that hybrid CW system with anaerobic pretreatment is an effective method to treat domestic wastewaters of small communities with populations below 2,000.

Environmental Engineering and Management Journal

Surface and ground water in rural areas where there is a lack infrastructure of sewage is exposed... more Surface and ground water in rural areas where there is a lack infrastructure of sewage is exposed to a risk of bacteriological contamination. Combined constructed wetland (CW) systems appear to be the most feasible solution in preventing bacteriological contamination of waters in these areas. In this study, a pilot-scale combined CW system was designed to remove coliform source pollution in surface water. The system comprised a vertical, non-vegetated CW (Stage I), a horizontal-subsurface flow bed vegetated with Iris (Stage II), and a vertical-subsurface flow bed vegetated with Phragmites (Stage III) connected in series. Coliform bacteria counts (cfu/100 mL) were made in the input and output of all stages under different hydraulic and loading conditions. The average inflow coliform bacteria in stages I, II and III were 4.26, 3.51, and 2.07 for fecal coliforms (FC) and 5.15, 4.38 and 3.05 cfu/100 mL for total coliforms (TC), respectively. The system was capable of significantly reducing FC and TC in septic wastewater effluent. The second stage removed approximately 95%, with higher elimination than in stage II and III. The average overall reductions of fecal and total coliforms were approximately 99%. No seasonal effects on the average removals were observed. Average removal efficiencies were affected by hydraulic residence time (HRT) and input bacteria counts. TUKEY-HSD tests demonstrated that there were statistically significant differences between stages in coliform removal. The results of this study demonstrated that removal efficiency of the system may enhanced due to a longer HRT when singlestage systems are connected in series.

İTÜDERGİSİ/d, Feb 5, 2011

Water Science and Technology, 2004

Water Science and Technology, 2005

İTÜDERGİSİ/e, 2010

Water Science and Technology, 1995

İTÜDERGİSİ/e, 2010

Water Science and Technology, 2000

Water Science and Technology, 2005

Water Science and Technology, 2006

Water Science and Technology, 2011

21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, May 27-June 1, 2012, Bari, Italy, 2012

Transboundary Water Resources in the Balkans, 2000

Water Science and Technology, 1999

Ecological Engineering, 2012

Water Research, 1993

Desalination and Water Treatment, 2015

Environmental Engineering and Management Journal