Raimund Haberl - Academia.edu (original) (raw)

Papers by Raimund Haberl

Nature Reviews Earth & Environment

Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qua... more Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qualität des Abwassers und oft sehr sensible Gewässer gekennzeichnet sind, stellen heute in abwassertechnischer Hinsicht die größten Probleme dar. Vor allem die hohen spezifischen Kosten für eine den geltenden gesetzlichen Regelungen entsprechende Lösung haben zu einer weiten Palette an Lösungsmöglichkeiten geführt, die von zentralen bis zu dezentralen und von "konventionellen" bis zu "alternativen" Systemen reichen. Leider gibt es für diese ländlichen Gebiete kein Patentrezept, vielmehr muß für jeden Einzelfall die angepaßte Optimallösung gesucht werden. Dabei ist der Einsatz objektivierbarer und nachvollziehbarer Entscheidungskriterien sehr hilfreich und die Einbindung aller Beteiligten Grundvoraussetzung für eine breite und nachhaltige Akzeptanz der schließlich zur Ausführung gelangenden Variante.

Obwohl über den Einsatz und den Betrieb von Pflanzenkläranlagen mittlerweile sowohl national wie ... more Obwohl über den Einsatz und den Betrieb von Pflanzenkläranlagen mittlerweile sowohl national wie international eine relativ breite und auch verlässliche Datenbasis mit entsprechend positiven Erfahrungen vorliegt, führt der Wunsch nach Anwendung dieser naturnahen Technologie in der Regel nach wie vor zu einem erhöhten (Erklärungs)Aufwand im Genehmigungsverfahren. Durch die Erstellung und rasche Verbreitung von Regelwerken (Normen, Richtlinien) auf Basis des aktuellen Wissensstandes sollen einerseits der Planungsprozeß in technischer und ökonomischer Hinsicht verbessert werden und andererseits die Einsatzmöglichkeiten und -grenzen von Pflanzenanlagen besser beschrieben werden. Die Anwendung der unterschiedlichen Konstruktionsprinzipien ist im Zusammenhang mit der Stellung im Reinigungsprozeß zu beurteilen, wobei die Nitrifikation durch vertikal durchströmte, intermittierend beschickte bepflanzte Bodenfilter am besten gesichert erscheint. Die in der aktuellen Forschung behandelten Frag...

Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qua... more Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qualität des Abwassers und oft sehr sensible Gewässer gekennzeichnet sind, stellen heute in abwassertechnischer Hinsicht die größten Probleme dar. Vor allem die hohen spezifischen Kosten für eine den geltenden gesetzlichen Regelungen entsprechende Lösung haben zu einer weiten Palette an Lösungsmöglichkeiten geführt, die von zentralen bis zu dezentralen und von "konventionellen" bis zu "alternativen" Systemen reichen. Leider gibt es für diese ländlichen Gebiete kein Patentrezept, vielmehr muß für jeden Einzelfall die angepaßte Optimallösung gesucht werden. Dabei ist der Einsatz objektivierbarer und nachvollziehbarer Entscheidungskriterien sehr hilfreich und die Einbindung aller Beteiligten Grundvoraussetzung für eine breite und nachhaltige Akzeptanz der schließlich zur Ausführung gelangenden Variante.

Water Science and Technology, 1992

The “Rapid Sludge Dewatering System (RSDS)”, in which the sludge is dewatered by way of vacuum su... more The “Rapid Sludge Dewatering System (RSDS)”, in which the sludge is dewatered by way of vacuum supported sludge drying beds, was tested for performance, efficiency and applicability. Generally, the RSD-System can be regarded as an alternative to other sludge dewatering systems, especially for small purification plants, for agricultural use and composting of sewage sludge. It is also applicable for (industrial) sludge with a high percentage of grease or coarse materials.

Water Practice and Technology, 2007

Regarding the average age of sewers in Austria, rehabilitation becomes more and more important. I... more Regarding the average age of sewers in Austria, rehabilitation becomes more and more important. In Austria so far no guideline for sewer maintenance and rehabilitation strategies exists. The paper reports about the preparation for developing a guideline to raise the working quality of several branches involved in sewer maintenance like e. g. high pressure jetting, CCTV-inspection together with the development of standardised tender documents. A Pilot-Study was financed by the ministry of environment and the regional government of Styria to develop in several theoretical workshops and practical implementations a guideline for sewer operation and maintenance. With 4 operators the project has been carried out to test the proposed instructions described in the guideline which will be revised for an Austrian-wide application.

Water Science and Technology, 2003

Substrate clogging is by far the biggest operational problem of vertical flow constructed wetland... more Substrate clogging is by far the biggest operational problem of vertical flow constructed wetlands. The term “substrate clogging” summarises several processes which lead to reduction of the infiltration capacity at the substrate surface. The lower infiltration rate causes a reduced oxygen supply and further leads to a rapid failure of the treatment performance. Reasons for substrate clogging include accumulation of suspended solids, surplus sludge production, chemical precipitation and deposition in the pores, growth of plant-rhizomes and roots, generation of gas and compaction of the clogging layer. However, it is not clear how much each process contributes to the clogging process. Detailed investigations were carried out at pilot-scale constructed wetlands (PSCWs) using a variety of methods: e.g. soil physical investigations, microbial methods, and various analysis methods of drinking water and wastewater. The paper shows the results of these investigations and presents an equatio...

Österreichische Wasser- und Abfallwirtschaft, 2012

Österreichische Wasser- und Abfallwirtschaft, 2013

Die Abwasserentsorgung steht aktuell vor einer Vielzahl von Herausforderungen, die sich gleicherm... more Die Abwasserentsorgung steht aktuell vor einer Vielzahl von Herausforderungen, die sich gleichermaßen auf die Abwasserableitung und die Abwasserreinigung beziehen. Dabei geht es u. a. um die Anpassung der bestehenden Infrastruktur an neue Umweltbedingungen, um die Umsetzung gesetzlicher Vorgaben und um die Verbesserung bestehender Technologien zur Erfüllung des Gewässerund Ressourcenschutzes. Ein sehr umfangreicher Themenkatalog, der leicht einige Nummern der ÖWAW füllen könnte. Einigen Themen davon ist dieses Heft gewidmet.

Water Research, 2008

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state o... more Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the ''black-box'' constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial 14 C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10 cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

Water Science and Technology, 2009

In a first phase of this study it was shown that the Austrian effluent standards for organic matt... more In a first phase of this study it was shown that the Austrian effluent standards for organic matter could not be met in winter for vertical flow (VF) beds designed for and loaded with 27 g COD.m−2.d−1 (3 m2 per person equivalent). The aim of this second phase of the study was to investigate, if the performance of a constructed wetland can be enhanced, i.e. if the effluent requirements can be met, when an additional gravel layer (15 cm, 4–8 mm) is added on top of the main layer of the VF bed. The hypothesis was that this top layer would increase the thermal insulation and consequently the temperatures in the filter bed during cold periods, thus resulting in higher removal efficiencies during winter. Two VF beds were operated in parallel; one bed with such a 15 cm top layer, one without. Otherwise the construction of both beds was identical: surface area of about 20 m2, 50 cm main layer (grain size 0.06–4 mm, d10=0.2 mm; d60=0.8 mm), planted with common reed (Phragmites australis). Th...

Water Science & Technology: Water Supply, 2007

Recently, many countries have started benchmarking studies with the aim of improving performance ... more Recently, many countries have started benchmarking studies with the aim of improving performance in their water sectors. To see regional differences in water supply, a cross-country comparison based on five benchmarking projects of Austria and different German federal states was done. It was verified that the influencing factors on costs are mainly related to regional and structural parameters, causing the crosscountry differences. Besides the age of the mains, urbanity is one of the major influencing factors on burst rates, leakage, and also on mains rehabilitation. The survey on the benefits of benchmarking suggests that it more than pays for itself. Most participants found opportunities to optimize operation and efficiency. No company stated higher costs than benefits. Benchmarking does not only optimize efficiency, but more importantly, quality, reliability and sustainability of supply services.

Water Science and Technology, 2011

In the first two years of operation a nitrogen removal efficiency of 53% and a high average elimi... more 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 ...

Water Science and Technology, 1997

In Strengberg, Lower Austria, a vertical flow reed bed system (gravel/sand) was chosen as a new t... more In Strengberg, Lower Austria, a vertical flow reed bed system (gravel/sand) was chosen as a new type of tertiary treatment which was designed as a full scale pilot plant with various possibilities of operational use. The surface of the vertical flow pilot plant amounts to about 600 m2 and is divided into four beds whereby two different depths of substrate are used. The application of the conventional plant effluent is carried out in intermittent flushes and at changeable time intervals. Final nitrification and partial denitrification and elimination of phosphorus are the main goals to be achieved. In the framework of the present research project the load limits will be determined by gradually raising the influent load. The efficiency and operational reliability within the whole year period (summer/winter) are considered to be an important factor for establishing general dimensioning approaches. The pilot plant has been in operation for more than one year now. Different operational stages up to a hydraulic load of 1.3 m2.p.e.−1 (i.e. 0.75 m2.p.e.−1) were carried out. The average chemical oxygen demand (COD) of the reed bed effluents varied from 1 to 20 mg.1−1. Not surprisingly the ammonium (NH4-N) results showed more variation. Results, thus far, indicate NH4-N removal efficiencies between 40% and 90%.

Water Science and Technology, 1999

There is a great lack of proper wastewater treatment in developing countries. With respect to the... more There is a great lack of proper wastewater treatment in developing countries. With respect to the environment this situation should be changed as fast as possible. Due to the financial situation and to the more stringent standards, wastewater sewerage and treatment are much more developed in industrialized countries. Consequently there is an enormous pool of experience and knowledge in these countries with a lot of different systems based on scientific and practical work. One of the most promising technologies for application in developing countries seems to be constructed wetlands (CW), due to their characteristic properties like utilization of natural processes, simple construction, simple operation and maintenance (O/M), process stability, cost effectiveness, etc. Our Institute has been dealing a lot with CW and now feels obliged to transfer its know-how in this field to developing countries to help them in solving their problems. At the moment we are cooperating with the following countries: China, Kenya, Mexico, Nepal, Nicaragua, Tanzania and Uganda. Different ways are being followed to realize this together with several organisations and partners. The paper will deal with these cooperative arrangements in detail, demonstrating different projects, describing the procedures in the projects, discussing experiences and last but not least giving recommendations for future optimum ways of proceeding.

Water Science and Technology, 2010

Constructed wetlands (CWs) are known to be robust wastewater treatment systems and are therefore ... more Constructed wetlands (CWs) are known to be robust wastewater treatment systems and are therefore very suitable for small villages and single households. When nitrification is required, vertical flow (VF) CWs are widely used. This contribution compares the behaviour and treatment efficiencies of a single-stage VF CW and a two-stage VF CW system under varying operating and loading conditions according to standardized testing procedures for small wastewater treatment plants as described in the European standard EN 12566-3. The single-stage VF CW is designed and operated according to the Austrian design standards with an organic load of 20 g COD m−2 d−1 (i.e. 4 m2 per person equivalent (PE)) The two-stage VF CW system is operated with 40 g COD m−2 d−1 (i.e. 2 m2 per PE). During the 48 week testing period the Austrian threshold effluent concentrations have not been exceeded in either system. The two-stage VF CW system showed to be more robust as compared to the single-stage VF CW especia...

Water Science & Technology, 2007

This paper reports a recently finished, interdisciplinary project on rural wastewater management ... more This paper reports a recently finished, interdisciplinary project on rural wastewater management in Austria. The objective of the project was to study alternative wastewater management options based on separation of the wastewater into its constituent parts, and to compare them with conventional ones. Thereby, a feasibility study of both conventional and alternative options for wastewater management in six model regions was carried out. Life cycle costs and social acceptance were analysed by using a case study-based assessment approach. However, hygienic and environmental risks were evaluated on a more general level. In order to complement the findings, a survey on urine separation system users in the Solar City of Linz was conducted. Based on these assessments and empirical findings, the paper concludes that options using a full separation of all wastewater fractions should be considered with care. Options based on a separation of only grey water and black water or in the liquid/so...

Water Science and Technology, 2007

Constructed wetlands (CWs) use the same processes that occur in natural wetlands to improve water... more 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, ...

Water Science and Technology, 1997

Since 1991 the institute for water provision has run two vertical flow constructed wetlands for d... more Since 1991 the institute for water provision has run two vertical flow constructed wetlands for domestic wastewater treatment at two farm houses (8 p.e.) in Upper Austria. The systems are designed for elimination of organic compounds and for nitrification which was no problem even under winter conditions. In 1995 two methods were tested to achieve denitrification also in both systems. System A is a one-stage system, system B has two stages operated in series. The approach to the one-stage system consisted in pumping a part of the nitrified effluent from the soil filter back to the settling tank of the influent, where the raw wastewater mixes with the nitrified effluent-water. The approach to the two-stage system B consisted in adding an external carbon source (methanol) into the second, water saturated stage. The research was undertaken during several experimental stages to test the influence of the recirculation ratio (system A) respectively of the feeding (system B; intermittent, continuous, batch). The highest elimination rates could be achieved with system B (dosage of methanol) during experimental stage 1 (intermittent loading four times a day). The mean elimination rates were 82% for Ninorg and 78% for TN. The TN elimination performance of system A was only a little lower (72%). The elimination of COD, BOD5 and TOC was no problem throughout the whole experimental period (effluent concentrations of both systems were well below the Austrian standards).

Nature Reviews Earth & Environment

Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qua... more Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qualität des Abwassers und oft sehr sensible Gewässer gekennzeichnet sind, stellen heute in abwassertechnischer Hinsicht die größten Probleme dar. Vor allem die hohen spezifischen Kosten für eine den geltenden gesetzlichen Regelungen entsprechende Lösung haben zu einer weiten Palette an Lösungsmöglichkeiten geführt, die von zentralen bis zu dezentralen und von "konventionellen" bis zu "alternativen" Systemen reichen. Leider gibt es für diese ländlichen Gebiete kein Patentrezept, vielmehr muß für jeden Einzelfall die angepaßte Optimallösung gesucht werden. Dabei ist der Einsatz objektivierbarer und nachvollziehbarer Entscheidungskriterien sehr hilfreich und die Einbindung aller Beteiligten Grundvoraussetzung für eine breite und nachhaltige Akzeptanz der schließlich zur Ausführung gelangenden Variante.

Obwohl über den Einsatz und den Betrieb von Pflanzenkläranlagen mittlerweile sowohl national wie ... more Obwohl über den Einsatz und den Betrieb von Pflanzenkläranlagen mittlerweile sowohl national wie international eine relativ breite und auch verlässliche Datenbasis mit entsprechend positiven Erfahrungen vorliegt, führt der Wunsch nach Anwendung dieser naturnahen Technologie in der Regel nach wie vor zu einem erhöhten (Erklärungs)Aufwand im Genehmigungsverfahren. Durch die Erstellung und rasche Verbreitung von Regelwerken (Normen, Richtlinien) auf Basis des aktuellen Wissensstandes sollen einerseits der Planungsprozeß in technischer und ökonomischer Hinsicht verbessert werden und andererseits die Einsatzmöglichkeiten und -grenzen von Pflanzenanlagen besser beschrieben werden. Die Anwendung der unterschiedlichen Konstruktionsprinzipien ist im Zusammenhang mit der Stellung im Reinigungsprozeß zu beurteilen, wobei die Nitrifikation durch vertikal durchströmte, intermittierend beschickte bepflanzte Bodenfilter am besten gesichert erscheint. Die in der aktuellen Forschung behandelten Frag...

Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qua... more Die ländlichen Gebiete, die durch dünne Besiedelung, starke Schwankungen in der Quantität und Qualität des Abwassers und oft sehr sensible Gewässer gekennzeichnet sind, stellen heute in abwassertechnischer Hinsicht die größten Probleme dar. Vor allem die hohen spezifischen Kosten für eine den geltenden gesetzlichen Regelungen entsprechende Lösung haben zu einer weiten Palette an Lösungsmöglichkeiten geführt, die von zentralen bis zu dezentralen und von "konventionellen" bis zu "alternativen" Systemen reichen. Leider gibt es für diese ländlichen Gebiete kein Patentrezept, vielmehr muß für jeden Einzelfall die angepaßte Optimallösung gesucht werden. Dabei ist der Einsatz objektivierbarer und nachvollziehbarer Entscheidungskriterien sehr hilfreich und die Einbindung aller Beteiligten Grundvoraussetzung für eine breite und nachhaltige Akzeptanz der schließlich zur Ausführung gelangenden Variante.

Water Science and Technology, 1992

The “Rapid Sludge Dewatering System (RSDS)”, in which the sludge is dewatered by way of vacuum su... more The “Rapid Sludge Dewatering System (RSDS)”, in which the sludge is dewatered by way of vacuum supported sludge drying beds, was tested for performance, efficiency and applicability. Generally, the RSD-System can be regarded as an alternative to other sludge dewatering systems, especially for small purification plants, for agricultural use and composting of sewage sludge. It is also applicable for (industrial) sludge with a high percentage of grease or coarse materials.

Water Practice and Technology, 2007

Regarding the average age of sewers in Austria, rehabilitation becomes more and more important. I... more Regarding the average age of sewers in Austria, rehabilitation becomes more and more important. In Austria so far no guideline for sewer maintenance and rehabilitation strategies exists. The paper reports about the preparation for developing a guideline to raise the working quality of several branches involved in sewer maintenance like e. g. high pressure jetting, CCTV-inspection together with the development of standardised tender documents. A Pilot-Study was financed by the ministry of environment and the regional government of Styria to develop in several theoretical workshops and practical implementations a guideline for sewer operation and maintenance. With 4 operators the project has been carried out to test the proposed instructions described in the guideline which will be revised for an Austrian-wide application.

Water Science and Technology, 2003

Substrate clogging is by far the biggest operational problem of vertical flow constructed wetland... more Substrate clogging is by far the biggest operational problem of vertical flow constructed wetlands. The term “substrate clogging” summarises several processes which lead to reduction of the infiltration capacity at the substrate surface. The lower infiltration rate causes a reduced oxygen supply and further leads to a rapid failure of the treatment performance. Reasons for substrate clogging include accumulation of suspended solids, surplus sludge production, chemical precipitation and deposition in the pores, growth of plant-rhizomes and roots, generation of gas and compaction of the clogging layer. However, it is not clear how much each process contributes to the clogging process. Detailed investigations were carried out at pilot-scale constructed wetlands (PSCWs) using a variety of methods: e.g. soil physical investigations, microbial methods, and various analysis methods of drinking water and wastewater. The paper shows the results of these investigations and presents an equatio...

Österreichische Wasser- und Abfallwirtschaft, 2012

Österreichische Wasser- und Abfallwirtschaft, 2013

Die Abwasserentsorgung steht aktuell vor einer Vielzahl von Herausforderungen, die sich gleicherm... more Die Abwasserentsorgung steht aktuell vor einer Vielzahl von Herausforderungen, die sich gleichermaßen auf die Abwasserableitung und die Abwasserreinigung beziehen. Dabei geht es u. a. um die Anpassung der bestehenden Infrastruktur an neue Umweltbedingungen, um die Umsetzung gesetzlicher Vorgaben und um die Verbesserung bestehender Technologien zur Erfüllung des Gewässerund Ressourcenschutzes. Ein sehr umfangreicher Themenkatalog, der leicht einige Nummern der ÖWAW füllen könnte. Einigen Themen davon ist dieses Heft gewidmet.

Water Research, 2008

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state o... more Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the ''black-box'' constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial 14 C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10 cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

Water Science and Technology, 2009

In a first phase of this study it was shown that the Austrian effluent standards for organic matt... more In a first phase of this study it was shown that the Austrian effluent standards for organic matter could not be met in winter for vertical flow (VF) beds designed for and loaded with 27 g COD.m−2.d−1 (3 m2 per person equivalent). The aim of this second phase of the study was to investigate, if the performance of a constructed wetland can be enhanced, i.e. if the effluent requirements can be met, when an additional gravel layer (15 cm, 4–8 mm) is added on top of the main layer of the VF bed. The hypothesis was that this top layer would increase the thermal insulation and consequently the temperatures in the filter bed during cold periods, thus resulting in higher removal efficiencies during winter. Two VF beds were operated in parallel; one bed with such a 15 cm top layer, one without. Otherwise the construction of both beds was identical: surface area of about 20 m2, 50 cm main layer (grain size 0.06–4 mm, d10=0.2 mm; d60=0.8 mm), planted with common reed (Phragmites australis). Th...

Water Science & Technology: Water Supply, 2007

Recently, many countries have started benchmarking studies with the aim of improving performance ... more Recently, many countries have started benchmarking studies with the aim of improving performance in their water sectors. To see regional differences in water supply, a cross-country comparison based on five benchmarking projects of Austria and different German federal states was done. It was verified that the influencing factors on costs are mainly related to regional and structural parameters, causing the crosscountry differences. Besides the age of the mains, urbanity is one of the major influencing factors on burst rates, leakage, and also on mains rehabilitation. The survey on the benefits of benchmarking suggests that it more than pays for itself. Most participants found opportunities to optimize operation and efficiency. No company stated higher costs than benefits. Benchmarking does not only optimize efficiency, but more importantly, quality, reliability and sustainability of supply services.

Water Science and Technology, 2011

In the first two years of operation a nitrogen removal efficiency of 53% and a high average elimi... more 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 ...

Water Science and Technology, 1997

In Strengberg, Lower Austria, a vertical flow reed bed system (gravel/sand) was chosen as a new t... more In Strengberg, Lower Austria, a vertical flow reed bed system (gravel/sand) was chosen as a new type of tertiary treatment which was designed as a full scale pilot plant with various possibilities of operational use. The surface of the vertical flow pilot plant amounts to about 600 m2 and is divided into four beds whereby two different depths of substrate are used. The application of the conventional plant effluent is carried out in intermittent flushes and at changeable time intervals. Final nitrification and partial denitrification and elimination of phosphorus are the main goals to be achieved. In the framework of the present research project the load limits will be determined by gradually raising the influent load. The efficiency and operational reliability within the whole year period (summer/winter) are considered to be an important factor for establishing general dimensioning approaches. The pilot plant has been in operation for more than one year now. Different operational stages up to a hydraulic load of 1.3 m2.p.e.−1 (i.e. 0.75 m2.p.e.−1) were carried out. The average chemical oxygen demand (COD) of the reed bed effluents varied from 1 to 20 mg.1−1. Not surprisingly the ammonium (NH4-N) results showed more variation. Results, thus far, indicate NH4-N removal efficiencies between 40% and 90%.

Water Science and Technology, 1999

There is a great lack of proper wastewater treatment in developing countries. With respect to the... more There is a great lack of proper wastewater treatment in developing countries. With respect to the environment this situation should be changed as fast as possible. Due to the financial situation and to the more stringent standards, wastewater sewerage and treatment are much more developed in industrialized countries. Consequently there is an enormous pool of experience and knowledge in these countries with a lot of different systems based on scientific and practical work. One of the most promising technologies for application in developing countries seems to be constructed wetlands (CW), due to their characteristic properties like utilization of natural processes, simple construction, simple operation and maintenance (O/M), process stability, cost effectiveness, etc. Our Institute has been dealing a lot with CW and now feels obliged to transfer its know-how in this field to developing countries to help them in solving their problems. At the moment we are cooperating with the following countries: China, Kenya, Mexico, Nepal, Nicaragua, Tanzania and Uganda. Different ways are being followed to realize this together with several organisations and partners. The paper will deal with these cooperative arrangements in detail, demonstrating different projects, describing the procedures in the projects, discussing experiences and last but not least giving recommendations for future optimum ways of proceeding.

Water Science and Technology, 2010

Constructed wetlands (CWs) are known to be robust wastewater treatment systems and are therefore ... more Constructed wetlands (CWs) are known to be robust wastewater treatment systems and are therefore very suitable for small villages and single households. When nitrification is required, vertical flow (VF) CWs are widely used. This contribution compares the behaviour and treatment efficiencies of a single-stage VF CW and a two-stage VF CW system under varying operating and loading conditions according to standardized testing procedures for small wastewater treatment plants as described in the European standard EN 12566-3. The single-stage VF CW is designed and operated according to the Austrian design standards with an organic load of 20 g COD m−2 d−1 (i.e. 4 m2 per person equivalent (PE)) The two-stage VF CW system is operated with 40 g COD m−2 d−1 (i.e. 2 m2 per PE). During the 48 week testing period the Austrian threshold effluent concentrations have not been exceeded in either system. The two-stage VF CW system showed to be more robust as compared to the single-stage VF CW especia...

Water Science & Technology, 2007

This paper reports a recently finished, interdisciplinary project on rural wastewater management ... more This paper reports a recently finished, interdisciplinary project on rural wastewater management in Austria. The objective of the project was to study alternative wastewater management options based on separation of the wastewater into its constituent parts, and to compare them with conventional ones. Thereby, a feasibility study of both conventional and alternative options for wastewater management in six model regions was carried out. Life cycle costs and social acceptance were analysed by using a case study-based assessment approach. However, hygienic and environmental risks were evaluated on a more general level. In order to complement the findings, a survey on urine separation system users in the Solar City of Linz was conducted. Based on these assessments and empirical findings, the paper concludes that options using a full separation of all wastewater fractions should be considered with care. Options based on a separation of only grey water and black water or in the liquid/so...

Water Science and Technology, 2007

Constructed wetlands (CWs) use the same processes that occur in natural wetlands to improve water... more 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, ...

Water Science and Technology, 1997

Since 1991 the institute for water provision has run two vertical flow constructed wetlands for d... more Since 1991 the institute for water provision has run two vertical flow constructed wetlands for domestic wastewater treatment at two farm houses (8 p.e.) in Upper Austria. The systems are designed for elimination of organic compounds and for nitrification which was no problem even under winter conditions. In 1995 two methods were tested to achieve denitrification also in both systems. System A is a one-stage system, system B has two stages operated in series. The approach to the one-stage system consisted in pumping a part of the nitrified effluent from the soil filter back to the settling tank of the influent, where the raw wastewater mixes with the nitrified effluent-water. The approach to the two-stage system B consisted in adding an external carbon source (methanol) into the second, water saturated stage. The research was undertaken during several experimental stages to test the influence of the recirculation ratio (system A) respectively of the feeding (system B; intermittent, continuous, batch). The highest elimination rates could be achieved with system B (dosage of methanol) during experimental stage 1 (intermittent loading four times a day). The mean elimination rates were 82% for Ninorg and 78% for TN. The TN elimination performance of system A was only a little lower (72%). The elimination of COD, BOD5 and TOC was no problem throughout the whole experimental period (effluent concentrations of both systems were well below the Austrian standards).