Long-term behaviour of a two-stage CW system regarding nitrogen removal

2011 ◽  
Vol 64 (5) ◽  
pp. 1137-1141 ◽  
Author(s):  
Guenter Langergraber ◽  
Alexander Pressl ◽  
Klaus Leroch ◽  
Roland Rohrhofer ◽  
Raimund Haberl
Keyword(s):  
Grain Size ◽  
Nitrogen Removal ◽  
Elimination Rate ◽  
Organic Load ◽  
Two Stage ◽  
Drainage Layer ◽  
Main Layer ◽  
In Series ◽  
Biofilm Development ◽  
Nitrogen Elimination

In the first two years of operation a nitrogen removal efficiency of 53% and a high average elimination rate of 1,000 g N m−2 yr−1 could be observed for a two-stage vertical flow (VF) constructed wetland (CW) system. The two-stage system consists of two VF beds with intermittent loading operated in series, each stage having a surface area of 10 m2. The first stage uses sand with a grain size of 2–3.2 mm for the 50 cm main layer and has a drainage layer that is impounded; the second stage sand with a grain size of 0.06–4 mm and a conventional drainage layer (with free drainage). The two-stage VF system was designed for and operated with an organic load of 40 g COD m−2 d−1 (i.e. 2 m2 per person equivalent). Data from the following years of operation showed that from the third year nitrogen elimination increased and stabilized. The median values of the nitrogen elimination rate in the first five years of operation have been 3.51, 2.76, 4.20, 3.84 and 4.07 g N m−2 d−1, the median value of the last three years being 3.8 g N m−2 d−1 and 1,380 g N m−2 yr−1, respectively, and the nitrogen removal >60%. It can be assumed that the vegetation as well as the biofilm development in the two-stage VF CW system plays the major role for the enhancement of the nitrogen elimination rate.

A two-stage subsurface vertical flow constructed wetland for high-rate nitrogen removal

2008 ◽  
Vol 57 (12) ◽  
pp. 1881-1887 ◽  
Author(s):  
Guenter Langergraber ◽  
Klaus Leroch ◽  
Alexander Pressl ◽  
Roland Rohrhofer ◽  
Raimund Haberl
Keyword(s):  
Grain Size ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
High Rate ◽  
Organic Load ◽  
Vertical Flow ◽  
Two Stage ◽  
Drainage Layer ◽  
Main Layer ◽  
Specific Investment

By using a two-stage constructed wetland (CW) system operated with an organic load of 40 g COD·m−2·d−1 (2 m2 per person equivalent) average nitrogen removal efficiencies of about 50% and average nitrogen elimination rates of 980 g N·m−2·yr−1 could be achieved. Two vertical flow beds with intermittent loading have been operated in series. The first stage uses sand with a grain size of 2–3.2 mm for the main layer and has a drainage layer that is impounded; the second stage sand with a grain size of 0.06–4 mm and a drainage layer with free drainage. The high nitrogen removal can be achieved without recirculation thus it is possible to operate the two-stage CW system without energy input. The paper shows performance data for the two-stage CW system regarding removal of organic matter and nitrogen for the two year operating period of the system. Additionally, its efficiency is compared with the efficiency of a single-stage vertical flow CW system designed and operated according to the Austrian design standards with 4 m2 per person equivalent. The comparison shows that a higher effluent quality could be reached with the two-stage system although the two-stage CW system is operated with the double organic load or half the specific surface area requirement, respectively. Another advantage is that the specific investment costs of the two-stage CW system amount to 1,200 EUR per person (without mechanical pre-treatment) and are only about 60% of the specific investment costs of the singe-stage CW system.

Optimization of subsurface vertical flow constructed wetlands for wastewater treatment

2007 ◽  
Vol 55 (7) ◽  
pp. 71-78 ◽  
Author(s):  
G. Langergraber ◽  
Ch. Prandtstetten ◽  
A. Pressl ◽  
R. Rohrhofer ◽  
R. Haberl
Keyword(s):  
Grain Size ◽  
Specific Surface ◽  
Surface Area ◽  
Constructed Wetlands ◽  
Organic Load ◽  
Vertical Flow ◽  
Two Stage ◽  
Main Layer ◽  
Free Drainage ◽  
Stage System

Constructed wetlands (CWs) use the same processes that occur in natural wetlands to improve water quality and are used worldwide to treat different qualities of water. This paper shows the results of an Austrian research project having the main goals to optimize vertical flow beds in terms of surface area requirement and nutrient removal, respectively. It could be shown that a subsurface vertical flow constructed wetland (SSVFCW) operated with an organic load of 20 g COD.m−2.d−1 (corresponding to a specific surface area demand of 4 m2 per person) can fulfil the requirements of the Austrian standard regarding effluent concentrations and removal efficiencies. During the warmer months (May – October), when the temperature of the effluent is higher than 12 °C, the specific surface area might be further reduced. Even 2 m2 per person have been proven to be adequate. Enhanced nitrogen removal of 58 % could be achieved with a two-stage system (first stage: grain size for main layer 1–4 mm, saturated drainage layer; and second stage: grain size for main layer 0.06–4 mm, free drainage) that was operated with an organic load of 80 g COD.m−2.d−1 for the first stage (1 m2 per person), i.e. 40 g COD.m−2.d−1 for the two-stage system (2 m2 per person). Although the two-stage system was operated with higher organic loads a higher effluent quality compared to a single-stage SSVFCW (grain size for main layer 0.06–4 mm, free drainage, organic load 20 g COD.m−2.d−1) could be reached.

Comparison of nitrogen elimination rates of different constructed wetland designs

2011 ◽  
Vol 64 (5) ◽  
pp. 1122-1129 ◽  
Author(s):  
Eriona Canga ◽  
Sara Dal Santo ◽  
Alexander Pressl ◽  
Maurizio Borin ◽  
Guenter Langergraber
Keyword(s):  
Constructed Wetland ◽  
Elimination Rate ◽  
Domestic Wastewater ◽  
High Strength ◽  
Pilot Scale ◽  
Synthetic Wastewater ◽  
Main Layer ◽  
Average Value ◽  
In Series ◽  
Nitrogen Elimination

In this paper the nitrogen elimination rates of different constructed wetland (CW) designs reported in literature are compared with those obtained for outdoor and indoor 2-stage vertical flow (VF) systems. The outdoor system is located about 150 km west of Vienna. Both stages are planted with Phragmites australis and the system has been operated for 4 years continuously. During this period the average value of the nitrogen elimination rate was 3.30 g N m−2 d−1. The indoor system comprises three parallel operated 2-stage VF systems and is located in the technical lab hall at BOKU University. The design of the indoor system resembles the outdoor system. However, there are a few differences: (1) the indoor systems are not planted, and (2) different filter media have been used for the main layer of the first stages. With the indoor system the highest nitrogen elimination rate achieved was 2.24 g N m−2 d−1 for the system with zeolite and impounded drainage layer. Similar results have been found in France for treating raw wastewater with VF and horizontal flow (HF) beds in series with nitrogen elimination rates of 1.89 and 2.82 g N m−2 d−1 for differently designed HF beds. The highest nitrogen elimination rates of 15.9 g N m−2 d−1 reported were for pilot-scale VF CWs treating high-strength synthetic wastewater (total nitrogen of 305 mg L−1 in the influent) in Thailand. It has been shown that the outdoor two-stage VF CW system has one of the highest nitrogen elimination rates of CWs treating domestic wastewater.

The first two years of full scale operation of the two-stage Main Wastewater Treatment Plant of Vienna

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
G. Wandl ◽  
H. Schaar ◽  
M. Papp ◽  
K. Svardal
Keyword(s):  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plant ◽  
Evaluation Studies ◽  
Treatment Plant ◽  
Full Scale ◽  
Two Stage ◽  
Effluent Recirculation ◽  
Nitrogen Elimination ◽  
Year 2000

The Main Wastewater Treatment Plant of Vienna had to be extended to guarantee sufficient nitrogen removal. After intensive evaluation studies a two-stage activated sludge system was chosen for the plant-extension. Due to the very small specific reactor tank volume of two-stage treatment plants in comparison with low loaded single-stage plants internal cycles had to be applied to ensure sufficient nitrogen removal. Starting in the year 2000 the plant extension was finished by the beginning of 2005 and the extended plant went into operation in spring. The Austrian effluent standards had to be fulfilled by December 2005. This paper presents a description of the plant layout and gives an overview of the operating results of the first two years of full scale operation. Mass balances were used to evaluate the pathways of nitrogen removal. The results confirmed the expected flexibility of the chosen concept; nitrogen elimination did not decrease although the effluent recirculation that has been implemented to ensure sufficient nitrogen removal efficiency especially during winter had been reduced markedly due to energy reasons. The treatment efficiency that was observed at pilot plant investigations was clearly exceeded.

Improvement of nitrogen removal at WWTP Zürich Werdhöelzli after connection of WWTP Zürich-Glatt

2004 ◽  
Vol 50 (7) ◽  
pp. 35-43 ◽  
Author(s):  
H. Siegrist ◽  
L. Rieger ◽  
Ch. Fux ◽  
M. Wehrli
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Substantial Reduction ◽  
Operating Conditions ◽  
Operating Costs ◽  
Effluent Quality ◽  
In Series ◽  
Nitrogen Elimination ◽  
Anammox Process ◽  
P Removal

Optimisation of nitrifying activated sludge plants towards nutrient removal (denitrification and enhanced P-removal) leads to a substantial reduction of operating costs and improves effluent and operating conditions. At WWTP Zürich-Werdhöelzli, initially designed for nitrification only, an anoxic zone of 28% of total activated sludge volume was installed and allowed 60% nitrogen elimination besides several other optimisations. In 2001 the operation of WWTP Zürich-Glatt was stopped and the wastewater was connected to WWTP Werdhöelzli. To improve nitrogen removal, WWTP Werdhöelzli co-financed two research projects; one for separate digester supernatant treatment with the anammox process operating two SBRs in series and the other applying NH4 sensors for aeration control in order to decrease energy consumption and raise effluent quality. The results of both projects and the consequences for WWTP Werdhöelzli are discussed in this paper.

Two-stage biofilm-MBR for nitrogen removal and enhanced membrane performance

2012 ◽  
Vol 66 (3) ◽  
pp. 588-593 ◽  
Author(s):  
Cheng Sun ◽  
TorOve Leiknes
Keyword(s):  
Nitrogen Removal ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Suspended Solids ◽  
Feed Solution ◽  
Organic Load ◽  
Two Stage ◽  
Membrane Unit ◽  
Membrane Performance ◽  
Recycle Ratio

A two-stage biofilm-membrane bioreactor (MBR) was developed in this study. High total nitrogen removal (maximum: 81.4% with recycle ratio = 3.5) was observed by recycling the suspension liquid between an anaerobic FBBR and an aerobic MBBR. Very low (less than 60 mg/L) suspended solids was kept in the membrane unit, which could improve the membrane filtration performance. Membrane fouling was further reduced by increasing the recycle ratio. When influent organic load increased, the membrane fouling rate increased, coupling with higher FCOD and suspended solids (SS) values in the feed solution around the membrane.

The Implementation of Biological Phosphorus and Nitrogen Removal with the Bio-Denipho Process on a 265,000 PE Treatment Plant

1992 ◽  
Vol 25 (4-5) ◽  
pp. 161-168 ◽  
Author(s):  
J. Einfeldt
Keyword(s):  
Nitrogen Removal ◽  
Treatment Plant ◽  
First Year ◽  
In Series ◽  
Design Loads ◽  
Last Stage ◽  
Two Stages ◽  
The City ◽  
Biological Phosphorus

A process, called Bio-Denipho, for combined biological phosphorus and nitrogen removal in a combination of an anaerobic tank and two oxidation ditches is described. In this process the anaerobic tank consisting of three sections working in series is followed by two oxidation ditches. These too are working in series, but with both inlet to and outlet from the tanks changing in a cycle. The Bio-Denipho process is described specifically for the process itself and as a case study for the implementation of the process on a 265,000 pe wastewater treatment plant for the city of Aalborg in Denmark. The plant was designed and erected in two stages and the last stage was inaugurated October 31,1989. Lay-out and functions for the plant is described and design loads, plan lay-out and tank volumes are given in this paper together with performance data for the first year in operation.

Electroflotation clarifier to enhance nitrogen removal in a two-stage alternating aeration bioreactor

2013 ◽  
Vol 34 (19) ◽  
pp. 2765-2772 ◽  
Author(s):  
Kangwoo Cho ◽  
Chong Min Chung ◽  
Yun Jung Kim ◽  
Michael R. Hoffmann ◽  
Tai Hak Chung
Keyword(s):  
Nitrogen Removal ◽  
Two Stage
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