Search

The goal of this study was to unravel the impact of high and low temperatures (T) on glycogen-accumulating microorganisms (GAOs) which were stimulated in an aerobic granular sludge plant fed with industrial wastewater, which is derived from the cleaning of trucks transporting chocolate and beer. Among GAOs, Candidatus Competibacter (Ca. Competibacter) was the most abundant. The long-term impact on (1) anaerobic dissolved organic carbon (DOC) uptake, (2) sludge morphology, and (3) microbial community composition was investigated. In addition, the short-term impact of T changes on the anaerobic uptake rate was evaluated. High T (above 38 °C) and low T (below 11 °C) had a negative impact on the relative read abundance of Ca. Competibacter and the anaerobic DOC uptake. Nevertheless, the carbon removal efficiency and the settleability of the biomass were not affected. Denitrifiers such as Thauera and Zoogloea were promoted over Ca. Competibacter under high T and low T, respectively, indicating their positive contribution to granulation maintenance. HIGHLIGHTS The long-term exposure to high T completely inhibited Ca. Competibacter.; The long-term exposure to low T decreased the Ca. Competibacter population but not at an alarming level.; The short-term exposure of sludge enriched with Ca. Competibacter to high T did not affect the carbon uptake rate.; The short-term exposure of sludge enriched with Ca. Competibacter to low T negatively affected the carbon uptake rate.;

The application of a hybrid-fruit-peel (HFP) coagulant used as an external carbon source (ECS) in both simulated water and real sewage having a low carbon source treated with sequencing batch reactor (SBR) was studied, compared with that of sodium acetate (NaAc). The impact of HFP on sludge properties (such as extracellular polymer substance (EPS), dehydrogenase activity (DHA), charged property, size, microscopic images and bacteria phase) was characterized. The results showed that as an ECS, HFP basically gave similar nitrogen removal to NaAc and also gave a similar developing trend of both dissolved oxygen (DO) and pH. HFP promoted more proliferation of microorganisms and posed higher levels of protein (PN) and polysaccharide (PS) than NaAc, but gave slightly lower DHA than NaAc. After HFP was added as an ECS, the types and quantities of microorganisms increased significantly, the effluent qualities were improved and the sludge size and extensibility became larger, which was conducive to direct contact and remove pollutants. HFP played a similar role to NaAc as ECS and can be used as a quality and slow-releasing ECS for low carbon source wastewaters. HIGHLIGHTS Application of HFP coagulant as an external carbon source (ECS) for low C/N wastewater was studied and gave a similar effect to NaAc.; HFP can be used as a quality and slow-releasing ECS for low C/N wastewater.; HFP produced sludge has a larger size and better extensibility.; HFP promoted more proliferation of microorganisms and gave better effluent qualities.;

The presence of colonial and solitary ciliated peritrichous protozoa was determined in a Sequencing Batch Reactor system filled with tezontle, a volcanic rock, economic, and abundant material that can be found in some parts of the world, like Mexico. The presence of these protozoa was related to the removal efficiencies of organic matter. Also, two novel staining techniques are proposed for staining both colonial and solitary peritrichous protozoa. The results show that tezontle promotes the growth of solitary and colonial ciliated peritrichous protozoa, which, once identified, could be used as indicators of the efficiency of the wastewater treatment process. Additionally, the staining techniques established in the current study allowed the precise observation of protozoan nuclei. They can represent a useful complementary methodology for identifying protozoan species present in water treatment processes, along with the already existing identification techniques. The number and variety of protozoa found in the system may be considered potential bioindicators of water quality during biological treatments.

In this study, sequencing batch reactor (SBR) using anaerobic/aerobic/anoxic process was coupled to a solar photocatalytic reactor (SPCR) for greywater treatment. The greywater effluent from SBR (operated at the optimal condition: 6.8 h hydraulic retention time (HRT), 0.7 Volumetric exchange ratio (VER) and 7.94 d solids retention time (SRT) with optimal corn cob adsorbent dosage (0.5 g/L)) was fed to the SPCR (operated at optimal conditions: pH – 3, H2O2 dosage – 1 g/L, catalyst dosage – 5 g/L). Chemical oxygen demand (COD) removal of 92.8±0.5% and ∼100% were achieved in SBR and SBR-SPCR, respectively. Similarly, total organic carbon (TOC) removal of 91±0.9% and ∼100% were observed in SBR and SBR-SPCR, respectively. After SBR treatment, average total nitrogen (TN) removal of 84% was found and this TN removal increased to 93% after combined SBR-SPCR treatment. The maximum PO43−_P reduction of 80±1.5% % was achieved with SBR-adsorption system. In addition, a maximum of 87±0.9% of net PO43−_P removal was reached after SBR-SPCR treatment. 58.9±2.3% BP (benzophenone-3) removal was obtained in the SBR while the integration of SBR and SPCR treatment was resulted in 100% BP removal. An effective anionic surfactant (AS) removal rate (80.1±2.2%) was observed in the SBR phase, which further improved to 94.9±1% at the end of 4 h SPCR treatment. HIGHLIGHTS Biological – photochemical system successfully treated greywater.; The coupled system efficiently mineralizes COD, TOC and BP.; Significant removal of TN (93%), PO43−_P (87%) and AS (94.9%) was achieved.; Solar photocatalysis was able to remove emerging contaminants.; Treated SBR-SPCR greywater could meet reuse standards (toilet flushing and others).;

This article discusses the results of a scientific research work on the use of various types of small wastewater treatment plants for objects of various purposes in conditions of periodic use. The study was carried out on model and real wastewater with subsequent refinement of the characteristics using the calculation methods of the DWA standard.The results of the operation of laboratory facilities operated in the restart mode after a certain time are presented. As a result, the duration of restoration of the operating mode under periodic operating mode was considered for each plant under study and the effectiveness of biological wastewater treatment was determined. More promising technological solutions for small wastewater treatment plants under intermittent use conditions have been identified. According to the sum of the characteristics, the operation of the flooded biofilter system, which is capable of entering the operating mode within 5 days after a long shutdown, is highlighted. These technologies are recommended for use in resort areas and hotels.

ABSTRAK Limbah cair tahu dari industri tahu di Kabupaten Bandung Barat memiliki kandungan senyawa organik yang tinggi. Salah satu sistem pengolahan air limbah yang dapat dilakukan secara efektif adalah Sequencing Batch Reactor (SBR). Tujuan dari penelitian ini adalah untuk mengetahui peforma terbaik SBR dalam meningkatkan efisiensi pengolahan limbah cair tahu. Pada penelitian ini dilakukan pembibitan (seeding), aklimatisasi, dan sistem SBR dengan tahapan variasi kecepatan pengumpanan. Kecepatan pengumpanan SBR pada saat pembibitan (seeding), aklimatisasi, dan running 1 sebesar 200 ml/hari dan sebesar 400 ml/hari pada saat running 2. Hasil penelitian ini memperoleh penurunan konsentrasi COD terbaik dari 8.000 mg/L menjadi 96 mg/L diperoleh pada running 1 dan penurunan konsentrasi COD dari 8.000 mg/L menjadi 160 mg/L diperoleh pada running 2. Efisiensi tertinggi yang dihasilkan adalah 98,8% pada running 1 dan 98% pada running 2. Kata kunci : Limbah cair tahu, Sequencing Batch Reactor (SBR), Kecepatan Pengumpanan ABSTRACT Tofu wastewater collected from the tofu industries in West Bandung Regency has a high organic content. One of the wastewater treatment systems that can be applied effectively is the Sequencing Batch Reactor (SBR) system. The purpose of this study was to find out the best performance of SBR in improving the efficiency of tofu wastewater treatment. This study conducted seeding, acclimatization, and SBR system that varied the feeding rates to find optimum value. The SBR feeding rate at the times of seeding, acclimatization, and running 1 amounted to 200 ml/day and amounted to 400 ml/day at the time of running 2. The results of this study were the best reduction in COD concentration from 8,000 mg/L to 96 mg/L obtained in the first running and reduction in COD concentration from 8,000 mg/L to 160 mg/L obtained in 2nd running. The highest efficiency produced was 98.8% on the first running 1 and 98% obtained from the 2nd running. Keywords: Tofu Wastewater, Sequencing Batch Reactor (SBR), Feeding Rates

Small scale business / Usaha Skala Kecil (USK) X currently does not have a batik wastewater treatment unit. This condition causes the possibility of contamination to water bodies. USK X wastewater treatment applications' planning needs to be carried out sustainably, namely by reusing water. The process units needed in this planning are the sequencing batch reactor (SBR) and constructed wetlands. The effluent of textile wastewater with this system for parameters BOD, COD, TSS, sulfide, total oil & fat, and color were 0.13 mg/L; 106.5 mg/L; 2.4 mg/L; 0.036 mg/L; 0.07 mg/L; and 90.67 PtCo, respectively. The dimensions of the SBR unit required are 0.75 x 0.6 x 1 m. Modification of the SBR unit uses an ozone generator to produce ozone gas which functions as oxidation of organic pollutants and colors in batik waste. After processing in the SBR unit, it is carried out using a constructed wetland with 2.56 m2.

This review explores recent progress in sequencing batch reactors (SBRs) and hybrid systems for wastewater treatment, emphasizing their adaptability and effectiveness in managing diverse wastewater compositions. Through extensive literature analysis from 1985 to 2024, the integration of advanced technologies like photocatalysis within hybrid systems is highlighted, showing promise for improved pollutant removal efficiencies. Insights into operational parameters, reactor design, and microbial communities influencing SBR performance are discussed. Sequencing batch biofilm reactors (SBBRs) demonstrate exceptional efficiency in Chemical Oxygen Demand, nitrogen, and phosphorus removal, while innovative anaerobic-aerobic-anoxic sequencing batch reactors (AOA-SBRs) offer effective nutrient removal strategies. Hybrid systems, particularly photocatalytic sequencing batch reactors (PSBRs), show potential for removing persistent pollutants like antibiotics and phenols, underscoring the significance of advanced oxidation processes. However, research gaps persist, including the need for comparative studies between different SBR types and comprehensive evaluations of long-term performance, environmental variability, and economic viability. Addressing these gaps will be vital for the practical deployment of SBRs and hybrid systems. Further exploration of synergies, economic considerations, and reactor stability will enhance the sustainability and scalability of these technologies for efficient and eco-friendly wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, the performance of the membrane bioreactor (MBR) and anoxic–aerobic sequencing batch reactor (SBR) are compared in treating municipal wastewater. The aim of the work was to determine the feasibility of these systems for the removal of organics matter and nutriments from the municipal wastewater. The MBR displayed a superior performance with removal efficiencies exceeding 99% for TSS, 94% for chemical oxygen demand (COD) and an improvement on SBR efficiencies was found. In the same way, the MBR produced an effluent with much better quality than SBR in terms of total nitrogen (TN) and total phosphorus (TP) removal efficiencies. Combining membrane separation and biodegradation processes or the membrane bioreactor (MBR) technology improved pollution removal efficiencies significantly. Highlights Municipal wastewater treatment.; Membrane bioreactor process.; SBR process evaluation.; Organic pollution removal.; Reuse in irrigation.;

This study investigated the individual and synergy effects of tetracycline (TC) and zinc oxide nanoparticles (ZnO-NPs) accumulation on both short-term and long-term nitrogen removal processes in the bench-scale sequencing batch reactors (SBR). During short-term (10 hour) analysis, the removal rates of NH4+-N in 0.1 mg·L−1 ZnO-NPs (98.3%), 5 mg·L−1 TC (97.5%), and the co-addition reactor (96.9%) were significantly higher (P < 0.05) than the control reactor (94.4%) at minimum dosages. Ammonification processes were inhibited by the increasing dosage of ZnO-NPs (≥ 5 mg·L−1) and TC (≥ 15 mg·L−1) due to the cumulative toxic interference. Ultraviolet (UV) radiation with the co-addition of ZnO-NPs and TC promoted NH4+-N removal, and nitrification processes might be enhanced by UV exposure through the produced hydroxyl radicals (·OH) from ZnO-NPs. In the long-term operation, the effect of 0.1 mg·L−1 ZnO-NPs on nitrogen removal was negligible even over 15 days. Although NH4+-N removal rates were initially decreased, they recovered with the prolongation of dosages and operating time due to self-adjustment and the existence of extracellular polymeric substances (EPS) in activated sludge. Fourier transform infrared (FTIR) analysis revealed that the absence of —CH3 may explain the inhibition of NH4+-N removal during TC accumulation. Research results can be served as indications for the understanding of the synergistic effects of ZnO-NPs and TC on the performance of biological treatments used in wastewater systems.

The main purpose of this study was to investigate the effect of operating conditions on the performance of two methods used for dairy wastewater treatment. First, conventional activated sludge (AS). Second, conventional sequencing batch reactor (SBR). On one side, the study included the comparison between the two basic systems. On the other side, it studied the influence of adding plastic media on both systems. The modified systems are known as biofilm conventional activated sludge (BAS) and biofilm sequencing batch reactor (BSBR). Four pilot-scale bioreactors, were operated in parallel under different conditions of temperature; 20, 35 and 45 °C. Synthetic dairy wastewater was used with characterizations of COD; 5000 mg/l, NH3-N; 250 mg/l and TP; 50 mg/l. The results recorded that the optimum temperature was 35 °C where removal efficiencies for COD were (93.52%, 96.63%, 94.74% and 97.79%), (89.01%, 91.14%, 90.45% and 93.22%) for NH3-N, and the concentration of NO3-N in effluents was (7.56 mg/l, 10.58 mg/l, 8.72 mg/l and 14.12 mg/l) for AS, BAS, SBR and BSBR respectively. At temperature equals to 45 °C; the oxygen consumption recorded the highest level of consumption, it was (1.07 mg/l, 1.64 mg/l, 0.98 mg/l and 1.23 mg/l) for AS, BAS, SBR and BSBR respectively. The results indicated that the sludge settleability was enhanced with the decrease of temperature. Furthermore GPS-X simulator was employed to predicting the performances of the biological systems under high COD concentrating reaching up to 17500 mg/l. GPS-X results indicated that SBR effluent could comply with Egyptian standard NO 2000. An overview, comparing with various treatment systems, it can be concluded that the SBR was the optimum treatment method for dairy wastewater based on the investigated conditions.

The formation and characteristics of aerobic granular sludge (AGS) under different operational conditions in a sequencing batch reactor (SBR), designed to treat Mustard tuber wastewater (MTW, characterized as saline wastewater), had been investigated in this study. Morphology and structure during granulation were determined using a microscope with digital camera and scanning electron microscope (SEM). Granules formed in the reactors could be classified as zoogloea granules with a clear boundary outline and filamentous granules with mycelia bestrewing boundary. Zoogloea granules, cultivated in reactor R1 and R2, were with higher density than filamentous granules, cultivated in reactor R3, and consequently had a higher settling velocity. Results showed that divalent metal ions such as Ca2+ and Mg2+ with phosphate in inflow could transform into precipitates, serving as crystal nucleus and carriers for granulation. Moreover, appropriate organic loading, hydrodynamic

The main purpose of this study was to investigate the effect of operating conditions on the performance of two methods used for dairy wastewater treatment. First, conventional activated sludge (AS). Second, conventional sequencing batch reactor (SBR). On one side, the study included the comparison between the two basic systems. On the other side, it studied the influence of adding plastic media on both systems. The modified systems are known as biofilm conventional activated sludge (BAS) and biofilm sequencing batch reactor (BSBR). Four pilot-scale bioreactors, were operated in parallel under different conditions of temperature; 20, 35 and 45 °C. Synthetic dairy wastewater was used with characterizations of COD; 5000 mg/l, NH 3 -N; 250 mg/l and TP; 50 mg/l. The results recorded that the optimum temperature was 35 °C where removal efficiencies for COD were (93.52%, 96.63%, 94.74% and 97.79%), (89.01%, 91.14%, 90.45% and 93.22%) for NH 3 -N, and the concentration of NO 3 -N in effluents was (7.56 mg/l, 10.58 mg/l, 8.72 mg/l and 14.12 mg/l) for AS, BAS, SBR and BSBR respectively. At temperature equals to 45 °C; the oxygen consumption recorded the highest level of consumption, it was (1.07 mg/l, 1.64 mg/l, 0.98 mg/l and 1.23 mg/l) for AS, BAS, SBR and BSBR respectively. The results indicated that the sludge settleability was enhanced with the decrease of temperature. Furthermore GPS-X simulator was employed to predicting the performances of the biological systems under high COD concentrating reaching up to 17500 mg/l. GPS-X results indicated that SBR effluent could comply with Egyptian standard NO 2000. An overview, comparing with various treatment systems, it can be concluded that the SBR was the optimum treatment method for dairy wastewater based on the investigated conditions. [ABSTRACT FROM AUTHOR]

This study evaluated the properties and pollutant removal ability of sludge from low-strength synthetic wastewater during the formation of aerobic granules at low dissolved oxygen (DO) (1.0 ± 0.2 mg L–1). After 141 d operations, the aerobic granules were successfully cultivated. The removal efficiencies of chemical oxygen demand, NH4 +, total nitrogen and total phosphorus were 91.0%, 98.6%, 77.6% and 92.5%, respectively. The morphology of the mature granules was almost spherical, with an average granule size of 436.5 ± 12 μm. Filamentous bacteria on the surface were embedded in extracellular polymeric substances. The protein amount (190.4 mg g–1 VSS) was greater than that of polysaccharide (30.0 mg g–1 VSS). Aerobic granule at low DO (1.0 ± 0.2 mg L–1) consumed a 27.9% less aeration rate compared with conventional biological treatment methods. The good removal performance of aerobic granule at low DO could be suitably applied in wastewater treatment with low energy consumption. [ABSTRACT FROM AUTHOR]

This study was conducted to determine alkaline pre-chlorination effects on chemical oxygen demand (COD) removal and poly-β-hydroxybutyrate (PHB) production in tapioca wastewater treatment. The alkaline pre-chlorination effect was evaluated by applying various chlorine (Cl2) dosages (0, 2, 4, 6, and 8 mg/L) to the wastewater with a pH of 8 before being treated in a sequencing batch reactor (SBR). The cycle time of the SBR consisted of 1 h of filling and 8 h of aeration. COD and mixed liquor suspended solids (MLSS) of the effluent were measured at 2 h intervals during the aeration period. Both parameters were to estimate the optimum Cl2 dosage corresponding to the organic removal kinetics, the maximum specific growth rate, and the relationship between substrate utilization and microorganism's growth rate. The effluent of tapioca wastewater pre-chlorination under optimum Cl2 dosage was treated using the SBR with the cycle period: filling (1 h), aeration (8 h), and settling (8 h). PHB, COD, and MLSS of effluent were measured at 2 h intervals of aeration and settling period for estimating PHB formation kinetics parameter values. For the Cl2 dosage of 6 mg/L, SBR shows the best performance in terms of COD removal rate constant (k) and maximum specific growth rate (μmax) with values of 0.327 and 2.681 h-1, respectively. First-order kinetics, Contois equation, substrate utilization rate based on Monod equation considers cell death, and non-growth associated product formation was being appropriate models to describe organic removal rate, specific growth rate, kinetic of COD conversion to PHB, and PHB production rate, respectively. Another result showed excessive aeration time and settling time application decreased the level of microbial conversion of COD to PHB and PHB production rate per cell mass formed. Maximum yield coefficient of COD to PHB (YP/S) of 0.01 mg PHB/mg COD and non-growth associated PHB yield coefficient (β) of 9.07 × 10-4 mg PHB/mg MLSS/h was achieved when the aeration time was about 6 h. These results suggest that the alkaline pre-chlorination can effectively enhance the performance of the SBR system, especially treating the tapioca wastewater. The optimum process of this treatment is when SBR operated with a cycle consisted of 1 h of filling, 6 h of aeration, and 0.5 h of settling with a Cl2 dosage of 6 mg/L (pH 8) as wastewater pretreatment. [ABSTRACT FROM AUTHOR]

Sequencing batch reactor (SBR) technology has found many applications in industrial wastewater treatment in recent years. The aim of this study was to determine the optimal time for a cycle of the sequencing batch reactor (SBR) and evaluate the performance of a SBR for petrochemical wastewater treatment in that cycle time. The reactor was operated with a suspended biomass configuration under aerobic conditions. Carbon removal and operating parameters such as pH, temperature and dissolved oxygen (DO) were monitored during the wastewater treatment. The SBR was run at different cycle times and amongst the cycle times tested, the best performance was obtained with a 7 h cycle time composed of a fill time of 15min, reaction of 6 h, settling of 30 min, and withdrawal of 15 min. The SBR with the determined cycle time was used to study the treatment of wastewater with various organic loading rates (12.88 gr COD/L.d, 18.02 gr COD/L.d and 31.39 gr COD/L.d). The SBR performance was evaluated by chemical oxygen demand (COD), total solids (TS) total suspended solids (TSS) removal efficiencies. During the shock loading tests, the maximum COD, TS and TSS removal efficiencies were 84%, 67% and 92%, respectively.

Comparing the problems in Romania and Senegal, regarding wastewater treatment, the present paper aims to identify the best methods and techniques to treat the municipal wastewater in small treatment plants with sequential operation. This paper examines the possibility of using Sequencing Batch Reactor (SBR) process to treat the municipal wastewater characterized by low flow. This paper also presents a comparative analysis of the degree of purification achieved in a SBR wastewater treatment plant, as well as legislative regulations in Romania and Senegal. Finally, the paper identifies the possible uses of the treated wastewater in different household activities.

The formation and characteristics of aerobic granular sludge (AGS) under different operational conditions in a sequencing batch reactor (SBR), designed to treat Mustard tuber wastewater (MTW, characterized as saline wastewater), had been investigated in this study. Morphology and structure during granulation were determined using a microscope with a digital camera and scanning electron microscope (SEM). Granules formed in the reactors could be classified as zoogloea granules with a clear boundary outline and filamentous granules with mycelia bestrewing boundary. Zoogloea granules, cultivated in reactor R1 and R2, was with higher density than filamentous granules, cultivated in reactor R3, and consequently had a higher settling velocity. Results showed that divalent metal ions such as Ca2+ and Mg2+ with phosphate in inflow could transform into precipitates, serving as crystal nucleus and carriers for granulation. Moreover, appropriate organic loading, hydrodynamic shear and salt-stress selection can induce moderate growth of filamentous bacteria to act as granulation backbone and consequently granulation process under salt stress was a result together with crystal nucleus, filamentous bacteria, and extracellular polymeric substances (EPS), which could be affected by salinity-shifting strategies and dosage of aluminum salt coagulant. [ABSTRACT FROM AUTHOR]

Abstract Phosphorus recovery is usually based on the chemical precipitation of struvite from the supernatant comming from anaerobic digestion of surplus sludge of wastewater treatment plants. However, the recovery of phosphorus from the mainstream would be very beneficial to the operation of the plant. This work represents a step forward in this challenge. The configuration of a sequencing batch reactor performing Enhanced Biological Phosphorus Removal (EBPR) was modified to include the extraction of a P-rich supernatant after a settling period. The liquid extracted after the anaerobic phase has the highest phosphorus concentration in all the reactor cycle and is therefore suitable for implementing P-recovery strategies. This is the first experimental system operated under this configuration and in a long-term basis (more than one year) under different influent COD/P ratios with good performance and stability. This work shows experimentally that up to 60% of the P could be extracted without a deleterious effect on EBPR. The system could even operate at high COD/P ratio (7.5) with high activity. Finally, anaerobic supernatant extraction was linked to anaerobic sludge purging and it was demonstrated that higher methane production (24.3%) was obtained compared to the default case with the sludge purged at the end of the aerobic phase. Highlights • Long-term assessment of the EBPR2 configuration for P-recovery from mainstream line. • 60% P-recovery with anaerobic supernatant extraction without adverse effect on EBPR. • Long-term good performance under low influent COD/P ratio with high EBPR activity. • 24.3% higher methane production with sludge purged at anaerobic phase vs aerobic. [ABSTRACT FROM AUTHOR]

This study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.

A modified sequencing batch reactor, which adds a pre-anoxic phase before the aeration phase, was used to treat toxic landfill leachate, and high-throughput sequencing technology used to study how the classification, distribution and abundance of functional bacterial communities varies during system operation. The system operation results are as follows: in the full load steady operation period (II), influent/effluent chemical oxygen demand (COD) and total nitrogen (TN) concentrations were approximately 6,421/645 and 1,210/19 mg/L, respectively; TN and COD removal rates of the system were above 93% and 87%, respectively. The bacterial community structure of the system is as follows: when compared with the bacterial community structure of the inoculation sludge, the final dominant phyla of the system were Proteobacteria (49.4%) and Bacteroidetes (36.5%), while β-Proteobacteria (30.05%) and α-Proteobacteria (16.4%) under Proteobacteria were the two dominant classes in the full load steady operation period (II). Nitrosomonas (22.56%) was the main ammonia-oxidizing bacteria within β-Proteobacteria. The bacterial community associated with endogenous denitrification included Paracoccus (α-Proteobacteria, 19.15%), Thauera (β-Proteobacteria, 8.36%), and Truepera (4.96%). Paracoccus and Thauera were endogenous denitrifying bacteria that could transform organic matter into polyhydroxyalkanoates (PHA) and use PHA to remove nitrogen under anaerobic conditions, and Truepera could resist leachate toxicity. [ABSTRACT FROM AUTHOR]

Aerobic Granulation Technology for treatment of wastewater is developed in last two decades. Aerobic Granules are special type of self-immobilization of microorganisms, without any surface medium for growth of microbial film. They have compact cores and have high diffusional confrontations to external particles and, hence have high acceptance of the toxic compounds to their integral cells. Most aerobic granules are large and have a compact core, and so are recommended for use in the biological treatment of high-strength industrial wastewaters. This technology requires small foot print, 25% of the area of conventional activated sludge setup and this process can reduce up to 50% on energy-costs. This paper reviews on start-ups, advances in aerobic granulation technology from laboratory studies to pilot scale and to its full-scale application for treatment of different types of domestic and industrial wastewater. Gaps in knowledge and new ideas for future work of aerobic granulation technology are also being discussed. [ABSTRACT FROM AUTHOR]

The sequencing batch reactor (SBR) has been increasingly applied in the control of high organic wastewater. In this study, SBR with aerobic granular sludge was used for wastewater treatment in a noodle-manufacturing village in Vietnam. The results showed that after two months of operation, the chemical oxygen demand, total nitrogen and total phosphorous removal efficiency of aerobic granular SBR reached 92%, 83% and 75%, respectively. Bacterial diversity and bacterial community in wastewater treatment were examined using Illumina Miseq sequencing to amplify the V3-V4 regions of the 16S rRNA gene. A high diversity of bacteria was observed in the activated sludge, with more than 400 bacterial genera and 700 species. The predominant genus was Lactococcus (21.35%) mainly containing Lactococcus chungangensis species. Predicted functional analysis showed a high representation of genes involved in membrane transport (12.217%), amino acid metabolism (10.067%), and carbohydrate metabolism (9.597%). Genes responsible for starch and sucrose metabolism accounted for 0.57% of the total reads and the composition of starch hydrolytic enzymes including α-amylase, starch phosphorylase, glucoamylase, pullulanase, α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, and 1,4-α-glucan branching enzyme. The presence of these enzymes in the SBR system may improve the removal of starch pollutants in wastewater. [ABSTRACT FROM AUTHOR]

Enterobacter sp. strain FL was newly isolated from activated sludge and exhibited significant capability of auto-aggregation as well as aerobic denitrification. The removal efficiencies of NO3−-N, total nitrogen (TN), and TOC by strain FL in batch culture reached 94.6, 63.9, and 72.5% in 24 h, respectively. The production of N2O and N2 in the presence of oxygen demonstrated the occurrence of aerobic denitrification. The auto-aggregation index of strain FL reached 54.3%, suggesting a high tendency that the cells would agglomerate into aggregates. The production of extracellular polymeric substances (EPSs), which were mainly composed of proteins followed by polysaccharides, was considered to be related to the cell aggregation according to Fourier transform infrared (FT-IR) and confocal laser scanning microscopy (CLSM). The proteins in EPS were evenly and tightly combined to cells and altered the protein secondary structures of cell surface from random coils to β-sheets and three-turn helices. The alteration of protein secondary structures of cell surface caused by the proteins in EPS might play a dominant role in the auto-aggregation of strain FL. To further assess the feasibility of strain FL for synthetic wastewater treatment, a sequencing batch reactor (SBR), solely inoculated with strain FL, was conducted. During the 16 running cycles, the removal efficiency of NO3−-N was 90.2–99.7% and the auto-aggregation index was stabilized at 35.0–41.5%. The EPS promoted the biomass of strain FL to aggregate in the SBR. [ABSTRACT FROM AUTHOR]

Partial-denitrification (nitrate (NO 3 − -N) → nitrite (NO 2 − -N)) holds great potential in treating NO 3 − -N contained wastewater, by combining with anammox process. In this study, performance of NO 2 − -N production in partial-denitrification was investigated in two installations: sequencing batch reactor (SBR) and upflow sludge blanket (USB) reactor. Results indicated that partial-denitrification was established successfully in both of SBR and USB, with the NO 2 − -N production rate (NPR) of 0.13–2.11 kg N m −3 d −1 and 0.90–13.03 kg N m −3 d −1 , respectively. The NO 3 − -N to NO 2 − -N transformation ratio (NTR) was approximately 83.3% in SBR, while NTR of 51.0%–71.3% was obtained in USB. Sludge granulation was observed in both two reactors during the operation. In SBR, granular diameter of 1.5–2.0 mm was reached with sludge volume index (SVI) of 54.3 mL gSS −1 , and 2.0–3.0 mm in USB with SVI of 62.1 mL gSS −1 . Additionally, the ratio of COD to NO 2 − -N (COD/NO 2 − -N) and NO 3 − -N to NO X − -N percentage (NP) in partial-denitrification effluent demonstrated its suitability for subsequent anammox. While, partial-denitrification conducted in SBR was more suitable for low NO 3 − -N wastewater (30 mg L −1 ), and USB was appropriate for high-strength sewage. Results obtained in this study provide a solid foundation for future applying partial-denitrification combined with anammox process in treating NO 3 − -N contained wastewater. [ABSTRACT FROM AUTHOR]

Olive oil mill wastewaters (OMW) cause serious environmental pollution problems due to their high level of production and specific chemical characteristics. An innovative disposal treatment and simultaneous valorization technology consists of using OMW as a no-cost substrate for mixed microbial culture (MMC)-based polyhydroxyalkanoates (PHAs) production process. Here, an MMC multi-stage process was developed in which after acidogenic fermentation, OMW was subjected to a solid liquid separation step by centrifugation. The resulting solid fraction was converted into methane through anaerobic digestion in order to recover energy for the process, whereas the liquid fraction was used as feedstock for both the biomass selection and the PHA accumulation step. Most of OMW soluble chemical oxygen demand (COD) content in the liquid fraction (approximately 70%) was removed in a sequencing batch reactor (SBR) obtaining a high PHA production (about 532 mgCOD, in the feast phase). In particular, the strategy to uncouple COD feed from nitrogen supply within the SBR cycle, along with the operation of a settling phase before the famine phase, allowed to enhance the selective pressure towards PHA-storing microorganisms. Polymer production significantly increased in the accumulation reactor up to approximately 2470 mgCOD/L. Finally, anaerobic digestion tests on the OMW solid fraction showed a relevant COD conversion into methane (up to 100%). [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the new structure of SBR (placement of baffles in different way) and its ability to treat petroleum wastewater, compared to a conventional system, as well as investigate the effects of pollutant concentration on the granules' performance at ambient temperature (24 ± 1°C). Two SBR were tested. R1 had baffles including three risers and three down-comers, and R2 had one riser and one down-comer. After an adaptation period of about 59 d, granules with a mean diameter of 6 mm and 5 mm, medium density of 1.0132 and 0.87720 gr/ml, and settling velocity of 2.51 and 2.13 cm/s were observed in R1 and R2, respectively. Stepwise increasing the OLR in R1 and R2, affected size, density, settling velocity, and the granules' stability, by increasing them and gradually decreasing the COD removal efficiency. Maximum COD removal in R1 and R2 was achieved in OLR equal to 0.9 kg/m3d (95.4%-91.4%), and minimum COD removal was achieved in OLR equal to 2.4 kg/m3d (85.5-71.1%). Corresponding amounts for maximum removal of total petroleum hydrocarbon (TPH) were 94.2% and 90.8% (TPHin equal to 104.2 mg/l) and minimum amounts (TPHin equal to 157.9 mg/L) were equal to 82.1% and 70.4%, respectively. Appropriate placement of baffles in R1 caused faster formation of granules, improved their physical properties and increased removal efficiency compared to R2. By increasing in OLR and consequently, increasing in granule size and according to cell death, an anaerobic core generated in the center of the granules. Instability of anaerobic core as well as reduction of the granules' ability to tolerate oil and toxic pollutants, gradually decreased removal efficiency, integrity coefficient and increased SVI. [ABSTRACT FROM AUTHOR]

This research aims to comparatively study the efficiency of piggery wastewater treatment by the moving-bed sequencing batch reactor (moving-bed SBR) system with held medium, and the conventional sequencing batch reactor (SBR) system, by varying the organic load from 0.59 to 2.36 kgCOD/m3.d. The COD treatment efficiency of the SBR and moving-bed SBR was higher than 60% at an organic load of 0.59 kgCOD/m3.d and higher than 80% at the organic loads of 1.18-2.36 kgCOD/m3.d. The BOD removal efficiency was greater than 90% at high organic loads of 1.18-2.36 kgCOD/m3.d. The moving-bed SBR gave TKN removal efficiency of 86-93%, whereas the SBR system exhibited the removal efficiency of 75-87% at all organic loads. The amount of effluent suspended solids for SBR systems exceeded the piggery wastewater limit of 200 mg/L at the organic load of 2.36 kgCOD/m3.d while that for the moving-bed SBR system did not. When the organic load was increased, the moving-bed SBR system yielded better treatment efficiency than that of the SBR system. The wastewater treated by the moving-bed SBR system met the criteria of wastewater standard for pig farms at all organic loads, while that treated by the SBR system was not satisfactory at a high organic load of 2.36 kgCOD/m3.d.

The sequencing batch reactor (SBR) has been increasingly applied in the control of high organic wastewater. In this study, SBR with aerobic granular sludge was used for wastewater treatment in a noodle-manufacturing village in Vietnam. The results showed that after two months of operation, the chemical oxygen demand, total nitrogen and total phosphorous removal efficiency of aerobic granular SBR reached 92%, 83% and 75%, respectively. Bacterial diversity and bacterial community in wastewater treatment were examined using Illumina Miseq sequencing to amplify the V3-V4 regions of the 16S rRNA gene. A high diversity of bacteria was observed in the activated sludge, with more than 400 bacterial genera and 700 species. The predominant genus was Lactococcus (21.35%) mainly containing Lactococcus chungangensis species. Predicted functional analysis showed a high representation of genes involved in membrane transport (12.217%), amino acid metabolism (10.067%), and carbohydrate metabolism (9.597%). Genes responsible for starch and sucrose metabolism accounted for 0.57% of the total reads and the composition of starch hydrolytic enzymes including α-amylase, starch phosphorylase, glucoamylase, pullulanase, α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, and 1,4-α-glucan branching enzyme. The presence of these enzymes in the SBR system may improve the removal of starch pollutants in wastewater.

A mixture of Industrial wastewater from chemical industry (varnish, paint and pigments production) and municipal wastewater was treated in pilot sequencing batch reactor (SBR). Results of the pilot experiments show that the foaming problem has great influence on the behavior of SBR, especially when the ratio between industrial and municipal wastewater is very high. Foaming problem was negligible when the mixture with φ; 20 % of the industrial wastewater and j = 80 % of the municipal wastewater was treated.With the operational cycle of 6 h with anoxic (non-aerated) and aerobic (aerated) phase the required effluent quality was obtained according to regulations for treated wastewater that flows into the recipient. Operational cycle (aerobic phase) can be 60 min shorter at minimal organic and nitrogen loading.

El tratamiento de las aguas de producción de petróleo, Tía Juana Liviano (TJL) y Urdaneta Pesado (UP), proveniente del Patio de Tanque ULÉ, ubicado en la Costa Oriental del Lago de Maracaibo, se estudió bajo condiciones aerobias, utilizando reactores secuenciales por carga (SBR) de operación continua, construidos a escala de laboratorio, determinándose la eficiencia del sistema en la remoción de materia orgánica biodegradable, hidrocarburos y fenoles totales. El agua de producción fue caracterizada para conocer sus condiciones de entrada y salida además de verificar si la descarga cumplía con los límites permisibles para descargas, establecidos por la legislación venezolana. Los parámetros evaluados fueron pH, Alcalinidad, SST, SSV, OD, DQO, COT, nitrógeno, hidrocarburos y fenoles totales. En el Efluente Producto de la Extracción de Petróleo Liviano (EEPL) los porcentajes de remoción de la Demanda Química de Oxígeno (DQO), Fenoles e Hidrocarburos Totales, alcanzaron hasta un 96%; mientras que para el Efluente Producto de la Extracción de Petróleo Pesado (EEPP), la eficiencia en la remoción de DQO, fenoles e hidrocarburos totales fue aproximadamente de un 72%.Tía Juana Liviano (TJL), Urdaneta Pesado (UP) oil wastewaters from the Tank-Yard Ulé in the west cost of Lago de Maracaibo of Petroleum Venezuelan industry, were treated in aerobics conditions by Sequencing Batch Reactors (SBR) to determinate the organic matter (hydrocarbons and phenols) removal efficiency. The evaluated parameters in this study were pH, Alkalinity, TSS, DO, COD, TOC, Total Nitrogen, THC and total Phenols. The COD, totals phenols and totals hydrocarbons removal observed in Light Petroleum Extraction effluent (EEPL) and the Heavy Petroleum Extraction effluent (EEPP) were maximum 96% and 72%, respectively.

The effects of mixed liquor suspended solids (MLSS), hydraulic retention time (HRT) and anoxic:oxic ratio on the sequencing batch reactor (SBR) system efficiency with synthetic textile industrial wastewater (STIW) containing direct dyes were investigated. The results showed that the system had the highest removal efficiency at MLSS of up to 2,500 mg/L. Moreover, its efficiency was increased with the increase of HRT or decrease of organic loading rate. To increase the nitrogenous compounds removal efficiencies, the reaction step of SBR operation should be modified by adding the anoxic period. The optimal operation conditions of the SBR system for highest nitrogen and textile dye removal efficiencies were MLSS of 2,500 mg/L, HRT of 7.5 d (organic loading rate of 0.11 kg BOD5/m3-d) and anoxic:oxic ratio of 15:4. The system showed the highest direct red 23 and direct blue 15 removal efficiencies of 90.61% ± 2.14% and 83.82% ± 2.60%, respectively, resulting from the activity of denitrifying bacteria. [ABSTRACT FROM AUTHOR]

The treatment of wastewater from a cellulosic ethanol biorefinery presents special challenges. A pilot-scale process that utilized a continuous stirred tank reactor (CSTR), an internal circulation reactor (IC), and a sequencing batch reactor (SBR) with ozone oxidation enhancement was developed for the treatment of this challenging biorefinery wastewater. The CSTR and IC were used for COD removal through anaerobic treatment, and the SBR process was used for nitrogen removal through alternating aerobic nitrification and anaerobic denitrification. The combined process removed 85% of chemical oxygen demand (COD) and 80% of ammonium. The corresponding effluent concentrations of COD and ammonium were 1591 ± 226 mg/L and 61 ± 8 mg/L, respectively. Ozonation enhanced the biodegradability of the anaerobic effluent, the BOD 5 /COD ratio of which increased from 0.15 ± 0.02 to 0.33 ± 0.05. The BOD 5 /COD ratio of the effluent from the SBR was 0.07 ± 0.01, which indicated the effluent was no longer treatable using a biological process. A total sulfate removal efficiency of 65% was obtained through an alternating anaerobic and aerobic process, and the final effluent sulfate concentration was 217 ± 10 mg/L. [ABSTRACT FROM AUTHOR]

This study investigated the influence of different factors in maximizing poly-β-hydroxybutyrate (PHB) accumulation in low-carbon urban sewage. The effects of chemical oxygen demand and total phosphorus (TP) concentrations on PHB accumulation were analyzed using an anaerobic/oxygen sequencing batch reactor. Both the anaerobic phase and the aeration phase were studied. The results showed that maximum PHB accumulations increased as the carbon source increased, growing from 5.45 to 27.51 mg/g, when the carbon source concentration increased from 140 to 400 mg/L, at the end of anaerobic phase. Maximum PHB accumulation decreased from 15.89 to 13.88 mg/g when exposed to influent carbon–phosphorus C/P, suggesting that carbon source is more influential and beneficial for PHB accumulation than TP. With an increase in pre-aeration time from 10 to 50 min, PHB accumulation rose from 21.12 to 31.96 mg/g; this is higher than 15.54 mg/g PHB accumulation without pre-aeration. When the pre-aeration time was fixed at 15 min, but with different pre-aeration fluxes ranging from 20 to 50 L/h, PHB accumulation increased from 23.79 to 30.09 mg/g. These results demonstrate that pre-aeration treatment facilitates PHB accumulation. [ABSTRACT FROM AUTHOR]

Application of sequencing batch reactor (SBR) system for treatment of synthetic industrial estate wastewater (SIWW) containing high Cr3+and Ni2+concentrations of 3.0 mg/L (SIWW + Cr3+and SIWW + Ni2+) at hydraulic retention time (HRT) of 1.5 d at various oxic:anoxic ratios of 19:0, 13:6, 11:8, and 9:10 in the reaction step of operation was examined. The highest Ni2+and Cr3+removal efficiencies of 93.1 ± 0.9% and 95.4 ± 0.2%, respectively, were detected with SIWW + Cr3+and SIWW + Ni2+at the oxic:anoxic ratio of 9:10. Moreover, the maximum Cr3+and Ni2+adsorption abilities of bio-sludge in the system were 36.00 ± 9.80 and 31.59 ± 9.67 mg/g of bio-sludge at the 19:0 oxic:anoxic ratio. Heavy metals (HM) adsorption abilities could be increased by adding anoxic period in the reaction step. The average Cr3+and Ni2+adsorption abilities of bio-sludge at oxic:anoxic ratio of 9:10 were 20.8 ± 4.1 mg Ni2+/g bio-sludge and 23.12 ± 6.0 mg Cr3+/g bio-sludge. Cr3+and Ni2+concentrations of 3.0 mg/L had a strong repression effect on the growth and activity of the carbonaceous BOD5removal microbes (heterotrophic bacteria). However, they slightly affected nitrifying and denitrifying bacteria. Nitrifying and denitrifying bacteria were the main microbes for HM adsorption mechanism in the SBR system. The advantage of SBR system was that after adding anoxic period in the reaction step, removal efficiencies of organic matter and HM increased. [ABSTRACT FROM PUBLISHER]

The effect of silver nanoparticles on the system performance and the bacterial community dynamics in a sequencing batch reactor was investigated, along with the removal and the fate of silver nanoparticles within the system. Results showed that silver nanoparticles did not significantly affect organic matters removal, nitrification and denitrification. However, adverse effects were observed on sludge settleabilities, which were related to the over-production of extracellular polymeric substances and a sequential change in activated sludge structure and morphology. Polymerase chain reaction–Denaturing gradient gel electrophoresis revealed that silver nanoparticles caused significant shifts in bacterial community structures. Different species were affected and eliminated at each dosage of silver nanoparticles. Silver nanoparticles were effectively removed in the bioreactor, with the main removal pathway being deposited in the activated sludge. [ABSTRACT FROM AUTHOR]

The process for non-axenic polyhydroxyalkanoate (PHA) production from organic waste generally comprises three steps: acidogenic fermentation of the waste stream, enrichment of a PHA-producing culture, and production of the PHA. This study assesses the feasibility of combining the enrichment and production step. Harvesting PHA-rich biomass directly from the sequencing batch reactor (SBR) used for enrichment of the microbial culture reduces capital cost, but may increase downstream-processing cost if the PHA content is significantly lowered. Operating an acetate-fed SBR at a volume exchange ratio of 0.75 (18 h cycles, 1 d SRT) allowed the production of biomass with 70 wt% poly(3-hydroxybutyrate) (PHB) in a single-step process. By increasing the exchange ratio to 0.83 (20 h cycles) the PHB content of the harvested biomass increased to 75 wt%, but the operational stability decreased. SBR operation at these high exchange ratios makes that bacteria have to increase their growth rate and external substrate is available for relatively long periods. This allows the establishment of larger flanking populations and negatively affected the kinetic properties of Plasticicumulans acidivorans , the predominant organism. Maximizing the volume exchange ratio is, therefore, a suitable strategy to produce large amounts of PHA in the SBR, but does not ensure the enrichment of a culture with superior PHA productivity. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to provide an cost-effective methodology for assessing wastewater treatment technology. This methodology may be useful in the planning of treatment facilities in rural regions. The existing cost models focus mainly on municipal wastewater treatment plants, which mostly consider the influence of the capacity of plant ordinarily expressed as inhabitants or flow rate. In this paper, we propose a new model of cost function in rural regions that includes both the capacity of plant and the removal rate of pollutants. The water quality indicator chemical oxygen demand and NH3-N are chosen to be factors for a rural wastewater treatment model. The cost model enables us to understand the influence of pollutants’ removal rate and to compare various treatment technologies from an economic point of view. The statistical information comes from a sample of 221 wastewater treatment plants in rural regions located in Changshu, Jiangsu province of China adopting four treatment technologies such as membrane bioreactor technology, sequencing batch reactor, purification tank, biological filter and artificial wetland. [ABSTRACT FROM PUBLISHER]

The aeration rate as an intrinsic factor influencing shortcut nitrification process while treating ammonium-rich anaerobic-digested piggery wastewater (ADPW) in a sequencing batch reactor (SBR) was investigated. Diluted ADPW with nitrogen loading rate (NLR) of 0.56 ± 0.12 kg/(m3 d) was fed to start up the SBR at 0.1 L/min aeration rate. After 24 d of operation, the shortcut nitrification process was established, 71.1% ammonium was removed and a nitrite accumulation rate (NAR) of 96.8% was obtained. Ammonium removal decreased remarkably to 48.6% as raw undiluted ADPW with an NLR of 2.55 kg/(m3 d) was fed to the system. Intriguingly, aeration rate was raised to 0.4 L/min in the latter feed and an enhanced ammonium removal of 68.9% was observed while NAR decreased to 94.4%. [ABSTRACT FROM PUBLISHER]

The ability of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to carry out nitrification in an environment with high ammonia levels was evaluated with the aim to suggest a suitable strategy for a quick start-up of nitrifying reactors treating reject water. It was proved that nitrification could be initiated even without any inoculation of nitrifying biomass. The nitritation was achieved faster (23 d after beginning of reactor operation) than nitratation (after 180 d) due to the presence of AOB and the absence of NOB in raw reject water. Free ammonia (FA) concentration reaching up to 160 mg N L−1strongly inhibited nitrifying bacteria during the initial phase of reactor operation. Consequently, free nitrous acid (FNA) with a concentration up to 1.25 mg N L−1supported NOB inhibition after the initiation of AOB activity. High AOB, as well as NOB, activity was observed even during the first day of the operation in a completely stirred tank reactor (CSTR, nitrogen loading rate—NLR 0.5 kg N (m3 d)−1, nitrogen oxidation rate—NOR 0.25 ± 0.05 kg N (m3 d)−1) as well as a sequencing batch reactor (SBR, NLR 0.3 kg N (m3 d)−1, NOR 0.14 ± 0.01 kg N (m3 d)−1) inoculated with common activated sludge at a zero initial total ammonium nitrogen concentration. It was proved that temporary inhibition of NOB activity induced by FA concentration elevated to 88 mg N L−1may lead to the permanent transformation of standard nitrification into shortcut nitrification in SBRs, thanks to periodical exposition of NOB to high FA and FNA concentration during SBR cycle. Thus, it was demonstrated that the possibility to initiate this process very quickly is essential as a first stage for subsequent anaerobic oxidations of ammonium or shortcut denitrification. [ABSTRACT FROM AUTHOR]

The process of anaerobic ammonium oxidation (Anammox) requires a proper ratio of NH 4 + -N and NO 2 − -N in the influent, which is difficult to control upon treating domestic wastewater. In this study, a control strategy of semi-nitritation (SN) process based on monitoring the pH profile and NH 4 + -N concentration in a sequencing batch reactor (SBR) was developed. The aeration time of each cycle in SN-SBR was calculated using the established equation t S N = t C O D + 0.56 α n S 0 / ( S 0 − S n ) . To verify the suitability of the control strategy, SN-SBR was operated continuously for 20 cycles, fed with real domestic wastewater with a fluctuating COD of 200–400 mg L −1 and NH 4 + -N of 65–80 mg L −1 . The nitrogen removal performance of SN-anammox system using the developed control strategy was also monitored. Results showed that SN-SBR was able to generate a suitable ratio of NH 4 + -N to NO 2 − -N for the following anammox process, the TN removal rate of the SN-anammox system achieved 91.7 ± 0.4% and the average ammonium, nitrite and nitrate concentration of effluent was only 0.50 ± 0.24, 0.13 ± 0.09 and 4.9 ± 0.22 mg L −1 , respectively. This study has potential application in the treatment of domestic wastewater using combined SN-anammox process. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia e Ingenieria Neogranadina is the property of Ciencia e Ingenieria Neogranadina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of two sequencing batch reactor operation strategies for phosphorus stream enrichment over the biological phosphorus removal performance have been studied. The objective of both strategies is of performing an extraction cycle in order to obtain a new stream highly enriched with phosphorus. In the 1st strategy the amount of influent volatile fatty acids (VFAs) is the same in each cycle; while in the 2nd strategy the influent VFAs concentration is increased during phosphorus extraction experiments. Despite the strong decrease of the stored poly-P inside the cells in both strategies after the recovery cycles, the ability of the systems to remove phosphorus was not affected. The P release /HAc uptake ratio (changing from 0.73 to 0.21 mmol P mmol C −1 ) together with FISH analyses (around 85% of Accumulibacter through the experimental period) confirmed that a shift from PAM to GAM occurred after phosphorus enrichment in the 2nd strategy experiments. These results suggest that energy required for VFA uptake by polyphosphate-accumulating organisms (PAOs) was not only derived from polyphosphates degradation, but also from glycogen degradation. FISH also revealed that Type II Accumulibacter species are responsible of the metabolic shift. The strategy based on increasing influent VFAs concentration during phosphorus extraction experiments showed a higher extraction efficiency (from 46% to 76%), as higher phosphorus concentration within supernatant can be achieved (from 113.9 to 198.7 mg P l −1 ). Following this strategy, it is possible to concentrate up to 81% of the incoming phosphorus in a single enriched stream. This suggests that, despite the extra addition of carbon source needed (9%), this strategy is more appropriate if phosphorus recovery for reuse purposes is required. [ABSTRACT FROM AUTHOR]

Short initial settling time and rapidly increased ammonium nitrogen loading were employed to cultivate nitrifying granular sludge treating inorganic wastewater with 1000 mg/L ammonium nitrogen. It was found that the nitrifying granule-dominant sludge was formed in a sequencing batch reactor (SBR) with influent ammonium concentration increased from 200 to 1000 mg N/L within 55 days. During the following 155-day operation period, nitrifying granules exhibited good performance with an ammonium removal efficiency of 99 %. In the meantime, sludge volume index (SVI) decreased from 92 to 15 mL/g and the mean size of the nitrifying granules increased from 106 to 369 μm. Mixed liquor suspended solids (MLSS) decreased from the initial 6.4 to around 3 g/L during the granulation period and increased to over 10 g/L at the end of the operation. The long-term stability of nitrifying granules and the reactor performance were not negatively affected by inhibition from free ammonia (FA) and free nitrous acid (FNA) in this study. This makes the granule sludge technology promising in treating high-strength ammonium wastewater in practice. [ABSTRACT FROM AUTHOR]

This study investigated the influence of temperature (20 and 30 °C) on the formation and stability of aerobic granules in sequential batch reactors (SBR). Therefore, two lab-scale SBRs operated at 20 and 30 °C (SBR 20 and SBR 30) were used. The reactors were fed with municipal wastewater (COD t :TN:TP 100:15:1.7), leading to mean organic loading rates (OLR) of 1.3 ± 0.4 kgCOD t m−3 day−1. Both reactors had the same height/diameter ratio of 4.2 and were inoculated with activated sludge from a municipal wastewater treatment plant. The operational conditions were also the same for both temperatures and lasted in stable process parameters for over 100 days. By optimizing the aeration and oxygen concentration, a high removal efficiency of NH 4 –N (∼99%) and COD (∼90%) was achieved in both reactors, despite the poor C:N:P ratio at the influent. Furthermore, a relatively low oxygen concentration of 2 mg L−1 was defined as the set point for the control strategy. Nevertheless, granulation at 30 °C was significantly faster, resulting in more stable sludge volume index (SVI) values (SVI 10 /SVI 30 < 1.1). The granules formed at 30 °C were also larger, more compact, and considerably more stable against system disturbances. However, at higher temperatures, larger granules might be required for nitrate removal because of the increased oxygen diffusion rates. Finally, microbiological 16S rRNA gene amplicon analysis for both systems indicated major differences relatively to the inoculum sludge only for nitrogen-degrading organisms. [Display omitted] • Temperature significantly influences the structure of the granules. • Long-term performance similar for operation at 20 and 30 °C. • Stable operation for over 100 days for both temperatures. • Optimization of TN removal by low O 2 levels (2 g.L−1) and feeding with air pulses. • Inoculum microbiome adaptation identified for N-degrading organisms. [ABSTRACT FROM AUTHOR]

The rapidly increasing use of engineered nanoparticles (NPs) in consumer products inevitably leads to their greater presence in wastewater treatment plants. In this study, the effects of zinc oxide nanoparticles (ZnO-NPs) on system performance and bacterial community dynamics of biological wastewater treatment in a lab-scale sequencing batch reactor were evaluated, along with their fate within the system. It was found that ZnO-NPs caused poor settleability of the activated sludge and a significant decrease in the removal of nitrogen and phosphorus over time. Denaturing gradient gel electrophoresis analysis revealed that the bacterial community in the activated sludge became less diverse after exposure to ZnO-NPs. In addition, the production of extracellular polymeric substances (EPS) increased, with the EPS forming a tight matrix to protect the cells from the NPs. The NPs were removed very effectively from wastewater, mainly via sorption to the sludge. [ABSTRACT FROM AUTHOR]