Batch Activated Sludge Process Research Articles

An investigation based on removal of ibuprofen and its transformation products by a batch activated sludge process: A kinetic study

Ibuprofen metabolites can form in humans as a result of metabolic activities or can be produced by microorganisms in wastewater treatment plants and receiving environments, which increases their likelihood of being present in the environment. In this study, various experiments were conducted to determine the removal degree for ibuprofen, ibuprofen carboxylic acid (IBU-CBX), and 2-hydroxylated ibuprofen (IBU-2-OH) metabolites with an activated sludge reactor. Furthermore, the pseudo-first-order biodegradation rate constant (kbiol) (17.76 L/g SS day) was calculated to determine the decomposition degree of ibuprofen in the batch activated sludge system. The effects of different ibuprofen concentrations (8.2, 5.6, 3.2, 1.51 mg/L) at constant biomass concentration (3 g/L) on the biodegradation mechanism were investigated. In addition, IBU-2-OH and IBU-CBX were tested in a batch activated sludge reactor with a volume of 2 L individually at 100 μg/L with activated sludge containing 3 g/L biomass. It was observed that ibuprofen had a removal efficiency of more than 90%. IBU-CBX and IBU-2-OH were removed at approximately 27-91% and 18-82%, respectively. In abiotic conditions, the removal of ibuprofen was found to be 7.07%. It was confirmed that the removal of ibuprofen largely depended on biological degradation. This study enabled us to know which metabolites are involved in the biodegradation process of ibuprofen in batch experiments with the activated sludge process.

Effect of ozonation on activated sludge from pulp and paper industry

Aerobic biological treatment with activated sludge is the predominant process all over the world for treatment of pulp and paper industry wastewater. 50-70% of the biodegradable organic material is oxidized to CO₂ and the rest is converted to bacterial biomass, typically termed as excess sludge or waste activated sludge (WAS). Handling and disposal of WAS in general and in particular from the pulp and paper industry face different processing difficulties, regulatory stringency due to organochlorine contamination and reluctance of people for reuse. With an objective of reducing the net disposable biomass, ozonation of WAS from a pulp and paper mill and from a laboratory scale batch activated sludge process operated with the wastewater and bacterial seed of the same pulp and paper mill have been carried out. With the mill sludge having predominant filamentous organisms 18% MLSS was reduced at an ozone dosage of 55 mg O₃/g dry MLSS solid (DS) resulting in 2.5 times COD increase. With the laboratory sludge which is well structured and flocculating, only 6% MLSS was reduced at an ozone dosage of 55 mg O₃/g DS. Ozonation mineralizes 26% and 20% AOX compounds embedded in the secondary sludge in the mill and laboratory sludge respectively at an ozone dosage of 55 mg O₃/g DS. During ozonation, absorbed/adsorbed lignin on biomass was released which resulted in increased colour concentration. Ozonation can be a potential oxidative pretreatment process for reducing the WAS and paving the way for cost effective overall treatment of WAS.

The Characteristics of N<sub>2</sub>O Production in Sequencing Batch Activated Sludge Process Treating Swine Wastewater

The Characteristics of N<sub>2</sub>O Production in Sequencing Batch Activated Sludge Process Treating Swine Wastewater

Behaviour of arsenic species in batch activated sludge process: biotransformation and removal

The behaviour of As(III), As(V), MMA(v) and DMA(v) in batch activated sludge process were investigated. Experiments were carried out by using aerobic and anoxic reactors with an initial As concentration of 100 microjg I(-1). Under aerobic condition, As(III) was oxidized to As(V) within 9 hours, some part of MMA(v) was methylated to DMA(v) and some other part was demethylated to As(III), which in turn was immediately oxidized to As(V). Under anoxic condition, As(V) was reduced to As(III) within the same time-course. No significant transformation occurred during experiments conducted with DMA(v). It was found that all reactions were biologically mediated. The overall As removal was low (< 20%) during the experiments. Although a relationship seems to exist between the sludge concentration and As removal, it is concluded, under the conditions of our study, that the activated sludge process cannot remove arsenicals efficiently. However, it can control their transformations well. Thus, if associated with an appropriate technology, the activated sludge can be used for As pre-oxidation to treat As contaminated wastewaters. Finally, care must be taken on possible presence of MMA(v) in the influent of any wastewater treatment plant as it can be easily oxidized by the activated sludge.

Biodegradation of Cypermethrin by Pseudomonas in a batch activated sludge process

The biodegradation of Cypermethrin (20 to 125 mg/L) in an effluent using batch activated sludge was studied. Degradation was found to occur to a great extent only in the presence of Pseudomonas (IES-Ps-1) culture. Under aerobic conditions using mechanical aerators, Cypermethrin (20 mg/L) was almost completely degraded in just over 48 h at ambient temperature. Further loading of organic compound in subsequent experiments demonstrated that IES-PS-1was capable to degrade 82 % Cypermethrin at 40 mg/L dose in approximately 48 h. When the concentration was increased to 80 mg/L, 50% degradation of this compound was observed. Over this time period the cells could utilize only 17 % of Cypermethrin when it was given 125 mg/L, respectively. These findings indicate that increased concentration of Cypermethrin has a marked effect on biodegradation performance of IES-Ps-1 with a modest increased in the duration of lag phase, but did not lead to complete inhibition or cell death. These results proved that IES-Ps-1 is responsible for Cypermethrin degradation. Such finding may be useful in designing a scale-up in situ or on-site hazardous waste bioremediation process for field application.

Application of an automatic control system with ORP to the batch activated sludge process

Application of an automatic control system with ORP to the batch activated sludge process

Textile Wastewater Treatment With Activated Sludge And Powdered Activated Carbon

The objective of the study is to determine the effectiveness of batch activated sludge process and powdered activated carbon adsorption for organic and color removal from textile wastewaters. Factors affecting treatment performance investigated in the study included raw wastewater strength, various combinations of dye to starch in the wastewater, aeration time. Synthetic wastewaters using starch solution and disperse-red-60 dye were used in the adsorption study. The 3 wastewater strengths used included low, medium and high strength. The 5 different dye to starch combinations used included 0% dye+100% starch, 25% dye+75% starch, 50% dye+50% starch, 75% dye+25% starch, and 100% dye+0% starch. The batch bio-oxidation was conducted for a period of 24 hours. The COD removal efficiency, color removal, bio-oxidation rate constant, F/M ratio, SVI, pH and temperature were determined. The results indicated that starch was much easier to remove by the batch activated sludge process compared to disperse-red-60 dye, which was virtually non-biodegradable. Wastewaters containing 100% starch had the highest COD removal efficiency. Increase in dye concentration in wastewater resulted in decrease in the COD removal efficiency. The COD removal efficiency ranged from 6 to 45% for low strength wastewater of 100mg/L COD, 27 to 80% for medium strength wastewater of 500mg/L COD, and 23 to 65% for high strength wastewater of 1000mg/L COD. The low strength wastewaters had the best settling characteristics, while the medium strength wastewaters had the worst. For high PAC dosage of 15g/L, high COD removal efficiencies of 88 to 98% removal and E * ab of 36 to 47 were obtained. It is recommended that activated sludge be used to remove high COD organic pollutants first, followed by PAC adsorption to remove dye waste in the treatment of textile wastewaters.

A simple settling model for batch activated sludge process

A simple settling model for the batch activated sludge process was proposed that could predict sludge concentration profile as a function of time. The predicted dynamic biomass profile would be used to quantify biological reactions during settling. The model can be applied by giving easily measurable parameters such as initial MLSS concentration, sludge interface variation which characterizes the settling rate, and SVI as an index of biomass settleability. The model describes the sedimentation process of the sludge by linking three concentrations, namely the MLSS on sludge interface (XH), constant MLSS on sediment surface (XC), and the variable MLSS at the bottom (XB). It was tested for wide ranges of activated sludge concentrations (1750 mg/L-4630 mg/L) and SVI (104-265). The model was applied to express MLSS profile for a full scale SBR as well as for 1 and 2 m column settling tests. The simulated MLSS profile by linking three critical concentrations agrees well with the observed data. Mass balance applied at each time step indicated that the deviation was from −2 to +12% of the total initial mass. The stratified MLSS profile simulated from the model was applied to predict denitrification rate during settling.

Sodium Dodecylbenzenesulfonate Removal from Water and Wastewater. 2. Kinetics of the Integrated Ozone-Activated Sludge System

A batch-activated sludge process (AS) has been applied to eliminate sodium dodecylbenzenesulfonate (NaDBS), a linear alkylbenzenesulfonate (LAS) compound, from synthetic and real domestic wastewater. The kinetics of surfactant biodegradation was best described by first-order kinetics with rate constants of 1.28 and 1.15 L·(g VSS·day)-1 for synthetic and real domestic wastewater, respectively. The effect of preozonation on the overall surfactant and COD removal rates was also studied. The results indicated that treatment by combined ozone−AS leads to negligible foam ability and low residual surfactant concentration and COD in the treated effluent. Acclimation of a mixed culture to ozonated products was beneficial to highly improve biodegradation rates after preozonation. Thus, when applying ozone at a dose of 100 mg·L-1, the first-order surfactant biodegradation rate constant increased up to 1.79 and 3.09 L·(g VSS·day)-1 for synthetic and real wastewater, respectively. Continuous experiments of ozonation f...

Performance evaluation of small treatment systems in Turkey

In accordance with the development of tourism, sea pollution has become the major problem of the coastal zones. In order to realize sustainable touristic activities in Turkey, it is very important to treat wastewater and preserve the environmental quality. It is roughly estimated that there are around 2000 small treatment plants in Turkey. However, it is necessary to construct 10,000 more wastewater treatment plants to solve the wastewater problems in small settlements. In this study, performances of small treatment systems were investigated. Two types of the treatment plants were of concern. The first one is a continuous system based on fixed bed activated sludge process, whereas the second system is based on batch activated sludge process. 96 treatment plants have been investigated in this study. The wastewater characteristic is determined as strong domestic wastewater. It has been observed that the effluent quality of the batch activated sludge and aerated biofilter systems meet the discharge requirements of Water Pollution Control Regulation in Turkey. Furthermore, they would be easily adapted to meet the stringent standards that are proposed for sensitive zones.

回分式活性汚泥・生物膜法による低水温下のＢＯＤ，窒素およびリンの処理特性

In order to improve nitrogen and phosphorus removal efficiencies at low water temperature, intermittent aeration batch activated sludge process combined with biofilm process (media-added batch activated sludge process) was applied and its treatment performance was investigated for a different packing rate of string contact media with range of 0-21%. With the increase of packing rate of contact media, successful nitrification occurred. However, the dentrification efficiency decreased at the packing rate of 21%. This is because the relatively high DO concentration at the packing rate of 21% was not suitable for the denitrification condition. The optimal packing rate of media was 13% for simultaneous removal of BOD and nitrogen at 10°C.Removal efficiencies of BOD, DTN (disoluble total nitrogen) and DTP (disoluble total phosphorus) were 90%, 31% and 20%, respectively under operating condition of 3cycle a day at 10°C. Moreover, removal efficiencies of BOD, DTN and DTP increased to 94%, 64% and 22%, respectively by combining with biofilm process. Nitrogen removal efficiency was significantly enhanced.In spite of introduction of biofilter process, removal efficiency of phosphorus was not improved. It was observed that anaerobic phosphorous release and aerobic phosphorous uptake was significantly affected by low water temperature.As a biological removal of phosphorus cannot be expected at low water temperature, it is necessary to consider the combination with a physical treatment method.

鉄濃厚溶液滴下回分式活性汚泥・生物膜法による低水温時のリン除去効果の改善

In order to improve efficiencies of phoshorus removal at low water temperature, media-added batch activated sludge process combined with droplet method of thick iron solution as a chemical dosing was investigated in a process treating a sewage wastewater.An thick iron solution is able to be made by heating the crystal of the iron (III) chlorid hexahydrate within one hour at 50-60°C. However, it was shown that the dilution of thick iron solution was necessary to prevent solidification of the solution due to lowering of temperature. The optimal dilution ratio (the ratio of water volume to the volume of thick iron solution) was 0.4 v/v and it was observed the diluted solution did not solidify at 2°C.Removal efficiency of phosphorus by using the dosage of diluted thick iron solution was remarkably enhanced up to 79-82% at 10°C and it was not observed the inhibitive effect of the dosage on the nitrification and the BOD removal. These results indicate that biological process combined with the droplet method of thick iron solution improve treatment efficiency of phosphorus significantly at low water temperature.This method could decrease the frequency of maintenance because smaller quantity of dosage is required comparing with the conventional chemical method.

豚舎排水を処理する活性汚泥法の管理指標 有機物酸化活性，硝化活性の評価

To achieve high removal of both organic matter and nitrogen, the advanced management of activated sludge process was required. We studied on the simple methods for the determination of organic matter oxidizing and nitrifying activities by measuring oxygen uptake rate (OUR), dehydrogenase activity and ATP (adenosine 5'-triphosphate) activity using specific inhibitors for ammonia and nitrite oxidizing bacteria. The methods were mainly applied to a sequential batch activated sludge process with intermittent aeration treating swine wastewater. The results obtained were summarized as follows: It was possible to determine both organic matter oxidizing and nitrifying activities by measuring OUR, dehydrogenase activity and ATP activity according to our methods. Linear correlations among OUR, dehydrogenase activity and ATP activity related to organic matter oxidation were observed in spite of the origin of activated sludge. Ammonia oxidizing and nitrite oxidizing activities also had similar correlations. It became clear that the relationship between organic matter oxidizing and nitrifying activities was characterized by the supply of oxygen and substrates to activated sludge. Rational management of activated sludge process for the removal of both organic matter and ammonia was considered to be possible by keeping the maximum nitrifying activity.

Effects of inoculation of a genetically engineered bacterium on performance and indigenous bacteria of a sequencing batch activated sludge process treating phenol

A genetically engineered microorganism (GEM) Pseudomonas putida BH (pS10-45), which was designed to exhibit higher phenol-degrading activity than the wild strain, was inoculated into a model activated sludge process to improve its phenol-treatment performance. The model activated sludge process was operated as a 24-h-cycle sequencing batch reactor in a shake flask, into which phenol-containing wastewater (500 mg/ l) was fed in the form of a shock loading three times at 7-d intervals and, subsequently, semi-continuously (at 100–200 mg/ l). After the shock loadings, the phenol-removal efficiency of the GEM-inoculated activated sludge was much enhanced in comparison to that of a control process without GEM-inoculation for as long as the GEM population survived at a relatively high level. During the semi-continuous feedings, the GEM-inoculated activated sludge settled much better than that in the control process, though phenol was completely removed in both processes. The improvement in the settling properties was gradually lost as the GEM population declined. It was also observed that GEM-inoculation had a considerable effect on the behavior of the indigenous phenol-degrading bacterial population, indicating that inoculation of the GEM delayed the occurrence of indigenous phenol-degraders. These results suggest that GEM-inoculation can be a useful means of improving phenol-treating activated sludge processes.

Monitoring and control using on-line orp on the continuous-flow activated sludge batch reactor system

On-line monitoring of ORP has been proved to be a practical and useful technique for process control of wastewater treatment systems. This paper presents the feasibility of using on-line ORP monitoring system on a laboratory scale single tank continuous-flow activated sludge batch reactor, which is capable of removing carbon, nitrogen and phosphorus pollutants. Two control strategies, fixed-time and real-time, are applied for process control. Results obtained from fixed-time control study indicate that the variations and the ORP profile can accurately represent dynamic characteristics of system; the pH profile can also indicate some of those characteristics. Also, the breakpoints, setpoints and settime on the ORP and pH profiles are used to establish the real-time control strategy to determine the transfer of operation stages. The real-time experiments show a better performance than fixed-time, thus, on-line ORP and pH monitoring and control is practical for continuous-flow batch activated sludge process control.

Monitoring and control using on-line ORP on the continuous-flow activated sludge batch reactor system

On-line monitoring of ORP has been proved to be a practical and useful technique for process control of wastewater treatment systems. This paper presents the feasibility of using on-line ORP monitoring system on a laboratory scale single tank continuous-flow activated sludge batch reactor, which is capable of removing carbon, nitrogen and phosphorus pollutants. Two control strategies, fixed-time and real-time, are applied for process control. Results obtained from fixed-time control study indicate that the variations and the ORP profile can accurately represent dynamic characteristics of system; the pH profile can also indicate some of those characteristics. Also, the breakpoints, setpoints and settime on the ORP and pH profiles are used to establish the real-time control strategy to determine the transfer of operation stages. The real-time experiments show a better performance than fixed-time, thus, on-line ORP and pH monitoring and control is practical for continuous-flow batch activated sludge process control.

Treatment of septage using single and two stage activated sludge batch reactors systems

The cyclic or sequencing batch activated sludge process was applied for the treatment of septage originating from cesspools serving non-sewered areas. Single and two stage systems were investigated in bench scale units. The single stage aerated system was capable in removing practically all the biodegradable COD and producing a well stabilised excess sludge with excellent settling and thickening characteristics. With respect to nitrogen the average removal rate was to the order of 70%, but the performance was unstable due to periodic strong inhibition of the nitrification process. Subsequent treatment in a second stage aerated unit improved nitrification but did not result in higher nitrogen removal rates due to the increased concentrations of oxidised nitrogen. An anoxic second stage post denitrification unit resulted in an overall nitrogen removal of 88%, through a substantial reduction of nitrates. Further improvement of the system, with nitrogen removal of about 95% and average effluent nitrogen concentrations lower than 10 mg.1−1, can be achieved by adoption of a two stage system consisting of a first aerated stage unit, followed by a second stage unit with alternating aerated and anoxic cycles and addition of external carbon during the anoxic cycle.

Treatment of septage using single and two stage activated sludge batch reactors systems

The cyclic or sequencing batch activated sludge process was applied for the treatment of septage originating from cesspools serving non-sewered areas. Single and two stage systems were investigated In bench scale units. The single stage aerated system was capable in removing practically all the biodegradable COD and producing a well stabilised excess sludge with excellent settling and thickening characteristics. With respect to nitrogen the average removal rate was to the order of 70%, but the performance was unstable due to periodic strong inhibition of the nitrification process. Subsequent treatment in a second stage aerated unit improved nitrification but did not result in higher nitrogen removal rates due to the increased concentrations of oxidised nitrogen. An anoxic second stage post denitrification unit resulted in an overall nitrogen removal of 88%, through a substantial reduction of nitrates. Further improvement of the system, with nitrogen removal of about 95% and average effluent nitrogen concentrations lower than 10 mg.l−1, can be achieved by adoption of a two stage system consisting of a first aerated stage unit, followed by a second stage unit with alternating aerated and anoxic cycles and addition of external carbon during the anoxic cycle.

Treatment System of Wastewater from Rural Settlements with Batch-Activated Sludge Process

The treatment system for rural communities with Batch-Activated Sludge Process was improved. The focus was on removal of nitrogen by intermittent aeratyion. Following the experimental results, treated water quality lower than 10 mg/l of BOD and T-N was ensured throughout the year, under the operational conditions of hydraulic retention time in aeration tank longer than 24 h and MLSS higher than 2,500 mg/l. Treated water quality of T-N was less than 5 mg/l within cumulative frequency of 66%. Removal capacity of T-N did not reach its limit under condition less than 0.05 kgN/m3d−1 of influent load. Estimating from the nitrogen removal rate, consumption of alkalinity, characteristics of biomass growth and the amount of nitrogen content in MLSS, 77% of influent nitrogen was denitrified, 18% of that was discharged as treated water and 5% of that was extracted as excess sludge or SS in treated water. Fluctuation patterns of DO and ORP in a cycle by seasonally changed water temperature were effective indices for regulation of operation. A remote monitoring system was helpful to support the management, because it enabled maintenance staff to judge urgency of management from the latest real time data.

Organic Carbon and Nitrogen Removal from Wastewaters of Single Houses and Small Separate Establishments Using a Simple Sequencing Batch Reactor

Purification capacity of a low-loaded sequencing batch activated sludge process pilot-plant, operated in a way to simulate the flow profile in small point sources, was studied. Oxidation capacity of organic matter and ammonium nitrogen, capacity to denitrify the oxidised nitrogen by alternating aerobic and anoxic operation, suspended solids removal and sludge settling characteristics were determined. Best results were obtained in a 24 h total cycle with three anoxic hours in addition to a three hours settling period. BOD7 removal was 94 %, residual concentration being less than 20 mg/l. Suspended solids were removed with equal efficiency. Hydrolysis of solid organic waste in a low loaded plant was efficient, and no excess sludge had to be removed. Almost complete nitrification could be maintained at 13°C, and 60 % of the oxidised nitrogen was denitrified without supplementary carbon source.