Moving Bed Bioreactor Research Articles

Effect of advanced oxidation processes on the micropollutants and the effluent organic matter contained in municipal wastewater previously treated by three different secondary methods

In this study, wastewater from the output of three different secondary treatment facilities (Activated Sludge, Moving Bed Bioreactor and Coagulation-Flocculation) present in the municipal wastewater treatment plant of Vidy, Lausanne (Switzerland), was further treated with various oxidation processes (UV, UV/H2O2, solar irradiation, Fenton, solar photo-Fenton), at laboratory scale. For this assessment, 6 organic micropollutants in agreement with the new environmental legislation requirements in Switzerland were selected (Carbamazepine, Clarithromycin, Diclofenac, Metoprolol, Benzotriazole, Mecoprop) and monitored throughout the treatment. Also, the overall removal of the organic load was assessed. After each secondary treatment, the efficiency of the AOPs increased in the following order: Coagulation-Flocculation < Activated Sludge < Moving Bed Bioreactor, in almost all cases. From the different combinations tested, municipal wastewater subjected to biological treatment followed by UV/H2O2 resulted in the highest elimination levels. Wastewater previously treated by physicochemical treatment demonstrated considerably inhibited micropollutant degradation rates. The degradation kinetics were determined, yielding: k (UV) < k (UV/H2O2) and k (Fenton) < k (solar irradiation) < k (photo-Fenton). Finally, the evolution of global pollution parameters (COD & TOC elimination) was followed and the degradation pathways for the effluent organic matter are discussed.

Treatment of coke oven wastewater in an anaerobic–anoxic–aerobic moving bed bioreactor system

In this work, sequential moving bed bioreactor (MBBR) system with mixed heterogeneous biomass was selected for the treatment of coke oven wastewater (CW). The reactors were arranged in anaerobic (R1)–anoxic (R2)–aerobic (R3) sequence. CW was collected from an industrial site which contains phenol, ammonia, sulfate, iron, oil, and grease. Few heavy metals (cadmium, lead, and cobalt) were also detected in CW at low concentrations. Raw CW was pretreated by primary settling process to remove high solid concentrations. Thereafter, CW was spiked with synthetic pollutants to make the picture of model industrial wastewater. Phenol (1,350 mg/L), ammonia-N (500 mg/L), thiocyanate (800 mg/L), pyridine (50 mg/L), m-, o-, and p-cresols (50 mg/L each) were added as synthetic pollutants in CW. The system was operated at 6 d hydraulic retention time. R1 showed only less phenol (2–5%) and chemical oxygen demand (COD) (~2%) removal. However, R2 and R3 removed significant amount of thiocyanate (>85%), cresols (~88%), and pyridine (>48%) along with the residual phenol (R2: 88%; R3: 98%) and COD (R2: 58%; R3: 79%). Also, denitrification efficiency of R2 was ~94% throughout the study. Ammonia-N removal by R3 was 64–71% comprising 75–77% of total nitrogen removal. Hence, three stage sequential MBBR could be successfully used to treat high strength CW to achieve the discharge limit of effluent.

Optimization of a mainstream nitritation-denitritation process and anammox polishing.

This paper deals with an almost 1-year long pilot study of a nitritation-denitritation process that was followed by anammox polishing. The pilot plant treated real municipal wastewater at ambient temperatures. The effluent of high-rate activated sludge process (hydraulic retention time, HRT=30 min, solids retention time=0.25 d) was fed to the pilot plant described in this paper, where a constant temperature of 23 °C was maintained. The nitritation-denitritation process was operated to promote nitrite oxidizing bacteria out-selection in an intermittently aerated reactor. The intermittent aeration pattern was controlled using a strategy based on effluent ammonia and nitrate+nitrite concentrations. The unique feature of this aeration control was that fixed dissolved oxygen set-point was used and the length of aerobic and anoxic durations were changed based on the effluent ammonia and nitrate+nitrite concentrations. The anaerobic ammonia oxidation (anammox) bacteria were adapted in mainstream conditions by allowing the growth on the moving bed bioreactor plastic media in a fully anoxic reactor. The total inorganic nitrogen (TIN) removal performance of the entire system was 75±15% during the study at a modest influent chemical oxygen demand (COD)/NH4+-N ratio of 8.9±1.8 within the HRT range of 3.1-9.4 h. Anammox polishing contributed 11% of overall TIN removal. Therefore, this pilot-scale study demonstrates that application of the proposed nitritation-denitritation system followed by anammox polishing is capable of relatively high nitrogen removal without supplemental carbon and alkalinity at a low HRT.

Sequencing treatment of industrial wastewater with ultraviolet/H2O2 advanced oxidation and moving bed bioreactor

Aims: The main purpose of this study was to determine the efficiency of a sequencing treatment including ultraviolet (UV)/H 2 O 2 oxidation followed by a moving bed bioreactor (MBBR). Materials and Methods: Effect of solution pH, reaction time, and H 2 O 2 concentration were investigated for an industrial wastewater sample. The effluent of the advanced oxidation processes unit was introduced to the MBBR operated for three hydraulic retention times of 4, 8, and 12 h. Results: The optimum condition for industrial wastewater treatment via advanced oxidation was solution pH: 7, H 2 O 2 dose: 1000 mg/L and 90 min reaction time. These conditions led to 74.68% chemical oxygen demand (COD) removal and 66.15% biochemical oxygen demand (BOD 5 ) removal from presedimentation step effluent that initially had COD and BOD 5 contents of 4,400 and 1,950 mg/L, respectively. Conclusion: Combination of UV/H 2 O 2 advanced oxidation with MBBR could result in effluents that meet water quality standards for discharge to receiving waters.

Use of Electro-Chemical Process for Waste Sludge Generated from Moving Bed Bioreactor

Use of Electro-Chemical Process for Waste Sludge Generated from Moving Bed Bioreactor

Effects of alkalinity on ammonia removal, carbon dioxide stripping, and system pH in semi-commercial scale water recirculating aquaculture systems operated with moving bed bioreactors

When operating water recirculating systems (RAS) with high make-up water flushing rates in locations that have low alkalinity in the raw water, such as Norway, knowledge about the required RAS alkalinity concentration is important. Flushing RAS with make-up water containing low alkalinity washes out valuable base added to the RAS (as bicarbonate, hydroxide, or carbonate), which increases farm operating costs when high alkalinity concentrations are maintained; however, alkalinity must not be so low that it interferes with nitrification or pH stability. For these reasons, a study was designed to evaluate the effects of alkalinity on biofilter performance, and CO2 stripping during cascade aeration, within two replicate semi-commercial scale Atlantic salmon smolt RAS operated with moving bed biological filters. Alkalinity treatments of nominal 10, 70, and 200mg/L as CaCO3 were maintained using a pH controller and chemical dosing pumps supplying sodium bicarbonate (NaHCO3). Each of the three treatments was replicated three times in each RAS. Both RAS were operated at each treatment level for 2 weeks; water quality sampling was conducted at the end of the second week. A constant feeding of 23kg/day/RAS was provided every 1–2h, and continuous lighting, which minimized diurnal fluctuations in water quality. RAS hydraulic retention time and water temperature were 4.3 days and 12.5±0.5°C, respectively, typical of smolt production RAS in Norway.It was found that a low nominal alkalinity (10mg/L as CaCO3) led to a significantly higher steady-state TAN concentration, compared to when 70 or 200mg/L alkalinity was used. The mean areal nitrification rate was higher at the lowest alkalinity; however, the mean TAN removal efficiency across the MBBR was not significantly affected by alkalinity treatment. The CO2 stripping efficiency showed only a tendency towards higher efficiency at the lowest alkalinity. In contrast, the relative fraction of total inorganic carbon that was removed from the RAS during CO2 stripping was much higher at a low alkalinity (10mg/L) compared to the higher alkalinities (70 and 200mg/L as CaCO3). Despite this, when calculating the total loss of inorganic carbon from RAS, it was found that the daily loss was about equal at 10, and 70mg/L, whereas it was highest at 200mg/L alkalinity. pH recordings demonstrated that the 10mg/L alkalinity treatment resulted in the lowest system pH, the largest increase in [H+] across the fish culture tanks, as well as giving little response time in case of alkalinity dosing malfunction. Rapid pH changes under the relatively acidic conditions at 10mg/L alkalinity may ultimately create fish health issues due to e.g. CO2 or if aluminium or other metals are present. In conclusion, Atlantic salmon smolt producers using soft water make-up sources should aim for 70mg/L alkalinity considering the relatively low loss of inorganic carbon compared to 200mg/L alkalinity, and the increased pH stability as well as reduced TAN concentration, compared to lower alkalinity concentrations.

Seasonal Variation of Archaeal amoA In Two-Stage Trickling Filter and Moving Bed Bioreactor Systems

Seasonal Variation of Archaeal <i>amoA</i> In Two-Stage Trickling Filter and Moving Bed Bioreactor Systems

Impact of seeding on the start-up of one-stage deammonification MBBRs

Treating nitrogen-rich reject water from anaerobically digested sludge with deammonification has become a very beneficial side stream process. One common technique is the one-stage moving bed bioreactors (MBBRs), which in comparison with the other deammonification techniques can be started up without seeding anammox bacteria. This study investigated the impact of biofilm seeding on the start-up of one-stage deammonification MBBRs. Two lab-scale reactors were run in parallel with partial nitritation for 56 days until 11% of the carrier area in one reactor was replaced with fully developed deammonification biofilm to work as the seeding material. The seeded reactor started nitrogen reduction immediately up to a plateau of 1.3 g N m−2 d−1; after another 54 days on day 110, the reduction significantly increased. At the same time, the non-seeded reactor also started to reduce nitrogen due to deammonification. The development was followed with both nitrogen analyses and fluorescence in situ hybridization analyses. On day 134, the biofilm in both reactors contained>90% anammox bacteria and reached maximum nitrogen removal rates of 7.5 and 5.6 g N m−2 d−1 in the seeded and non-seeded reactor, respectively. Over 80% of the inorganic nitrogen was reduced. In conclusion, the seeding did not contribute to a shorter start-up time or the achieved anammox enrichment, although it did contribute to a partial, immediate nitrogen reduction. The boundary conditions are the most important factors for a successful start-up in a deammonification MBBR system.

Investigation of settleability of biologically produced solids and biofilm morphology in moving bed bioreactors (MBBRs)

The objective of this work is to investigate the effects of surface area loading rates (SALRs) and hydraulic retention times (HRTs) in moving bed bioreactor (MBBR) systems on the morphology and thickness of the attached biofilm along with subsequent effects on particle size distribution and the settling characteristics of the biologically produced solids. The morphology of biofilm attached to the MBBR carriers changed from a porous biofilm to a biofilm with a more filamentous structure throughout the study at various operating conditions without observable correlation with SALR and HRT. Although, biofilm morphology did not demonstrate an effect on the biologically produced solids observed in this study, the thinnest biofilms resulted in the highest concentration of solids in the effluent. Furthermore, the particle size distribution analysis demonstrated that both higher SALRs and longer HRTs resulted in a shift towards larger-sized particles. Increases in SALR and HRT, independent of each other, also showed increases in effluent solid concentration and lower settleability of the solids.

Removal and fate of micropollutants in a sponge-based moving bed bioreactor

This study investigated the removal of micropollutants using polyurethane sponge as attached-growth carrier. Batch experiments demonstrated that micropollutants could adsorb to non-acclimatized sponge cubes to varying extents. Acclimatized sponge showed significantly enhanced removal of some less hydrophobic compounds (log D<2.5), such as ibuprofen, acetaminophen, naproxen, and estriol, as compared with non-acclimatized sponge. The results for bench-scale sponge-based moving bed bioreactor (MBBR) system elucidated compound-specific variation in removal, ranging from 25.9% (carbamazepine) to 96.8% (β-Estradiol 17-acetate) on average. In the MBBR system, biodegradation served as a major removal pathway for most compounds. However, sorption to sludge phase was also a notable removal mechanism of some persistent micropollutants. Particularly, carbamazepine, ketoprofen and pentachlorophenol were found at high concentrations (7.87, 6.05 and 5.55 μg/g, respectively) on suspended biosolids. As a whole, the effectiveness of MBBR for micropollutant removal was comparable with those of activated sludge processes and MBRs.

Integrated Membrane Bioreactor for Water Quality Control in Marine Recirculating Aquaculture Systems

The aquaculture live feed organisms Acartia tonsa (a calanoid copepod, experiment 1) and Brachionus “Cayman” (a rotifer, experiment 2) were cultivated in marine recirculating aquaculture systems (RAS), respectively. The pilot plant was built as a combination of conventional RAS (cRAS) and as a modified RAS which implemented an ultrafiltration membrane bioreactor (MBR) for the removal of fine suspended solids and colloidal particles as part of the treatment system (mRAS). The two treatment schemes were connected to the same biofilter (a moving bed bioreactor). In the first experiment, the membrane was operated with no extraction of concentrate, and hydraulic retention time (HRT) of 6 hours (i.e., water exchange in the cultivation tanks of 4 times per day). In the second experiment, the membrane was operated with daily extraction of concentrate, and HRT of 12 hours. Results show that the MBR option is more efficient in removing particles from the recycle stream than conventional RAS. However, the impact this has on the number of particles in the live feed cultivation tanks is not readily apparent based on particle analysis. The amount of suspended solids added during feeding exceeds the amount removed in the recycle system. This requires a higher recirculation rate and different membrane operating conditions.

The Role of Tourmaline Particles in the Moving Bed Bioreator for Coking Wastewater Treatment

Tourmaline is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been a kind of promising environmental material in wastewater treatment. This study was to investigate the aerobic biofilm treatment of coking wastewater with and without tourmaline addition. The results indicated that tourmaline added in moving bed bioreactor (MBBR) process could enhance the removal efficiency of chemical oxygen demand (COD).The organic contaminants could be removed by tourmaline added. The mechanisms of increase of organic contaminants removal may correlate to the existence of tourmaline spontaneous electrode. Micrograph of the excess sludge in the tourmaline-MBBR system indicated that the tourmaline added could be the carrier of the microbe and also affect the biomass and pollutant removal.

Attachment surface energy effects on nitrification and estrogen removal rates by biofilms for improved wastewater treatment

Submerged biofilm systems, such as integrated fixed-film activated sludge (IFAS) and moving bed bioreactors (MBBRs), are increasingly being used for domestic wastewater treatment, often to improve nitrification. Little is known about whether and how biofilm attachment surface chemical properties affect treatment performance, although surface chemistry is known to affect attachment in other systems, and work with pure strains has suggested that attachment of nitrifying bacteria may be enhanced on high surface energy surfaces. The objective of this research was to systematically evaluate the effects of surface chemistry on biofilm quantity and rates of nitrification and estrogen removal. Biofilms were grown on four plastic attachment surfaces with a range of hydrophobicity and surface energy values (nylon, melamine, high-density-polyethylene [HDPE], and acetal polymeric plastic) by immersing them in a full scale nitrifying activated sludge wastewater treatment system, followed by batch test experiments. The attachment surface water contact angles ranged from 53° to 98° and surface energies ranged from 48.9 to 20.9 mJ/m2. Attachment surface hydrophilicity and surface energy were positively correlated with total biomass attachment, with more than twice as much biomass on the highest surface energy, most hydrophilic surface (nylon) than on the lowest surface energy, least hydrophilic surface (acetal plastic). Absolute and specific nitrification rates were also correlated with hydrophilicity and surface energy (varying by factors of 5 and 2, respectively), as were absolute and specific removal first order rate constants of the hormones estrone (E1), β-estradiol (E2) and 17α-ethynylestradiol (EE2). These results suggested that attachment surface chemistry may be a useful design parameter for improving biofilm performance for removal of ammonia and endocrine disrupting hormones from wastewater. Further research is required to verify these results at longer time scales and with typical media geometries.

Production of 1,3-propanediol by Clostridium butyricum DSM 5431 in an Anaerobic Moving-Bed Bioreactor

Production of 1,3-propanediol (PD) by Clostridium butyricum DSM 5431 was investigated in a moving-bed bioreactor with BCN-009 as the cell-supporting material. The results of steady state operation indicated that PD production in a moving-bed bioreactor was feasible. The moving-bed bioreactor provided good liquid mixing, resulting in a suitable pH range (i.e., pH = 6.9 – 7.0) throughout the experiment. Maximum PD concentration (33.8 g/L), product yield (0.7), and productivity (16.9 g/L/h) were obtained when the bioreactor was operated using an inlet glycerol concentration and a dilution rate of 60 g/L and 0.5 h-1, respectively. Finally, we conclude that moving-bed bioreactors are attractive for future development as seen by higher effluent PD concentrations and productivity compared to other suspended-growth and immobilized bioreactor configurations.

Effect of feed concentration and hydraulic retention time on removal of phenol, thiocyanate, and nitrate–nitrogen in anoxic-fed batch moving bed reactor

Simultaneous removal of phenol, thiocyanate (SCN−), and nitrate–nitrogen (–N) were studied in four anoxic-fed batch moving bed bioreactors (MBR) with the feed concentration and hydraulic retention time (HRT) as variable parameters. SCN− removal increased from 5% to 95% with increase in feed -N concentration from 0 to 350 mg L−1. Phenol and SCN− inhibited degradation of each one with a respective threshold concentration of 350 mg L−1 and 60 mg L−1. –N was used as the electron acceptor for removal of both phenol and SCN−. The minimum HRT of fed batch MBR was suggested as 3.7 days to achieve an effluent quality of COD (140 mg L−1), phenol (2 mg L−1), and SCN− (1.9 mg L−1) from an influent concentration of 720, 200, and 40 mg L−1, respectively. The modified Stover–Kincannon model equation showed best fit for pollutant degradation. –N and sulfate were generated as by-products from SCN− degradation in an anoxic environment.

Integrated fungal biomass and activated sludge treatment for textile wastewaters bioremediation

A combined biological process was investigated for effective textile wastewater treatment. The process consisted of a first step performed by selected fungal biomasses, mainly devoted to the effluent decolourisation, and of a subsequent stage by means of activated sludge, in order to reduce the remaining COD and toxicity. In particular, the treatment with Trametes pubescens MUT 2400, selected over nine strains, achieved very good results in respect to all parameters. The final scale-up phase in a moving bed bioreactor with the supported biomass of the fungus allowed to verify the effectiveness of the treatment with high volumes. Despite promising results, further steps must be taken in order to optimize the use of these biomasses for a full exploitation of their oxidative potential in textile wastewater treatment.

Effect of organic load and nutrient ratio on the operation stability of the moving bed bioreactor for kraft mill wastewater treatment and the incidence of polyhydroxyalkanoate biosynthesis

This paper studies the effect of organic load rate (OLR) and nutrient ratio on operation stability of the moving bed bioreactor (MBBR) for kraft mill wastewater treatment, analyzing the incidence of polyhydroxyalkanoate (PHA) production. The MBBR operating strategy was to increase OLR from 0.25 ± 0.05 to 2.41 ± 0.19 kg COD m(-3) d(-1) between phases I and IV. The BOD(5):N:P ratio (100:5:1 and 100:1:0.2) was evaluated as an operation strategy for phases IV to V. A stable MBBR operation was found when the OLR was increased during 225 days in five phases. The maximum absolute fluorescence against the proportion of cells accumulating PHA was obtained for an OLR of 2.41 ± 0.19 kg COD m(-3)d(-1) and a BOD(5):N:P relationship of 100:1:0.2. The increase of PHA biosynthesis is due to the increased OLR and is not attributable to the increased cell concentration, which is maintained constant in stationary status during bioreactor biosynthesis.

Comparison between a moving bed bioreactor and a fixed bed bioreactor for biological phosphate removal and denitrification

Moving bed bioreactors (MBBR) and fixed bed bioreactors (FBBR) were compared for biological phosphorus removal and denitrification. The sorption denitrification P-elimination (S-DN-P) process was selected for this study. Results indicated that all nutrients were removed by the FBBR process compared with the MBBR process: 19.8% (total COD), 35.5% (filtered COD), 27.6% (BOD(5)), 62.2% (acetate), 78.5% (PO(4)-P), and 54.2% (NO(3)-N) in MBBR; 49.7% (total COD), 54.0% (filtered COD), 63.2% (BOD(5)), 99.6% (acetate), 98.6% (PO(4)-P), and 75.9% (NO(3)-N) in FBBR. The phosphate uptake and NO(3)-N decomposition in the FBBR process during the denitrification phase were much higher than for the MBBR process despite being of shorter duration. Results obtained from this study are helpful in elucidating the practical implications of using MBBR and FBBR for the removal of bio-P and denitrification from wastewater.

Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor

Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH3, the un-ionized form of ammonium NH4+) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2mgNL−1. In the pH range 7–8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120mgNL−1 did not negatively affect NRR for up to 3.5h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2mgNL−1 when the pH was maintained between 7 and 8.

A calibration protocol of a one-dimensional moving bed bioreactor (MBBR) dynamic model for nitrogen removal

This work suggests a procedure to correctly calibrate the parameters of a one-dimensional MBBR dynamic model in nitrification treatment. The study deals with the MBBR configuration with two reactors in series, one for carbon treatment and the other for nitrogen treatment. Because of the influence of the first reactor on the second one, the approach needs a specific calibration strategy. Firstly, a comparison between measured values and simulated ones obtained with default parameters has been carried out. Simulated values of filtered COD, NH(4)-N and dissolved oxygen are underestimated and nitrates are overestimated compared with observed data. Thus, nitrifying rate and oxygen transfer into the biofilm are overvalued. Secondly, a sensitivity analysis was carried out for parameters and for COD fractionation. It revealed three classes of sensitive parameters: physical, diffusional and kinetic. Then a calibration protocol of the MBBR dynamic model was proposed. It was successfully tested on data recorded at a pilot-scale plant and a calibrated set of values was obtained for four parameters: the maximum biofilm thickness, the detachment rate, the maximum autotrophic growth rate and the oxygen transfer rate.