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Wastewater and landfill leachate treatment processes have the potential to generate nitrous oxide (N 2 O) and methane (CH 4), both significant greenhouse gases (GHG). However, little is known about these emissions when a combined treatment approach (wastewater with leachate) is utilized. This study aimed to assess the emissions of these gases and nutrient removal in an anaerobic/aerobic/anoxic sequencing batch reactor (SBR) employed for treating wastewater with landfill leachate (1% v/v). Leachate contributes significantly to the removal of organic matter and nutrients, primarily phosphorus. The production and emission of N 2 O occurred during the aerobic phase, whereas CH 4 was produced in the anaerobic and anoxic phases. This gas was emitted at the beginning of the aerobic phase and in the end of anoxic phase. The emission factors obtained in this work were 0.0108 and 0.0119 kg N 2 O-N per kg TN influent and 0.000225 and 0.000253 kg CH 4 -C per kg COD influent with and without landfill leachate, respectively. Regarding CO 2 -equivalent, the N 2 O was the major contributor, accounting for 99% of the emitted GHG by the process. Further studies are required; however, the main findings of this study suggest that this system may be appropriate when lower GHG emissions are required. [Display omitted] • The performance of anaerobic/aerobic/anoxic SBR was not impacted by adding of 1% leachate into wastewater. • The introduction of leachate increased significantly the N 2 O production and emissions. • CH 4 production and emission were similar in two experiments (processes with and without leachate). • N 2 O was the major contributor to CO 2 -equivalent emissions (90%) in two experiments. • Emission factors from these two systems were lower than those cited by the IPCC protocols. [ABSTRACT FROM AUTHOR]

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]

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]

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To develop a shortcut nitrification process for treating anaerobic digested piggery wastewater with a high ammonia concentration, a sequencing batch reactor (SBR) was introduced, and the temperature, ammonia nitrogen loading rate (Rnl) and aeration time were investigated as the significant influence factors of the shortcut nitrification. The shortcut nitrification process could be established in the SBR at 28 °C or 15 °C with the identical dissolved oxygen (DO), ranged from 1 to 2 mg ⋅ L-1. But the ammonia removal and nitrite accumulation rate Rna were decreased from 71. 1% and 96.7% to 52.8% and 85.4%, respectively, when the temperature was dropped from 28 °C to 15 °C. Though the ammonia removal rate was decreased to 48. 6% since the Rnl had been increased from 0. 56 to 2.18 kg ⋅ m-3 ⋅ d-1 at 28 °C, a Rna as high as 96. 8% was obtained, indicating that an excellent shortcut nitrification occurred in the SBR. To obtain a superior ammonia oxidation with a higher Rnl, extension of aeration time would be supportive. But an excessive aeration could result in an increase in nitrate and a decrease in Rna, which was unfeasible for the shortcut nitrification process in the SBR. [ABSTRACT FROM AUTHOR]

To improve the nitrification efficiency of activated sludge in a low temperature ( 15°C) sequencing batch reactor ( SBR), the performance and characteristics in nitrification of the activated sludge were investigated by batch culture with regulation of initial pH. The results indicated that the ammonia oxidation efficiency of the activated sludge was the best with initial pH ranged from 8.0 to 9.0. In the NO2--N accumulating process, the specific ammonia nitrogen (NH4+ - N) removal rate and specific nitrite nitrogen (NO2--N) producing rate were 25.49 g ⋅ kg-1 ⋅ d1 and 22 g ⋅ kg-1 ⋅ d-1 (as MLSS), respectively. For nitrite oxidation, the favorable initial pH ranged from 7.5 to 8.0, under which a specific nitrate nitrogen (NO3--N) producing rate of 35.6 g ⋅ kg-1 ⋅ d-1 (as MLSS) was obtained. It showed that the satisfactory ammonia oxidation and nitrite oxidation efficiency would be obtained by the enhancement of metabolic activity both of the nitrite and nitrate bacteria when the pH of wastewater was kept at about 8. 0 in the nitrification process. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of fast granulation by manipulating organic loading rate and hydraulic selection pressure. With high organic loading rate and strong hydraulic selection pressure, such as organic loading rate (OLR) of 24 kg m-3 d-1, cycle time of 30 mm, and fixed settling time of 1 mm, aerobic granules could be observed obviously, even with naked eyes within 7 h. However, the rapidly formed aerobic granules disintegrated after 2-day operation. In the meantime, aerobic granules formed within 24 h under operational conditions of OLR of 6 or 12kg m-3 d-1, cycle time of! h, fixed settling time of 2 mm, stability was successfully maintained and reactor reached the steady state within 12 days. The mixed liquor volatile suspended solids (MLVSS) of aerobic granules reached 6.3 g L1 at the steady state. This is the shortest time for formation of aerobic granules and achievement of steadily operated aerobic granule reactor in the published literature. Granules formed in this study did not show notable differences in terms of morphology and oilier main physical characteristics compared with those reported in other researches. The results indicate that in the case of fast granulation under extreme selection pressures, strong hydrodynamic selection pressure plays a key role in the initial stage for granulation while high OLR is important for the subsequent fast biomass accumulation, once granules are formed. [ABSTRACT FROM AUTHOR]

Aerobic granules were cultivated in a sequencing batch reactor (SBR) fed with sucrose as a sole carbon source at superficial upflow air velocity of 1.9 cm/s and under an organic loading rate (OLR) of 2 g COD/L.d. This study shows that cultivated granules during 1 year were stable and had capability in simultaneous removal of carbon, nitrogen and phosphorus from wastewater. At a 6 h SBR cycle removal efficiency of chemical oxygen demand (COD), N-NH4+, P-PO43- were 93%, 66% and 83%, respectively. The value of sludge volume index (SVI) was between 90-110 mL/g and biomass concentration reached up to 8.0 g/L. With the granulation, the specific gravity and surface hydrophobicity of sludge increased and aerobic granules mean diameter was 4.9 mm. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the feasibility of several different cyclic anaerobic/aerobic (An/A) conditions in sequencing batch reactor (SBR) system for treating of simulated dye (reactive blue19) wastewater. To achieve this goal, five identical SBR (SBR 1 to SBR 5) were used. The SBR1 was fully aerobic whole reaction time whereas the reaction time was divided into 1, 2, 3 and 4 An/A cycles in SBR2, SBR3, SBR4 and SBR5, respectively. Initial COD and dye concentrations were selected to be 1500 and 100 mg/L for all reactors. During the last 15 days of operation, the dye removal efficiency approximately reached stable level of 50, 64.5, 74.8, 77 and 70.2 % in SBR1, SBR2, SBR3, SBR4 and SBR5, respectively. According to the obtained results, the COD removal efficiencies were in the range of 94-96 percent in all SBRs and no significant influence on COD removal was observed with altering operation conditions in SBRs. Average effluent TSS of reactors decreased by increasing number of An/A cycles. Average effluent turbidity of reactors increased with altering operation type from fully aerobic in SBR1 to An/A in SBR2-SBR5 as well. On the other hand, average MLSS in all reactors were in the range of 2760-2990 mg/L and did not experience significant change during the operation time. [ABSTRACT FROM AUTHOR]

In this study, the treatability of raw and anaerobically pre-treated domestic sewage in sequencing batch reactor systems was compared. In this context, two sequencing batch reactors, the first one (SBR1) fed with raw domestic sewage and the second one (SBR2) fed with anaerobically pre-treated domestic sewage, were operated at six cycles per day operation. The feeding was introduced into the reactor by pumping for 30 mm (the last 15 mm with mixing), mixed and aerated for 180 mm, followed by 20 mm of settling. The effluent COD concentrations of SBRs were 50-70 mgL-1. The effluent orthophosphate concentrations of SBR 1 and SBR 2 were 4-1.5 mgL-1 and 5.5-3 mgL-1, respectively. Experimental results showed that in both SBR1 and SBR 2 the removal efficiency of NH4-N was about 100%, and nitrification rates in SBRI and SBR2 were 12.2 mg g-1 VSS h-1 and 21.8 mg g-1 VSS h-1, respectively. Activated sludge samples for microscopic and microbiological examinations have been collected from both reactors. The SBR1 activated sludge system showed better and richer microbial diversity structure, and the filamentous bacteria abundances have frequently reached high values in the SBR2 system. On the other hand, because of macrostructure failure and loose floc structure, the effluent quality and treatment efficiency of the SBR2 system was not so good as in SBR1 system. [ABSTRACT FROM AUTHOR]

The decolorization capacity of three single-grown white rot fungi, Phanerochaete chrysosporium, Trametes versicolor and Pleurotus sajur-caju, for an original textile wastewater was investigated. In experimental studies, to a sequencing batch reactor (SBR) fungal biomass was added during the beginning of reaction phase, and it was operated to obtain advanced activated sludge. At the end of the 1.5-h of reaction and 1.5-h of settling phases, increasing of decolorization efficiencies 67-77% at 436 nm, 64- 79% at 525 nm, and 69-76% at 620 nm from 0 (zero) to 1600 mm residence time were observed for P. chrysosporium, where-as those of T versicolor were 71-84% at 436 nm, 72-85% at 525 nm and 70-80% at 620 nm, and for P. sajur-caju 74-80% at 436 nm, 75-81% at 525 nm and 72-78% at 620 nm, under the same residence times. Major decolorization rates (at 525 nm), 75 and 85%, were obtained by T. versicolor at 30 mm and 1600 mm, respectively. The average decolorization efficiency was approx. 80%. Results suggested. that advanced activated sludge exhibited a capacity to decolorize the original effluent of dying textile wastewater within 3 hour additionally 30 mm. Therefore, the optimum operation time for the advanced activated sludge system can be chosen to be 4 hours. [ABSTRACT FROM AUTHOR]

The effect of sludge retention time on biological nutrient removal in a sequencing batch reactor was investigated in this study. The effect of three different sludge ages (10, 15 and 25 d) on phosphorus release and uptake as well as on nitrification and denitrification was tested in a lab scale sequencing batch reactor having a simultaneous fill and draw system operating according to anaerobic-anoxic-aerobic principles. It was found that the system possessed better P removal (98 %) with shorter SRT (10 d). The phosphorus concentration in the effluent changed between 0 and 1.0 mg/l at this sludge age. When SRT was increased to 25 d, in contrast to decrease in effluent ammonium concentration (3 mg/l), P concentration increased in the effluent (5 mg/l). The system showed a very stable chemical oxygen demand removal efficiency during the entire operational period. [ABSTRACT FROM AUTHOR]

Experimental and theoretical studies of treatment of industrial wastewaters by a Sequencing Batch Reactor (SBR) have been examined. The chosen pharmaceutical and textile industries have been established in Adapazari, Turkey. In the wastewater treatment plants, the experimental parameters are measured. The theoretical study for kinetics of SBR was chosen from literature survey and compared with the experimental results for both industrial wastewater treatment plants. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the influence of operational factors (i.e. substrate concentration, activated sludge concentration and acclimation concentration) and the microbial communities of activated sludge on the aerobic biodegradation of phenol and p -nitrophenol (PNP). During the biodegradation process, the phenol or PNP biodegradation and activated sludge growth kinetics were determined and the interaction effects of the operational factors on the kinetics were assessed. The phenol biodegradation kinetics was well described by zero-order model (R2 > 0.813). At low phenol concentration (< 200 mg/L), the biodegradation rate can be enhanced by increasing activated sludge concentration and acclimation concentration. From the specific oxygen uptake rate (SOUR) analysis, lower SOUR values for PNP relative to phenol suggests higher toxicity of PNP, with inhibition detected above 50 mg/L for both phenol and PNP. In view of the inadequacy of zero-order equation for PNP biodegradation, the kinetic data was fitted into Haldane equation that incorporate the inhibitory effect. From the results, the value of critical PNP concentration was observed to increase at higher acclimation concentration, indicating the attenuation of inhibitory effects on PNP-acclimated activated sludge. For microbial growth, only the factor of acclimation concentration greatly affected the growth kinetics, in which the K s /K i ratio was greatly reduced when the acclimation concentration was doubled. Lastly, potential degrading strains of Acinetobacter sp. USM, Rhodococcus sp. USM1 and Caballeronia sp. USM2, were successfully isolated from the acclimated activated sludge. From the results of dioxygenase genes amplification, the phenol degradation mechanism was identified following ortho fission pathway. [Display omitted] • Biodegradation of toxic p-nitrophenol (PNP) was well described by Haldane substrate utilization model. • Interaction effects of operating parameters on biodegradation kinetics of phenol and PNP were studied. • Acclimation concentration affected the growth of acclimated activated sludge. • Phenol degradation by Acinetobacter sp. USM and Rhodococcus sp. USM1. was identified following ortho fission pathway. • Caballeronia sp. USM2 was recognized as the outstanding PNP-degrading bacteria with potential application for future use. [ABSTRACT FROM AUTHOR]

• SBR integrated with CEPS and acidogenic fermentation for enhanced nutrient removal. • Organics in wastewater were reserved and utilized for biological denitrification. • Acidogenic fermentation greatly improved the biodegradability of CEPS sludge. • Self-sufficient carbon supply in side-stream was achieved for nitrogen removal. To treat municipal wastewater with a low carbon to nitrogen ratio, the addition of an external carbon source is often needed to achieve enhanced nutrient (nitrogen and phosphorus) removal. To meet this need, this research developed an innovative strategy for reserving and utilizing organic pollutants to achieve a self-sufficient organic carbon supply for wastewater treatment. In the new system, before biological treatment by a sequencing batch reactor (SBR), Fe-based chemically enhanced primary sedimentation (CEPS) was used to reserve part of the organics from the wastewater in the CEPS sludge. By acidogenic fermentation in the side-stream, the settled organics in the CEPS sludge were converted into volatile fatty acids and other soluble organics to provide a suitable carbon source for denitrification in the anoxic phase of the SBR. The experimental results showed that the new SBR system integrated with CEPS and acidogenic sludge fermentation removed up to 89% of the total phosphorus (TP) and 83% of the total nitrogen (TN) from the wastewater. Compared with the conventional SBR system, TP and TN removal was increased by more than 65% and 50%, respectively. As well as increasing nutrient removal efficiency without the need for external carbon addition, the Fe-based CEPS greatly reduced the organic load on the SBR biological treatment process, reducing the aeration cost. Overall, a cost-effective wastewater treatment process is developed that can be used to upgrade existing wastewater treatment plants to improve the nutrient removal performance and meet more stringent discharge standards. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In the context of xenobiotics' removal in biological wastewater treatment processes, this study investigated the biodegradation of phenol and paracetamol as sole carbon sources by open mixed cultures. Biodegradation of these chemicals was investigated in batch and SBR (Sequencing Batch Reactor) lab-scale experiments. In batch experiments, phenol was biodegraded by unacclimated microorganisms at concentrations 0.2-0.5 g/l. The acclimation time increased with increasing phenol concentration and no biodegradation was observed with an initial concentration of 1 g/l. However, 1 g/l of phenol was biodegraded after previous exposure of the microorganisms to lower concentrations of phenol or to yeast extract and peptone. Batch degradation of paracetamol (0.5 g/l) only occurred after previous exposure of the microorganisms to yeast extract and peptone. SBR experiments were run with 1.0 g/L feed concentration of phenol or paracetamol in a range of SRT (solids residence time, 1–45 d for phenol and 1–145 d for paracetamol). Both substrates were removed as sole carbon sources and COD removal generally increased as the SRT increased, and was higher than 90% for phenol and 80% for paracetamol. A higher fraction of the removed substrate was assimilated into microorganisms for paracetamol than for phenol with growth yields 0.51 and 0.20 g/g COD, respectively. This study shows how process conditions (acclimation, substrate concentration, medium composition, SRT) affect the removal of phenol and paracetamol and gives guidance on their selection for the optimum biodegradation performance. [ABSTRACT FROM AUTHOR]