Cake layer reformation rates on self forming dynamic membranes and performance comparison with microfiltration membranes

Dynamic membranes (DMs) keep on attracting attention progressively as an alternative to conventional membranes because they can be operated with relatively higher fluxes and lower fouling rates. However, there are many factors affecting the performance of DMs, such as DM pore size, structure, and operating conditions. In this study, mainly focused on the investigation of cake formation rates both in initial formation and reformation rates after physical/chemical cleaning. In this context, it has been evaluated the performances of DMs with different pore sizes (171 μm, 90 μm, and 30 μm) and different structures under the same conditions and compared their performances with microfiltration (MF) membranes (0.45 μm and 0.22 μm) in a single reactor. In the study, the effects of different fluxes (15-, 20-, 25 L/m2·h (LMH), SADm (1-, 0.8-, 0.5 m3-air /m2·h) and F/M (0.095, 0.125, 0.19 g-COD/g-MLSS·day) conditions on the treatment and filtration performance of DMs were investigated. High COD (>95%) and turbidity (<10 NTU) removals were obtained in this study. In particular, the 30 μm DM (0.65 ± 0.47 NTU) produced quite close effluent turbidity compared to MFs (0.12 ± 0.05 NTU). Low SADm and high F/M values resulted in increased effluent COD concentrations and turbidity values. By decreasing the SADm, the cake formation rate and the fouling rate increased, which showed that there is a definite relationship between the cake formation rates and the fouling rates. Additionally, considering all the results, the most stable operation was obtained in the 30 μm DM, although it has been occurred the least fouling in the 90 μm membrane in the study. This study, focused on cake reformation rates, attempts to show that DMs can be used as an alternative to MBRs. Especially, when taking into account the results of the reformation rate of 30 μm DM (6.09 NTU/h) and other high filterability features. © 2022 Elsevier B.V

Optimization of arsenic removal from an acid mine drainage in an anaerobic membrane bioreactor

This study aims at optimizing the arsenic removal performance of a sulfidogenic anaerobic MBR treating acid mine drainage (AMD). The feed sulfate concentration was kept constant at 2,000 mg/L and ethanol concentration was decreased steadily from 1,500 mg COD/L to 500 mg COD/L. Metal concentrations were kept at 75 or 150 mg/L Fe, 25 mg/L Cu, 5 mg/L Zn, 5 mg/L Co, 5 mg/L Mn, 2.5 mg/L Ni and 2.5 mg/L As. High sulfide concentration led to dissolution of orpiment (As2S3) and low As removal efficiency. Later, decrease of sulfide concentration in the bioreactor resulted in increasing As removal efficiency over 99% due to formation of orpiment and co-precipitation of As with amorphous iron precipitates. Flux was increased up to around 10 L/(m2h) (LMH). It was concluded that heavy metals in the AMD behaved as a filtration aid and increased the sludge filterability, which was assessed by the regular analyses of supernatant filterability, specific resistance to filtration and capillary suction time. © 2020 Elsevier B.V

Streamflow forecasting using a hybrid LSTM-PSO approach: the case of Seyhan Basin

The conditions which affect the sustainability of water cause a number of serious environmental and hydrological problems. Effective and correct management of water resources constitutes an effective and important issue among scales. In this sense, a precise estimation of streamflow time series in rivers is one of the most important issues in optimal management of surface water resources. Therefore, a hybrid method combining particle swarm algorithm (PSO) and long short-term memory networks (LSTM) are proposed to predict flow with data obtained from different flow measurement stations. In this respect, the data gathered from three Flow Measurement Stations (FMS) from Zamanti and Eglence rivers located on Seyhan Basin are utilized. Besides, the proposed LSTM-PSO method is compared to an adaptive neuro-fuzzy inference system (ANFIS) and the LSTM benchmark model to demonstrate the performance achievement of proposed method. The prediction performances of the developed hybrid model and the others are tested on the determined stations. The forecasting performances of the models are determined with RMSE, MAE, MAPE, SD, and R-2 metrics. The comparison results indicated that the LSTM-PSO method provides highest results with values of R-2 (approximate to 0.9433), R-2 (approximate

ELECTROCOAGULATION PROCESS for SHORT TREATMENT PERIOD of ARSENIC CONTAMINATED WATER

The effective arsenic removal rate was achieved by the electrocoagulation (EC) method. The aim of this paper is to study the arsenic removal by EC method applied for short period and to investigate the effects of current density, pH, salt addition, and conductivity on the removal rate and energy consumption. The EC experiments started in batch mode in 10 L plexiglass reactor with five aluminum electrodes. The electrocoagulation was started with the initial arsenic (As) concentration of 1.00 mg/L. Current intensity and voltage values ranged between 1-2 A and 2-15 V, respectively for the process time of 10 min. The highest As removal rate (99%) was found for 5 V and 1 A current application. 1.29 mA/cm2 current density provided the optimum energy consumption (0.60 Wh) for 99% As removal. Increased removal was noticed above pH 8. Current density, pH, and conductivity were found effective factors on the As removal. © 2021 Gheorghe Asachi Technical University of Iasi, Romania. All rights reserved

Short-Term Streamflow Forecasting Using Hybrid Deep Learning Model Based on Grey Wolf Algorithm for Hydrological Time Series

The effects of developing technology and rapid population growth on the environment have been expanding gradually. Particularly, the growth in water consumption has revealed the necessity of water management. In this sense, accurate flow estimation is important to water management. Therefore, in this study, a grey wolf algorithm (GWO)-based gated recurrent unit (GRU) hybrid model is proposed for streamflow forecasting. In the study, daily flow data of uctepe and Tuzla flow observation stations located in various water collection areas of the Seyhan basin were utilized. In the test and training analysis of the models, the first 75% of the data were used for training, and the remaining 25% for testing. The accuracy and success of the hybrid model were compared via the comparison model and linear regression, one of the most basic models of artificial neural networks. The estimation results of the models were analyzed using different statistical indexes. Better results were obtained for the GWO-GRU hybrid model compared to the benchmark models in all statistical metrics except SD at the uctepe station and the whole Tuzla station. At uctepe, the FMS, despite the RMSE and MAE of the hybrid model being 82.93 and 85.93 m(3)/s, was 124.57 m(3)/s, and it was 184.06 m(3)/s in the single GRU model. We achieved around 34% and 53% improvements, respectively. Additionally, the R-2 values for Tuzla FMS were 0.9827 and 0.9558 from GWO-GRU and linear regression, respectively. It was observed that the hybrid GWO-GRU model could be used successfully in forecasting studies

Anaerobik Dinamik Membran Biyoreaktör Kullanılarak Tekstil Endüstrisi Atıksularının Arıtılması

Yürütmüs oldugumuz projemizin amacı ise, tekstil endüstrisi atıksularının anaerobik dinamik MBR (AnDMBR) sistemiyle arıtılması ve fltrasyon özelliklerinin incelenmesidir. Çalısmada farklı isletim kosullarında arıtım performansı incelenmis olup, ayrıca dinamik membran isletiminin en önemli unsuru olan kek olusumu ve bunu etkileyen parametreler arastırılmıstır. Bunun yanısıra da tıkanmayı ve filtrayonu etkileyen hem kirletici parametreleri hem de reaktör içi çamurunun reolojik özellikleri belirlenmistir. Proje iki asamadan olusmakta olup, ilk asamada kısa süreli isletimle 3 farklı destek tabakasının performans denemeleri ve optimizasyon yapılmıs olup, ikinci asamada seçilen destek tabakasının uzun süreli isletimle performansı test edilmistir. Yürütülen projede, birinci asamada tekstil endüstrisi atıksuyunun anaerobik kosullarda yüksek oranlarda arıtılması saglanmıs olup, %95 oranında KOI ve %96 oranında renk giderimleri elde edilmistir. Yüksek oranlardaki arıtım performansının yanısıra yapılan çalısmada yüksek filtrasyon performansları da gözlenmis olup, özellikle 20 μm dinamik membranda membranda vakum isleminin baslamasından kısa süre sonra çok düsük konsantrasyonlarda çıkıs AKM elde edilmistir. Özellikle stabil isletimde 1 mg-AKM/L seviyelerine kadar inmistir. Yapılan farklı isletim strastejileriyle (kesikli gaz geri devri, SADm degerinin düsürülmesi, akının arttırılması) çıkıs AKM konsantrasyonu düsürülmeye çalısılmıs olup, 53 μm?de stabil olarak 10 mg- AKM/L?nin altında isletim saglanabilmistir. Çıkısta elde edilen düsük AKM konsantrasyonlarına baglı olarak 20 μm gözenek boyutuna sahip dinamik membranda daha sık basınç artısı gözlense de yapılan gaz geri yıkamalarla AnDMBR ortalama 8.05±3.01 LMH akıda stabil bir sekilde isletilmistir. Projenin ikinci asamasında da ortalama %93 oranında KOI giderimi ve yaklasık %98 oranında renk giderimlerinin yanısıra, oldukça düsük seviyelerde çıkıs AKM konsantrasyonları elde edilmistir. Çalısmada, kek olusumuna kadar geçen sürede çıkıs AKM konsantrasyonu oldukça yüksek seviyelerde ölçülmüs olup, kek olusumu ile birlikte hızlı bir sekilde 10 mg-AKM/L?nin altına düsmektedir. Sonuç olarak uzun süreli isletimde dinamik membran tarafından ortalama %99,8 oranında AKM giderimi/tutulması gerçeklestirilmistir. Uzun süreli isletimde 175 günlük süreçte yalnızca 4 kez kimyasal yıkama yapılmıs olup, 2 günde bir gerçeklestirilen 1 dakikalık gaz geri yıkamaları ile AnDMBR ortalama 8,65±1,72 LMH akıda stabil bir sekilde isletilmistir. Projede ayrıca kirletici analizleri ve reaktör içi çamurunun reolojik özellikleri de incelenmis olup, filtrasyon performansı ile iliskilendirilmeye çalısılmıstır. Yapılan GPC analizlerinde reaktör içi numunesinde gözlenen piklerin süzüntü numunelerine kıyasla oldukça yüksek oldugu belirlenmis olup, bu nedenle de gözlenen piklere ait moleküllerin konsantrasyonlarının süzüntüde azaldıgı yani kek tarafından tutuldugu belirlenmistir. EPS ve kek tabakasına ait GPC ölçümlerine bakıldıgında ise her iki numunede de yüksek molekül agırlıga sahip organik maddeler benzer elüsyon zamanlarında tespit edilmis olup, bu nedenle bu maddelerin EPS kaynaklı oldugu söylenebilir. SEM taramalarında kek tabakasının gözeneksiz bir sekilde dinamik membran yüzeyini kapladıgı ve buna baglı olarak düsük çıkıs AKM konsantrasyonları elde edildigi belirlenmistir. Yapılan SEM-EDS ve ICP analizleri ile kek tabakasının olusmasında inorganik maddelerin de önemli rol oynadıgı tespit edilmis olup, sülfat ilavesi neticesinde kek tabakasında Fe ve Cu elementlerinin sülfürle çökerek konsantrasyonlarının arttıgı tespit edilmistir. Çamur karakteristik testleri neticesinde ise filtrasyona karsı direncin artmasıyla filtrelenebilirligin düstügü gözlenmistir. Sonuç olarak yapmıs oldugumuz çalısmayla elde edilen sonuçlar neticesinde, AnDMBR?nin tekstil endüstrisi atıksularının arıtılmasında kullanılabilecegi net bir sekilde ortaya konmustur

Treatment of textile industry wastewater using dynamic membrane bioreactor: Impact of intermittent aeration on process performance

This study aims at investigating the performance of intermittently aerated dynamic membrane bioreactor for the treatment of chromium containing synthetic textile wastewater. Nylon meshes with two different pore sizes, i.e. 20 mu m and 53 mu m, were tested. The bioreactor was operated under continuous or intermittent aeration conditions with aeration on/off durations of 5/3 min, 1/10 min, and 1/15 min. Although high suspended solid rejection was observed with the support layer having 20 mu m pore size, TMP quickly exceed 400-600 mbar, which caused increased suspended solid concentrations in the permeate. Whereas, when the support layer with 53 mu m pore size was used, the bioreactor was operated around 100 days without cleaning and with low permeate suspended solid concentration at fluxes of 23-29 LMH. In continuous aeration mode, color removal performance was negligible and the removal efficiency increased with lengthening unaerated period duration and reached 97%, when aeration on/ off duration was 1/15 min. In the dynamic layer, high molecular weight soluble organics were detected by gel permeation chromatographic analyses together with the identification of proteins and polysaccharides by the FT-IR analyses. SEM-EDS and metal analyses illustrated that inorganics may also have significant contribution to dynamic layer composition. (C) 2016 Elsevier B.V. All rights reserved

Impact of SRT on the efficiency and microbial community of sequential anaerobic and aerobic membrane bioreactors for the treatment of textile industry wastewater

The aim of this study is to evaluate the impact of SRT (infinite, 60 and 30 days) on the treatment and filtration characteristics of sequential anaerobic sulfate-reducing and aerobic sulfide-oxidizing MBRs treating textile wastewater. The influent COD, dye and sulfate concentrations were kept constant at 2000, 200 and 1000 mg/L, respectively. The decreased SRT caused substantial and partial decreases in COD oxidation and sulfate reduction, respectively, due to decrease of biomass concentration. Complete color removal was observed in the AnMBR and a slight increase in color was detected in the AeMBR. Sludge filterabilities were assessed with specific resistance to filtration, capillary suction time, and supernatant filterability tests. Compact and non-porous cake layer formed in the AnMBR. Metal-sulfide and Ca-P were detected in the cake layers of AnMBR and AeMBR, respectively, by SEM-EDS analyses. Desulfiiromonas thiophila and Thioalkalivibrio sulfidiphilus were dominant sulfate-reducing and sulfide oxidizing bacteria in AnMBR and AeMBR, respectively. (C) 2016 Elsevier B.V. All rights reserved

Performance and foulant characteristics of an anaerobic membrane bioreactor treating real textile wastewater

Treatment and the recovery of textile wastewater are important due to their high volume and toxicity. Although several studies have been conducted on the use of membrane bioreactors (MBR) for textile wastewater treatment, they have mainly focused on synthetic wastewater or aerobic MBRs. However, anaerobic MBR (AnMBR) offers potential advantages of high color removal with lower energy consumption. In this context, this study aims at investigating the performance of AnMBR for the treatment of real textile wastewater. In addition to treatability studies, the membrane foulants were investigated in detail, which may be used in the design and operation of real scale plants. The permeate COD and color concentrations were decreased down to 70 mg/L and 150 Pt-Co, respectively. In the GPC analysis, pollutants with molecular weights greater than 15 kDa detected in the supernatant were removed by the dynamic cake layer developed on the membrane and only low molecular weight organics appeared in the permeate. AnMBR was operated successfully at a flux of 4.1 ± 0.7 LMH with a cleaning cycle of once a week. The impact of physical and chemical cleaning of the fouled membrane on the TMP elevation rate was also evaluated to determine the cleaning efficiency

Recovery of biologically treated textile industry wastewaters by reverse osmosis membranes in the lab-scale cross-flow system

Bu çalışmanın amacı; üç farklı ters ozmoz (TO) membranının gerçek tekstil endüstrisi atıksularının arıtımındaki performanslarının değerlendirilmesi ve kıyaslanmasıdır. Çalışmada tekstil endüstrisi atıksularını arıtan gerçek ölçekli atıksu arıtma tesisi çıkış suları kullanılmış olup, membran performansları kimyasal oksijen ihtiyacı (KOİ), renk, iletkenlik ve membran akısı açısından değerlendirilmiştir. Çalışmada 10 saatlik filtrasyon çalışmalarında çapraz akışlı filtrasyon düzeneği ile B400FR, B400HR ve BW30 membranları test edilmiştir. Aynı basınçta yapılan çalışmada, en yüksek permeabilite değerini (3,45±0,12 LMH/bar) ve en düşük akı kaybını (%69) B400HR membranı verirken, akıdaki en fazla azalma (%82) BW30 membranında gözlemlenmiştir. Kullanılan atıksu 4570±130 µS/cm iletkenlik, 188±2 Pt-Co renk ve 35±2 KOİ konsantrasyonlarına sahip olup, test edilen tüm membranlar için süzüntü KOİ değeri 10 mg/L'nin altına düşürülmüş olup, en iyi KOİ giderim performansını B400FR membranı göstermiştir. Ortalama iletkenlik giderimi ise tüm membranlar için %92 değerinin üzerinde olup, B400FR, B400HR ve BW30 için sırasıyla %96, 94 ve 92 değerlerindedir. Benzer şekilde tüm membranlar için renk giderimi %99’un üzerinde gerçekleşmiştir. Elde edilen sonuçlarla süzüntü suyunun aynı endüstride geri kullanımı mümkündür.The aim of this study is the evaluation and comparison of the performance of three different reverse osmosis membranes on the treatment of real textile industry wastewater. The effluent of a real scale wastewater treatment plant which treats the textile industry wastewater, were used and the membrane performances were evaluated in terms of COD, color, conductivity removal and membrane flow rate. B400FR, B400HR and BW30 membranes were tested in a 10-hour filtration tests with a crossflow filtration system. In the studies conducted at same pressure, the highest permeability value (3.45 ± 0.12 LMH/bar) and the lowest flux loss (69%) were found in the B400HR membrane while the highest decrease in flow was observed in the BW30 membrane (82%). The wastewater conductivity, color and COD concentrations were 4570±130 μS/cm; 188±2 Pt-Co and 35±2 mg/L, respectively and permeate COD values for all tested membranes were reduced below 10 mg/L and B400FR membrane was showed the best COD removal performance. The conductivity removal rates for B400FR, B400HR and BW30 membranes were 96, 94 and 92%, respectively and the average conductivity decrease for tested membranes were over 92%. Similarly, the color removal efficiency for all membranes was over 99%. According to these results, it is possible to reuse the filtrate of tested membranes in the same industry