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  • 1.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term hydraulic and treatment performance of a 19-year old constructed stormwater wetland: Finally maturated or in need of maintenance?2016Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 95, s. 73-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.

  • 2.
    Amofah, Lea Rastas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Mattsson, Jonathan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Willow bed fertigated with domestic wastewater to recover nutrients in subarctic climates2012Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 47, s. 174-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conventional methods for wastewater treatment emphasise protecting human health, receiving waters and the environment. Consequently, they are generally designed to reduce pollutant levels and are not well-suited for creating resources. This paper describes a new, more sustainable and energy-efficient approach to wastewater treatment that satisfies health and environmental standards while also facilitating resource recovery. A full-scale compact willow bed was intensively fertigated with domestic wastewater in a cold climate to examine biomass production, the recovery of nutrients in willow biomass, and wastewater treatment. The performance of the willow bed was assessed for two years, covering three growing seasons. The studied frost-tolerant willow clones produced good biomass yields per unit area (6–7 ton dry matter/ha and year) under intensive fertigation with dense planting and continuous harvesting. The biomass yield of willow species exhibiting vertical growth seemed to be greater than that for lateral growth species in the dense stands studied. In contrast to biomass production, nutrient recovery was facilitated by intensive fertigation, continuous harvesting and less dense planting with a horizontally growing willow clone. The estimated nitrogen accumulation in above-ground biomass was 210 kg/ha and that of phosphorus was 30 kg/ha. 90% of the accumulated nutrients in the above-ground biomass were removed from the site during the experimental period. However, the quantity of nutrients accumulated in the willow biomass represented only a small fraction of the loaded or removed amount. The willow bed was shown to be an efficient prefilter for reducing the abundance of particulate and organic matter, leaving the bulk of the remaining nutrients in forms that could be recovered in subsequent treatment steps.

  • 3. Blecken, Godecke-Tobias
    et al.
    Zinger, Yaron
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Deletic, Ana
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Fletcher, Tim D.
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Impact of a submerged zone and a carbon source on heavy metal removal in stormwater biofilters2009Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 35, nr 5, s. 769-778Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biofilters are an effective treatment option for the substantial heavy metal loads in urban stormwater. However, to increase their nitrogen treatment efficacy, the introduction of a submerged (anoxic) zone (SZ) and a cellulose based carbon source (C) has been recommended because it has been shown to enhance denitrification and thereby increase overall nitrogen removal. To examine the impact of this design modification on heavy metal treatment, a laboratory study using biofilter mesocosms with different levels of SZ and with or without added C was conducted. The results show that SZ and C have a significant impact on metal treatment. In particular, the removal of Cu was improved significantly. The presence of SZ and C allows outflow Cu concentrations to meet Swedish and Australian water quality guidelines, which are not met with a standard biofilter without SZ or C. Although Zn and Pb removal was enhanced slightly by the presence of a SZ, this improvement is of less practical importance, since Zn and Pb removal is already very high (>95%) in standard biofilters. The best metal treatment was achieved with 450 and 600 mm SZ. Based on these results, the incorporation of SZ with C in stormwater biofilters is recommended.

  • 4.
    Grönlund, Erik
    et al.
    Luleå tekniska universitet.
    Klang, Anders
    Mittuniversitetet.
    Falk, Stefan
    Mittuniversitetet.
    Hanaeus, Jörgen
    Sustainability of wastewater treatment with microalgae in cold climate, evaluated with emergy and socio-ecological principles2004Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 22, nr 3, s. 155-174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The sustainability of a microalgae wastewater treatment plant model (ALGA), assumed serving a small Swedish town with 10,000 inhabitants at latitude 60°N, was tested by comparing it to a conventional three-step treatment plant (WWTP), and a mechanical and chemical treatment plant (TP) complemented with a constructed wetland (TP + CW). Using two assessment methods-the socio-ecological principles method and emergy analysis-the ALGA model considered to have a better position for sustainable development, than the other two. In emergy terms the ALGA model had about half the resource use of the other two alternatives, and used most local free environmental resources, four times the TP + CW, and 100 times the WWTP. The violations against the second and third socio-ecological principles were considered equal for the three alternatives, the fourth was estimated to be in favor of the ALGA model, and the first principle was calculated to be in favor of the ALGA model with about eight times lower indicator value sum. Recirculation of nutrients back to society or production of economically viable products from the treatment by-products would strongly influence the sustainability. The ALGA model has a potential advantage due to interesting biochemical contents in the microalgae biomass, depending on what species will become dominating.

  • 5.
    Hellström, Daniel
    et al.
    Luleå tekniska universitet.
    Johansson, Erica
    Luleå tekniska universitet.
    Grennberg, Kerstin
    Luleå tekniska universitet.
    Storage of human urine: acidification as a method to inhibit decomposition of urea1999Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 12, nr 3-4, s. 253-269Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One strategy to increase the recycling ratio of nutrients from wastewater to agriculture is to handle urine separately and use it as a fertiliser in agriculture. Potential drawbacks to urine handling systems are the risk of ammonia evaporation and the relatively large volumes to be handled. The amount of urine solution could be reduced by using drying techniques if ammonia evaporation could be avoided. The objective of this project was to study how different acids could be used to prevent the decomposition of urea into ammonia during storage. The project was performed in two phases. The initial phase was conducted with one time dosage of urine in bottles of 0.5 l each to evaluate the effect of different storage conditions and to estimate suitable amounts of acids to be added. The second phase was conducted with multi-time dosages of urine, simulating the continuous addition of urine found in full-scale systems, in plastic cans of 10 l each. The results show that a one-time dosage of 60 meq sulphuric or acetic acid per litre undiluted urine at the beginning of the storage period could inhibit the decomposition of urea during more than 100 days of storage in cans with multi-time dosages of urine.

  • 6. Søberg, Laila C.
    et al.
    Blecken, Godecke
    Viklander, Maria
    Nitrogen removal in stormwater bioretention facilities: effect of drying, temperature and submerged zoneInngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992Artikkel i tidsskrift (Fagfellevurdert)
  • 7.
    Zinger, Yaron
    et al.
    Centre for Water Sensitive Cities, Department of Civil Engineering, Monash University.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Fletscher, Tim D.
    Department of Geography & Resource management, Melbourne University.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Deletic, Ana
    Centre for Water Sensitive Cities, Department of Civil Engineering, Monash University.
    Optimising nitrogen removal in existing stormwater biofilters: Benefits and tradeoffs of a retrofitted saturated zone2013Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 51, s. 75-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen excess is a key trigger for eutrophication of water bodies. Stormwater can be an important N source in urban environments and thus requires effective treatment. Stormwater biofilters can remove a wide range of pollutants. However, removal of N is often insufficient due to a lack of denitrification in freely drained biofilters. We tested whether existing stormwater biofilters with poor N removal could be enhanced if a saturated zone is retrofitted to create anaerobic conditions for effective denitrification. We evaluated this by measuring removal of nitrogen, phosphorus and metals in retrofitted biofilters using laboratory mesocosms. For over 18 months five replicates of typical biofiltration configurations, that include freely draining 690 mm deep loamy sand media above a 140 mm deep transition layer and a 70 mm gravel layer planted with popular plant species (Dianella revoluta, Microlaena stipoides and Carex appressa), were tested for typical operational conditions. The biofilter columns planted with D. revoluta and M. stipoides showed poor N removal, while biofilters planted with C. appressa were performing well. All columns were then retrofitted with a 450 mm deep saturated zone, and testing continued using the same operational conditions. After retrofitting the saturated zone, NOx removal was significantly increased (mean increase: 370% for Dianella and 180% for Microlaena) which enhanced overall N removal. TP removal was less efficient after retrofitting the saturated zone due to presence of organic matter in the filter media within the saturated zone. The removal of metals was not affected in practical terms, despite some statistically significant effects. The results of this study suggest that retrofitting a saturated zone in existing standard biofilters should be recommended if the existing filter has inadequate N removal and if N discharges pose a potential threat to the receiving environment.

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