The work presented in this thesis leads to the formulation of a dynamic mathematical model of an immersed membrane bioreactor (iMBR) for wastewater treatment. This thesis is organised into three parts, each one describing a different set of tasks associated with model development and simulation. In the first part, the Author qualitatively and quantitatively compares various published activated sludge models, i.e. models of biochemical processes associated with bacterial growth, decay, lysis and substrate utilisation in activated sludge systems. As the thesis is focused on modelling membrane bioreactors (MBRs) which are known to experience membrane fouling as a result of adsorption of biopolymers present in the bulk liquid onto and within the membrane, all activated sludge models considered in this thesis are able to predict, with various levels of accuracy, the concentrations of biopolymeric substances, namely soluble microbial products (SMP) and extracellular polymeric substances (EPS). Some of the published activated sludge models dedicated to modelling SMP and EPS kinetics in MBR systems were unable to predict the SMP and EPS concentrations with adequate levels of accuracy, without compromising the predictions of other sludge and wastewater constituents. In other cases, the model equations and the assumptions made by their authors were questionable. Hence, two new activated sludge models with SMP and EPS as additional components have been formulated, described, and simulated. The first model is based on the Activated Sludge Model No. 1 (ASM1) whereas the second model is based on the Activated Sludge Model No. 3 (ASM3). Both models are calibrated on two sets of data obtained from a laboratory-scale system and a full-scale system and prove to be in very good agreement with the measurements. The second part of this thesis explains the development of two membrane fouling models. These models are set to describe the loss of membrane permeability during filtration of various solutions and suspensions. The main emphasis is placed on filtration of activated sludge mixtures, however the models are designed to be as general as feasibly possible. As fouling is found to be caused by a large number of often very complex processes which occur at different spatial as well as temporal scales, the two fouling models developed here have to consider a number of significant simplifications and assumptions. These simplifications are required to balance the model's accuracy, generality and completeness with its usability in terms of execution times, identifiability of parameters and ease of implementation in general purpose simulators. These requirements are necessary to ascertain that long term simulations as well as optimisation and sensitivity studies performed in this thesis either individually on fouling models or on the complete model of a MBR can be carried out within realistic time-scales. The first fouling model is based on an idea that fouling can be subdivided into just two processes: short-term reversible fouling and long-term irreversible fouling. These two processes are described with two first order ordinary differential equations (ODEs). Whilst the first model characterises the membrane filtration process from an observer's input-output point of view without any rigorous deterministic description of the underlying mechanisms of membrane fouling, the second model provides a more theoretical and in-depth description of membrane fouling by incorporating and combining three classical macroscopic mechanistic fouling equations within a single simulation framework. Both models are calibrated on a number of experimental data and show good levels of accuracy for their designated applications and within the intended ranges of operating conditions. In the third part, the first developed biological model (CES-ASM1) is combined with the behavioural fouling model and the links between these two models are formulated to allow complete simulation of a hollow fibre (HF) immersed membrane bioreactor (iMBR). It is assumed that biological processes affect the membrane through production of mixed liquor suspended solids (MLSS), SMP and EPS which cause pore blockage, cake formation, pore diameter constriction, and affect the specific cake resistance (SCR). The membrane, on the other hand, has a direct effect on the bulk liquid SMP concentration due to its SMP rejection properties. SMP are assumed to be solely responsible for irreversible fouling, MLSS is directly linked to the amount of cake depositing on the membrane surface, whereas EPS content in activated sludge affects the cake's SCR. Other links provided in the integrated MBR model include the effects of air scouring on the rate of particle back-transport from the membrane surface and the effects of MLSS concentration on oxygen mass transfer. Although backwashing is not described in great detail, its effects are represented in the model by resetting the initial condition in the cake deposition equation after each backwash period. The MBR model was implemented in Simulink® using the plant layout adopted in the MBR benchmark model of Maere et al. [160]. The model was then simulated with the inputs and operational parameters defined in [36, 160]. The results were compared against the MBR benchmark model of Maere et al. [160] which, contrary to this work, does not take into account the production of biopolymers, the membrane fouling, nor any interactions between the biological and the membrane parts of an MBR system.

<p>The most common way to treat wastewater in Sweden today is by a combination of an activated sludge process and a chemical treatment. These processes are not very energy efficient and may not be the most environmentally friendly. That is why it is interesting to evaluate new alternative methods to see if they can be less harmful to the environment and help to a lower resource consumption. New techniques are tested in a pilot installation at Hammarby Sjöstad, Sjöstadsverket. To be able to evaluate these techniques in a wide perspective system analyses are conducted where different impacts can be considered, advantages and disadvantages in the systems.</p><p>Five system structures for water treatment have been constructed in Matlab/Simulink in this study. The URWARE (URbanWAter REsearch) model was used to conduct a system analysis, which made a comparison of the different systems possible. Four of the systems contained a new technique for water treatment, consisting of an anaerobic membrane bioreactor (MBR) combined with a VSEP (Vibratory Shear Enhanced Process) unit. This is one of the techniques that now are tested in Sjöstadsverket. The fifth system was a reference system designed as a conventional treatment plant. The wastewater treated in the different systems was in some cases mixed wastewater, in other source sorted, with or without food waste from kitchen waste disposers.</p><p>Results from the system analysis shows that the MBR technique gives some advantages compared to the conventional water treatment. A large part of the nutrients in incoming materials are recycled. The highest recycling percent is reached when the MBR technique is combined with compost that handles the food waste. The total impact on the environment by greenhouse gases and eutrophic substances is lower in all the alternative systems compared to the reference system. The system with the source sorted urine has the most favourable exergy turnover. When reversed osmosis is used in the treatment a lot of energy is needed which leads to a poor exergy turnover and the conventional technique is more advantageous in these cases. All the alternative systems give a larger acidification which is a disadvantage with the MBR technique.</p> / <p>Vid behandling av avloppsvatten i Sverige används idag i de flesta fall en aktivslamprocess kompletterad med kemiskfällning. Denna process är inte så energieffektiv och kanske inte heller den mest optimala ur miljösynpunkt. Därför kan det vara intressant att utvärdera nya alternativa metoder för att se om dessa kan vara skonsammare mot miljön och bidra till en minskad resursförbrukning. I Sjöstadsverket, som är en försöksanläggning vid Hammarby Sjöstad, undersöks flera nya tekniker i mindre skala. För att kunna utvärdera dessa tekniker utifrån ett helhetsperspektiv görs systemanalyser, där för- och nackdelar och andra effekter kan vägas in.</p><p>I föreliggande studie har fem systemstrukturer för vattenrening byggts upp i Matlab/Simulink. Substansflödesmodellen URWARE (URban WAter REsearch) användes för att utföra en systemanalys, som gjorde en jämförelse av de olika systemen möjlig. Fyra av systemen innehöll ny reningsteknik bestående av en anaerob membranbioreaktor (MBR) kopplad till en VSEP- enhet (Vibratory Shear Enhanced Process). Det är en teknik som nu testas i Sjöstadsverket. Det femte systemet var ett referenssystem utformat som ett konventionellt reningsverk. De vatten som behandlades i reningsverken var i vissa fall blandat avloppsvatten, i andra källsorterat, med och utan matavfall från köksavfallskvarnar.</p><p>Utifrån systemanalysen kan det konstateras att MBR-tekniken ger en del fördelar gentemot den konventionella reningen. Bland annat eftersom en stor andel av näringsinnehållet i avloppsvattnet kan fångas upp och återföras till åkermark. Bäst kretsloppspotential fås när membranbioreaktorn kombineras med en kompost som tar hand om allt matavfall. Totalt sett bidrar också alla de nya reningssystemen till lägre växthusgasutsläpp och lägre utsläpp av eutrofierande ämnen än referenssystemet med konventionell rening. Ur exergisynpunkt är den nya tekniken bättre än den konventionella i det fall då urin källsorteras. I de fall då omvänd osmos används vid behandling är den konventionella processen mer fördelaktig. En nackdel med MBR-tekniken är att utsläpp av försurande ämnen är markant större än för den konventionella tekniken.</p>

Managed aquifer recharge (MAR) consists of artificially replenishing groundwater to facilitate reuse and/or the associated environmental benefits. Meanwhile, soil aquifer treatment (SAT) is a process of geo-purification designed and operated to improve the quality of the infiltrating water and is thus a type of MAR. SAT consists of a basin operating under rotation of drying and wetting periods. Often, SAT involves water of impaired quality applied onto soil and consequently it implies various risks of health, geochemical and physical nature with difficult or irreversible remediation. To study the effect of pre-treatment on SAT a pilot plant including conventional activated sludge (CAS), a membrane bioreactor (MBR), tertiary and secondary vertical flow reed beds (VFRB) and SAT soil columns. The sludge retention time (SRT) in the CAS and MBR processes was changed every 6 months to look at the impact of SRT on SAT. Each unit and treatment train effluent was characterised to determine the impact of effluent quality on SAT performance. This study showed that tertiary VFRB, especially when fed with MBR effluent, was the best option for SAT and irrigation reuse as it provided the best compliance with reuse standards and the best fertilisation potential. However, long-term clogging occurred in SAT after tertiary VFRB, suggesting the need for a longer resting period or shorter wetting period. This study also highlighted the importance of total suspended solids (TSS) content for SAT removal mechanisms and infiltration rate. In particular, SAT fed with high TSS content effluent was susceptible to temperature variation. Hence the duration of wetting and flooding periods should be adapted according to the season. Further, variation in SRT only indirectly affected pollutants removal by the system including CAS treatment set up at 6 d SRT where the N compounds balance was favourable to an autotrophic N removal.

The performance of an MBR under chemical shock loading conditions was investigated, to ascertain the robustness of the treatment system for urban water reuse. 32 household products and industrial substances, likely to be found in urban wastewater were assessed for toxicity, using Microtox and respirometry to obtain EC50 values. Six of these toxins were dosed into bench scale porous pots to observe any detrimental effects on the treatment system, in terms of effluent quality and potential foulant release. Four toxins were dosed into a pilot scale MBR to observe the effects of scale and enhanced biomass retention on the perturbations seen at bench scale. Mitigation of the foulants observed was investigated by the addition of ancillary chemicals. 10 household products and 6 industrial products were identified as being of risk to a biological treatment system with EC50 concentrations of the order that could be present in urban wastewater. 2 of the 6 toxins dosed into the porous pots caused a serious impact on the system reducing COD removal rates to 45%, compared with 92% average for the control pots, and increasing SMP turbidity to 11 NTU. 1 of the 4 toxins dosed into the MBR caused an impact, although less than observed in the porous pots, with the COD removal rate reducing to 77% and SMP turbidity increasing to a maximum of 9 NTU. Jar tests carried out to investigate mitigation potential of SMP turbidity found the cationic polymers MPE50 and high molecular weight polyDADMAC most efficient with reductions of SMP turbidity to <1 NTU possible although the toxins increased the dose necessary to achieve this.

Les BioRéacteurs à Membranes (BàM) sont une technologie adaptée à l’un des challenges du 21ème siècle : la réutilisation des eaux usées.En combinant un traitement biologique et une filtration membranaire, ce procédé permet d’atteindre une qualité d’eau adaptée à la réutilisation en permettant une désinfection physique totale. Néanmoins, son essor économique est fortement limité par le colmatage membranaire qui, quand le système est optimisé, est dû principalement à la Matière Organique Dissoute (DOM). Afin de comprendre et de maitriser ce colmatage, des outils ont été développés pour identifier les composés de la DOM responsables du colmatage. Ainsi, au cours de cette thèse, la DOM de deux BàM, alimentés par des effluents réels, a été étudiée ; un BàM traitant des eaux usées urbaines(station d’épuration de La Grande Motte) et un BàM échelle pilote traitant des urines réelles. La matière organique dissoute issue du premier BàMa ainsi été fractionnée par taille et par hydrophobicité pour identifier les mécanismes de colmatage associés à chaque fraction.Des tests de filtration, réalisés sur les différentes fractions, ont permis d’identifier les colloïdes (protéines) comme responsables majeurs du colmatage externe (gâteau) et les substances humiques comme responsables du colmatage interne. En combinant ces tests de filtration avec des mesures de fluorescence3D (3DEEM), étant une méthode rapide dont le signal facilement exploitable, il a été possible de définir des indicateurs qualitatifs pour ces deux familles de colmatants. Par la suite, en combinant la 3DEEM avec une méthode de séparation et quantification par taille (LC-OCD), le signal de 3DEEM qualitatif a été calibré pour donner une information quantitative et de taille au travers d'une analyse rapide.Ces nouveaux indicateurs ont ensuite été mesurés sur site et ont permis d’établir des liens entre les paramètres opératoires ou la qualité de l’intrant pour le suivi global de la DOM et son impact sur le colmatage. Ces outils soulignent toute la potentialité de la fluorescence 3D comme indicateur en temps réel du suivi, du contrôle et de l’optimisation de l‘étape de séparation membranaire. / Membrane BioReactors (MBR) are suitable technology to face one of the major 21th century challenges : wastewater reuse.Combining biological treatment with membrane separation step, MBR produce reusable water through total physical disinfection. Nevertheless, it democratization is limited by membrane fouling that is mainly caused by Dissolved Organic Matter (DOM) compounds when the system is optimized.In order to understand and control membrane fouling, tools were developed to identify DOM compounds responsible for this phenomenon.Thus, this PhD work, focused on studying the DOM taken from two MBR fed with real wastewater: a full-scale MBR treating urban wastewater (La Grande-Motte wastewaster treatment plant) and a lab-scale MBR treating urine from source-separated toilets.Dissolved organic matter collected in the first MBR was fractionated by size and hydrophobicity to identify fractions’ fouling mechanisms. Then, filtration tests performed on the different fractions highlighted the role of colloids (proteins) in external fouling (cake) and humic substances in internal fouling. Filtration tests were combined with fluorescence3D (3DEEM) measurements, which is a quick identification method with an easy extracted signal, allowing to define qualitative indicators for both foulants classes.After, coupling 3DEEM with a size separation and quantification method (LC-OCD), qualitative signals from foulants indicators were calibrated. Thus, using 3DEEM it was possible to obtain a quantitative and size information about DOM foulants. These new indicators were used on-site and allowed establishing links between DOM and operating parameters or influent quality, which is necessary for DOM global control and its impact on membrane fouling. These tools highlight the potentiality for 3DEEM on-line application for separation step monitoring, control and optimization.

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.

The most common way to treat wastewater in Sweden today is by a combination of an activated sludge process and a chemical treatment. These processes are not very energy efficient and may not be the most environmentally friendly. That is why it is interesting to evaluate new alternative methods to see if they can be less harmful to the environment and help to a lower resource consumption. New techniques are tested in a pilot installation at Hammarby Sjöstad, Sjöstadsverket. To be able to evaluate these techniques in a wide perspective system analyses are conducted where different impacts can be considered, advantages and disadvantages in the systems. Five system structures for water treatment have been constructed in Matlab/Simulink in this study. The URWARE (URbanWAter REsearch) model was used to conduct a system analysis, which made a comparison of the different systems possible. Four of the systems contained a new technique for water treatment, consisting of an anaerobic membrane bioreactor (MBR) combined with a VSEP (Vibratory Shear Enhanced Process) unit. This is one of the techniques that now are tested in Sjöstadsverket. The fifth system was a reference system designed as a conventional treatment plant. The wastewater treated in the different systems was in some cases mixed wastewater, in other source sorted, with or without food waste from kitchen waste disposers. Results from the system analysis shows that the MBR technique gives some advantages compared to the conventional water treatment. A large part of the nutrients in incoming materials are recycled. The highest recycling percent is reached when the MBR technique is combined with compost that handles the food waste. The total impact on the environment by greenhouse gases and eutrophic substances is lower in all the alternative systems compared to the reference system. The system with the source sorted urine has the most favourable exergy turnover. When reversed osmosis is used in the treatment a lot of energy is needed which leads to a poor exergy turnover and the conventional technique is more advantageous in these cases. All the alternative systems give a larger acidification which is a disadvantage with the MBR technique. / Vid behandling av avloppsvatten i Sverige används idag i de flesta fall en aktivslamprocess kompletterad med kemiskfällning. Denna process är inte så energieffektiv och kanske inte heller den mest optimala ur miljösynpunkt. Därför kan det vara intressant att utvärdera nya alternativa metoder för att se om dessa kan vara skonsammare mot miljön och bidra till en minskad resursförbrukning. I Sjöstadsverket, som är en försöksanläggning vid Hammarby Sjöstad, undersöks flera nya tekniker i mindre skala. För att kunna utvärdera dessa tekniker utifrån ett helhetsperspektiv görs systemanalyser, där för- och nackdelar och andra effekter kan vägas in. I föreliggande studie har fem systemstrukturer för vattenrening byggts upp i Matlab/Simulink. Substansflödesmodellen URWARE (URban WAter REsearch) användes för att utföra en systemanalys, som gjorde en jämförelse av de olika systemen möjlig. Fyra av systemen innehöll ny reningsteknik bestående av en anaerob membranbioreaktor (MBR) kopplad till en VSEP- enhet (Vibratory Shear Enhanced Process). Det är en teknik som nu testas i Sjöstadsverket. Det femte systemet var ett referenssystem utformat som ett konventionellt reningsverk. De vatten som behandlades i reningsverken var i vissa fall blandat avloppsvatten, i andra källsorterat, med och utan matavfall från köksavfallskvarnar. Utifrån systemanalysen kan det konstateras att MBR-tekniken ger en del fördelar gentemot den konventionella reningen. Bland annat eftersom en stor andel av näringsinnehållet i avloppsvattnet kan fångas upp och återföras till åkermark. Bäst kretsloppspotential fås när membranbioreaktorn kombineras med en kompost som tar hand om allt matavfall. Totalt sett bidrar också alla de nya reningssystemen till lägre växthusgasutsläpp och lägre utsläpp av eutrofierande ämnen än referenssystemet med konventionell rening. Ur exergisynpunkt är den nya tekniken bättre än den konventionella i det fall då urin källsorteras. I de fall då omvänd osmos används vid behandling är den konventionella processen mer fördelaktig. En nackdel med MBR-tekniken är att utsläpp av försurande ämnen är markant större än för den konventionella tekniken.

The study aims to investigate an appropriate wastewater treatment process to treat domestic wastewater in Hanoi City which contain low-strength for COD (120-200 mg/L) but high in nitrogen content (10-40 mg/L). A lab scale anoxic-oxic system with a hollow fiber-Membrane Separation Bioreactor was operated at a flow rate of 5-10 L/h over a period of 150 days. The reactor was operated at different sludge recirculation rates. The MBR maintained relatively constant transmembrane pressure. During 150 days of reactor operation, treated water quality have COD of around 20 mg/L, NH4-N of less than 1 mg/L, NO3-N of less than 5 mg/L. The system shows good and stable efficiency for organic matter and nitrogen removal without adding an external carbon source and coagulants. The results based on the study indicated that the proposed process configuration has potential to treat the low-strength wastewater in Hanoi. / Mục tiêu của nghiên cứu là đề xuất được một công nghệ hiệu quả và phù hợp để xử lý nước thải sinh họat ở các đô thị của Việt nam, là loại nước thải được thu gom từ hệ thống thoát nước chung có nồng độ chất hữu cơ thấp (COD 120-200 mg/l) nhưng hàm lượng chất dinh dưỡng như Nitơ, Phốt pho khá cao (T-N: 10-40 mg/L). Chúng tôi đã nghiên cứu và vận hành chạy thử mô hình xử lý sinh học yếm khí - kỵ khí (AO) kết hợp với màng vi lọc ở quy mô mô hình phòng thí nghiệm (công suất 5-10 L/h) ở các chế độ công suất bùn tuần hoàn khác nhau. Kết quả xử lý trong thời gian 5 tháng vận hành mô hình cho thấy chất lượng nước thải sau xử lý có hàm lượng COD nhỏ hơn 20 mg/L, NH4-N nhỏ hơn 1 mg/L, NO3-N nhỏ hơn 5 mg/L. Hiệu suất xử lý chất hữu cơ và chất dinh dưỡng rất ổn định và hệ thống không phải sử dụng các nguồn bổ sung chất hữu cơ hay các hóa chất trợ lắng như các công nghệ đang áp dụng. Kết quả cho thấy công nghệ AO kết hợp màng vi lọc có khả năng áp dụng thực tế, phù hợp với những nơi có quỹ đất nhỏ, chất lượng nước sau xử lý rất cao có thể phục vụ cho mục đích tái sử dụng.

Wastewater recycling and reuse is an important issue in the coming years due to the increasing water demand and the decreasing water supply. MBR (membrane bioreactor) technology has become an important pretreatment technology for reclaiming treated effluent from, for example, domestic, dyestuff, and pharmaceutical wastewater plants. However, variations in wastewater flow rate and polluted materials can be a great influence to the performance of MBR. The applications of MBR to the treatment of various industrial wastewaters are worthy of further investigation. The present study investigated performances of MBR for treating wastewaters from a tannery plant and an industrial park. In addition, a pilot-scale UASB (upflow anaerobic sludge blanket) reactor was used for the pretreatment of the tannery plant wastewater for COD (chemical oxygen demand) removal. Results from tannery wastewater treatment indicate that using effluent from the activated sludge ponds of plant A as an influent to the pilot MBR, COD and SS (suspended solids) of the MBR filtrates could always be kept at <100 and <30 mg/L, respectively. Both COD and SS of the filtrates meet effluent regulations of <160 and <30 mg/L, respectively. The operation conditions were HRT (hydraulic retention time) = 12.2-20.4 hr, flux = 4.92-8.17 L/m2.hr, and MLSS (mixed liquor suspended solids) = 5,060-37,800 mg/L. Because the effluent had high TDS (total dissolved solids) contents of 8,700-9,700 mg/L resulted from chloride and sulfate ions, the permissible operational fluxes (4.92-8.17 L/m2.hr) were far below the normal ones (20-30 L/m2.hr). Experiments from the UASB test indicate that on an average 70% of the influent COD (2,200 mg/L) could be removed. Wastewater plant for the industrial park had influent and effluent COD of 93-144 and 11-65 mg/L, respectively. By the MBR with EBRT of 2.16-12.2 hr, flux of 5.0-28 L/m2.hr, and MLSS of 1,550 mg/L, the filtrates had COD of 11-81 mg/L. In addition, COD of the MBR filtrates could be decreased from 77 to 20-40 mg/L after supplementation of PAC (powdered activated carbon) at a concentration of 500 mg/L, and a clearer filtrate was obtained. After 30 days of operation, COD of the filtrates could be maintained at 30-48 mg/L. Regular addition of PAC to the MBR reactor is necessary for keeping the effluent quality to meet the reuse requirements.

Though erasure codes are widely adopted in high fault tolerance storage systems, there exists a serious small-write problem. Many algorithms are proposed to improve small-write performance in RAID systems, without considering the network bandwidth usage. However, the network bandwidth is expensive in cloud systems. In this thesis, we proposed an ECL-based (E-MBR codes, Caching and Logging-based) technique to improve the small-write performance without using extra network bandwidth. In addition, the ECL-based technique also reduces the delayed parity update and data recovery latency compared with the competing algorithm.