Aeration Reactor Research Articles

Oil Bioremediation in a Tropical Contaminated Soil Using a Reactor.

This research was implemented in the Colombian Amazon forest area; to assess the effect of Tween-80® surfactant in the degradation of the Total Petroleum Hydrocarbons (TPH) in bioremediation treatments under aerobic conditions in the laboratory and pilot-scale. One control treatment, Natural Attenuation (AT) and four biostimulation treatments with leonardite with four different dosages of Tween-80® were proposed. The efficacy of organic stimulators and nonionic surfactant in soil microbiota was studied at laboratory and pilot scales, the latter in a passive aeration reactor. The test that presented a better performance was carried out with a Convective Flow Reactor (CFR) at pilot-scale. The results showed that bioremediation strategies improved the natural degradation process; the best outcomes were obtained in a treatment that includes Leonardite and Tween-80® (1.5 g/L) with 52% TPH degradation in 80 days (d).Tween-80® produced an effect in TPH solubility, and increased the production of CO2 in distinctive bioremediation treatments in both periods. The kinetics of CO2 production showed that the system required a periodic addition of a co-substrate as well as an increase of soil microbiota through the addition of compost (pilot scale). In this stage more than 76% of contaminant was degraded in 60d.

Model of Aeration Tank for Activated Sludge Process

Background and Objective: A model for the activated sludge aeration reactor is developed to study the effect of operating conditions on biodegradable organic pollutants treatment. Methods: The model was developed and fitted using an experimental study conducted for wastewater collected from meat processing industrial units in Egypt. Inlet biomass and substrate concentrations are the operating parameters considered in our study. Results: After treatment; biomass outlet concentration was reduced substantially. After reaching steady-state operation, outlet biomass concentration was not affected by the inlet biomass concentration, while outlet substrate concentration showed great dependency on the inlet substrate concentration. The model agrees well with the experimental data collected from an industrial activated sludge treatment unit. Conclusion: By varying process parameters, the model can be used effectively to predict and optimize the system behavior under different operating conditions. Varying the substrate concentration may lead to optimizing the process conditions for the system under study.

Optimization of operations for nitrous oxide production and mitigation in aerobic and Aerobic-Anaerobic landfill method on MSW degradation

N2O is a potent greenhouse gas, induced by aeration coupled with leachate recirculation in Municipal Solid Waste (MSW) landfills. In this study, N2O emission was measured in the aerobic and Aerobic-Anaerobic Landfill Method (AALM) with or without leachate recirculation at two aeration rates in synthetic MSW. The experiment was carried out for six Plexiglass® landfill simulation reactors. Low aeration (1.6 l/kg-DM/h) was supplied in RLA, RLAA (Recirculatory) and LAA (non-recirculatory) reactors, while an aeration rate three times higher (4.8 l/kg-DM/h) was performed for RHA, RHAA, and HAA reactors. Based on the supplied leachate quantity, leachate recirculation was performed in five different phases. The results showed that a significant amount of N2O was produced in all reactors. The largest N2O emission of 0.11 and 0.13 g/kg-DM were observed in the RHA and RHAA reactors, respectively. Higher N2O and cumulative GHG was produced in high aeration reactors compared to the low aeration reactors. Recirculated leachate promoted waste stabilization, as reflected in the diminishing CH4 production and other leachate pollutant parameters, especially NH4+-N. It has been evaluated that in the operative or newly placed waste landfill, in-situ aeration with leachate recirculation exhibits the significant N2O production. However, lower amount of leachate in the later stage beneficial to inhibit the N2O production. It is recommended that in-situ aeration will become more effective after the recovery of CH4 from newly placed waste in an operative landfill for net GHG reduction, especially N2O reduction and early stabilization of landfills.

Influence of aeration rate and reactor shape on the composting of poultry manure and sawdust

ABSTRACTTo achieve successful composting, all the biological, chemical, and physical characteristics need to be considered. The investigation of our study was based on various physicochemical properties, i.e., temperature, ammonia concentration, carbon dioxide concentration, pH, electrical conductivity (EC), carbon/nitrogen (C/N) ratio, organic matter (OM) content, moisture content, bacterial population, and seed germination index (GI), during the composting of poultry manure and sawdust for different aeration rates and reactor shapes. Three cylindrical-shaped and three rectangular-shaped pilot-scale 60-L composting reactors were used in this study, with aeration rates of 0.3 (low), 0.6 (medium), and 0.9 (high) L min−1 kg−1 DM (dry matter). All parameters were monitored over 21 days of composting. Results showed that the low aeration rate (0.3 L min−1 kg−1 DM) corresponded to a higher and longer thermophilic phase than did the high aeration rate (0.9 L min−1 kg−1 DM). Ammonia and carbon dioxide volatilization were directly related to the temperature profile of the substrate, with significant differences between the low and high aeration rates during weeks 2 and 3 of composting but no significant difference observed during week 1. At the end of our study, the final values of pH, EC, moisture content, C/N ratio, and organic matter in all compost reactors were lower than those at the start. The growth rates of mesophilic and thermophilic bacteria were directly correlated with mesophilic and thermophilic conditions of the compost. The final GI of the cylindrical reactor with an airflow rate of 0.3 L min−1 kg−1 DM was 82.3%, whereas the GIs of the other compost reactors were below 80%. In this study, compost of a cylindrical reactor with a low aeration rate (0.3 L min−1 kg−1 DM) was more stable and mature than the other reactors.Implications: The poultry industry is growing in South Korea, but there are problems associated with the management of poultry manure, and composting is one solution that could be valuable for crops and forage if managed properly. For high-quality composting, the aeration rate in different reactor shapes must be considered. The objective of this study was to investigate various physicochemical properties with different aeration rates and rector shapes. Results showed that aeration rate of 0.3 L min−1 kg−1 DM in a cylindrical reactor provides better condition for maturation of compost.

Different bioreactors for treating secondary effluent from recycled paper mill

Secondary effluent from paper mill was characterized by poor biodegradability and containing recalcitrant compounds. In this study, four bioreactors, including a sequencing batch biofilm reactor (SBBR), a stirred-tank reactor (STR) and two submerged aeration reactors (SAR) were used to treat secondary effluent from a recycled paper mill respectively. The results indicated that chemical oxygen demand (COD) was increased by SAR2 treatment and COD removal efficiency for SBBR, SAR1 and STR was 39.7%, 15.7% and 30.9% respectively. It is suggested that recalcitrant compounds were removed by SBBR, SAR1 and STR respectively. Total nitrogen (TN) and total phosphorus (TP) of wastewater were increased by treatments of each bioreactor, which suggested that endogenous respiration of biomass occurred during the treatment. Microbial analysis of sludge from different bioreactors suggested that the removal of recalcitrant compounds in SBBR and STR might be related to the presence of unique microorganisms in each reactor.

Effect of pure oxygen aeration on extracellular polymeric substances (EPS) of activated sludge treating saline wastewater

This study aimed to investigate the effects of pure oxygen aeration on extracellular polymeric substances (EPS) of activated sludge treating saline wastewater in a sequencing batch reactor (SBR). Activated sludge with pure oxygen aeration was more effective for TOC removal than that with air aeration when salinities were less than 3.0%. The soluble microbial products (SMP) concentrations with pure oxygen aeration were higher at low salinities (0.5%, 1.0%), while the opposite occurred at high salinities (2.0%, 3.0%, 4.0%). The EPS concentrations of the two aeration methods were similar when salinities were at 0.5% and 1.0%, while higher amount of total EPS would be produced in pure oxygen aeration reactor when the salinities were above 2.0% (p＜0.05). The fluorescence peaks in both loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) of activated sludge with pure oxygen aeration at 3.0% salinity were attributed to tryptophan PN-like substances and humic acid-like substances. The sludge volume index (SVI) showed linear correlations with EPS (R2 = 0.9057), PN (R2 = 0.9741) and PS (R2 = 0.8833) at 3.0% salinity, respectively. In pure oxygen aeration system, SVI was more sensitive with EPS and PN, which may worsen settling performance of the sludge.

Hydrodynamic characteristics of an activated sludge bubble column through computational fluid dynamics (CFD) and response surface methodology (RSM)

AbstractThe aeration process is widely used in wastewater treatment plants to remove microorganisms from sludge. Among aeration reactors, bubble columns have been extensively used due to their simple geometry. In this study, a computational fluid dynamics (CFD) technique was applied to investigate the hydrodynamics involved in an activated sludge bubble column. The CFD modelling integrated an incorporation of the continuity, momentum, and Eulerian‐Eulerian multiphase equations along with the species transport equation. The validated CFD model was then applied to explore the effect of superficial gas velocity, the location of the tracer's injection, and the sparger type on mixing time. The design of experiment (DOE) and full factorial design method were carried out to investigate the interaction among the independent variables. A significant relationship between superficial gas velocity and tracer injection location on the mixing time have been noticed. The performance of a novel gas sparger, the modified star‐shape gas sparger, was also evaluated. The modified gas sparger showed an enhanced hydrodynamic performance compared to the typical sparger.

Dominance of the genus Polaromonas in the microbial ecology of an Intermittently Aerated Sequencing Batch Reactor (IASBR) treating dairy processing wastewater under varying aeration rates.

In this Research Communication we investigate potential correlations between key bacterial groups and nutrient removal efficiency in an Intermittently Aerated Sequencing Batch Reactor (IASBR) treating synthetic dairy processing wastewater. Reactor aeration rates of 0·6 and 0·4 litre per minute (LPM) were applied to an 8 l laboratory scale system and the relative impacts on IASBR microbial community structure and orthophosphate (PO4-P) and ammonium (NH4-N) removal efficiencies compared. Aeration at 0·6 LPM over several sludge retention times (SRTs) resulted in approximately 92% removal efficiencies for both PO4-P and NH4-N. Biomass samples subjected to next-generation sequencing (NGS), 16S rRNA profiling revealed a concomitant enrichment of Polaromonas under 0·6 LPM conditions, up to ~50% relative abundance within the reactor biomass. The subsequent shift in reactor aeration to 0·4 LPM, over a period of 3 SRTs, resulted in markedly reduced nutrient removal efficiencies for PO4-P (50%) and NH4-N (45%). An 85·7% reduction in the genus level relative abundance of Polaromonas was observed under 0·4 LPM aeration conditions over the same period.

Preliminary investigation of quorum quenching effects on sludge quantity and quality of activated sludge process

The Quorum Sensing (QS) system has attracted the interest of researchers as a cell-cell communication system. In activated sludge processes, the production of extracellular polymeric substances (EPS), biofilms and floc formation are regulated by the QS system. Hence, disruption of the QS system, called Quorum Quenching (QQ), could have a significant effect on the quality and quantity of excess sludge. In the present research, the quorum quenching bacteria, Rhodococcus sp. BH4 was used as a quorum quencher and was entrapped in an alginate structure (QQ beads). Three separate sequential batch reactors (SBR) were constructed and operated as a control reactor, a Low-QQ reactor (containing 150 QQ beads), and a High-QQ reactor (containing 600 QQ beads). Results indicated that the presence of QQ beads in the aeration reactor leads to a decrease in EPS content and mean floc particle size in the both Low-QQ and High-QQ reactors. The eukaryotic community was changed significantly so that the QS disruption caused an enhancement in microbial predation. The presence of QQ beads also led to a 16 and a 26% decrease in the Yobs coefficient within the Low-QQ and High-QQ reactors, respectively. Findings of this research revealed a new application of the QQ system in the activated sludge process, but additional studies are needed.

Anaerobic treatment of N, N-dimethylformamide-containing wastewater by co-culturing two sources of inoculum

The complete methanogenic degradation of N, N-dimethylformamide (DMF) was achieved in this study. Initially, DMF was found to be feebly degradable by a lab-scale submerged anaerobic membrane bioreactor (SAnMBR) using normal anaerobic digestion sludge (ADS) even after 120-day's culturing. However, aerobic DMF-degrading activated sludge (AS) was rapidly cultivated in a continuous aeration reactor (CAR). A specially designed anaerobic co-cultured sludge (ACS) made by artificially mixing AS with ADS was successfully domesticated by a long term repeated batch experiment. The results demonstrated that ACS could effectively degrade over 5000 mg L−1 DMF for methane recovery. The metabolic pathway and stoichiometric equation of DMF methanogenic degradation were also revealed and verified in detail. It was confirmed that under the anaerobic condition, with the help of enzyme, DMF converts into dimethylamine and formic acid, and the intermediates are effectively fermented through methylotrophic/hydrogenotrophic methanogenesis. Analysis of the microbial community suggested that some facultatively anaerobic bacteria played the key roles in methanogenic degradation due to their DMF-hydrolyzing ability. By co-culturing two sources of inoculum under the anaerobic condition, the symbiosis of facultatively anaerobic DMF-hydrolyzing bacteria and methylotrophic/hydrogenotrophic methanogens makes methanogenic degradation of DMF available. This study also provides a novel sludge cultivation method for anaerobic treatment of degradation-resistant organics.

Concentration of active sludge in the aeration reactors

The purpose of the paper was to study the dehydrogenase activity (DHA) of activated sludge in aeration tank. The article describes a change in enzyme activity, (dehydrogenase activity of sludge-DHA) of activated sludge while various time of aeration as well as various dose in sludge of aeration tank. Assessment changes enzyme activity were done on two indicators - on DHAor. (original dehydrogenase activity of sludge) and DHAH2O (dehydrogenase sludge activity with tap water). In the first case - DHA with the actual substrate, in the second case - DHA with poorly concentrated substrate. The work was performed on a pilot installation consisting of four models of aeration tanks blocked with sedimentation tanks, on a real city waste water. Working doses of sludge in biological wastewater treatment process was ranged from 2 to 6 g/l, time of aeration in aeration tanks changed from 3.5. up to 0.8 hours. Experimental studies have shown that regardless of the size of working sludge dose in aeration tank character of changes DHA or and DHAH2O is identical.

Simulation of Bio-drying of Bio-waste using Static Pile Forced Aeration Reactors

Simulation of Bio-drying of Bio-waste using Static Pile Forced Aeration Reactors

Research of polystyrene floating material application parameters for wastewater treatment

The article reveals researches aimed to estimate if it is possible to intensify wastewater treatment processes by means of floating feed. There was a lab-scale experiment carried out in conditions of artificial wastewater treatment. Laboratory model to perform conventional treatment process was assembled and included aeration reactor and secondary clarifier. It is stated that optimal amount of floating material inside the reactors has to be no less 10% of volume; otherwise, it may not provide positive result. However, if this amount is higher than 30% of volume it may require higher costs. Three ratios were chosen for current lab-scale experiment: 10%, 20% and 30% of reactor volume. In this viewpoint there were four laboratory models in operation with three different amount of floating material inside. The fourth model has no floating media to compare the parameters of operation. The material in use is made of polystyrene to provide its floating ability and accumulation of sludge biomass. The samples of wastewater were investigated to according to the requirements of standard methods. Model with floating material provided 95% efficiency for BOD5 removal and 83% efficiency of nitrogen removal, comparing to efficiency of 92% and 55% correspondingly in the model with no floating material.

Brewery wastewater treatment using laboratory scale aerobic sequencing batch reactor

This study evaluates the performance of two laboratory scale aerobic sequencing batch reactor operated under continuous low aeration and cyclic aeration scheme for the treatment of wastewater generated from a local brewery in Durban South Africa. The continuous low aeration scheme was intended to determine its effect on the performance of the reactor in terms of organic material removal compared to a typical cyclic aeration reactor for biological organic material removal. The performance of the two laboratory scale reactor was determined in terms of removals of chemical oxygen demand and biological oxygen demand. These two parameters were selected because they are priority pollutants and organic components in brewery wastewater. The experimental results demonstrated that reductions in chemical oxygen demand and biological oxygen demand in wastewater generated from the breweries can be successfully achieved using both aeration configurations. However, the treatment efficiencies in terms of the removal of chemical oxygen demand was consistently maintained above 90% and for biological oxygen demand it was observed to be above 80% with the reactor operated under the continuous low aeration scheme performing significantly better than the reactor operated under the cyclic aeration scheme.

Improved removal of Trinitrotoluene (TNT) from contaminated soil by inducing aerobic process: kinetic and chemical byproducts

This study describes the biological degradation of TNT by using induced aeration. Three plastic reactors were used. In each reactor 3 kg of soil were used. In order to increase the porosity of the soil, sawdust was added to soil. Textile wastewater treatment plant sludge was also added to soil. TNT at the concentrations of 1000 mg/kg of soil was added thereafter. Rhamnolipid biosurfactant at the concentration of 60 mg/L was added to related reactors. Aeration interval was at every 3 to 5 days. Every two weeks, sampling of soil were done to analyze the explosives. Samples were analyzed by HPLC. The results showed that at the end of 120 days, TNT removal efficiency in induced aeration in reactors containing sludge and biosurfactant was 98 percent. COD removal efficiency in induced aeration in reactors amended by rhamnolipid was 58 percent and in reactors to which rhamnolipid was not added was 41 percent. Follow-up kinetic studies revealed that explosives removal follow the pseudo first order reaction. The pseudo first-order rate constants of rhamnolipid amended experiments were at least 3.89 orders of magnitude higher for TNT than those found for experiments without rhamnolipid. Application of Rhamnolipid biosurfactant could have a protective effect against the toxicity of explosives for bacteria. Textile sludge from wastewater treatment plant can decrease the time needed for explosive removal. Growth of bacteria and degradation of explosives showed that explosives have been used as a nitrogen source.

Research for waste water treatment technology with low production of excessive active sludge

The article reflects the possibility to create a technological scheme of waste water treatment of domestic and similar type of sewage within minimal amount of excessive active sludge by means of bioreactors with immobilized feed. There are various aspects to be considered: technical, economic, social and ecological. According to the above it is strongly needed to provide a combination of proper waste water treatment, minimal sludge formation and the possibility for a further use of the sludge. One of the ways to achieve the goal above is to use an immobilized feed in the aeration tank. The necessary experiments were carried out in the department of waste water treatment and water ecology. The article includes the scheme of the facility and other parameters of the experiments, which has been carried. The combination of aerobic and anaerobic processes helps to provide proper quality of integrated biological treatment. Chambers of the aeration reactor were also equipped with the polymer feed of various structures. The sludge treatment that was also strongly needed was made by means of aerobic stabilization with the use of ejecting aeration. The results of experiment showed a good effect in both components – sewage and sludge treatment. Afterwards there was also an industrial model launched which confirmed the results of the previous stage.

Single chamber microbial fuel cell with Ni-Co cathode

The possibility of wastewater treatment and the parallel energy production using the Ni-Co alloy as cathode catalyst for single chamber microbial fuel cells is presented in this research. The research included a preparation of catalyst and comparison of COD, NH4 + and NO3 - reduction in the reactor without aeration, with aeration and with using a single chamber microbial fuel cell with Ni-Co cathode. The reduction time for COD with the use of microbial fuel cell with the Ni-Co catalyst is similar to the reduction time with aeration. The current density (2.4 A·m-2 ) and amount of energy (0.48 Wh) obtained in MFC is low, but the obtained amount of energy allows elimination of the energy needed for reactor aeration. It has been shown that the Ni-Co can be used as cathode catalyst in single chamber microbial fuel cells.

Achieving partial nitrification by inhibiting the activity of Nitrospira-like bacteria under high-DO conditions in an intermittent aeration reactor

It is generally accepted that a low dissolved oxygen (DO) concentration is more beneficial for achieving partial nitrification than high-DO. In this study, partial nitrification was not established under low-DO conditions in an intermittent aeration reactor for treating domestic wastewater. During the operational period of low-DO conditions (DO: 0.3±0.14mg/L), stable complete nitrification was observed. The abundance of Nitrospira-like bacteria, which were the major nitrite-oxidizing bacteria, increased from 1.03×106 to 2.64×106cells/mL. At the end of the low-DO period, the batch tests showed that high-DO concentration (1.5, 2.0mg/L) could inhibit nitrite oxidation, and enhance ammonia oxidation. After switching to the high-DO period (1.8±0.32mg/L), partial nitrification was gradually achieved. Nitrospira decreased from 2.64×106 to 8.85×105cells/mL. It was found that suddenly switching to a high-DO condition could inhibit the activity and abundance of Nitrospira-like bacteria, resulting in partial nitrification.

Mineralizing urban net-zero water treatment: Field experience for energy-positive water management

An urban net-zero water treatment system, designed for energy-positive water management, 100% recycle of comingled black/grey water to drinking water standards, and mineralization of hormones and other organics, without production of concentrate, was constructed and operated for two years, serving an occupied four-bedroom, four-bath university residence hall apartment. The system comprised septic tank, denitrifying membrane bioreactor (MBR), iron-mediated aeration (IMA) reactor, vacuum ultrafilter, and peroxone or UV/H2O2 advanced oxidation, with 14% rainwater make-up and concomitant discharge of 14% of treated water (ultimately for reuse in irrigation). Chemical oxygen demand was reduced to 12.9 ± 3.7 mg/L by MBR and further decreased to below the detection limit (<0.7 mg/L) by IMA and advanced oxidation treatment. The process produced a mineral water meeting 115 of 115 Florida drinking water standards that, after 10 months of recycle operation with ∼14% rainwater make-up, had a total dissolved solids of ∼500 mg/L, pH 7.8 ± 0.4, turbidity 0.12 ± 0.06 NTU, and NO3-N concentration 3.0 ± 1.0 mg/L. None of 97 hormones, personal care products, and pharmaceuticals analyzed were detected in the product water. For a typical single-home system with full occupancy, sludge pumping is projected on a 12–24 month cycle. Operational aspects, including disinfection requirements, pH evolution through the process, mineral control, advanced oxidation by-products, and applicability of point-of-use filters, are discussed. A distributed, peroxone-based NZW management system is projected to save more energy than is consumed in treatment, due largely to retention of wastewater thermal energy. Recommendations regarding design and operation are offered.

Transformation of Palm Oil Mill Effluent to Terpolymer Polyhydroxyalkanoate and Biodiesel Using Rummeliibacillus pycnus Strain TS8

This study aimed to transform wastewater from palm oil mill to the valuable products, especially the terpolymer PHA and biodiesel using Rummeliibacillus pycnus TS8. The cultivation of R. pycnus TS8 in POME was conducted in a 1-L aeration reactor. The optimization of bioproducts production was investigated by a statistical method with the central composite rotatable design. The result found that the highest cell dry weight (CDW) and bioproduct accumulation was obtained at the C/N ratio, aeration rate and phosphorus addition of 10, 1.00 vvm and 0.10 g/L, respectively. Moreover, R. pycnus TS8 accumulated P (3HB-co-3HV-co-3HHx) with 42.8 mol% 3HB, 34.9 mol% 3HV and 22.38 mol% 3HHx. In addition, R. pycnus TS8 also accumulated lipid, especially oleic acid (59.5 % CDW). In addition, the experiment was examined in a 72-L bioreactor to determine the properties of PHA and further used as feedstock for biodiesel production. Afterward, biomass and bioproducts were recovered. The terpolymer PHA and intracellular fatty acid were extracted. The characteristics of terpolymer showed that Tg, Tm, tensile strength, Young’s modulus and elongation at break were −21 °C, 147 °C, 27.67 MPa, 1260 MPa and 11.7 %, respectively. The bioproducts were hydrolyzed to fatty acid methyl ester (FAME) with a heating value, flash point and pour point of 32.9 kJ/g, 132 °C and 7 °C, respectively. The results illustrated that the properties of terpolymer PHA and FAME produced from this study showed a possibility for further application in biopolymer and biodiesel.