Moving Bed Biofilm Reactor System Research Articles

A pilot-scale anoxic-anaerobic-anoxic-oxic combined with moving bed biofilm reactor system for advanced treatment of rural wastewater

Rural domestic poses a significant challenge to treatment technologies due to significant fluctuations in both water quality, particularly in terms of carbon concentration, and quantity. Conventional biological technology, such as anaerobic-anoxic-oxic (A2O) systems, is inefficient. In this work, a continuous pilot-scale anoxic-anaerobic-anoxic-oxic (A3O) reactor with a moving bed biofilm reactor (MBBR) system was constructed and optimized to improve the treatment efficiency of rural domestic wastewater. The sludge return ratio, volume ratio of the oxic-to-anoxic zone (Voxi/Vano), step-feeding and hydraulic retention time (HRT) at low temperature were considered the main parameters for optimization. Microbial analysis was performed on both the mixed liquor and carrier of the A3O-MBBR system under initial and post-optimized conditions. The results indicated that the A3O-MBBR improved the treatment efficiency of rural domestic wastewater, especially for total phosphorus (TP), which increased by 20 % compared with that of the A2O-MBR. In addition, the removal efficiencies of nitrogen and phosphorus were further optimized, and the average concentrations of total nitrogen (TN) and TP in the effluent reached 2.46 and 0.364 mg/L, respectively, at a sludge reflux ratio of 100 or 150 %, Voxi/Vano =200 %, step-feeding of 0.5Q/0.5Q (anaerobic/anoxic) and HRT of 15 h at low temperature in the A3O-MBBR, which met standard A of GB18918–2002, China (TN < 15 mg/L, TP < 0.5 mg/L). The average rate of attaining the standard increased by 58.63 % (post optimization). The microbial analysis showed an increase in species diversity and richness after the parameters were optimized. Moreover, compared to the microbial community structure before optimization, the post-optimization exhibited a more stable microbial structure with a significant enrichment of functional bacteria. Defluviimonas, Novosphingobium and Bifidobacterium, considered as the dominant nitrification or denitrifying bacteria, were enriched in the suspended sludge of the MBBR reactor, which the relative abundance increased by 3.11 %, 3.84 %, and 3.24 %, respectively. Further analysis of the microbial community in the carrier revealed that the abundance of Nitrospira and the denitrifying bacteria carried by the carrier were much greater than those in the suspended sludge. Consequently, the microorganism cooperation between suspended sludge and biofilm might be responsible for the improved performance of the optimized A3O-MBBR.

Recent developments in moving bed biofilm reactor (MBBR) for the treatment of phenolic wastewater -A review

BackgroundPhenol, a toxic and carcinogenic compound found in industrial effluent, poses a severe threat to the environment and aquatic life. Conventional methods such as physio-chemical techniques have limitations in efficiency, cost, and sustainability, leading to the development of advanced hybrid approaches like the Moving Bed Biofilm Reactor (MBBR) to treat phenols. Review methodIn this study, we aimed at an in-depth review of MBBR for the remediation of phenolic wastewater at an industrial scale. The review uses a methodology that involves a comparative analysis of various conventional methods, including activated sludge process (ASP), sequencing batch biofilm reactor (SBBR), Fluidized Bed Biofilm Rector (FBBR), and trickling filter (TF) with MBBR, to determine their efficacy in phenol degradation. In this context, a thorough bibliometric assay of MBBR is carried out to understand the recent publication trends. The study also examines the impact of different types and shapes of bio-carriers and their filling ratios on phenol biodegradation. Significant findingThe present work demonstrates the feasibility of using an aerobic MBBR along with a Fenton-like system (advanced oxidation processes) to treat phenolic effluent LCCA is discussed for selected treatment methods for assessing the sustainability aspects. In light of recent advancements, future research endeavors should prioritize the refinement and optimization of MBBR systems to strengthen their efficiency and sustainability, thus paving the way for a greener and cleaner future.

Performance and life cycle assessment of moving-bed biofilm and integrated fixed-film reactors to upgrade activated sludge systems

Upgrading the capacity of existing wastewater treatment plants (WWTPs) is hindered by the limited space for extension. This matter is particularly crucial in developing countries where dense urban areas experience unexpectedly growing populations. Herein, we study the capacity upgrading of a WWTP working by a conventional activated sludge (CAS) system from 180,000 m3/d to 240,000 and 300,000 m3/d. The WWTP case study focuses on a large plant in Mansoura, Egypt, requiring capacity upgrades to accommodate population growth. For this purpose, we used mathematical modeling to simulate current and suggested WWTP designs. Moving bed biofilm reactor (MBBR) and integrated fixed film-activated sludge (IFAS) systems were designed to increase the WWTP capacity to 240,000 and 300,000 m3/d by the addition of plastic biofilm carrier to 25% and 50% of the aeration basins, respectively. IFAS outperformed conventional and MBBR systems in terms of BOD, COD, TSS, NH4, TP, and PO4, in addition to increased capacity. We moreover used life cycle assessment (LCA) to comprehend the environmental favorability of upgrading scenarios. The most affected environmental categories are global warming and eutrophication due to the operation stage (especially electricity). Global warming potential for CAS, MBBR, and IFAS (300,000 m3/d) are 2.19, 1.69, and 1.73 kg CO2 eq respectively. Eutrophication potential for CAS, MBBR, and IFAS (300,000 m3/d) are 0.0025, 0.0022, and 0.0017 kg PO4- eq respectively. We also estimated the amortization and running costs for various upgrading scenarios, providing an integrated analysis for decision-making purposes.

A novel process based on powder carriers demonstrates robustness in nitrogen and phosphorus removal from real municipal wastewater

The development of efficient and low-consumption wastewater upgrading process is currently at the forefront of the wastewater treatment field. In this study, a novel wastewater treatment process based on powder carriers was proposed. Three systems, namely the activated sludge (AS) system, powder carrier (PC) system, and moving bed biofilm reactor (MBBR) system, were established and operated for over 140 days to treat real municipal wastewater. The characteristics and differences between the three systems were comprehensively investigated. The results suggested that the PC system exhibited notable advantages in nitrogen and phosphorus removal, especially under high influent load and low aeration conditions. The PC system, characterized by a higher nitrification rate compared to the MBBR system and a higher denitrification rate compared to the AS system, contributed to the stable nitrogen removal performance. The particle size of the zoogloea increased under the linkage of the powder carriers, and the mean size of micro-granules reached 170.88 μm. Large number of hydrophobic functional groups on sludge surface, coupled with increased protein content in EPS, further promoted sludge aggregation. Micro-granules formation improved settling performance and enhanced the abundance and activity of functional microbes. A significant enrichment in denitrifying bacteria and denitrifying phosphorus accumulating bacteria was observed in PC system. Up-regulation of the napA, narG, and nosZ genes was responsible for efficient nitrogen removal of the PC system. Moreover, a higher abundance in polyphosphate phosphotransferase (2.11 %) was found in PC system compared with AS and MBBR systems. The increase in the enzymes associated with poly-β-hydroxybutyrate (PHB) synthesis metabolism in PC system provided the energy for denitrification and phosphorus removal processes.

EXPERIMENTAL INVESTIGATION AND ITS ANALYSIS IN TANNERY WASTEWATER USING MOVING BED BIOFILM REACTOR AND ACTIVATED SLUDGE PROCESS

The Tannery Industry produces a massive amount of toxic effluent which needs to be treated properly. It contains high organic matter, suspended solids, and chromium which in turn can cause environmental problems. This study provides valuable insights into the potential of Moving Bed Biofilm Reactor (MBBR) and Activated Sludge Process (ASP) for treating tannery wastewater. It also highlights the importance of proper wastewater treatment in the tannery industry to mitigate environmental impacts. The batch analysis was conducted to find out removal efficiencies for Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5), Sulphide (S2-), Ammonia (NH4), Nitrate (NO3). Kaldness K1 bio-media was used with a 50% filling ratio in the laboratory setup of the MBBR and aeration was provided to both setups. The results for the MBBR system showed chromium removal of 95.4% with the obtained reduction of biochemical oxygen demand (BOD), chemical oxygen demand (COD), sulfide (S2-), and nitrate (NO3) 93.5%, 88.8%, 93.7%, and 97.09%, respectively. It indicates significant removal efficiencies for various pollutants in the tannery wastewater, suggesting the effectiveness of the MBBR system.

Optimization of a continuous hybrid moving bed biofilm reactor and constructed wetland system for the treatment of paracetamol-spiked domestic wastewater

A continuous system of moving bed biofilm reactor (MBBR) integrated with horizontal subsurface flow constructed wetland (HSSFCW) followed by a sedimentation tank (PUMBBR-CW) was used for the removal of chemical oxygen demand (COD), ammonia (NH4+), and paracetamol. The removal performance of the reactor was analyzed by varying the initial concentration of the pollutants, hydraulic retention time (HRT), and COD to NH4+ ratio (C/N ratio). Polyurethane foam (PUF) waste was used as the bio-carrier in the MBBR system. Microbial degradation, plant uptake, and substrate adsorption were the most dominant removal mechanisms in the PUMBBR-CW. Further insights into the degradation mechanisms were investigated by characterizing the substrate and bio-carrier and analyzing the degradation by-products. More than 95 % of COD removal was achieved with 30.6 h HRT and 550 mg/L initial concentration at a C/N ratio of 10. At 30.6 h HRT and a C/N ratio of 4, 87 % NH4+ and 94 % paracetamol removal were achieved. The low C/N ratio favors paracetamol removal, as the microorganism uses paracetamol as the sole carbon source under low C/N conditions. Moreover, it was found that paracetamol was uptake and stored in the Canna indica L. plant leaves (216 µg/g). An artificial neural network (ANN) was developed to find the optimum operating condition with maximum removal efficiency. The PUMBBR-CW system effectively overcame the drawbacks of conventional wastewater technologies, such as high footprint, variable pollutant loads, and high maintenance. Hence, it can be used as a highly efficient method of treating wastewater.

Machine learning model optimization for removal of steroid hormones from wastewater

In the past few decades, there has been a significant focus on detecting steroid hormones in aquatic environments due to their influence on the endocrine system. Most compounds of these pollutants are the natural steroidal estrogens, i.e., estrone (E1), 17β-Estradiol (E2), and the synthetic estrogen 17α-Ethinylestradiol (EE2). The Moving-Bed Biofilm Reactor (MBBR) technique is appropriate for eliminating steroid hormones. This study centers on creating a model to estimate the effectiveness of the MBBR system regarding its ability to eliminate E1, E2, and EE2. The results were modeled with artificial neural networks (ANNs). The Particle Warm Optimization (PSO) and Levenberg Marquardt (LM) algorithms were selected for network training. The models incorporated five input parameters, encompassing the COD loading rate, initial levels of E1, E2, and EE2 steroid hormones, and Hydraulic Retention Time (HRT). The optimum removal conditions (three steroid hormones and COD) were determined using the optimized ANN based on both PSO and LM algorithms. The optimal transfer functions for the hidden and output layers were identified as tan-sigmoid and linear, respectively. The best ANN structures (Neurons in input, hidden, and output layers) and correlation coefficients (R) were 5:9:4, with R = 0.9978, and 5:10:4, with R = 0.9982 for the trained networks with LM and PSO algorithms, respectively. Eventually, the input parameters' importance was ranked using sensitivity analysis (SA) through Pearson correlation and developed ANNs.

Sequential adaptation strategies of SPDA systems to low temperature: EPS mediation and community structure evolution

Temperature stands as a vital factor in the practical application of simultaneous partial-denitrification/anammox (SPDA) systems in mainstream wastewater treatment, thus it is necessary to understand the adaptation strategy of SPDA systems to low temperature. To address this, the potential adaptation of different coupling forms to low temperatures was investigated in a moving bed biofilm reactor (MBBR) and an integrated fixed-film activated sludge (IFAS) reactor for 182 days. The results showed that IFAS reactor achieved higher total nitrogen removal rates (TNRRs) at 15 °C (89.67 ± 0.01%) than MBBR system (77.28 ± 0.02%). Nitrogen conversion in the typical cycles showed that PD process was more sensitive to low temperatures than anammox process in SPDA systems. Meanwhile, the significant increase of total extracellular polymeric substances (EPS) content in each biophase and the change of community structure indicated that EPS mediation and community structure evolution in different biophases are two adaptive strategies of SPDA system to temperature decreasing. Biofilm phase tends to produce more EPS to resist the temperature decrease than floc phase. The highly negative relationship between EPS content at 15 °C and the initial temperature of change in community structure (p = 0.036＜0.05, r = -0.964) suggested that microorganisms always tend to resist the adverse environment through EPS mediation first, and then adapt to the low-temperature environment through community structure evolution with the temperature further decreased. This study guided the selection of SPDA coupling system in practical engineering applications, and laid a foundation for efficient biological nitrogen removal at low temperatures.

Moving bed biofilm reactor combined with an activated carbon filter for biological nitrate removal

Abstract A massive use of nitrogen based fertilizers in agriculture is worldwide one of the main causes for nitrate contamination of groundwater. Methods for removing nitrate from aquatic environment through physical and/or chemical processes often turn out to be not applicable because of unaffordable financial resource as well as essential infrastructure lack. On the other hand, biological processes seem to have potentiality to overcome these limitations since they are less expensive and easier to be performed. Accordingly, in the present work, a moving bed biofilm reactor (MBBR) filled with Kaldnes K1 as carrier media was used to remove nitrate from a synthetic groundwater at bench scale. Acetate was used as organic source. Different operational conditions were tested: influent nitrate concentrations of 30, 40, 50 and 60 mg/L; hydraulic retention times of 24, 18, 12 and 8 h; and COD/NO3-N mass ratios of 3.00 and 2.98. Experimental results showed that NO3-N = 60 mg L−1, HRT = 8 h and COD/NO3-N ratio = 2.98 were the optimal operating conditions that allowed achieving a NO3-N removal by 99 % and a COD removal by almost 100 %. Moreover, almost no NO2 −-N accumulation and null COD concentration were observed at the optimal operating conditions. An activated carbon filter was placed downstream to remove residual organic compounds prior to disinfection unit, thus avoiding the potential formation of harmful disinfection by-products (e.g. trihalomethanes (THMs)). The MBBR was able to show a rapid recovery whenever the operating conditions were defined as more severe, thus proving that the operating conditions can vary over a wider range. Furthermore, the results showed that the MBBR system can be used effectively as a biological process to remove nitrate from groundwater.

Effect of biocarriers on the nitrification and microbial community in moving bed biofilm reactor for anaerobic digestion effluent treatment

The performance of a moving bed biofilm reactor (MBBR) depends largely on the type of biofilm carrier used. However, how different carriers affect the nitrification process, particularly when treating anaerobic digestion effluents, is not completely understood. This study aimed to evaluate the nitrification performance of two distinct biocarriers in MBBRs over a 140-d operation period, with a gradually decreasing hydraulic retention time (HRT) from 20 to 10 d. Reactor 1 (R1) was filled with fiber balls, whereas a Mutag Biochip was used for reactor 2 (R2). At an HRT of 20 d, the ammonia removal efficiency of both reactors was >95%. However, as the HRT was reduced, the ammonia removal efficiency of R1 gradually declined, ultimately dropping to 65% at a 10-d HRT. In contrast, the ammonia removal efficiency of R2 consistently exceeding 99% throughout the long-term operation. R1 exhibited partial nitrification, whereas R2 exhibited complete nitrification. Analysis of microbial communities showed that the abundance and diversity of bacterial communities, particularly nitrifying bacteria such as Hyphomicrobium sp. And Nitrosomonas sp., in R2 was higher than that in R1. In conclusion, the choice of biocarrier significantly impact the abundance and diversity of microbial communities in MBBR systems. Therefore, these factors should be closely monitored to ensure the efficient treatment of high-strength ammonia wastewater.

Quantitative study of biofilm yield and biomass distribution of a multi-stage moving-bed biofilm system

Abstract A multi-stage anoxic/oxic (A/O) moving-bed biofilm reactor (MBBR) system with multiple chambers was established for municipal wastewater treatment. The active biomass quantity, bioactivity, and biomass yield of a pilot-scale multi-stage MBBR were investigated in this study. The microbial activity and heterotrophic yield coefficients (YH) were measured using respirometric techniques in each chamber at different temperature conditions. Meanwhile, the growth, nitrification, and denitrification rates of functional biomass were also quantified as specific respiration rate (SOUR). The total active biomass in the multi-stage A/O-MBBR system was 0.71–1.68 g COD/m2 for the aerobic reactor and 0.39–1.44 g COD/m2 for the anoxic reactor at 10–19 °C. The YH values for the anoxic reactors were 0.61–0.69, which were comparable to the recommended value of the activated sludge model (ASM1). The correlation coefficient between Nitrospira and the autotrophic specific respiration rate (SOURA) was 0.82. Meanwhile, denitrifying genera showed a significant correlation with the heterotrophic specific respiration rate (SOURH) and the active heterotrophic biomass (XH). This study provided insights into biomass distribution and the corresponding kinetic parameters for the multi-stage MBBR systems, which may serve as a reference for process design and trouble shooting.

A Study on The Carriers Compound Multi-Stage MBBR Biological Treatment Process for Domestic Sewage

Biocarriers are a key factor in moving bed biofilm reactors (MBBR) for domestic wastewater treatment and studies targeting biocarriers can be explored in more depth. In this study, two different types of biocarriers, namely anaerobic microbial carriers (AMC) and porous biogels (PBG), were used to treat real domestic wastewater and acted on a lab-scale tertiary MBBR system. The effects of the start-up process, water quality degradation, secondary start-up, and organic loading rate (OLR) on MBBR performance at room temperature (19–24 °C) and the same filling ratio (40%) were investigated, as well as the calculation of sludge yield. The results showed that the AMC–PBG/MBBR biological treatment process could complete the start-up process quickly in a short time and the OLR was finally determined to be 1.5 kgCOD/(m3·d). In this case, the system was able to operate stably and complete the secondary start-up relatively quickly, with 80% and 95% removal of COD and NH4+-N, respectively. The biofilm was characterized by scanning electron microscopy (SEM) and high-throughput sequencing which revealed the changes of microorganisms in the biofilm during operation, among which the dominant phyla were Euryarchaeota and Proteobacteria. Finally, the apparent production of process sludge was monitored and calculated to be 0.043 kgMLSS/kgCOD which is a significant reduction in sludge compared to the conventional activated sludge method. These conclusions provide valuable information for the full-scale treatment of domestic wastewater.

Design strategy and mechanism of nitrite oxidation suppression of elevated loading rate partial nitritation system.

There is a current need for a low operational intensity, effective and small footprint system to achieve stable partial nitritation for subsequent anammox treatment at mainstream municipal wastewaters. This research identifies a unique design strategy using an elevated total ammonia nitrogen (TAN) surface area loading rate (SALR) of 5 g TAN/m2.d to achieve cost-effective, stable, and elevated rates of partial nitritation in a moving bed biofilm reactor (MBBR) system under mainstream conditions. The elevated loaded partial nitritation MBBR system achieves a TAN surface area removal rate (SARR) of 2.01 ± 0.07 g TAN/m2.d and NO2 --N: NH4 +-N stoichiometric ratio of 1.15:1, which is appropriate for downstream anammox treatment. The elevated TAN SALR design strategy promotes nitrite-oxidizing bacteria (NOB) activity suppression rather than a reduction in NOB population as the reason for the suppression of nitrite oxidation in the mainstream elevated loaded partial nitritation MBBR system. NOB activity is limited at an elevated TAN SALR likely due to thick biofilm embedding the NOB population and competition for dissolved oxygen (DO) with ammonia-oxidizing bacteria for TAN oxidation to nitrite within the biofilm structure, which ultimately limits the uptake of DO by NOB in the system. Therefore, this design strategy offers a cost-effective and efficient alternative for mainstream partial nitritation MBBR systems at water resource recovery facilities.

Novel carrier for seafood wastewater treatment using moving bed biofilm reactor system

In this work, seafood wastewater was treated by using MBBR reactor over a novel carrier (PUF-PVA gel) derived from the combination of a porous (PUF) and hydrophilic surface (PVA gel). A freezing-thawing method was used for the preparation of the novel PUF-PVA gel which is reported for the first time. Experimental results indicated that PUF-PVA gel carrier which possesses an excellent textural structure (specific surface area of 3.4 m2/g, pore size in the range of 10 – 40 μm and hydrophilic surface) accounts for faster water immersion and better microbial adhesion, resulting in the biofilm content attached at the start-up stage 2.4 times higher relative to conventional PUF carrier alone. The MBBR system can be operated stably at a hydraulic retention time (HRT) of 7 hours in which the organic loading rate ranged from 2.5 kg COD/m3.day to 5.1 kg COD/m3.day. When operated at the organic loading rate of 2.5 kg COD/m3.day, the maximum COD and the nitrogen removal efficiency of MBBR based on the PUF-PVA gel carrier were 92 ± 0.6% and 89 ± 3.4%, respectively, which is higher than that of the PUF carrier.

Quantification of some ARVs' removal efficiency from wastewater using a moving bed biofilm reactor.

To date, in South Africa alone, there are an estimated 4.5 million people receiving antiretroviral (ARV) therapy. This places South Africa as the country with the largest ARV therapy programme in the world. As a result, there are an increasing number of reports on the occurrence of ARVs in South African waters. Achieving efficient and bio-friendly methods for the removal of these pollutants is considered as a concern for environmental researchers. This study aims at studying the efficiency of a moving bed biofilm reactor (MBBR) system for removing ARVs from wastewater. A continuous-flow laboratory scale system was designed, built, installed, and operated at a carrier filling rate of 30%, an organic loading rate of 0.6 kg COD/m3.d-1 OLR, a hydraulic retention time of 18h, and a 27.8 mL/min flow rate. The systems were monitored over time for the elimination of conventional wastewater parameters i.e., Biological Oxygen Demand, Chemical Oxygen Demand, and nutrients. The results showed that the MBBR system as a bio-friendly method has high efficiency in removing Nevirapine, Tenofovir, Efavirenz, Ritonavir and Emtricitabine from the synthetic influent sample with an average removal of 62%, 74%, 94%, 94% and 95%, respectively, after 10 days of operation.

Morphological image analysis of biofilm evolution with quantitative analysis in a moving bed biofilm reactor

The quantitative analysis of biomass is essential for the research and application of moving bed biofilm reactors (MBBRs). However, the difficulty in measuring the attached growing biomass hinders the quantitative analysis of biofilm processes. In this study, a pilot-scale MBBR system was established to investigate biofilm evolution. The quantity of active heterotrophic and autotrophic biomass was measured throughout the entire culturing process. The total active biomass reached 250 mg COD/m2 when the biofilm attachment and detachment were balanced, and the corresponding autotrophic biomass contributes to as high as 17 % of the total biomass. Furthermore, quantitative image analysis was performed to obtain the thickness and morphological data of the biofilm evolution. Multivariate regression models were constructed based on the morphological data, which provided satisfactory prediction accuracy for the biofilm thickness and maturation. The most suitable carrier spots for biomass quantification and biofilm maturation were suggested. This work provided the life-cycle information of biofilm quantity and morphology of the MBBR, which contributes to the quantitative understanding of biofilm evolution at MBBRs.

Acceleration of start-up of moving bed biofilm reactor at low temperature by adding specialized quorum sensing bacteria

This study aims to accelerate biofilm formation and operational performance of moving bed biofilm reactor (MBBR) at 5 ℃ by adding specialized Quorum Sensing bacteria (sphingomonas rubra BH3T). Results showed that bio augmented MBBR (RS) achieved a higher chemical oxygen demand and NH4+-N removal rate (93% and 75%), which in accordance with its increased biofilm thickness, higher biofilm activity, and nitrifying bacteria abundance (Nitrospira). The increased biofilm thickness (60.23 %) during the whole operating time, accompanied by more potent adhesion force (61.59 %), was related to increased polysaccharides and proteins in the biofilm. Pyrosequencing analysis indicated that BH3T contributed to higher species richness and triggered the rapid growth of precursor microorganisms (Nakamurella, Micropruina, and Zoogloea) and the enrichment of multifunctional microorganisms (Pseudomonas, Aeromonas, Arcobacter, Dechloromonas, and Flavobacterium) at low temperatures. This study provides an economical and practical new insight into accelerating start-up of MBBR system at low temperature.

Moving Bed Biofilm Reactor (MBBR) for Decentralized Grey Water Treatment: Technical, Ecological and Cost Efficiency Comparison for Domestic Applications

The reuse of greywater has several advantages, including reduced freshwater extraction from rivers, aquifers, and groundwater; reduced need for desalination; less environmental impact from septic tanks and water treatment plants; decreased energy consumption; and reduced chemical pollution. The main objectives of this review study are to assess the technical attributes, ecological impacts, and cost-efficiency of Moving Bed Biofilm Reactor (MBBR) water treatment technology compared to similar available technology for small to medium-sized, decentralized applications in residential and commercial settings such as home gardening, sanitation, and landfills. Previous studies indicate that hybrid technologies such as MBBR are the most promising methods for the total removal of contaminants in wastewater in a decentralized setting. However, the initial capital cost of this technology for small and medium-scale domestic applications worldwide is high and so is a limiting factor in the expansion of its utilization. Expansion of domestic use of such Decentralized Wastewater Treatment Systems (DWTS) could increase the economies of scale and therefore reduce the initial capital costs for this useful water treatment. For the MBBR system, Chemical Oxygen Demand (COD) removal efficiency was found to be 70%, Total Suspended Solids (TSS) removal was found to be 97%, and turbidity removal was 98%

Bioaugmentation for low C/N ratio wastewater treatment by combining endogenous partial denitrification (EPD) and denitrifying phosphorous removal (DPR) in the continuous A2/O - MBBR system

Endogenous partial denitrification (EPD) and denitrifying phosphorous removal (DPR) were combined in a novel A2/O - MBBR (Anaerobic Anoxic Oxic - Moving Bed Biofilm Reactor) system for low carbon/nitrogen (C/N) ratio wastewater treatment. The DPR performance was compared and the nutrient metabolism was elucidated based on the optimization of hydraulic retention time (HRT, 4–12 h) and nitrate recycling (R, 200%–600%). In the continuous-flow, the nitrate (NO3−) denitrification accompanied by nitrite (NO2−, via EPD) accumulation with the nitrate-to-nitrite transformation ratio (NTR) of 35.87%–43.31% in the anoxic zones. At HRT of 12 h with R of 500%, batch test initially revealed the DPR mechanism using both NO3− and NO2− as electron acceptor, where denitrifying phosphorus accumulation organisms (DPAOs) and denitrifying glycogen accumulation organisms (DGAOs) were the main contributors for EPD with incomplete denitrification (NO3− → NO2−). Furthermore, stoichiometry-based functional bacteria analysis displayed that higher bioactivity of DPAOs (NO2−→N2, 57.30%; NO3−→N2, 35.85%) over DGAOs (NO3−→N2, 6.85%) facilitated the anoxic NO3− reduction. Microbial community analysis suggested that Cluster I of Defluviicoccus-GAO group (∼4%) was responsible for stable NO2− accumulation performance via EPD, while increased Accumulibacter-PAO group (by ∼15%) contributed to the advanced nutrient removal. Based on the achievement of NO2− accumulation, the application feasibility of integrated EPD - DPR - Anammox for deep-level nutrient removal was discussed.

A Comparison of Biosolids Production and System Efficiency between Activated Sludge, Moving Bed Biofilm Reactor, and Sequencing Batch Moving Bed Biofilm Reactor in the Dairy Wastewater Treatment

Dairy industry wastewater is rich in organic content, presenting a high biodegradability, and therefore biological treatments are widely employed. This study aimed to evaluate biosolids production in three systems: activated sludge (AS), movingbed biofilm reactor (MBBR), and sequencingbatch movingbed biofilm reactor (SBMBBR). Simulated dairy wastewater was used at different organic load rates (OLRs): 1.22, 2.87, and 5.44 gCOD L−1d−1. Besides biosolids production, COD, total carbon (TC), and total nitrogen (TN) removal efficiency was evaluated. Biosolids production was measured in the mixed liquor, carrier-adhered biomass, treated wastewater, and surplus sludge. The operational conditions were kept similar for the three systems, with a carrier filling ratio of 50% for MBBR and SBMBBR. The SBMBBR proved to have better performance in the removal efficiencies of COD, TC, and TN for all OLRs studied. The MBBR presented a similar COD and TC removal efficiency as the SBBR for the two highest OLRs (2.87 and 5.44 gCOD L−1d−1). Concerning biosolids production, the MBBR system produced less biomass and delivered the lowest amount of adhered biomass inside the carriers. The AS treatment generated the highest amount of sludge and offered the worst treatment capability for all OLRs evaluated.