Bendern wastewater treatment plant
The Bendern wastewater treatment plant (ARA) (ARA Bendern for short) was put into operation in 1976 and is operated by the municipal wastewater association founded in 1971 . This has been the central sewage treatment plant for Liechtenstein since 2004 . All other sewage treatment plants were largely shut down.
The ARA Bendern is located in the Liechtenstein municipality of Bendern (belonging to Gamprin ) at one of the lowest points in the populated area.
history
The ARA Vaduz wastewater treatment plant with mechanical cleaning was put into operation in 1956 (shut down in 2000). The Malbun sewage treatment plant was built in 1967 and was taken out of service in 1992. The Liechtenstein Unterland and Schaan wastewater association was founded in July 1971. From this, the waste water association of the municipalities of Liechtenstein developed by 2000 through the accession of several municipalities in stages. The main collecting canal Schaan -Bendern, Mauren -Bendern, Schellenberg - Ruggell and the pumping station Ruggell-Bendern took place in the years 1972-1976. The Balzers sewage treatment plant was built in 1972 and was taken out of service in 2004. In parallel to the construction work on the main collectors, the ARA Bendern was built in 1974–1976 and put into operation on October 6, 1976. The official and solemn inauguration of the ARA Bendern took place on September 2, 1978. In 1980, the municipality of Planken joined the Liechtenstein Unterland and Schaan wastewater association, changing the name to the Liechtenstein Unterland, Schaan and Planken wastewater association . 1981–1982 the small sewage treatment plant “Hinterschellenberg” was built and in 1999 it was converted into a pumping station with a rainwater clarifier. In 1996 the municipalities of Vaduz, Triesen and Triesenberg joined the Liechtenstein Unterland, Schaan and Planken wastewater association , and the name was changed to Liechtenstein's wastewater association . In 1997, a decision was made to renovate and expand the ARA Bendern. With the expansion of the wastewater treatment facility on four streets, optimal management was achieved. After the municipality of Balzers joined in 2000, the name of the association was changed to the Wastewater Association of the Municipalities of Liechtenstein and the originally planned expansion goal has been achieved. In 2000 the ARA company building in Bendern was also increased and the main collecting sewer Vaduz-Bendern was put into operation (costs around CHF 14.5 million).
In 2001 a further expansion and renovation of the mechanical cleaning, construction of the exhaust air cleaning system / biofilter, a new construction of the rain overflow and emergency basin was carried out. In 2002, two new biology basins and the round secondary clarifier, the energy building were built and the biology basins 3 + 4 and the round secondary clarifier 3 were put into operation. In 2003 further renovations and extensions took place. From 2004, when the ARA Balzers was shut down, all domestic and commercial wastewater from the eleven Liechtenstein municipalities will be treated in the ARA Bendern. The main collecting sewer Düker-ARA Bendern was commissioned in 2005 and the existing digester was renovated. In 2013, the cooperation project between the Liechtenstein gas supply and ARA Bendern for feeding biogas into the pipeline network of the Liechtenstein gas supply went into operation.
Technical installation
The plant cleans the wastewater for over 34,000 residents and the wastewater of the companies located here. The three stages of the WWTP, mechanical, biological and chemical, are structurally separate parts of the system.
System structure
The ARA Bendern consists of five cleaning levels:
- Rough cleaning (rake 17 mm, approx. 200 tons / year of waste)
- Sand and fat separation (pool volume 2 x 140 m³, sand accumulation approx. 35 m³ / year, fat and oil accumulation 160 m³ / year)
- Primary clarification in the primary clarification tank (cleaning effect approx. 30%)
- Ventilation and then with phosphate precipitation (cleaning effect approx. 63%)
- Secondary clarifier
The sludge from the 3rd to 5th cleaning levels is treated in the digestion towers, the sludge is dewatered, dried and burned several times. The resulting biogas is used energetically for drying and fed into the pipeline network of the Liechtenstein gas supply.
Plant data
- Catchment area: All 11 municipalities in Liechtenstein
- Year of construction: 1974–1976 with extensions
- Wastewater flow time to the WWTP: max. 6 hours
- Wastewater treatment time in the WWTP:
- Wastewater (QTA) 19 h
- Mud about 55 days
- Population equivalents:
- hydraulic 75,000 EG
- organic 105,800 EC
- Size of the company premises: 23,500 m²
- Building volume: 34,000 m³
- Container volume
- Waterway: 27,200 m³
- Mud road: 8100 m³
- Gas road: 2160 m³
- Hydraulic load
- Dry weather (QTA): 381 l / s or 24,300 m³ / d
- Rainfall (2 QTA): 743 l / s
- Maximum waste water flow: 1280 l / s
- Annual wastewater volume: 9.5 million m³ / a
- Material pollution (raw sewage)
- Carbon (organic) COD: 11,000 kg / d
- Suspended solids CIS: 5320 kg / d
- Total nitrogen N tot : 676 kg / d
- Ammonium NH 4 -N: 386 kg / d
- Phosphorus P tot : 147 kg / d
- Mechanical cleaning (1st cleaning stage) elevator and rake system
- Conveying capacity screws: 3 × 380 l / s, 1 x 150 l / s
- Fine rake with gap width: 17 mm
- Ventilated sand and grease trap
- Pool volume: 2 × 140 m³ (residence time (QTA): 12 min.)
- Primary settling tank tank volume: 2 × 1150 m³ (residence time (QTA): 1.5 h)
- Cleaning effect: 30%
- Rain and emergency basins (basin volume: 2 × 500 m³)
- Biological cleaning (2nd cleaning stage)
- Residence time (QTA): 17 h
- Aeration basin with OKI aerator
- Pool volume and water depth: 2 x 3250 m³ and 4.2 m / 2 x 3500 m³ and 6.0 m³ Maximum air requirement: 18,200 m³ / h
- Cleaning effect: 63%
- Recirculation volume: 190 - 770 l / s
- BioP, Nitri and Deni zones: 24 individual basins can be used variably
- Secondary clarifier
- Basin volume and water depth: rectangular basin 2 x 2275 m³ and 2.8 m round basin 1 x 4600 m³ and 4.5 m
- Return sludge volume: 290 - 580 l / s
- Excess sludge load: 4100 kg / d
- Dry cleaning (3rd cleaning stage)
- Precipitant: aluminum sulfate, consumption: 1500 l / d
- Container volume: 2 x 25 m³, 2 × 17.5 m³
- Sludge treatment pre-drainage
- Fresh sludge volume or load: 100 m³ / d or 7100 kg / d
- Thickening performance: from 4% to 8%
- Container volume: 2 × 2400 m³ digestion room, 1 × 2400 m³ stacking room
- Sludge composition: organic 42%, mineral 58%
- Sludge treatment post-drainage
- Decanter thickening performance: from 4% to 32%
- Granulate accumulation (93% DM): 8 m³ / d, 1596 m³ / a
- Biogas requirement: 1728 m³ / d
- Container volume silo: 2 × 50 m³
- Storage capacity: for 8 days
- Disposal frequency: 5 silo trucks per month
- Biogas plant
- Biogas production: 3000–4000 m³ / d, 1.08 million m³ / a
- Gasometer container volume: 1 × 560 m³, 2 × 800 m³
- Gas engine power:
- Electricity production 2 × 157 kW, 1 × 197 kW
- Heat production 2 × 297 kW, 1 × 332 kW
Sewage sludge
Around 100 m³ of sewage sludge are produced in the Bendern ARA every day. The sewage sludge produced is processed on site in a sewage sludge drying plant, dried and then incinerated and completely disposed of in the cement kiln of Holcim AG as part of an acceptance contract for dry sewage sludge . The biogas requirement for sludge drying is around 2000 m³ / day.
Biogas and combined heat and power plant
In the ARA Bendern around 1,000,000 m³ of sewage gas are generated annually with an amount of energy of 6,500,000 kWh . The biogas is mainly used for drying sewage sludge and in a combined heat and power unit (CHP). The combined heat and power plant has three gas engines with a combustion output of 1 × 617 kW and 2 × 520 kW, which converts a maximum of 1 × 197 kW or 2 × 157 kW of electrical energy.
location
The ARA Bendern is located at one of the lowest points in Liechtenstein in the municipality of Gamprin - Bendern .
Web links
- Website of the waste water association of the municipalities of Liechtenstein
- Mission statement of the waste water association of the municipalities of Liechtenstein
- Wastewater regulations of the communities of Liechtenstein (example community Eschen )
See also
Web links
- Website of the waste water association of the municipalities of Liechtenstein
- Mission statement of the waste water association of the municipalities of Liechtenstein
- Wastewater regulations of the communities of Liechtenstein (example community Eschen )
- Werner Steiner: Sewage. In: Historical Lexicon of the Principality of Liechtenstein .
Individual evidence
- ↑ Entry in the commercial register on May 24, 2013, commercial register number: FL-0000.001.008-0.
- ↑ Liechtensteiner Volksblatt of October 6, 2016, p. 13.
- ↑ Liechtensteiner Volksblatt of October 6, 2016, p. 13.
- ↑ Herbert Beck, President of the Liechtenstein Wastewater Association in the Liechtenstein Fatherland, May 13, 2000, page 45.
- ↑ Liechtensteiner Volksblatt of October 6, 2016, p. 13.
- ↑ Technical information according to: Completion of the ARA Bendern plant expansion , documentation of the construction phase 1998 - 2005.
- ↑ Overview ARA Bendern ( Memento from November 12, 2016 in the Internet Archive ).
- ↑ Overview ARA Bendern ( Memento from November 12, 2016 in the Internet Archive ).