Three membrane bioreactors, a low flux filter (LFF), a diafilter (DF), and an ion-exchange (IE) membrane bioreactor were used to treat water polluted with 50 ppm-N nitrate. The three systems were compared in terms of removal efficiency of nitrate, operational complexity, and overall quality of the treated water. In the low flux filter (LFF) membrane bioreactor an hemo-dialysis hollow fiber module was used and operated continuously for 29 days with a constant flux of permeate. The performance of the system was constant during the span of the experiment, which demonstrated that when the module was operated under constant low flux of permeate, the membrane filtration process was not affected by fouling. The removal rate of the LFF was 100% since the treated effluent did not contain nitrate or nitrite. The volumetric denitrification rate was 240 g-N day-1 m-3, which is within the range of denitrification rates obtained in tubular membrane modules. The treated effluent contained acetate, the carbon source of the biological process, and other inorganic nutrients, which showed that operating this ultrafiltration module at controlled flux did not improve the retention of these substances in the bioreactor. The same hemo-dialysis hollow fiber module employed in the LFF system was used in the diafilter (DF) membrane bioreactor. In the DF system, however, the membrane module was used as a contactor that separated the treated water and the bioreactor system, which allowed the transfer of solutes through the membrane porous structure and supported the growth of a biofilm on the membrane surface. The nitrate removal rate of the DF system increased from 76% to 91% during the 17 days assay. Unfortunately, this improvement could be attributed to microbial contamination of the water circuit because significant concentrations of the carbon source, acetate, nutrients, and nitrate were found in the treated effluent. The volumetric denitrification rate of the system was 200 g-N day-1 m-3, and the surface denitrification rate was lower than values previously reported for contactor membrane bioreactors. The results hereby presented do not evidence any advantage of operating the Filtral 20 ® membrane module as a contactor instead of as a filter such as in the LFF system. On the other hand, the third system herein presented, the IE membrane bioreactor, demonstrated several advantages of a contactor configuration but with a non-porous ion exchange membrane module in place of the Filtral 20 ®. As in a contactor system, the anion membrane provided a surface for biofilm growth, facilitated the transport of nitrate, and prevented mixing of treated water and bioreactor medium. Compared to the two previous systems, the most remarkable result of the IE was the reduction of secondary pollution in the treated water. The concentrations of phosphate and ethanol were zero and less than 1% of the concentration in the bioreactor, respectively. In addition, the IE system was less complex than the two other systems because the ion exchange membrane is non-porous. Therefore, unlike with porous contactors, it was not necessary to control the flux of treated water that could be lost through the bioreactor. The average surface denitrification rate of the IE system was 7.0 g-N day-1 m-2, which is higher than what had been reported for other contactor denitrification systems. However, because of the low surface to volume ratio of the membrane module that was used, the volumetric denitrification rate of the IE system was low, equivalent to 65 g-N day-1 m-3. / Master of Science

No description available.

Οι βιοαντιδραστήρες μεμβρανών αποτελούν μια καινοτόμο τεχνολογία, ιδανική για την αποκατάσταση προηγμένων αστικών και βιομηχανικών λυμάτων, τα οποία περιέχουν υψηλά ποσοστά βιοαποικοδομήσιμων οργανικών ενώσεων. Η παρούσα εργασία αποτελεί ένα μέρος μιας ευρύτερης προσπάθειας ανάπτυξης μιας νέας κατηγορίας λειτουργικών μεμβρανών τεχνολογίας “Βιοαντιδραστήρα Μεμβρανών” (Membrane Bioreactors, MBRs) ή/και βελτίωσης των ήδη χρησιμοποιούμενων μεμβρανών τεχνολογίας MBR με την ενσωμάτωση στο ενεργό πορώδες τους νανοσωλήνες άνθρακα. Οι νανοσωλήνες άνθρακα δυνητικά θα προσέφεραν ταυτόχρονα υψηλότερες ταχύτητες ροής νερού, υψηλότερο ποσοστό απόρριψης οργανικών ενώσεων και ανόργανων αλάτων χαμηλού μοριακού βάρους, καθώς και υψηλότερη αντοχή της μεμβράνης στην εναπόθεση διαφόρων μικροοργανισμών. Η πρόκληση στην περίπτωση αυτή είναι η αποτελεσματική ενθυλάκωση τους στην ενεργή εκλεκτική στοιβάδα των μεμβρανών αυτών. Οι νανοσωλήνες άνθρακα από την πρώτη στιγμή της ανακάλυψης τους, έχουν προσελκύσει το ενδιαφέρον της επιστημονικής κοινότητας, λόγω της ευρείας εφαρμογής τους σε πολλά επιστημονικά και τεχνολογικά πεδία, ως συνέπεια των μοναδικών ιδιοτήτων τους. Οι χημικές, οπτικές, ηλεκτρικές και μηχανικές ιδιότητές τους, τους καθιστούν δυνητικά χρήσιμους σε πάρα πολλές εφαρμογές. Στη συγκεκριμένη περίπτωση, τα τελευταία 5-7 έτη, οι νανοσωλήνες άνθρακα έχουν ταυτοποιηθεί ως μια καινούργια γενιά νανο-πορωδών υλικών με τρομερό δυναμικό για εφαρμογές ως φίλτρα σε υλικά μεμβρανών που θα μπορούσε να φέρει πραγματική επανάσταση στο σχετικό χώρο. H δυνατότητα ελέγχου της διαμέτρου τους και κατά συνέπεια του μεγέθους των πόρων τους μέσω των οποίων λαμβάνει χώρα το φαινόμενο της διάχυσης ή ροής (από τα 4 Angstroms έως τα 15 nm), σε συνδυασμό με τα σχεδόν άτριβου χαρακτήρα γραφιτικά τους τοιχώματα, εξασφαλίζει εξαιρετικά ταχεία ροή μικρών μορίων με ταυτόχρονη καταπληκτική εκλεκτικότητα στη διαπερατότητα μορίων με βάση το μέγεθός τους. Η ροή υγρών μέσα από αυτές των νανοσωλήνων άνθρακα προβλέπεται να είναι 3-5 τάξεις μεγέθους πάνω απ’ ότι αναμένεται με βάση υπολογισμούς βασισμένους σε απλές αρχές της υδροδυναμικής. Στο πλαίσιο αυτό, μελετήθηκε ο εμβολισμός νανοπορωδών εμπορικών μεμβρανών με διάφορα είδη νανοσωλήνων άνθρακα (CNTs): μονοφλοιϊκών (με ένα τοίχωμα) (Single Wall CNT: SWCNT), διπλοφλοιϊκών (με δύο τοιχώματα) (Double Wall CNT: DWCNT), πολυφλοιϊκών (με πολλαπλά (~15) τοιχώματα) (Multi Wall CNT: MWCNT), λεπτών “πολλαπλού” τοιχώματος (με λίγα (~6-7 ) τοιχώματα) (thin MWCNT), αλλά και τροποποιημένων νανοσωλήνων άνθρακα πολλαπλού τοιχώματος με υδρόξυ-ομάδες (-OH) και καρβόξυ-ομάδες (-COOH) καθώς επίσης και νανοσωλήνων άνθρακα τροποποιημένων με διάφορα πολυμερή όπως πολυβινυλοπυρολιδόνη (PVP), πολυμεθακρυλικό γλυκιδιλεστέρα (PGMA), (PSSPC16). Οι νανοσωλήνες άνθρακα, αρχικά, χαρακτηρίσθηκαν με τη βοήθεια της φασματοσκοπίας Raman και της Ηλεκτρονικής Μικροσκοπίας Σάρωσης και μελετήθηκε η διασπορά τους σε νερό (H2O) και αιθανόλη (EtOH). Κατόπιν, εμβολίσθηκαν σε διαφόρων τύπων πορώδεις ανισοτροπικές μεμβράνες (πόρων κωνικού τύπου), αλλά και σε μεμβράνες καθορισμένου μεγέθους πόρων κυλινδρικού τύπου (track etched), στην προσπάθεια ανάδειξης μιας βέλτιστης ενθυλάκωσής τους στο ενεργό/εκλεκτικό τμήμα των μεμβρανών αυτών, κάτι που δεν είναι καθόλου προφανές. Αναπτύχθηκε μια πειραματική διάταξη εμβολισμού νανοσωλήνων άνθρακα, βασιζόμενη στην αρχή της διήθησης/φιλτραρίσματος, η οποία επέτρεψε ένα βαθμό εμβολισμού τους στις μεμβράνες και μια τάση βελτίωσης του χρόνου/των ρυθμών διέλευσης του νερού από αυτές. Στην προσπάθεια αυτή αρωγός σ’ ένα μεγάλο βαθμό αποδείχθηκε η Ηλεκτρονική Μικροσκοπία Σάρωσης. / Membrane Bioreactors are an innovative technology, ideal for the treatment and rehabilitation of advanced municipal and industrial wastewater which contain high biodegradable organic compounds. A new category of functional membranes for technology MBR, which offer higher water flow, higher rejection rate of organic compounds and inorganic salts of low molecular weight, and greater resistance to the deposition of the membrane of microorganisms may be ensured by the inclusion of various types of carbon nanotubes (CNT’s) into porous polymeric membranes and its basic principle is the efficient binding of modified carbon nanotubes in these membranes. Carbon nanotubes, from the first moment of their discovery, have attracted the interest of the scientific community, due to their wide application in many scientific and technological fields, as a result of their unique properties. More specifically, the chemical, optical, electrical and mechanical properties make them potentially useful in many applications. Important is the use of carbon nanotubes for the development of an innovative high performance membrane for use in Membrane Bioreactors Technology (Membrane Bioreactors, MBR’s). In the present study different types of carbon nanotubes were examined, such as single-wall carbon nanotubes (SWCNT’s), double-wall carbon nanotubes (DWCNT’s), multi-wall carbon nanotubes (MWCNT’s), thin multi-wall carbon nanotubes (thin MWCNT’s), and modified carbon nanotubes with hydroxy groups (-OH), carboxyl groups (-COOH) as well as carbon nanotubes modified with various polymers such as polyvinylpyrrolidone (PVP), phosphonium salt of polystyrene sulfonate (PSSPC16) and polyglycidyl methacrylate (PGMA). Initially, the different types of carbon nanotubes were characterized, using Raman Spectroscopy and Scanning Electron Microscopy. Their dispersion in H2O and ethanol was also examined. Then, they were infiltrated into various types of porous anisotropic membranes with conical porous and into defined pore size membranes (track etched), to find the most suitable combination, which would result to the best water flow through the infiltrated membrane. For this purpose, an experimental device was developed, based on the principle of filtration, which allowed both the filtration of the nanotubes in the films, and the measuring of the water flow through them. Furthermore, the optimal conditions of the system were studied that could both bring about the greater coverage of the membrane pores from nanotube suspensions, (probed by SEM), and result to the optimum water flow rate.

Lignocellulosic biomass is a potential feedstock for production of sugars, which can be fermented into ethanol. The work presented in this thesis proposes some solutions to overcome problems with suboptimal process performance due to elevated cultivation temperatures and inhibitors present during ethanol production from lignocellulosic materials. In particular, continuous processes operated at high dilution rates with high sugar utilisation are attractive for ethanol fermentation, as this can result in higher ethanol productivity. Both encapsulation and membrane bioreactors were studied and developed to achieve rapid fermentation at high yeast cell density. My studies showed that encapsulated yeast is more thermotolerant than suspended yeast. The encapsulated yeast could successfully ferment all glucose during five consecutive batches, 12 h each at 42 °C. In contrast, freely suspended yeast was inactivated already in the second or third batch. One problem with encapsulation is, however, the mechanical robustness of the capsule membrane. If the capsules are exposed to e.g. high shear forces, the capsule membrane may break. Therefore, a method was developed to produce more robust capsules by treating alginate-chitosan-alginate (ACA) capsules with 3-aminopropyltriethoxysilane (APTES) to get polysiloxane-ACA capsules. Of the ACA-capsules treated with 1.5% APTES, only 0–2% of the capsules broke, while 25% of the untreated capsules ruptured within 6 h in a shear test. In this thesis membrane bioreactors (MBR), using either a cross-flow or a submerged membrane, could successfully be applied to retain the yeast inside the reactor. The cross-flow membrane was operated at a dilution rate of 0.5 h-1 whereas the submerged membrane was tested at several dilution rates, from 0.2 up to 0.8 h-1. Cultivations at high cell densities demonstrated an efficient in situ detoxification of very high furfural levels of up to 17 g L-1 in the feed medium when using a MBR. The maximum yeast density achieved in the MBR was more than 200 g L-1. Additionally, ethanol fermentation of nondetoxified spruce hydrolysate was possible at a high feeding rate of 0.8 h-1 by applying a submerged membrane bioreactor, resulting in ethanol productivities of up to 8 g L-1 h-1. In conclusion, this study suggests methods for rapid continuous ethanol production even at stressful elevated cultivation temperatures or inhibitory conditions by using encapsulation or membrane bioreactors and high cell density cultivations. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 4 april 2014, klockan 9:30 i KE-salen, Kemigården 4, Göteborg.</p>

Biofuels production and utilisation can reduce the emission of greenhouse gases, dependence on fossil fuels and also improve energy security. Ethanol is the most important biofuel in the transportation sector; however, its production from lignocelluloses faces some challenges. Conventionally, lignocellulosic hydrolysis and fermentation has mostly been performed by separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). SHF results in product inhibition during enzymatic hydrolysis and increased contamination risk. During SSF, suboptimal conditions are used and the fermenting organism cannot be reused. Bacterial contamination is another major concern in ethanol production, which usually results in low ethanol yield. In these studies, the above-mentioned challenges have been addressed. A novel method for lignocellulosic ethanol production ‘Simultaneous saccharification filtration and fermentation (SSFF)’ was developed. It circumvents the disadvantages of SSF and SHF; specifically, it uses a membrane for filtration and allows both the hydrolysis and fermentation to be carried out at different optimum conditions. SSFF also offers the possibility of cell reuse for several cultivations. The method was initially applied to pretreated spruce, with a flocculating strain of yeast Saccharomyces cerevisiae. SSFF was further developed and applied to pretreated wheat straw, a xylose rich lignocellulosic material, using encapsulated xylose fermenting strain of S. cerevisiae. High solids loading of 12% suspended solids (SS) was used to combat bacterial contamination and improve ethanol yield. Oil palm empty fruit bunch (OPEFB) was pretreated with fungal and phosphoric acid in order to improve its ethanol yield. An evaluation of biofuel production in Nigeria was also carried out. SSFF resulted in ethanol yield of 85% of the theoretical yield from pretreated spruce with the flocculating strain. Combination of SSFF with encapsulated xylose fermenting strain facilitated simultaneous glucose and xylose utilisation when applied to pretreated wheat straw; this resulted in complete glucose consumption and 80% xylose utilisation and consequently, 90% ethanol yield of the theoretical level. High solids loading of 12% SS of pretreated birch resulted in 47.2 g/L ethanol concentration and kept bacterial infection under control; only 2.9 g/L of lactic acid was produced at the end of fermentation, which lasted for 160 h while high lactic acid concentrations of 42.6 g/L and 35.5 g/L were produced from 10% SS and 8% SS, respectively. Phosphoric acid pretreatment as well as combination of fungal and phosphoric pretreatment improved the ethanol yield of raw OPEFB from 15% to 89% and 63% of the theoretical value, respectively. In conclusion, these studies show that SSFF can potentially replace the conventional methods of lignocellulosic ethanol production and that high solids loading can be used to suppress bacterial infections during ethanol productions, as well as that phosphoric acid pretreatment can improve ethanol yield from lignocellulosic biomass. / <p>Thesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on 31 October 2014, 10.00 a. m. in room E310, University of Borås, Allégatan 1, Borås.</p>

Fruits are among the most important commodities in global trading due to its fundamental nutritional values. In 2012, the fruits supply was 115 kg/person/year, however, only 50 % of the fruits reached their consumers and the rest ended up as waste during the long fruit supply chain. The waste from fruits is mostly dumped or burned, creating a serious environmental problem. A more sustainable handling of the waste is therefore highly desirable. One of them is conversion of the fruits wastes into biogas through anaerobic digestion. One challenge with the conversion of fruits wastes into biogas is the presence of antimicrobial compounds in the fruits, which reduce the biogas yield or even cause a total failure of the process. Fruit flavors have been reported to have antimicrobial activity against several microorganisms and being responsible for the defense system in the fruits. However, there is only scarce information about the effect of fruit flavors on anaerobic digesting microbia. The objectives of the present thesis were: 1) to investigate the inhibitory activity of the fruit flavors on anaerobic digestion; 2) to remove the flavor compound by pretreatment; and 3) to protect the cell from the flavor compounds using a membrane bioreactor. The inhibitory activity of the fruit flavors was examined from different groups of flavors by adding a single flavor compound into the batch anaerobic digesting system, at three different concentrations. Among the flavors added, myrcene and octanol were found to exhibit a strong inhibitory activity, with 50 % reduction of the methane production at low concentrations, ca. 0.005–0.05 %. These flavors can be found in oranges, strawberries, grapes, plums, and mangoes. The other flavors tested showed moderate and low inhibitory activity, which might not affect the anaerobic digestion of the fruits wastes. In order to overcome the inhibitory effects of the fruit flavor, two approaches were proposed in this thesis, namely, fruit flavor removal by leaching pretreatment and cell protection from fruit flavor using a membrane bioreactor. Orange peel waste and D-limonene were used as a model of fruit waste and inhibitor, respectively. The leaching pretreatment uses solvent to extract the limonene from the orange peel. The methane yield increased by 356 % from 0.061 Nm3/kg VS to 0.217 Nm3/kg VS, by pretreating the peel using hexane with peel and a hexane ratio of 1:12 at room temperature for 10 min. Alternative to limonene removal, the cells were encased in a hydrophilic membrane, which is impermeable to hydrophobic limonene. This method yielded more than six times higher methane yield, compared to the free cell. At the highest organic loading rate, examined in this work, 3 g VS/L/day, the methane yield of the reactor containing the free cell was only 0.05 Nm3/kg VS, corresponding to 10 % of the theoretical yield, whereas 0.33 Nm3/kg VS methane yield was achieved using a membrane bioreactor corresponding to 75 % of the theoretical yield. / <p>Thesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on November 27th 2014, 10.00 a.m. in room E310, University of Borås, Allégatan 1, Borås.</p>

Previous membrane researches undertaken over the years to develop general deadend filtration models made use of an approach that combined all three classical fouling mechanisms, namely, pore blocking, pore constriction and cake filtration. More recently researchers have modified and adapted this modelling approach for a cross flow side-stream membrane bioreactor (MBR) system. Literature also reveals that there have been numerous recent experimental studies conducted on rotating membrane bioreactor (RMBR) systems. Some of these studies have resulted in the creation of RMBR models of the membrane fouling process as well. However, simulation and modelling of the fouling in RMBRs is still a nascent topic to date due to poor understanding and great complexity of the system hydrodynamics involved. Even when models are developed, they are either too complex to be useful at operational level, or not comprehensive enough to express all possible operational scenarios. In many cases they are simply too difficult to calibrate and thus ending up being more suited as research tools rather than for direct process control. As such, further research is required in this area. The research reported in this thesis consists of the development and validation of a RMBR system fouling model that incorporates all three classical fouling mechanisms. This thesis work is divided into two main sections. On top of a literature review that thoroughly describes the background theory and general information on MBRs along with their state of the art, the first section of the thesis also explains the specific methodologies used to accomplish all the main tasks carried out in this research work. The first step of these methodologies involves the setting-up of a rotating MBR system process based upon the FUV-185-A15R Flexidisks membrane module that was developed by Avanti Membrane Technology (USA). This system was used to collect the majority of the data used in this thesis. Since some of these data outputs were compared against non-rotating MBR systems, a similar setting-up process for a bespoke static square MBR system was carried out as well. Using synthetic wastewater in conjunction with activated sludge, mixed liquor suspended solids in both MBR system bioreactors were increased in levels over time to desired levels (i.e. by periodic excess sludge wasting). Trans-membrane pressure (TMP)-stepping fouling data was then acquired from operations of these membrane ultrafiltration processes. This data was obtained by measuring the flux decline or TMP increase. Following data collection, a dynamic fouling model for this RMBR system was then created in Matlab (using the Genetic Algorithm function). To do this, hydrodynamic regimes such as air scouring and rotating shear effects along with all the three classical fouling mechanisms were included in the mathematical fouling model that was created from first principles. For the purpose of comparison, a similar fouling model was created without incorporating the rotational effects for the static square MBR system. This included modelling of the hydrodynamics as well. Finally, both these models were validated and calibrated using the data that were collected from both laboratory-based MBR systems. The second phase of the thesis explores the numerous outputted results produced via model simulations which were then discussed and analysed in great detail. Results from this research indicate that the mathematical models give a decent portrayal and description of the fouling mechanisms occurring within a rotating MBR system. It was found that the rotational mechanisms in terms of fouling prevention accounted for only twelve percent of cake removal with the rest being accomplished through the air scouring mechanism. However, it was found that although the slowly rotating spindle induced a weak crossflow shear, it was still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded, which would lead to dramatic loss of flux. Furthermore, when compared against the static MBR system, the study concluded that a rotating MBR system could increase the flux throughput by a significant amount. In conclusion, RMBR systems appear to represent alternative viable solutions when compared against the traditional static MBR systems that currently dominate the industrial and municipal marketplace. In future, RMBR systems may become the systems of first choice once there is a better understanding of the rotational processes, and once research and design into this sector broadens. Future study areas should thus focus on: whether the forces acting on an activated sludge particle during rotation have a significant effect on the fouling or the shear hydrodynamic regimes; whether activated sludge and benchmark models could be created for rotating MBRs whilst including the shear effects and hydrodynamic regimes; whether model predictive control using these developed RMBR models would enhance efficiency gains within an operational plant; and, whether the real measured soluble microbial products (SMP) concentrations could be used to create an even better SMP predictive model that accurately explains fouling behaviour.

This study revealed that ammonium ion exchange of natural zeolite could be a feasible method of nitrogen removal and recovery from permeate from anaerobic membrane bioreactors (AnMBRs). NaCl concentrations optimized for chemical regeneration in batch experiments did not match those in continuous column tests. Instead, the mass ratio of Na+ to Zeolite-NH4+-N was significant for improving regeneration efficiency in column experiments; this mass ratio was 750 g Na+/g Zeolite-NH4+-N required for regeneration efficiency over 90% in 2 hours at pH 9. ???To decrease the NaCl dose in regeneration of exhausted zeolite, a high pH regeneration method was developed using an NaCl concentration of 10 g/L at pH 12 (the mass of Na+ to Zeolite-NH4+-N of 4.2 ) which achieved a regeneration efficiency about 85%. The recovery of ammonium nitrogen from the exhausted zeolite was assessed with air stripping followed by ammonia collection in an acid scrubber. The effects of shaking and air stripping were investigated in batch tests and the results showed the superiority of air stripping over shaking. Liquid circulation and air flow rates were varied for optimization of ammonia recovery in a continuous zeolite-packed column combined with a regeneration chamber and a stripping column. The liquid circulation rate had no significant effect on either the regeneration efficiency or the ammonia transfer efficiency from ammonium nitrogen to ammonia gas, while the ammonia transfer efficiency significantly increased with the air flow rate.??? Furthermore, the effect of pH on ammonia recovery was tested. Both the regeneration efficiency and the ammonia transfer efficiency were significantly improved with increasing pH. When the pH was increased from 9.5 to 12, the regeneration efficiency increased from 9.2% to 84% and the ammonia transfer efficiency increased from 54% to 92%. The nitrogen recovery process that combines zeolite ammonium exchange and air stripping can decrease chemical costs for regeneration of exhausted zeolite and efficiently collect ammonium nitrogen to be reused as fertilizers. Hence, the integrated nitrogen process can resolve the challenge of nitrogen removal in anaerobic membrane bioreactors treating organic wastewater in sustainable manners.

This study was carried out to investigate performance of a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR). During the study, the VRM plant was erected from scratch and operated in METU campus. The plant was composed of two tanks. First one was about 100 m3 and it was used for biological treatment / the second tank, about 30 m3, was used as filter chamber. The permeate flow rate was adjusted between 6 and 8.5 m3/h giving a hydraulic retention time (HRT) of 18 hours during the study. In the aeration tank, dissolved oxygen (DO) was adjusted to between 4 and 0.1 mg/L to see the effect of the dissolved oxygen concentration on the process. In the filter chamber, total of 540 m2 flat sheet membrane surface were used for the separation of the treated wastewater from the activated sludge. During the 140 days of operation, MLSS concentration increased from 2.5 g/L to 20 g/L. A 99.99% BOD removal and above 95% COD removal were achieved most of the time during the study. At the time when organic loading rate was between 0.35 and 0.1 kg COD/ kgVSS-day, sludge production was very low. Therefore, sludge retention time (SRT) was taken as infinite. The turbidity in the effluent was less than 1 NTU at all the time, and was below that of the tap water. In the aeration tank, 100% Total-N removal was observed when DO was 2 mg/L and MLSS was 8.36 mg/L on 80th day of operation. This indicates that simultaneous nitrification and denitrification was taking place at these conditions. Later, N-removal decreased when DO was deliberately decreased to 0.1 mg/L in the aeration tank to prevent nitrification / for treated wastewaters were intended to be used for irrigation. Since the pores of the membrane were 0.038 &amp / #956 / m, treated wastewaters were sterile with respect to bacteria

Thesis submitted in fulfilment of the requirements for the degree Master of Technologae: Chemical Engineering in the Faculty of Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2014 / Most softdrink industries in developing countries are moving towards wastewater reuse or recycling. Water and wastewater reutilization, costs of treatment and disposal guidelines, remain the most critical factors for the development of sustainable water use for softdrink industries. Wastewater reuse or recycle has potential in the softdrink industry, depending on the wastewater characteristics’ concentration and volume. During this study, an integrated laboratory scale anaerobic/aerobic sidestream membrane bioreactor (MBR) system was used for treating softdrink industry wastewater (SDIW). The aim was to evaluate the system’s performance, and identify potential opportunities to recycle the water, and therefore reduce freshwater intake and minimise wastewater production. The objectives were to: evaluate: 1) treatment efficiencies for the individual stages; 2) biogas production in the anaerobic stage; and 3) the overall performance of the integrated system under different operating conditions. The SDIW used in this study was classified as medium to high strength wastewater with a total chemical oxygen demand (CODt) ranging between 2 242 and 11 717 mg/L and a biological oxygen demand (BOD) of up to 1 150 mg/L. The major pollutants in the SDIW were caustic soda; dissolved sugars, namely fructose (1 071 mg/L) and sucrose (6 900 mg/L); with the pH ranging between 6.1 and 12. The SDIW was characterized by total suspended solids (TSS) of 66 mg/L, as well as fats, oils and greases (FOG) of 40 mg/L. The maximum turbidity and colour was 65.3 NTU and 42 mg Pt/L, respectively. All the physiochemical properties and inorganic parameters were within the within the City of Cape Town’s (CCT’s) industrial wastewater quality discharge standards by-law (South Africa, 2006). Excluding the total dissolved solids (TDS) and electrical conductivity (EC) with maximum values were 1 050 mg/L and 1 483 μS/cm, respectively. Anaerobic pre-treatment of this SDIW was studied using a laboratory-scale expanded granular sludge bed (EGSB) reactor maintained at mesophilic temperature of between 35 to 37˚C. An organic loading rate (OLR), upflow velocity (Vup) and hydraulic retention time (HRT) of 10.9 kg COD/m3d, 0.85 m/h and ~11.8 h, respectively, resulting in COD treatment efficiencies of up to 93% CODt. An increase in nitrate (NO3-) in the EGSB product stream was an indication of an anaerobic ammonium (NH4+) oxidation (ANAMMOX) process. Anaerobic digestion (AD) of SDIW in the EGSB resulted in biogas production with methane (CH4), carbon dioxide (CO2), nitrogen (N2), and oxygen (O2), concentrations of up to 70%, 11%, 14.8%, and 4.1%, respectively. At the OLR and Vup of 10.9 kg COD/m3d and 0.85 m/h, respectively, the EGSB produced 16.7 L/d of biogas. The EGSB anaerobic pre-treatment resulted in stable treatment efficiencies for the removal of organic constituents, as well as biogas production without adding an external carbon source. The MBR post-treatment satisfactorily operated at a feed flowrate of up to 33.7 L/d, OLR of 2.3 and 3.1 kg COD/m3d for the anoxic and aerobic zones, respectively, and an HRT of approximately 0.41 h for both zones. The average CODt removal achieved was 86%. The dissolved oxygen (DO) concentration of 2.1 mg/L in the anoxic zone combined with an aeration rate and DO concentration of 11.8 L/min and 5.7 mg/L, in the aerobic zone resulted in NH4+; NO3-; and orthophosphate (PO43-), removal rates up to 90%; 55% and 39%, respectively. However, the MBR post-treatment did not decrease the orthophosphate concentration to within the SANS 241:2011 drinking water standards. The integrated EGSB-MBR treatment for SDIW was able to achieve an overall CODt removal efficiency of up to 94%. Although the MBR performance was successful the EC, TDS, PO43-, and colour concentrations in the ultrafiltration (UF) permeate did not meet the CCT’s industrial wastewater standards by-law (2006) as well as the SANS’ drinking water standards 241:2011 and required further treatment for reuse.