Recep Kaan Dereli

A review on dynamic membrane filtration: Materials, applications and future perspectives

This paper presents a comprehensive evaluation of the current status of dynamic membrane (DM) technology as an alternative to membrane bioreactor (MBR) systems. DM filtration makes use of a physical barrier (e.g. cloth or mesh) on which a cake layer is formed. It is already used in traditional filtration systems, but applications in biological wastewater treatment are still at its infancy. Dynamic filtration of sludge has lower risk of fouling and requires less energy and lower capital costs compared to MBR. A review of the state-of-art in both DM materials and configurations is presented. Factors affecting DM performance are discussed in order to determine the optimum and critical approaches for membrane operation. Future perspectives to enhance the applicability and functionality of the technology regarding the treatment and membrane performance are presented.

Potentials of anaerobic membrane bioreactors to overcome treatment limitations induced by industrial wastewaters

This review presents a comprehensive summary on applications of anaerobic membrane bioreactor (AnMBR) technology for industrial wastewaters in view of different aspects including treatability and filterability. AnMBRs present an attractive option for the treatment of industrial wastewaters at extreme conditions, such as high salinity, high temperature, high suspended solids concentrations, and toxicity that hamper granulation and retention of biomass or reduce the biological activity. So far, most of the research has been conducted at laboratory scale; however, also a number of full-scale AnMBR systems is currently being operated worldwide. Membrane fouling, a multivariable process, is still a research quest that requires further investigation. In fact, membrane fouling and flux decline present the most important reasons that hamper the wide-spread application of full-scale reactors. This paper addresses a detailed assessment and discussion on treatability and filterability of industrial wastewaters in both lab- and full-scale AnMBR applications, the encountered problems and future opportunities.

Anaerobic Treatment of Industrial Effluents: An Overview of Applications

Anaerobic treatment is an energy generating process, in contrast to aerobic systems that generally demand a high energy input for aeration purposes. It is a technically simple and relatively inexpensive technology which consumes less energy, space and produces less excess sludge in comparison to the conventional aerobic treatment technologies. Net energy production from biogas makes the anaerobic treatment technology an attractive option over other treatment methods. Increasing industrialization trend in the worldwide has resulted in the generation of industrial effluents in large quantities with high organic content, which if treated appropriately, can result in a significant source of energy. Anaerobic digestion seems to be the most suitable option for the treatment of high strength organic effluents. Anaerobic technology has improved significantly in the last few decades with the applications of differently configured high rate treatment processes, especially for the treatment of industrial wastewaters. High organic loading rates can be achieved at smaller footprints by using high rate anaerobic reactors for the treatment of industrial effluents. This chapter intends to bring together the knowledge obtained from different applications of the anaerobic technology for treatment of various types of industrial wastewaters. The first part of the chapter covers brief essential information on the fundamentals of anaerobic technology. The remainder of this chapter focuses on various anaerobic reactor configurations and operating conditions used for the treatment applications of different industrial wastewaters. Examples of applications that reflect the state-of-the-art in the treatment of industrial effluents by high rate anaerobic reactors are also provided.

Co-digestion of the organic fraction of municipal solid waste with primary sludge at a municipal wastewater treatment plant in Turkey.

Co-digestion of the organic fraction of municipal solid waste (OFMSW) and sewage sludge may be an attractive alternative for sustainable management of two separate waste streams produced in large amounts in all countries. This study evaluates calculation-based results of an anaerobic co-digestion process for primary sludge (PS) together with the OFMSW. The calculations were carried out for the anaerobic digester of Kayseri municipal wastewater treatment plant (in Turkey) presently digesting only PS. Two alternatives were proposed using different solid waste contents in co-digesters. For achieving the optimal solids content, some treated wastewater should be recycled to the inlet of the digesters. The municipal solid waste collection method characterized as mechanically sorted (MS-OFMSW; Option 1) is evaluated as well as a source sorted (SS-OFMSW) alternative (Option 2). Utilizing the energy produced by the existing sludge digester, only 30% of the internal energy demand at the wastewater treatment plant can be covered. The aim of this study is to evaluate how energy production would be increased by co-digestion of OFMSW and PS. The best operational condition considering organic loading rate, hydraulic retention time and energy generation could be attained at 10% digester solids content for both options. According to Option 1, almost 77% of the energy demand could be covered by co-digestion of MS-OFMSW and PS. Results indicated that almost 100% energy coverage can be obtained when co-digestion (Option 2) was performed according to SS-OFMSW and PS.

A systematic study on the effect of substrate acidification degree and acidogenic biomass on sludge filterability.

The influence of substrate acidification on sludge filtration characteristics was systematically investigated by using short term filtration tests. Four reactors were operated with raw and acidified whey permeate in order to evaluate the effect of acidogens on sludge filterability. The results showed that feeding non-acidified substrate promoted the growth of acidogens which in return decreased the median particle size of the sludge and adversely influenced specific resistance to filtration (SRF). In addition to the presence of acidogens, the food to mass (F:M) ratio was found as an important operation parameter on sludge filterability. Various filterability indicators, such as capillary suction time (CST), SRF and supernatant filterability, tended to became worse at increased F:M ratios. The decreased filterability at high F:M ratio was attributed to the accumulation of soluble microbial products (SMP) in the reactors. Interestingly, impact of acidogens on short term critical flux tests was not significant, but this may be a consequence of the experimental set-up.

Confectionery industry: a case study on treatability-based effluent characterization and treatment system performance

Source-based wastewater characterization and stream segregation provide effective management of industrial wastewaters. The characterization of wastewater sources from a confectionery factory was presented and performance of the wastewater treatment plant was evaluated in this study. All of the wastewater sources in the factory, except the vacuum water line, can be characterized by high concentrations of soluble pollutants and low pH. High organic content of the wastewater generated from the confectionery industry promoted the application of anaerobic technology as a pre-treatment before the conventional aerobic treatment. The average chemical oxygen demand (COD) removal and biogas production for expanded granular sludge bed reactor were 88% and 1,730 Nm(3)/day, respectively. The effluent from the investigated facility can be used for irrigation provided that conductivity values are within acceptable limits.

Biological performance and sludge filterability of anaerobic membrane bioreactors under nitrogen limited and supplied conditions

The impact of nitrogen on biological performance and sludge filterability of anaerobic membrane bioreactors was investigated in two lab-scale cross-flow anaerobic membrane bioreactors that were fed with cheese whey at two different COD:TKN ratios (50 and 190). Nitrogen deprivation adversely affected the biological treatment performance and reactor stability, as indicated by volatile fatty acids accumulation. On the other hand, nitrogen (urea) supplementation resulted in a reduced sludge median particle size and decreased sludge filterability. Standard filterability parameters such as capillary suction time and specific resistance to filtration tended to rapidly increase in the nitrogen supplemented reactor. The critical fluxes in the nitrogen limited and supplemented reactors were 20 and 9 L m-2 h-1, respectively. The rapid deterioration of sludge filterability under nitrogen supplemented conditions was attributed to abundant growth of dispersed biomass. Thus, the COD:TKN ratio of wastewater affected both bioconversion and filterability performance in the anaerobic membrane bioreactors.

The feasibility of a centralized biogas plant treating the manure produced by an organized animal farmers union in Turkey.

The aim of this study is to evaluate the feasibility and the energy recovery potential of mesophilic (30-35 °C) anaerobic digestion of animal wastes (manure) at a centralized biogas plant (CBP) for 35,000 cattle. The proposed CBP is composed of an equalization tank followed by pasteurization and 3+[1/2] modules; i.e. each module consists of four completely mixed anaerobic reactors with a capacity of treating the manure from 10,000 cattle. The effect of maize silage loading, as the co-substrate, both on biomethane production and feasibility of the system was also evaluated. Besides, the transport fuel substitutes of the produced biomethane with or without co-substrate were also investigated. Results of the proposed CBP indicated that biomethane production increased ca. 1.65 fold with co-substrate addition and pay-back periods for one module treating 10,000 cattle manure are calculated to be ca. 11 and 7.0 yr without and with silage addition, respectively. Besides, considering the potential revenue when replacing transport fuels, about 74 heavy goods vehicles or 1,560 cars may be powered per year by the biogas produced from the proposed CBP where the co-digestion of manure and maize silage is applied.

Treatment of cheese whey by a cross-flow anaerobic membrane bioreactor: Biological and filtration performance

&NA; Whey, produced in large quantities during cheese production, is a rapidly fermentable high strength wastewater characterized by a high biodegradability and low alkalinity. In this study, a lab‐scale cross‐flow anaerobic membrane bioreactor was used to address the commonly experienced difficulties such as unstable reactor performance and unexpected biomass losses when treating whey wastewater with conventional anaerobic reactors. The anaerobic membrane bioreactor provided a stable treatment performance, i.e. more than 90% chemical oxygen demand removal, and moderate membrane fluxes between 8 and 11 L m−2 h−1 could be obtained, applying a low cross‐flow velocity of about 0.5 m s−1. Short term critical flux tests revealed that higher fluxes up to 36 L m−2 h−1 are possible at elevated cross‐flow velocities and/or reduced mixed liquor suspended solids concentrations. Sludge filterability indicated by capillary suction time and specific resistance to filtration deteriorated throughout the study. Chemical cleaning efficiency gradually decreased, indicating irreversible membrane fouling during long term operation.

Factors Affecting Fouling in Membrane Bioreactors Treating Leachate and Fouling Control

Anahtar kelimeler Aktif karbon; HPM; MBR; Sızıntı suyu arıtımı;ÇMÜ; Tıkanma kontrolü. Özet Katı atıkların arazide depolanması yüksek kirlilikte sızıntı suyu oluşumuna neden olduğu için yüzeysel ve yeraltı su kaynakları için önemli bir tehdit oluşturmaktadır. Diğer biyolojik arıtma yöntemleriyle karşılaştırıldığında, membran biyoreaktörler (MBR) ile yüksek kalitede arıtılmış su elde edilebildiğinden, MBR’lerin sızıntı suyu arıtımında son yıllarda daha çok tercih edildiği görülmektedir. Bu çalışmanın amacı sızıntı suyu arıtımı yapan MBR’lerde tıkanma nedenlerinin ortaya konulması ve tıkanmayı azaltmak için en uygun metodun belirlenmesidir. Sızıntı suyu arıtımı yapan tam ölçekli iki MBR tesisi (MBR-1 ve MBR-2) kıyaslandığında; karbonhidrat bazlı çözünmüş mikrobiyal ürünler (ÇMÜk) değeri MBR-2 tesisinde MBR-1’e göre yaklaşık 5 kat daha fazladır. Her iki tesis için hücre dışı polimerik maddeler (HPM) miktarında ÇMÜ miktarı kadar fark olmamakla birlikte, MBR-2’de MBR-1’e göre HPM miktarı daha yüksektir. Bu durum MBR-2’de görülen tıkanma problemlerinde, ÇMÜ’nün başlıca rol oynadığını göstermektedir. Tıkanma kontrolü ile ilgili deneysel sonuçlar dikkate alındığında, membran tıkanmasını azaltacak en uygun yöntemin 50 mg/L konsantrasyonda toz aktif karbon (TAK) eklenmesi olduğu belirlenmiştir.