Anaerobic Expanded Bed Reactor Research Articles

Technologies Used in the Wastewater Treatment for Nutrient Removal

In this paper will be showed some techniques employed effectively in wastewater treatment for nutrient removal. The results concerning biological phosphorus and nitrogen removal, from an anaerobic expanded bed reactor (AEBR), treating domestic wastewater, in an Intermittent Aeration Reactor (IAR) followed by dissolved air flotation (DAF); aiming to remove chemical oxygen demand (COD), nitrogen and phosphorus on the same unit. The DAF was used for separation of suspended solids. Conditions to obtain nitrification were assessed, denitrification and phosphorus removal in a reactor operated with alternate aerobic and anaerobic periods. The intermittent aeration system was operated with hydraulic detention time (θh) of 8 hour and 6 hours. The system with intermittent aeration (θh:6hr) showed stable results and presented average COD removal of 92% (90 to 94%) and average phosphorus removal of 90% (82 to 96%). For hour detention time, the average orthophosphate (PO4 -3-P) removal was: 84% (60 to 94%) for raw samples and 94% (60 to 98%) for filtered samples (filter: 0.45 µm). Neither the use of the external carbon source nor pH correction was necessary.

Influence of flocculation conditions in the performance of an experimental domestic sewage treatment plant consisting of an anaerobic expanded bed reactor followed by dissolved air flotation

This paper presents the results of a study performed with an experimental domestic sewage treatment plant (240 m3 x d(-1) flow) consisting of expanded bed anaerobic reactor (EBAR) followed by dissolved air flotation (DAF) unit. For the flotation step, the anaerobic reactor effluent was previously coagulated with 50 mgFeCl3 x l(-1) and flocculated under different conditions (mean velocity gradient, Gf, and flocculation time, Tf). The Gf values were from 60 to 100 s(-1) associated with 13 and 20 min Tf values. During the tests, the following operational conditions of the flotation unit were maintained: chemical addition (50 mgFeCl3 x l(-1)), 18% recirculation rate associated with a pressure of 450 +/- 10 kPa in the saturation chamber and overflow rate of 180 m3 x m(-2) x d(-1). Temperature ranged from 23.8 degrees C to 30.0 degrees C. Best results were achieved for Gf = 80 s(-1) and Tf = 20 min. For these conditions, the DAF unit removal efficiencies were: 94.4% for chemical oxygen demand (with 53 mg x l(-1) COD residual), 87% for phosphorus (with 0.80 mgP x l(-1) residual), 96.7% for total suspended solids (with 9 mg x l(-1) TSS residual) and 96.4% for turbidity (with 12.9 NTU residual), when the anaerobic reactor effluents have worst quality during the whole day.

Anaerobic Treatment of Low-Strength Domestic Wastewater Using an Anaerobic Expanded Bed Reactor

A significant potential exists to lower energy consumption and reduce sludge production by incorporating anaerobic processes into wastewater treatment trains. The specific treatment arrangement studied in this case is the anaerobic treatment of primary clarifier effluent of wastewater treatment plants. Anaerobic batch assays showed that the primary clarifier effluent used in this study was ultimately 90% or more anaerobically biodegradable, thus suitable for anaerobic treatment. The anaerobic expanded bed reactor (AEBR) performed well over a wide range of influent CODs and temperatures, especially under severe conditions (5°C and 50 mg/L influent COD). The most efficient treatment was obtained with HRTs of three to six hours and influent COD of approximately 150 mg/L. Start-up of the reactor took about 60 days at 30°C and 80 days at 20°C.

Optimal Design for Anaerobic Pretreatment of Municipal Wastewater

In recent years the advent of the anaerobic expanded bed reactor (AEBR) has made possible the treatment of wastewaters of comparatively lower strength than have been treated traditionally by anaerobic means. However, regardless of any benefits presented by its use, the process must be shown to be cost effective relative to other options before it will gain acceptance. This paper reports on the results of a series of optimization exercises in which the costs of the AEBR as an expansion alternative for organically overloaded treatment plants are compared with costs for more conventional remedies. The optimization model developed includes the unit processes of primary clarification, AEBR, trickling filtration, secondary clarification, activated sludge, gravity thickening, anaerobic digestion, and vacuum filtration. Several constraint parameters were varied to determine the cases for which the AEBR would be the cost-effective option. These parameters were primary effluent chemical oxygen demand (COD), hydraulic loading, temperature, cost of labor, cost of power, cost of sludge disposal, and amortization interest rate. The results suggest that the AEBR may be a competitive solution for organically overloaded facilities under selected conditions.

An examination into the attachment of bio‐organic material to the mineral particles in sewer sediments

Abstract Sonication was used to examine the release of particulate matter from three different sewer sediments, sediments taken from two gully pots and a sludge from an anaerobic expanded bed reactor. The results show that there are distinct differences in the pattern of volatile suspended solids’ released from the sewer sediments. The results also show that the gully pot samples behaved differently from one another, suggesting that a classification of this type of sediment might be appropriate.

Treatment of chloro-hydrocarbon contaminated ground water by an anaerobic expanded-bed reactor (ANEBR)

Treatment of chloro-hydrocarbon contaminated ground water by an anaerobic expanded-bed reactor (ANEBR)

Cotton yarn and fabric finishing wastewater treatment using an anaerobic expanded bed reactor

Abstract Wastewater from cotton yarn and fabric finishing was treated in an anaerobic expanded bed reactor at 35°C up to a COD loading of 0·63 kg/m3 day. The COD removal varied from 50 to 87% and the production of biogas was 0·06-0·35 litre/g COD removed or 0·015-0·040 vol./vol./day, having 70–80% CH4. At higher COD loading biogas production stopped although COD removal remained approximately at 35%.

Behaviour of an anaerobic expanded bed reactor in non-steady state conditions

This paper presents a series of experimental data on an expanded bed anaerobic reactor operating at high organic loading rates in non-steady state conditions. The first four experiments were conducted in start-up periods after shut-downs. In the section dedicated to behaviour in the face of fluctuations, two experiments with overloading, two with decrease in temperature and one with air inflow, have been included. In all cases, the reactor demonstrated great stability with short recovery periods.

Studies with an anaerobic expanded bed reactor comparing the performances achieved with synthetic waste and domestic sewage

The performance of an anaerobic expanded bed reactor has been examined during the treatment of a synthetic low strength waste whose consistency and composition were constant. The organic loading rates used were in the range 0.2–5 kg total organic carbon m −3 day −1 and the removal efficiencies varied from 89 to 52%. Comparing these results with those obtained previously for the treatment of domestic sewage, whose strength and composition was very variable, showed that not only can higher removal efficiencies be achieved with the synthetic waste but also that a significantly better ( R 2 > 0.85, as opposed to <0.5) correlation between data could be obtained. This indicates the potential danger of using synthetic feedstocks for the prediction of reactor performance under real conditions.

Microbial attachment in anaerobic expanded bed reactors

Abstract The examination of the rate of bacterial attachment to the sand support medium in an anaerobic expanded bed reactor showed that the greatest biofilm thickness developed at the top of the bed. After 80 days the amount of biofilm on sand taken from this point corresponded to an increase in particle diameter of 92 μm. In the same period, support media taken from the middle of the bed increased by only 25 μm.

The use of aim anaerobic expanded bed reactor for the treatment of domestic sewage

Abstract The performance of an anaerobic expanded bed reactor treating settled domestic sewage at 37 C has been evaluated over a period of some eight months. The organic strength of the sewage varied from day to day, as it would in a practical treatment plant. With these unsteady‐state conditions prevailing, the results showed that the process was unlikely to give the type of performance (in terms of the removal of organic matter and gas productivity) that would make it a serious competitor to existing methods of treating domestic sewage. This is contrary to the interpretation of other workers who used steady‐state conditions.