Performance of lagoon and constructed wetland systems for tertiary wastewater treatment and potential of reclaimed water in agricultural irrigation.

Climate change poses challenges to agricultural water resources, both in terms of quantity and quality. As an adaptation measure, the new European Regulation (EU) 2020/741 establishes different water quality classes for the use of reclaimed water in agricultural irrigation. Italy is also working on the definition of a new regulation on reclaimed water reuse for agricultural irrigation (in substitution of the current one) that will also include the specific requirements imposed by the European one.

Comparison of simple models for total nitrogen removal from agricultural runoff in FWS wetlands.

Free water surface (FWS) wetlands can be used to treat agricultural runoff, thereby reducing diffuse pollution. However, as these are highly dynamic systems, their design is still challenging. Complex models tend to require detailed information for calibration, which can only be obtained when the wetland is constructed.

Developing sanitation planning options: A tool for systematic consideration of novel technologies and systems.

To provide access to sustainable sanitation for the entire world population, novel technologies and systems have been developed. These options are often independent of sewers, water, and energy and therefore promise to be more appropriate for fast-growing urban areas. They also allow for resource recovery and and are adaptable to changing environmental and demographic conditions what makes them more sustainable.

Aeration intensity simulation in a saturated vertical up-flow constructed wetland.

Simulation and performance results of a saturated vertical up-flow constructed wetland (SVU CW) operated under different operational conditions are presented. The SVU CW consists of two different systems planted with Cyperus alternifolius and Iris pseudacorus, and each system consists of three SVU beds operated in series. The SVU CW operates in continuous aeration (CA) mode using different air-water ratios from 0.

Influence of design parameters on the treatment performance of VF wetlands - a simulation study.

The main approach for designing vertical flow (VF) treatment wetlands is based on areal requirements ranging from 2 to 4 m per person equivalent (PE). Other design parameters are the granularity of the filter material, filter depth, hydraulic and organic loading rates, loading intervals, amount of single doses as well as the number of openings in the distribution pipes. The influence of these parameters is investigated by running simulations using the HYDRUS Wetland Module for three VF wetlands with different granularity of the filter material (0.

The new German standard on constructed wetland systems for treatment of domestic and municipal wastewater.

The German Association for Water, Wastewater and Waste e.V. (DWA) has published a new standard for the dimensioning, construction, and operation of constructed wetlands for treatment of domestic and municipal wastewater.

Numerical simulation of vertical flow wetlands with special emphasis on treatment performance during winter.

In Austria, single-stage vertical flow (VF) wetlands with intermittent loading are a state-of-the-art technology for treating domestic wastewater. They are designed according to the Austrian design standard with a specific surface area of 4 m per person (i.e.

Treatment wetlands in decentralised approaches for linking sanitation to energy and food security.

Treatment wetlands (TWs) are engineered systems that mimic the processes in natural wetlands with the purpose of treating contaminated water. Being a simple and robust technology, TWs are applied worldwide to treat various types of water. Besides treated water for reuse, TWs can be used in resources-oriented sanitation systems for recovering nutrients and carbon, as well as for growing biomass for energy production.

Non-equilibrium model for solute transport in differently designed biofilters targeting agricultural drainage water.

Biogeochemical processes in subsurface flow constructed wetlands are influenced by flow direction, degree of saturation and influent loading position. This study presents a simulation tool, which aims to predict the performance of the unit and improve the design. The model was developed using the HYDRUS program, calibrated and verified on previously measured bromide (Br) pulse tracer tests.

Survey on number and size distribution of treatment wetlands in Austria.

In Austria, 1,840 wastewater treatment plants (WWTPs) with design size >50 population equivalent (PE) serve about 95% of the population. The remaining 5% of the population live in single houses and small settlements that require on site and decentralized wastewater treatment technologies. There is no common database on small WWTPs with design size <50 PE; thus data had to be collected from the Austrian federal states and compiled in a database.

Using numerical simulation of a one stage vertical flow wetland to optimize the depth of a zeolite layer.

This simulation study investigates the treatment performance of a compact French vertical flow wetland using a zeolite layer in order to increase ammonium nitrogen removal. For the modelling exercise, the biokinetic model CW2D of the HYDRUS Wetland Module is used. The calibrated model is able to predict the effect of different depths of the zeolite layer on ammonium nitrogen removal in order to optimize the design of the system.

Performance of subsurface flow constructed wetland mesocosms in enhancing nutrient removal from municipal wastewater in warm tropical environments.

Nutrient-rich effluents from municipal wastewater treatment plants (WWTPs) have significantly contributed to eutrophication of surface waters in East Africa. We used vertical (VF, 0.2 m(2)) and horizontal (HF, 0.

Sensitivity analysis of the CLARA Simplified Planning Tool using the Morris screening method.

The Morris screening sensitivity analysis (SA) has been used to assess how the uncertainty of input parameters influences the output of the CLARA Simplified Planning Tool (CLARA-SPT). To assess the sensitivity of the tool, four hypothetical waste collection and treatment alternatives, which planned to serve 10,000 people, have been proposed and analysed. These alternatives are (A1) dry sanitation with urine diversion dry toilets (UDDTs), (A2) water-aided sanitation with decentralised treatment units, (A3) water-aided sanitation with central technical treatment and (A4) water-aided sanitation with cesspits.

Experiences from the full-scale implementation of a new two-stage vertical flow constructed wetland design.

This paper describes the results of the first full-scale implementation of a two-stage vertical flow constructed wetland (CW) system developed to increase nitrogen removal. The full-scale system was constructed for the Bärenkogelhaus, which is located in Styria at the top of a mountain, 1,168 m above sea level. The Bärenkogelhaus has a restaurant with 70 seats, 16 rooms for overnight guests and is a popular site for day visits, especially during weekends and public holidays.

Experiences with pre-precipitation of phosphorus in a vertical flow constructed wetland in Austria.

Using constructed wetlands (CWs) with vertical flow and intermittent loading, high organic matter and ammonium removal can be achieved. In the case of additional requirements for phosphorus removal, which in Austria often occurs if the treated wastewater is discharged into small sensitive receiving waters, additional measures have to be taken. The objective of this work was to investigate the applicability of conventional phosphorus pre-precipitation with sodium aluminate for a CW system.

Are constructed treatment wetlands sustainable sanitation solutions?

The main objective of sanitation systems is to protect and promote human health by providing a clean environment and breaking the cycle of disease. In order to be sustainable, a sanitation system has to be not only economically viable, socially acceptable and technically and institutionally appropriate, but it should also protect the environment and the natural resources. 'Resources-oriented sanitation' describes the approach in which human excreta and water from households are recognized as resource made available for reuse.

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

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.

Comparison of nitrogen elimination rates of different constructed wetland designs.

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.

Numerical modelling: a tool for better constructed wetland design?

There is a need for a simplified computer-based design tool for subsurface flow constructed wetlands (CWs) which is based on process-based numerical models. Parameters of existing design guidelines and rules have been derived from experiments under specific conditions. Therefore designing CWs using these parameters is limited to these conditions (i.

Comparison of single-stage and a two-stage vertical flow constructed wetland systems for different load scenarios.

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.

CWM1: a general model to describe biokinetic processes in subsurface flow constructed wetlands.

This paper presents the Constructed Wetland Model No1 (CWM1), a general model to describe biochemical transformation and degradation processes for organic matter, nitrogen and sulphur in subsurface flow constructed wetlands. The main objective of CWM1 is to predict effluent concentrations from constructed wetlands without predicting gaseous emissions. CWM1 describes aerobic, anoxic and anaerobic processes and is therefore applicable to both horizontal and vertical flow systems.

Experiences with a top layer of gravel to enhance the performance of vertical flow constructed wetlands at cold temperatures.

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).