Processes in vertical-flow reed beds: nitrification, oxygen transfer and soil clogging

2005 ◽  
Vol 51 (9) ◽  
pp. 177-184 ◽  
Author(s):  
K. Kayser ◽  
S. Kunst
Keyword(s):  
Soil Column ◽  
Treatment Plant ◽  
Transport Processes ◽  
Vertical Flow ◽  
Reed Beds ◽  
Aerobic Conditions ◽  
Intermittent Feeding ◽  
Hydraulic Behaviour ◽  
Soil Clogging ◽  
Reed Bed

Vertical-flow reed beds (VF) with intermittent feeding are extremely reliable regarding aerobic processes. For a save operation with high nitrification rates and without soil clogging it is essential to preserve aerobic conditions in the filter. The challenge is to keep aerobic conditions in the filter without oversizing the system (economical aspects). It is very difficult to determine the current oxygen content in the filters because it ultimately results from complex interactions of a large number of different influencing parameters such as loading rate, degree of clogging, temperature, and hydraulic behaviour of the reed bed. To gain better knowledge of this complex system, different tests and examinations were carried out over several years. Focusing on the questions of identification and the description of conversion and transport processes (water/gas), a full-scale treatment plant under clogged and non-clogged conditions was investigated in detail. Additionally soil column test were carried out. The results make it possible to describe some of the processes and their interactions in the filter body. Recommendations for a safe and controlled operation can be derived.

Small wastewater treatment plants in Flanders (Belgium): standard approach and experiences with constructed reed beds

2000 ◽  
Vol 41 (1) ◽  
pp. 57-63 ◽  
Author(s):  
S. Vandaele ◽  
C. Thoeye ◽  
B. Van Eygen ◽  
G. De Gueldre
Keyword(s):  
Wastewater Treatment ◽  
Removal Efficiency ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Surface Flow ◽  
Limiting Factor ◽  
Vertical Flow ◽  
Reed Beds ◽  
Reed Bed

In Flanders (Belgium) an estimated 15% of the population will never be connected to a central wastewater treatment plant (WWTP). Small WWTPs can be a valuable option. Aquafin bases the decision to build SWWTPs on a drainage area study. To realise an accelerated construction the process choice is made accordingly to a standard matrix, which represents the different technologies in function of the size and the effluent consents. A pilot scale constructed two-stage reed bed is used to optimise the concept of the reed beds. The concept consists of a primary clarifier, two parallel vertical flow reed beds followed by a sub-surface flow reed bed. The removal efficiency of organic pollutants is high (COD: 89%, BOD: 98%). Phosphorus removal is high at the start-up but diminishes throughout the testing period (from 100% to 71% retention after 7 months). Nitrogen removal amounts to 53% on average. Nitrification is complete in summer. Denitrification appears to be the limiting factor. In autumn leakage of nitrogen is assumed. Removal efficiency of pathogens amounts to almost 99%. Clogging forms a substantial constraint of the vertical flow reed bed. Problems appear to be related with presettlement, feed interval and geotextile.

Soil clogging in vertical flow reed beds – mechanisms, parameters, consequences and.......solutions?

1997 ◽  
Vol 35 (5) ◽  
pp. 175-181 ◽  
Author(s):  
Christoph Platzer ◽  
Klaus Mauch
Keyword(s):  
Recovery Period ◽  
Critical Time ◽  
Weather Conditions ◽  
Infiltration Rate ◽  
Vertical Flow ◽  
Sand Filters ◽  
Reed Beds ◽  
Purification Efficiency ◽  
Volatile Solids ◽  
Soil Clogging

The purification efficiency of vertical flow reed beds (VFB) is dependent on a very efficient soil aeration. In most systems this is achieved by intermittent pulse loading at the surface providing an oxygenation by mass flow and diffusion. These oxygen transportation mechanisms only function as long as the upper layers of the bed have a high drainage capacity. Purification efficiency drops significantly when constant ponding occurs. A review of the literature on clogging in sand filters is given. In our evaluations the following observations are made. Clogging occurs only in the upper 0-15 cm of the bed. Clogging is dependent on the height of organic mass loading. The content of volatile solids in the upper layers could not be proven as a significant parameter influencing clogging. The infiltration rate can be restored by giving the beds a recovery period of several weeks. The required length of rest is dependent on weather conditions, winter is the most critical time.

Nitrification in reed beds - capacity and potential control methods

2002 ◽  
Vol 46 (6-7) ◽  
pp. 363-370 ◽  
Author(s):  
K. Kayser ◽  
S. Kunst ◽  
G. Fehr ◽  
H. Voermanek
Keyword(s):  
Ammonia Oxidation ◽  
Maximum Load ◽  
Nitrification Rate ◽  
Vertical Flow ◽  
Reed Beds ◽  
Potential Control ◽  
Conversion Rates ◽  
Nitrification Process ◽  
Hydraulic Load ◽  
Reed Bed

Vertical-flow reed beds (VFBs) are known to be very effective regarding nitrification. However, a generally accepted design formula for dimensioning reed beds for a controlled nitrification process has still not been found. Especially for the purpose of nitrification a vertical-flow reed bed (VFB) has been installed following an existing unaerated pond-system. The paper presents the results concerning the limits of the VFB's performance as well as the main factors influencing the nitrification process gained by balancing the conversion rates under different loads. Even under high loads the VFB provides an excellent nitrification performance, which is mainly influenced by the wastewater temperature. The ammonia oxidation rate is about 90% at temperatures over 10°C; at temperatures below 5°C the average nitrification rate is still approximately 50%. The hydraulic load and the TKN load have almost no impact on this efficiency (the maximum load has been: 180 mm/d, 7.1 g TKN/(m2*d)). The redox potenial, which is continuously measured in the effluent of the reed bed, proved to be dependent on the current nitrification performance and the oxygen supply of the VFB, and therefore appears to be a suitable control parameter for the operation of VFBs.

Design of a Hybrid Reed Bed System to Achieve Complete Nitrification and Denitrification of Domestic Sewage

1999 ◽  
Vol 40 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Paul Cooper ◽  
Paul Griffin ◽  
Stuart Humphries ◽  
Adrian Pound
Keyword(s):  
Horizontal Flow ◽  
Vertical Flow ◽  
Total N ◽  
Reed Beds ◽  
Loading Rates ◽  
Flow Systems ◽  
Reed Bed ◽  
And Performance ◽  
Sludge Drying ◽  
Complete Nitrification

The design of vertical-flow (VF) reed beds is reviewed and the performance of the few worldwide existing hybrid systems, combining both horizontal- and vertical-flow beds, is assessed. Horizontal-flow (HF) beds are good for suspended solids removal and will remove BOD5 up to a set loading. Vertical-flow beds can achieve BOD5 removal at much higher loading rates and they are capable of complete nitrification as tertiary or secondary treatment systems. It is possible to achieve biological denitrification in horizontal-flow beds. By combining horizontal- and vertical-flow systems in the appropriate process sequence it is thus possible to produce a system which removes BOD5, TSS and achieves complete nitrification as well as substantial removal of nitrate and hence a lowered Total N. The paper discusses the possible process options for combining horizontal- and vertical-flow systems. One example of these systems will be described in more detail. This is a flexible hybrid system being built by Severn Trent Water. Designed to treat the flow for a small village with a population of 129 it will have vertical-flow beds followed by horizontal-flow beds. The design allows for flexibility such that the size of the vertical-flow and horizontal-flow stages can be altered (for experimental purposes) to allow the design arrangement to be stressed and performance evaluated with the intention of defining the optimum loading rates for each of the stages. The same site also has sludge drying reed beds for treating the primary sludge.

Removal of hydrogen sulphide BOD from brackish water using vertical flow wetlands in a Caribbean environment

2001 ◽  
Vol 44 (11-12) ◽  
pp. 361-367 ◽  
Author(s):  
E. Giraldo ◽  
E. Zárate
Keyword(s):  
Hydraulic Conductivity ◽  
Hydrogen Sulphide ◽  
Native Species ◽  
Vertical Flow ◽  
System Operation ◽  
Reed Beds ◽  
Wetland System ◽  
Removal Efficiencies ◽  
Soil Clogging ◽  
High Concentrations

Wastewater from a 550-inhabitant community had been treated and discarded using an anaerobic filter. Due to seawater intrusion in the aquifer that supplies the water, high concentrations of hydrogen sulphide were detected in the effluent. A vertical flow wetland was designed in 1998 for treating this effluent. Four parallel reed beds with a total area of 556 m2 were constructed. During the first months of operation, a mean BOD5 removal efficiency of 91% was obtained, with loads to the wetland system up to 4g/m2/d of grease and oils (G&O). In 1999, problems of soil clogging were found due to high G&O content in the wastewater, with loads up to 15g/m2/d of G&O, which highly influenced the hydraulic conductivity of the beds, generating the clogging problems. The low hydraulic conductivity and the high effluent G&O content, caused low BOD5 and COD removal efficiencies. As G&O accumulated in the soil, the removal efficiencies decreased. Despite the clogging problems, there has been a high sulphide removal throughout the system operation. The wetlands removed sulphides successfully, under loads up to 20 gS=/m2/d. Four native species of macrophytes were planted: Paspalum penisetum, Typha sp, Conocarpres erectus and Scirpus lacustris. All of them but Typha sp. were established in the system.

Controlling a combined lagoon/reed bed system using the oxidation-reduction potential (ORP)

2003 ◽  
Vol 48 (5) ◽  
pp. 167-174 ◽  
Author(s):  
K. Kayser ◽  
S. Kunst ◽  
G. Fehr ◽  
H. Voermanek
Keyword(s):  
Reduction Potential ◽  
Vertical Flow ◽  
Oxidation Reduction ◽  
Hydraulic Behaviour ◽  
Oxidation Reduction Potential ◽  
Operation Control ◽  
Receiving Waters ◽  
Reed Bed ◽  
And Control ◽  
Lagoon Systems

Lagoon systems achieve good and stable effluent data in regard to organic pollutants, but they charge the receiving waters with relatively high ammonium loads. Therefore an existing lagoon-plant was extended by a vertical flow reed-bed for the special purpose of nitrification. This paper presents the efficiency of the combination plant as well as the possibility to monitor and control the reed-bed operation by the oxidation-reduction potential (ORP). The results show that the combination plant achieved excellent purification results, the average efficiency degrees were 97% for COD, 77% for Ntotal and 94% for the TKN elimination. The ORP in the effluent of the reed bed showed a clear dependence in its characteristic course and its absolute values on the current nitrification performance, the oxygen supply and the hydraulic behaviour of the reed bed. Therefore the ORP is a very good indicator for the state of the reed bed, which ultimately results from the accumulation of a large number of different influencing parameters. As the preservation of aerobic conditions in the reed bed is the crucial prerequisite for a high nitrification performance and for the avoidance of clogging, the ORP thus offers the possibility of immediate operation control.

Pond Treatment of Rettery Wastewaters

1987 ◽  
Vol 19 (12) ◽  
pp. 79-83
Author(s):  
K. Bartoszewski ◽  
A. Bilyk
Keyword(s):  
Activated Sludge ◽  
Treatment Process ◽  
New Technology ◽  
Treatment Plant ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Experimental Results ◽  
Aerobic Conditions ◽  
Aerobic Stabilization ◽  
In Series

Rettery wastewaters were treated in anaerobic and aerobic ponds. Anaerobic treatment yielded efficiencies of BOD5 and COD removal as low as 20%. The treatment process conducted under aerobic conditions in aerated and stabilizing ponds arranged in series took from 18 to 20 days and gave efficiencies of BOD5 and COD removal amounting to 90%. The experimental results were interpreted by virtue of the Eckenfelder equation. Excess activated sludge was subjected to aerobic stabilization in a separate tank. A new technology was suggested for the existing obsolete industrial treatment plant.

Constructed reed beds: appropriate technology for small communities

1995 ◽  
Vol 32 (3) ◽  
pp. 339-348 ◽  
Author(s):  
M. B. Green ◽  
J. Upton
Keyword(s):  
Sewage Treatment ◽  
Appropriate Technology ◽  
Great Promise ◽  
High Quality ◽  
Reed Beds ◽  
Small Communities ◽  
Operational Information ◽  
Reed Bed ◽  
Small Sites ◽  
Very High

Reed bed treatment is put in the context of a major water company’s need to provide reliable, high quality, effluents from small sewage treatment works whilst seeking to minimise running costs. Design and operational information is given for reed bed applications in Severn Trent Water. Performance details are provided for application to secondary, tertiary and storm overflow treatment. The results give particular confidence in the system’s ability to deliver very high quality effluents when used for tertiary treatment, the company’s biggest application. Reed beds work well against less demanding criteria for secondary treatment at small sites and show great promise for storm overflow treatment.

Analysis and design of suitable model structures for activated sludge tanks with circulating flow

1999 ◽  
Vol 39 (4) ◽  
pp. 55-60 ◽  
Author(s):  
J. Alex ◽  
R. Tschepetzki ◽  
U. Jumar ◽  
F. Obenaus ◽  
K.-H. Rosenwinkel
Keyword(s):  
Activated Sludge ◽  
Large Scale ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
High Sensitivity ◽  
Suitable Model ◽  
Model Structure ◽  
Analysis And Design ◽  
Hydraulic Behaviour ◽  
Model Structures

Activated sludge models are widely used for planning and optimisation of wastewater treatment plants and on line applications are under development to support the operation of complex treatment plants. A proper model is crucial for all of these applications. The task of parameter calibration is focused in several papers and applications. An essential precondition for this task is an appropriately defined model structure, which is often given much less attention. Different model structures for a large scale treatment plant with circulation flow are discussed in this paper. A more systematic method to derive a suitable model structure is applied to this case. Results of a numerical hydraulic model are used for this purpose. The importance of these efforts are proven by a high sensitivity of the simulation results with respect to the selection of the model structure and the hydraulic conditions. Finally it is shown, that model calibration was possible only by adjusting to the hydraulic behaviour and without any changes of biological parameters.

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