Pilot-scale Moving Bed Biofilm Reactor Research Articles

Salt-tolerant heterotrophic nitrification and aerobic denitrification (HNAD) bacterium enhancing a pilot-scale moving bed biofilm reactor (MBBR) treating mariculture wastewater treatment with different COD/TN ratios

Efficient nitrogen (N) removal from mariculture wastewater is one of the important measures to protect the marine ecological environment. A moving bed biofilm reactor (MBBR) inoculating heterotrophic nitrification and aerobic denitrification (HNAD) bacteria was set and the effects of chemical oxygen demand (COD) and total nitrogen (TN) (COD/TN) ratios on N removal performance, enzymatic activity, biofilm characteristics and microbial community were discussed. Results showed that a more stable N removal performance was obtained in the MBBR process inoculating HNAD bacteria under low COD/TN ratio compared with the conventional MBBR. The removal efficiency of nitrate nitrogen (NO3−-N) declined with COD/TN ratio decrease, and protein (PN) and polysaccharide (PS) concentration decreased from 284.3 and 37.1 mg (g VSS)−1 to 42.9 and 14.4 mg (g VSS)−1 with low ammonia monooxygenase (AMO), nitrite reductase (NIR) and nitrate reductase (NR) activities. Sequencing analysis revealed that strain Zobellella B307 became the dominant microorganism (the relatively abundance is 2.33–5.60 %), and its relatively abundance and the functional genes related to N metabolism reduced from 15.38 % to 9.66 % and 0.61 % to 0.55 % with COD/TN ratio decrease to explain the reason for the decrease of N removal efficiency. This study can provide a deep insight into N removal mechanism of the reactor inoculating HNAD bacteria under different COD/TN ratios.

Groundwater Denitrification by Using MBBR With KMT Packing

Many communities in the world use groundwater as a source of potable water. The high nitrate concentration is a serious problem in groundwater usage. This study utilizes a biological denitrification method to investigate a moving bed biofilm reactor (MBBR) for the case of Tehran's groundwater. One pilot-scale MBBR with a 3 liter volume was designed and used in this research. The denitrification reactor operates under anoxic conditions. Methanol was used as a carbon source in the reactor throughout the study, and fifty percent of the reactor volume was occupied with KMT packing (k1). To determine the optimum nitrate loading rate, the concentration of nitrate changed from 100 to 400 mg N/l. It was concluded that heterotrophic denitrifying bacteria converted nitrate to nitrogen. According to obtained results, the removal efficiency and optimum loading rate were estimated during the experiments in different concentrations and different HRTs for this type of reactor. Sodium nitrate was in the feed source in the anoxic reactor. The maximum removal rate of nitrate was measured to be 2.8 g of NO3-N m-2 carrier d-1. Therefore, it was shown that the optimum loading rate of nitrate and the optimum COD/N were equal to 3.2 g of NO3-N m-2 carrier d-1 and 6 g of COD/g N respectively.

Start-up of CANON Process and Short-cut Nitrification in a Pilot-scale MBBR Reactor

Using a 150 L moving bed biofilm reactor (MBBR), with the temperature controlled at 28℃ and high NH4+-N concentration (average concentration 350 mg·L-1), inorganic wastewater was used as an influent to start the completely autotrophic nitrogen removal over nitrite (CANON) process. Meanwhile, the flocculent sludge was taken into a 5 L sequencing batch reactor, and the influent NH4+-N concentration was maintained at 90-200 mg·L-1 for the recovery of short-cut nitrification. The results showed that in the MBBR reactor, when the average hydraulic retention time (HRT) was 12 h, short-cut nitrification and total nitrogen (TN) removal rate were mutually constrained, the average TN removal rate was 38.2%, and the average δNO3--N/TN value was 0.274; when the HRT dropped to 6 h, the δNO3--N/TN value decreased from 0.347 to 0.146. The sequencing batch reactor (SBR) maintained aeration and anoxic time for 30 min and 20 min, respectively, by intermittent aeration, while the dissolved oxygen concentration during the aerobic process was 0.5 mg·L-1 to 0.6 mg·L-1, the free nitrous acid concentration was higher than 0.18 mg·L-1 at the end of each cycle, NAR increased from 0 to 99.2% after 12 days, NUR decreased to 0 from an initial 24.8 mg·(g·h)-1, and the TN removal rate decreased from 13% to 3%; the system successfully converted to short-range nitrification. High-throughput sequencing results showed that the abundance of Candidatus Kuenenia in the flocculent sludge and biofilm in the MBBR reactor were 7.91% and 17.38% respectively, Nitrosomonas accounted for 27.43% and 2.55%, respectively, while Nitrospira accounted for 0.30% and 0.28%, respectively. After the recovery of short-cut nitrification in the SBR, the abundance of ammonia-oxidizing bacteria and anaerobic ammonia oxidation decreased to 1.18% and 0.01%, respectively, and the abundance of Nitrospira increased to 1.39%.

Removal of pharmaceuticals, toxicity and natural fluorescence through the ozonation of biologically-treated hospital wastewater, with further polishing via a suspended biofilm

In the present study, a pilot-scale ozonation system was introduced as post treatment to reduce the pharmaceuticals and toxicity in the effluent of a pilot-scale Moving Bed Biofilm Reactor (MBBR) treating hospital wastewater. The ozonated effluent was polished further by suspended biofilm carriers to remove biodegradable organic matter and toxicity generated from ozonation by-products. A laboratory ozonation system was used to mimic the experiments, which were carried out at the pilot plant so that the removal of pharmaceuticals in the pilot and laboratory experiments could be compared. Delivered ozone dose achieved 90% removal of pharmaceutical was obtained and it was normalised to dissolved organic carbon (DOC). These normalised results show that trimethoprim was eliminated by ozone easier than other pharmaceuticals.Fluorescence was found to be highly correlated to the removal of pharmaceuticals, and fluorescence with a wavelength of 275 nm of excitation and 310 nm of emission had the closest correlation. After polishing MBBR was introduced into the ozonated wastewater, half of its protein-like fluorophore was removed.The toxicity of the hospital wastewater during MBBR treatment was measured by Vibrio fischeri, the inhibition of which decreased from 80% to 50%. By applying ozonation, this inhibition reduced to 20%.

Start-up of a full-scale SNAD-MBBR process for treating sludge digester liquor

A simultaneous partial nitrification, anammox and denitrification (SNAD) process was started up successfully to treat sludge digester liquor in a full-scale moving bed biofilm reactor (MBBR). This reactor treated up to 530 kg N/d with a nitrogen removal efficiency of 70%. During the start-up period, efficient and stable partial nitrification was attained by controlling the concentration of DO (0.3–0.5 mg/L), free ammonia (0.6–8.2 mg/L) and free nitrous acid (0.03–1.20 mg/L). The full-scale anammox reactor (832 m3) took about 240 days to start up successfully after inoculation with nitrifying sludge and a small amount of anammox sludge. The preformation of anammox biofilm in the pilot-scale MBBR played a vital role in the fast start-up of the full-scale anammox MBBR. An average nitrogen removal rate of 0.41 kg N/m3/d was achieved. In the SNAD reactor, high-throughput sequencing techniques revealed that the anammox bacteria in the biofilm accounted for a higher proportion than in the suspended sludge, indicating that the carriers effectively protected the anammox from washout. This study provides valuable experience for treatment of wastewater with low carbon-to-nitrogen ratio.

Model extension, calibration and validation of partial nitritation–anammox process in moving bed biofilm reactor (MBBR) for reject and mainstream wastewater

ABSTRACTIn the paper, the extension of mathematical model of partial nitritation–anammox process in a moving bed biofilm reactor (MBBR) is presented. The model was calibrated with a set of kinetic, stoichiometric and biofilm parameters, whose values were taken from the literature and batch tests. The model was validated with data obtained from: laboratory batch experiments, pilot-scale MBBR for a reject water deammonification operated at Himmerfjärden wastewater treatment and pilot-scale MBBR for mainstream wastewater deammonification at Hammarby Sjöstadsverk research facility, Sweden. Simulations were conducted in AQUASIM software. The proposed, extended model proved to be useful for simulating of partial nitritation/anammox process in biofilm reactor both for reject water and mainstream wastewater at variable substrate concentrations (influent total ammonium–nitrogen concentration of 530 ± 68; 45 ± 2.6 and 38 ± 3 gN/m3 – for reject water – and two cases of mainstream wastewater treatment, respectively), temperature (24 ± 2.8; 15 ± 1.1 and 18 ± 0.5°C), pH (7.8 ± 0.2; 7.3 ± 0.1 and 7.4 ± 0.1) and aeration patterns (continuous aeration and intermittent aeration with variable dissolved oxygen concentrations and length of aerated and anoxic phases). The model can be utilized for optimizing and testing different operational strategies of deammonification process in biofilm systems.

Evaluation of a MBBR (Moving Bed Biofilm Reactor) Pilot Plant for Treatment of Pulp and Paper Mill Wastewater

Moving Bed Biofilm Reactor (MBBR) process is a technology for the wastewater treatment that incorporates the best characteristics of processes with growth of biomass in suspension and adhered biomass (biofilm). Therefore, it is possible to maintain a higher amount of biomass in the same biological reactor and thus add a larger amount of substrate for biodegradation. The main aim of this paper was to characterize the adhered biomass to the carriers and evaluate the operational parameters and performance of a pilot-scale MBBR for the treatment of a pulp and paper mill wastewater, after preliminary treatment, the primary decanting, the pH adjustment, addition of nutrients, cooling and, thermophilic conditions. The pilot plant was operated within the limits recommended by literature in relation the Volumetric and Superficial Organic loads (VOL and SOL), respectively of 4.3 kg solubleBOD m-3 d-1 and 43.8 g solubleBOD m-2 d-1, equal to the lower limit recommended considering the concentration of dissolved oxygen (DO) of 2 mg L-1 and carriers volume equal to 10% of the reactor volume. May be detached regarding the process performance that the removal efficiencies of Soluble Biochemical Oxygen Demand (solubleBOD) and Soluble Chemical Oxygen Demand (solubleCOD) obtained were respectively, 56 and 35%, and that process remained fairly stable under these conditions work and in no time during this study was observed clogging/fouling of carriers.

Responses of biofilm characteristics to variations in temperature and NH4+-N loading in a moving-bed biofilm reactor treating micro-polluted raw water

A pilot-scale moving-bed biofilm reactor (MBBR) for biological treatment of micro-polluted raw water was operated over 400days to investigate the responses of biofilm characteristics and nitrification performance to variations in temperature and NH4+-N loading. The mean removal efficiency of NH4+-N in the MBBR reached 71.4±26.9%, and batch experiments were performed to study nitrification kinetics for better process understanding. Seven physical–chemical parameters, including volatile solids (VS), polysaccharides (PS) and phospholipids (PL) increased firstly, and then rapidly decreased with increasing temperature and NH4+-N loading, and properly characterized the attached biomass during biofilm development and detachment in the MBBR. The biofilm compositions were described by six ratios, e.g., PS/VS and PL/VS ratios showed different variation trends, indicating different responses of PS and PL to the changes in temperature and NH4+-N loading. Furthermore, fluorescent in situ hybridization (FISH) analysis revealed that increased NH4+-N loadings caused an enrichment of the nitrifying biofilm.

Modelling respirometric tests for the assessment of kinetic and stoichiometric parameters on MBBR biofilm for municipal wastewater treatment

Moving Bed Biofilm Reactor (MBBR) technology is a suitable option for up-grading and retro-fitting wastewater treatment plants. Although being introduced in late 80s, design and operational guidelines of MBBR are mainly based on empirical approaches. This work was aimed to assess the biokinetics on both detached and undisturbed biofilm samples from a large pilot-scale MBBR treating pre-settled municipal wastewater. Experimental OUR profiles of heterotrophic biomass in detached and undisturbed biofilm have been obtained with respirometric tests and then modelled with an extended version of ASM3 which assumes biomass growth to take place on both readily biodegradable substrate and storage products. Results indicated the storage mechanism to be prevalent for heterotrophic biomass growth, with a 80% fraction of soluble substrate converted into storage products. The active heterotrophic biomass in the film was estimated in detached biofilm samples; on average, it corresponded to a 39% fraction of particulate COD. Tests on undisturbed biofilm were carried out to quantify autotrophic ammonia and nitrite removal, showing an effective specialisation of the nitrifying biomass. The parameters obtained could support a more rational design approach for the moving-bed biofilm process.

Microbial ecology and performance of ammonia oxidizing bacteria (AOB) in biological processes treating petrochemical wastewater with high strength of ammonia: effect of Na2CO3 addition

This study evaluated nitrification performance and microbial ecology of AOB in a full-scale biological process, powder activated carbon treatment (PACT), and a pilot-scale biological process, moving bed biofilm reactor (MBBR), treating wastewater collected from a petrochemical industry park. The petrochemical influent wastewater characteristics showed a relative low carbon to nitrogen ratio around 1 with average COD and ammonia concentrations of 310 mg/L and 325 mg-N/L, respectively. The average nitrification efficiency of the full-scale PACT process was around 11% during this study. For the pilot-scale MBBR, the average nitrification efficiency was 24% during the Run I operation mode, which provided a slightly better performance in nitrification than that of the PACT process. During the Run II operation, the pH control mode was switched from addition of NaOH to Na(2)CO(3), leading to a significant improvement in nitrification efficiency of 51%. In addition to a dramatic change in nitrification performance, the microbial ecology of AOB, monitored with the terminal restriction fragment length polymorphism (T-RFLP) molecular methodology, was found to be different between Runs I and II. The amoA-based TRFLP results indicated that Nitrosomonas europaea lineage was the dominant AOB population during Run I operation, while Nitrosospira-like AOB was dominant during Run II operation. To confirm the effects of Na(2)CO(3) addition on the nitrification performance and AOB microbial ecology observed in the MBBR process, batch experiments were conducted. The results suggest that addition of Na(2)CO(3) as a pH control strategy can improve nitrification performance and also influence AOB microbial ecology as well. Although the exact mechanisms are not clear at this time, the results showing the effects of adding different buffering chemicals such as NaOH or Na(2)CO(3) on AOB populations have never been demonstrated until this study.