Sequencing Batch Biofilm Reactor Research Articles

Treatment of Pickle Wastewater under Varying Salinity Conditions within the Sequencing Batch Biofilm Reactor System

Treatment of Pickle Wastewater under Varying Salinity Conditions within the Sequencing Batch Biofilm Reactor System

Influence of aeration modes and DO on simultaneous nitrification and denitrification in treatment of hypersaline high-strength nitrogen wastewater using sequencing batch biofilm reactor (SBBR)

Sequencing batch biofilm reactor (SBBR) has the potential to treat hypersaline high-strength nitrogen wastewater by simultaneous nitrification-denitrification (SND). Dissolved oxygen (DO) and aeration modes are major factors affecting pollutant removal. Low DO (0.35–3.5 mg/L) and alternative anoxic/aerobic (A/O) mode are commonly used for municipal wastewater treatment, however, the appropriate DO concentration and operation mode are still unknown under hypersaline environment because of the restricted oxygen transfer in denser extracellular polymeric substances (EPS) barrier and the decreased carbon source consumption during the anoxic phase. Herein, two SBBRs (R1, fully aerobic mode; R2, A/O mode) were used for the treatment of hypersaline high-strength nitrogen wastewater (200 mg/L NH4+-N, COD/N of 3 and 3% salinity). The results showed that the relatively low DO (2 mg/L) could not realize effective nitrification, while high DO (4.5 mg/L) evidently increased nitrification efficiency by enhancing oxygen transfer in denser biofilm that was stimulated by high salinity. A stable SND was reached 16 days faster with a ∼10% increase of TN removal under A/O mode. Mechanism analysis found that denser biofilm with coccus and bacillus were present in A/O mode instead of filamentous microorganisms, with the secretion of more EPS. Corynebacterium and Halomonas were the dominant genera in both SBBRs, and HN-AD process might assist partial nitrification-denitrification (PND) for highly efficient TN removal in biofilm systems. By using the appropriate operation mode and parameters, the average NH4+-N and TN removal efficiency could respectively reach 100% and 70.8% under the NLR of 0.2 kg N·m−3·d−1 (COD/N of 3), which was the highest among the published works using SND-based SBBRs in treatment of saline high-strength ammonia nitrogen (low COD/N) wastewater. This study provided new insights in biofilm under hypersaline stress and provided a solution for the treatment of hypersaline high-strength nitrogen (low COD/N) water.

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.

Phosphate recovery from urban sewage by the biofilm sequencing batch reactor process: Key factors in biofilm formation and related mechanisms

The biofilm sequencing batch reactor (BSBR) technique has been deployed in the laboratory to enrich phosphorus from simulated wastewater, but it is still not clear what its performance will be when real world sewage is used. In this work, the effluent from the multi-stage anoxic-oxic (AO) activated sludge process at a sewage plant was used as the feed water for a BSBR pilot system, which had three reactors operating at different levels of dissolved oxygen (DO). The phosphorus adsorption and release, the biofilm growth, and the extracellular polymeric substances (EPS) components and contents were examined. The microbial communities and the signaling molecules N-acyl-l-homoserine lactones (AHLs) were also analyzed. Gratifyingly, the BSBR process successfully processed the treated sewage, and the biofilm developed phosphorus accumulation capability within 40 days. After entering stable operation, the system concentrated phosphate from 2.59 ± 0.77 mg/L in the influent to as much as 81.64 mg/L in the recovery liquid. Sludge discharge had profound impacts on all aspects of BSBR, and it was carried out successfully when the phosphorus absorption capacity of the biofilm alone was comparable to that of the reactor containing the activated sludge. Shortly after the sludge discharge, the phosphate concentration of the recovery liquid surged from 50 to 140 mg/L, the biofilm thickness grew from 20.56 to 67.32 μm, and the diversity of the microbial population plunged. Sludge discharge stimulated Candidatus competibacter to produce a large amount of AHLs, which was key in culturing the biofilm. Among the AHLs, both C10-HSL and 3OC12-HSL were significantly positively correlated with EPS and the abundance of Candidatus competibacter. The current results demonstrated BSBR as a viable option to enrich phosphorus from real world sewage with low phosphorus content and fluctuating chemistry. The mechanistic explorations also provided theoretical guidance for cultivating phosphorus-accumulating biofilms.

Comparison of nitrification performance in SBR and SBBR with response to NaCl salinity shock: Microbial structure and functional genes

Ammonia removal by nitrifiers at the extremely high salinity poses a great challenge for saline wastewater treatment. Sequencing batch reactor (SBR) was conducted with a stepwise increase of salinity from 10 to 40 g-NaCl·L−1, while sequencing batch biofilm reactor (SBBR) with one-step salinity enhancement, their nitrification performance, microbial structure and interaction were evaluated. Both SBR and SBBR can achieve high-efficiency nitrification (98% ammonia removal) at 40 g-NaCl·L−1. However, SBBR showed more stable nitrification performance than SBR at 40 g-NaCl·L−1 after a shorter adaptation period of 4–15 d compared to previous studies. High-throughput sequencing and metagenomic analysis demonstrated that the abundance and capability of conventional ammonia-oxidizing bacteria (Nitrosomonas) were suppressed in SBBR relative to SBR. Gelidibacter, Anaerolineales were the predominant genus in SBBR, which were not found in SBR. NorB and nosZ responsible for reducing NO to N2O and reducing N2O to N2 respectively had s strong synergistic effect in SBBR. This study will provide a valuable reference for the startup of nitrification process within a short period of time under the extremely high NaCl salinity.

Cultivation of phosphate-accumulating biofilm: Study of the effects of acyl-homoserine lactones (AHLs) and cyclic dimeric guanosine monophosphate (c-di-GMP) on the formation of biofilm and the enhancement of phosphate metabolism capacity

This study investigated the mechanisms of microbial growth and metabolism during biofilm cultivation in the biofilm sequencing batch reactor (BSBR) process for phosphate (P) enrichment. The results showed that the sludge discharge was key to biofilm growth, as it terminated the competition for carbon (C) source between the nascent biofilm and the activated sludge. For the tested reactor, after the sludge discharge on 18 d, P metabolism and C source utilization improved significantly, and the biofilm grew rapidly. The P concentration of the recovery liquid reached up to 157.08 mg/L, which was sufficient for further P recovery via mineralization. Meta-omics methods were used to analyze metabolic pathways and functional genes in microbial growth during biofilm cultivation. It appeared that the sludge discharge activated the key genes of P metabolism and inhibited the key genes of C metabolism, which strengthened the polyphosphate-accumulating metabolism (PAM) as a result. The sludge discharge not only changed the types of polyphosphate-accumulating organisms (PAOs) but also promoted the growth of dominant PAOs. Before the sludge discharge, the necessary metabolic abilities that were spread among different microorganisms gradually concentrated into a small number of PAOs, and after the sludge discharge, they further concentrated into Candidatus_Contendobacter (P3) and Candidatus_Accumulibacter (P17). The messenger molecule C-di-GMP, produced mostly by P3 and P17, facilitated P enrichment by regulating cellular P and C metabolism. The glycogen-accumulating organism (GAO) Candidatus_Competibacter secreted N-Acyl homoserine lactones (AHLs), which stimulated the secretion of protein in extracellular polymeric substances (EPS), thus promoting the adhesion of microorganisms to biofilm and improving P metabolism via EPS-based P adsorption. Under the combined action of the dominant GAOs and PAOs, AHLs and C-di-GMP mediated QS to promote biofilm development and P enrichment. The research provides theoretical support for the cultivation of biofilm and its wider application.

Nitrogen removal from urea effluent in an anammox sequencing batch biofilm reactor with valorised dishwashing scrubber as biocarrier

BackgroundThis study aimed for efficient nitrogen removal from urea wastewater in an anammox SBBR with valorised dishwashing scrubber as biocarrier. MethodsThe study (225 d) comprised three discrete phases: Phase I [1 – 26 d; Inf. NH4+-N (Simulated ww)], Phase II [27 – 131 d; Inf. NH4+-N (Real ww) + Inf. NH4+-N (Simulated ww)] and Phase III [132 – 225 d; Inf. NH4+-N (Real ww)] in which the reactor was supplemented with varied ratios (0 – 7) of influent NH4+-N reflecting varying combinations of real and simulated wastewater. Significant findingsThe reactor exhibited average total nitrogen removal efficiency of approximately 83 %, 81 %, and 80 % in the subsequent phases I, II, and III, respectively at varied nitrogen loading rates (100 – 232 g N m−3 d−1). The 16S rRNA gene sequencing revealed significant enrichment of Candidatus Kuenenia (from 41.69 % to 48.11 %) on the 225th day which was primarily attributed to significant decline in Nitrospira from 23.9 % to 1.24 % (due to nitrite oxidizing bacteria inhibition on account of high free ammonia concentrations in the reactor) and Nitrosomonas from 4.32 % to 0.01 %. Additionally, genera that were not initially present (on the 1st day) including Stenotrophobacter (17.34 %), Sphingobium (8.41 %), Rhodococcus (5.88%) and Ohtaekwangia (5.84 %) were observed to emerge by the end of the experiment (225 d).

Evaluation of polyhydroxyalkanoate recovery from food waste by sequencing batch biofilm reactor with high mixed microbial biomass

In this study, the enrichment sequencing batch biofilm reactor (SBBR) and conventional enrichment reactor (SBR) were established, and a new strategy was developed to achieve higher biomass yield and polyhydroxyalkanoate (PHA) production from food waste than those achieved through the conventional method. After the 10th day of an expanded cultivation period, the respective active biomass concentrations in SBR and SBBR were 5.16 and 13.92 g/L, indicating a significant improvement in the biomass yield of mixed microbial culture in the SBBR. The PHA accumulation test revealed that maximum PHA concentration in SBR and SBBR reached 6.60 and 12.70 g/L, respectively, after 80 days of enrichment, indicating that compared to SBR, the SBBR could more effectively improve the PHA accumulation capacity. Meganema, Thauera, and Paracoccus were the dominant PHA-accumulating bacteria in the SBR and SBBR. Additionally, the volumetric productivity of the SBBR was 3.22 g COD/L/d, twice that of the SBR. This study provides new strategies and insights for improving PHA production and reducing the costs of PHA production and reactor investment.

Indole signaling enhances biofilm formation and quorum sensing in sequencing biofilm batch reactors

Indole is a heterocyclic organic compound that acts as a signaling molecule to regulate biofilm formation (BF) by microorganisms. However, the potential roles of indole in BF among microbial communities in wastewater treatment systems remain unknown. In this study, the effects of indole signaling on BF and quorum sensing (QS) of the complex microbial communities in sequencing batch biofilm reactors were systematically explored. The results showed that indole at 200 mg/L increased BF along with concentrations of homoserine lactones. High-throughput sequencing revealed the underlying mechanism of notable differences in the BF capacity of microbial communities between the indole-treated and control groups. The indole-related metabolic and QS functions of the genera in the biofilm were annotated based on the QS-related protein database and previous studies. Relative abundance analysis showed that the QS-related genera, such as Acinetobacter, that produce indole oxygenase were significantly enriched in the indole-treatment group. In addition, bioinformatics analyses revealed that indole at 200 mg/L enhanced BF, QS, and protein efflux. Based on a phylogenetic molecular ecological network, QS was positively correlated to indole treatment of Burkholderia, suggesting that indole promotes QS and BF. This study provides new insights into the effects of indole signaling on BF of microbes and sheds light on its potential regulatory mechanism in wastewater treatment plants.

Subtle magnesium liberation of self-fabricated functional filler actuates highly efficient phosphorus removal from source-separated urine by SBBR.

Domestic wastewater source-separated treatment has attracted wide attention due to the efficiency improvement of sewage treatment systems, energy saving, resource reuse, and the construction and operation cost saving of pipeline networks. Nonetheless, the excess source-separated urine still demands further harmless treatment. Sequencing batch biofilm reactor (SBBR), a new type of composite biofilm reactor developed by filling different fillers into the sequential batch reactor (SBR) reactor, has higher pollutant removal performance and simpler operation and maintenance. However, the phosphorus removal ability of the SBBR filling with conventional fillers is still limited and needs further improvement. In this study, we developed two new fillers, the self-fabricated filler A and B (SFA/SFB), and compared their source-separated urine treatment performance. Long-term treatment experimental results demonstrated that the SBBR systems with different fillers had good removal performance on the COD and TN in the influent, and the removal rate increased with the increasing HRT. However, only the SBBR system with the SFA showed excellent PO43--P and TP removal performance, with the removal rates being 83.7 ± 11.9% and 77.3 ± 13.7% when the HRT was 1 d. Microbial community analysis results indicated that no special bacteria with strong phosphorus removal ability were present on the surface of the SFA. Adsorption experimental results suggested that the SFA had better adsorption performance for phosphorus than the SFB, but it could not always have stronger phosphorus adsorption and removal performance during long-term operation due to the adsorption saturation. Through a series of characterizations such as SEM, XRD, and BET, it was found that the SFA had a looser structure due to the use of different binder and production processes, and the magnesium in the SFA gradually released and reacted with PO43- and NH4+ in the source-separated urine to form dittmarite and struvite, thus achieving efficient phosphorus removal. This study provides a feasible manner for the efficient treatment of source-separated urine using the SBBR system with self-fabricated fillers.

Impact of salinity and organic matter on the ammonia-oxidizing archaea and bacteria in treating hypersaline industrial wastewater: amoA gene abundance and ammonia removal contributions.

Studies publishedrecently proposed that ammonia-oxidizing archaea (AOA) may bebeneficial for hypersaline (salinity > 50g NaCl L-1) industrial wastewater treatment. However, knowledge of AOA activity in hypersaline bioreactors is limited. This study investigated the effects of salinity, organic matter, and practical pickled mustard tuber wastewater (PMTW) on AOA and ammonia-oxidizing bacteria (AOB) in two sequencing batch biofilm reactors (SBBRs). Results showed that despite observed salinity inhibition (p < 0.05), both AOA and AOB contributed to high ammonia removal efficiency at a salinity of 70 g NaCl L-1 in the two SBBRs. The ammonia removal efficiency of SBBR2 did not significantly differ from that of SBBR1 in the absence of organic matter (p > 0.05). Batch tests and quantitative real-time PCR (qPCR) reveal that salinity and organic matter inhibition resulted in a sharp decline in specific ammonia oxidation rates and amoA gene copy numbers of AOA and AOB (p < 0.05). AOA demonstrated higher abundance and more active ammonia oxidation activity in hypersaline and high organic matter environments. Salinity was positively correlated with the potential ammonia oxidation contribution of AOA (p < 0.05), resulting in a potential transition from AOB dominance to AOA dominance in SBBR1 as salinity levels rose. Moreover, autochthonous AOA in PMTW promoted the abundance and ammonia oxidation activities of AOA in SBBR2, further elevating the nitrification removal efficiency after feeding the practical PMTW. AOA demonstrates greater tolerance tothe challenging hypersaline environment, making it a valuable candidate for the treatment of practical industrial wastewater with high salinity and organic content.

Nitrogen removal intensification of biofilm through bioaugmentation with Methylobacterium gregans DC-1 during wastewater treatment

The increasing concern for environmental remediation has led to a search for effective methods to remove eutrophic nutrients. In this study, Methylobacterium gregans DC-1 was utilized to improve nitrogen removal in a sequencing batch biofilm reactor (SBBR) via aerobic denitrification. This bacterium has the extraordinary characteristics of strong auto-aggregation and a high ability to remove nitrogen efficiently, making it an ideal candidate for enhanced treatment of nitrogen-rich wastewater. This strain was used for the bioassessment of a test reactor (SBBRbio), which showed a shorter biofilm formation time compared to a control reactor (SBBRcon) without this strain inoculation. Moreover, the enhanced biofilm was enriched in TB-EPS and had a wider variety of protein secondary structures than SBBRcon. During the stabilization phase of SBBRbio, the EPS molecules showed the highest proportion of intermolecular hydrogen bonding. It is possible that bioaugmentation with this strain positively affects the structural stability of biofilm. At influent ammonia loadings of 100 and 150 mg. L−1, the average reduction of ammonia and nitrate-nitrogen was higher in the experimental system compared to the control system. Additionally, nitrite-N accumulation was lower and N2O production decreased compared to the control. Analysis of the microbial community structure demonstrated successful colonization in the bioreactor by a highly nitrogen-tolerant strain that efficiently removed inorganic nitrogen. These results illustrate the great potential of this type of denitrifying bacteria in the application of bioaugmentation systems.

Changes in Nitrification Kinetics and Diversity of Canonical Nitrifiers and Comammox Bacteria in a Moving Bed Sequencing Batch Biofilm Reactor—A Long-Term Study

A lab-scale pure moving bed sequencing batch biofilm reactor (MBSBBR) was employed to investigate changes in nitrification kinetics and microbial diversity. The MBSBBR operated under different aeration strategies (defined by the ratio of the duration of the subphases with (t1) and without (t2) aeration (R = t2/t1)) − continuous (R = 0) and intermittent (with constant time of non-aerated subphases (t2 = 10 min) and variable duration of subphases with aeration (t1 = 40 min–R = 1/4, t1 = 30 min–R = 1/3, t1 = 20 min–R = 1/2) and dissolved oxygen (DO) concentrations (6 mg/L; 3.5 mg/L). Moreover, the reactor’s organic (OLR) and nitrogen (NLR) loading rates were changed in the following ranges: OLR—537–402 gCOD/m3·d, NLR—64–48 gN/m3·d. The obtained results showed that, irrespective of changes introduced in particular series, a highly effective nitrification process (93.36 ± 2.13%) was achieved. The activity of bacteria capable of oxidizing ammonia nitrogen changed differently from that of bacteria capable of oxidizing nitrites (NOB). An increase in R was the primary factor changing the activity of ammonia-oxidizing microorganisms. NOB activity was affected only by the reduction of OLR and NLR. NOB were the predominant bacterial group, consistent with the kinetics studies. A DO decrease caused an increase in the abundance of AOB, NOB, and Comammox bacteria. Comammox bacteria were the most abundant at R = 1/2 and DO = 3.5 mg/L.

Effect of linear anionic surfactant (sodium dodecyl sulfate) dosage on nitrogen removal performance of an anammox reactor

AbstractThe impact of sodium dodecyl sulfate (SDS, as model linear anionic surfactant) dosage on overall nitrogen removal performance of anammox reactor alongside its microbial population and sludge properties was investigated. In this study (day 136), an anmmox sequencing batch biofilm reactor was subjected to gradual dosage of SDS from 0 to 20 mg L−1. Intriguingly, results revealed that SDS at ≥7.5 mg L−1 prompted sludge disintegration, evidenced by increased protein and polysaccharide content in the effluent. Nevertheless, reactor's average total nitrogen removal efficiency slightly improved from 83.12% (0 mg L−1) to 86.3% (20 mg L−1). The 16S rRNA gene sequencing revealed that SDS dosing significantly suppressed the unwanted and unavoidable nitrite oxidizing bacteria (NOBs) in the reactor as the abundance of genus Nitrospira declined from 40.68% (day 1) to 19.15% (day 136). The abundance of anammox genus Candidatus Kuenenia significantly improved from 1.86% (day 1) to 40.02% (day 136) as a result of NOB suppression. This study revealed that low concentration of surfactants in wastewater does not affect the anammox bacteria in a biofilm reactor. Furthermore, adding low concentrations of SDS (≥7.5 to 20 mg L−1) to wastewater may effectively suppress notorious NOBs in biofilm‐based anammox systems.

Decrease in Oxygen Concentration for the Fast Start-Up of Partial Nitritation/Anammox without Inoculum Addition

Initiating the partial nitritation and anammox (PN/A) process without inoculation poses a significant challenge. Thus, there is a notable amount of interest in devising a straightforward strategy for the start-up of PN/A. This study demonstrates the feasibility of achieving the rapid start-up of a one-stage PN/A process within a moving-bed sequencing batch biofilm reactor (MBSBBR) by reducing the oxygen concentrations: 3.0 mg O2/L (Stage I), 2.0 mg O2/L (Stage II), and 1.0 mg O2/L (Stage III). The anammox activity was observed 15 days after a gradual decrease in the oxygen concentration and confirmed using a specific anammox activity test (5.9 mg N/gVSS∙h). During Stage III, the average total inorganic nitrogen (TIN) removal efficiency was 60.6%. The relative abundance of planctomycetes, a typical phylum representing anammox microorganisms, increased almost three times from Stage I (2.8%) to Stage III (7.1%). These results demonstrate the potential of a decrease in oxygen concentration for the fast start-up of the one-stage partial nitritation and anammox process without inoculation. The implementation of the studied DO strategy has practical implications for wastewater treatment plant operators, particularly in the start-up of the PN/A processes. Additionally, batch assays allow for the rapid assessment of treatment plant performance, providing real-time insights into its functionality and, thereby, optimizing wastewater treatment practices.

Schwarzite-based 3D-printed carriers for enhanced performance of sequencing batch biofilm reactor (SBBR) for wastewater treatment

The energy-efficient, green, and sustainable wastewater treatment using biofilm reactors is gaining a lot of attention. The efficiency of biofilm-based reactors (e.g., sequencing batch biofilm reactor (SBBR) and moving bed biofilm reactor (MBBR), etc.) can be further improved with the help of strong, highly active, and functionally engineered carriers. Here, Schwarzite-based 3D-printed biocarriers were prepared to obtain optimum mechanical properties and enhanced organics and nutrient removal efficiencies. The optimized carrier (L2) possesses the highest porosity (∼75%) and specific modulus of resilience and lowest bulk density among the other prepared structures (i.e., L1, L3, and L4). High porosity and specific surface area of the carriers promote enhanced growth of biomass with a total of 0.3 g biomass/carrier. The optimized biocarrier showed ∼95% chemical oxygen demand and ∼84% ammonium nitrogen removal efficiencies, which were attributed to its high specific surface area and porosity. The performance of SBBR with 3D-printed biofilm carriers having only a 15% fill ratio was compared and found better than the conventional K2 carriers used with a filling ratio of 50%. The high mechanical stability and specific surface area of the L2 biocarrier make it feasible to be used as a biofilm carrier, which may drastically reduce the number of carriers thereby directly reducing the cost.

High-efficient nutrient removal in a single-stage electrolysis-integrated sequencing batch biofilm reactor (E-SBBR) for low C/N sanitary sewage treatment

To efficiently remove nutrients from low C/N sanitary sewage by conventional biological process is challenging due to the lack of sufficient electron donors. A novel electrolysis-integrated sequencing batch biofilm reactor (E-SBBR) was established to promote nitrogen and phosphorus removal for sanitary sewage with low C/N ratios (3.5–1.5). Highly efficient removal of nitrogen (>79%) and phosphorus (>97%) was achieved in the E-SBBR operating under alternating anoxic/electrolysis-anoxic/aerobic conditions. The coexistence of autotrophic nitrifiers, electron transfer-related bacteria, and heterotrophic and autohydrogenotrophic denitrifiers indicated synergistic nitrogen removal via multiple nitrogen-removing pathways. Electrolysis application induced microbial anoxic ammonia oxidation, autohydrogenotrophic denitrification and electrocoagulation processes. Deinococcus enriched on the electrodes were likely to mediate the electricity-driven ammonia oxidation which promoted ammonia removal. PICRUSt2 indicated that the relative abundances of key genes (hyaA and hyaB) associated with hydrogen oxidation significantly increased with the decreasing C/N ratios. The high autohydrogenotrophic denitrification rates during the electrolysis-anoxic period could compensate for the decreased heterotrophic rates resulting from insufficient carbon sources and nitrate removal was dramatically enhanced. Electrocoagulation with iron anode was responsible for phosphorus removal. This study provides insights into mechanisms by which electrochemically assisted biological systems enhance nutrient removal for low C/N sanitary sewage.

Optimization of alkalinity supplementation in the AnSBBR using acidified cassava starch wastewater

In aiming to enhance performance and minimize costs, it is important to conduct research centered on the significance of alkalinity supplementation in anaerobic reactors. This study evaluated the impacts of alkalinity supplementation in the methane production, in a second-stage anaerobic sequencing batch biofilm reactor (AnSBBR) fed by acidified cassava wastewater. The AnSBBR was operated at 30 °C, cycle time (CT) of 8 and 6 h and sodium bicarbonate (gNaHCO3.gCOD[chemical oxygen demand]−1. L−1) of 1, 0.66, 0.33 and 0. The organic loading rate (OLR) were 17.1 and 22.8 gCOD.L−1d−1 for the CT of 8 and 6 h, in that order. The results showed that the reactor has been able to supply the alkalinity demand in the system, presenting removal of COD higher than 70%, even without alkalinity supplementation in the influent. The methane production rates (MPR) reached 3.42 ± 0.21 LCH4 L−1d−1 in the condition with 1 gNaHCO3.gCOD−1. L−1, with CT of 6 h. The main soluble metabolite was acetic acid and butyric acid. There was a decrease in methane production and greater instability in the reactor monitoring parameters without NaHCO3 supply. However, the degree of acidification was low, compared to the conversion of organic matter in all conditions. Thus, the AnSBBR maintained stable up to the ratio of 0.66 gNaHCO3.gCOD−1. L−1. Conditions with 1 gNaHCO3.gCOD−1. L−1. (CT 8 and 6 h) exhibited notable energy potential (≥90.2 KJ.d−1), underscoring their capacity for energy generation, even within shorter CT (6 h), thus rendering them suitable for application in industrial facilities.

Performance Evaluation and Microbial Shift of Sequencing Batch Biofilm Reactor Treating Synthetic Mariculture Wastewater Under Different Dissolved Oxygen at Aerobic Phase

Performance Evaluation and Microbial Shift of Sequencing Batch Biofilm Reactor Treating Synthetic Mariculture Wastewater Under Different Dissolved Oxygen at Aerobic Phase

Polyethylene terephthalate cap‐based bioreactors for combined domestic and dye wastewater treatment

AbstractIn the current study, a sequencing batch reactor (SBR), a sequencing batch biofilm reactor (SBBR) and a moving bed biofilm reactor (MBBR) were designed and used to treat actual samples of combined domestic and dye (Congo red) wastewaters over a 10‐hour cycle. A new application of reusing plastic bottle caps in the SBBR and MBBR was examined. In the SBR, maximum chemical oxygen demand (COD) removal of up to 66% ± 3% was achieved after nine cycles of operation. In the SBBR, a rapid increase in COD removal efficiency was observed during the first cycle, with a noticeable improvement in performance in subsequent cycles, eventually reaching a maximum COD removal efficiency of 77% ± 3%. In the MBBR, maximum COD removal of up to 88% ± 3% was achieved after nine cycles of operation. The biodegradation occurred during two phases in the SBR and SBBR, as an anaerobic phase in the first 2 hours and then as an aerobic phase in the last 8 hours of operation; the MBBR operated in the fully saturated aerobic phase for 10 hours. Of the three reactors used, results for the MBBR in the fully aerobic condition by using polyethylene terephthalate caps as a biocarrier, demonstrated the optimum conditions under which to treat and biodegrade Congo red at all concentration in each cycle. The maximum removal efficiency, which equalled 99% ± 1%, was recorded at an optimal concentration of 50 mg/L. Additionally, five kinetic models were proposed to assess microbial growth activity, and the results demonstrated the elimination of toxic effects when using polyethylene terephthalate caps as biocarriers in the MBBR. The laboratory experiments were consistent with the Monod model.