| 1. |
- Batstone, Damien, et al.
(författare)
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Industrial applications of the IWA anaerobic digestion model No. 1 (ADM1)
- 2003
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Ingår i: Water Science and Technology. - 0273-1223. ; 47:12, s. 199-206
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the IWA anaerobic digestion model No. 1 (ADM1) is applied to two case studies from contract work on industrial treatment plants. The first was the assessment of acid addition for pH decrease and avoidance of calcium carbonate (CaCO3) precipitation in a paper mill fed UASB. The simulation work found, with a high degree of confidence, that acid dosing was neither economical for pH control, nor had any real effect on the CaCO3 levels present in the reactor. A specific calcium carbonate precipitation equation was added to the ADM1 to undertake this study. The second case study was an assessment of the benefits of thermophilic (as opposed to mesophilic operation) for reduced ammonia inhibition, improved stability and gas production in a solids digester at a gelatine production facility. Here, it was predicted that thermophilic operation could not attain either goal to a satisfactory extent. In addition to demonstrating the application of the ADM1 to the two systems, we have also assessed the predictions generated in the case studies in terms of quality and utility.
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| 2. |
- Biswas, AK, et al.
(författare)
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Workshop 3 (synthesis) : water, poverty alleviation and social programs
- 2003
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Ingår i: Water Science and Technology. - 0273-1223 .- 1996-9732. ; 47:6, s. 129-132
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Tidskriftsartikel (refereegranskat)abstract
- Poverty is a complex issue, which must be understood in a holistic manner. Low and variable income is certainly a key element, but it is far from enough to portray poverty. The various characteristics of poverty and their relative strength are determined through contextually specific circumstances, in terms of history, environmental preconditions, socio-cultural traits, etc. Much of this context is made up of local and national circumstances. The consequences of globalisation must, however, increasingly to be taken into account. At a larger scale, it is also relevant to mention that climate change will have a negative, although largely unpredictable, impact for the people in some parts of the world. For those who are already living on marginal lands or who are exposed to water problems, climate change is likely to create considerable adverse effects.
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| 3. |
- Bäckström, Magnus
(författare)
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Grassed swales for stormwater pollution control during rain and snowmelt
- 2003
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 48:9, s. 123-134
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Tidskriftsartikel (refereegranskat)abstract
- The retention of suspended solids, particles and heavy metals in different grassed swales during rain events and snowmelt is discussed. The experimental results derived from investigations performed in existing grassed swales in the Luleae. region, Northern Sweden. During high pollutant loading rates, grassed swales retain significant amounts of pollutants, mainly due to sedimentation of particulate matter. Low to moderate removal efficiencies could be expected for heavy metals, especially metals in solution (i.e. the dissolved phase). When grassed swales receive urban runoff with low pollutant concentrations, they may release rather than retain pollutants. Swales are important snow deposit areas in the city and particle bound pollutants do to a large extent remain in the swale after snowmelt. However, dissolved pollutants (i.e. dissolved heavy metals) are likely to escape the swale with the melt water. Grassed swales may be regarded as facilities that even out the peaks in pollutant loads without being capable of producing consistent high removal rates. This suggests that swales should be considered as primary treatment devices. Possible design parameters for grassed swales are mean hydraulic detention time, surface loading rate or specific swale area.
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| 4. |
- Cimbritz, Michael, et al.
(författare)
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Separation characteristics in dissolved air flotation - pilot and full-scale demonstration
- 2003
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Ingår i: Water Science and Technology. - 0273-1223. ; 48:3, s. 89-96
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Tidskriftsartikel (refereegranskat)abstract
- This study presents practical implications for particle separation in Dissolved Air Flotation (DAF). The objectives were to localise where particles are separated from the water phase and to determine what particles, in terms of size, are removed by the DAF-process. Both pilot- and full-scale plants were investigated. Particle sizes were analysed with a light-blocking particle counter and an optical borescope was used for visualisation of particle-bubble aggregates. It was found that particles are preferably separated upstream in the process, i.e. close to the contact zone. Furthermore, separation efficiency for particles increased with increasing particle size.
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| 5. |
- Farahbakhshazad, Neda
(författare)
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Phosphorus removal in a vertical upflow constructed wetland system
- 2003
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 48:5, s. 43-50
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Konferensbidrag (refereegranskat)abstract
- Mechanisms for P removal in a vertical upflow macrophyte system were studied in controlled laboratory columns filled with sand and planted with Phragmites australis. Substrate P removal was shown to increase with flow rate, a parameter which can be enhanced through effluent recirculation. An alternative substrate (leca, light expanded clay aggregate) provided improved equilibrium adsorption characteristics, but uncrushed and within the kinetic constraints of a macrophyte system gave no improvement for P adsorption over sand. Intermittent loading of the sand based macrophyte system permitted control of the P concentration, with lower effluent peak concentrations for increased resting interval (no P inflow). Where P loading was targeted, continuous flow provided the optimum mass removal conditions.
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| 6. |
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| 7. |
- Gruvberger, C, et al.
(författare)
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Sustainability concept for a newly built urban area in Malmo, Sweden
- 2003
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Ingår i: Water Science and Technology. - 0273-1223. ; 47:7-8, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- National goals regarding sustainable development from the Swedish government were decisive in the planning process when the newly built city district Western Harbour was established in the city of Malmo, Sweden. A systems analysis was used as a tool for evaluating different collection and treatment systems. This type of analysis does not include more subjective factors such as acceptance of organic fertilisers based on human waste and user acceptance of collection schemes. These aspects, however, will often determine the success of a technical solution. When the system for collection and treatment of solid organic waste and wastewater was designed, both subjective and objective factors were considered. This meant that a centralised solution for wastewater treatment was selected. In order to facilitate a more sustainable solution for sludge management a treatment process with recovery of phosphorus will have to be introduced. Organic waste is sorted out and treated in an anaerobic digestion process. Source sorting of solid organic waste has been difficult to implement in Sweden due to inadequate sorting discipline. As a consequence two relatively new systems are tested in the area. A comprehensive evaluation will be carried out during a period of two years.
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| 8. |
- Hansen, TL, et al.
(författare)
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Chemical characteristics and methane potentials of source-separated and pre-treated organic municipal solid waste
- 2003
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Ingår i: Water Science and Technology. - 0273-1223. ; 48:4, s. 205-208
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Tidskriftsartikel (refereegranskat)abstract
- A research project has investigated the biogas potential of pre-screened source-separated organic waste. Wastes from five Danish cities have been pre-treated by three methods: screw press; disc screen; and shredder and magnet. This paper outlines the sampling procedure used, the chemical composition of the wastes and the estimated methane potentials.
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| 9. |
- Ingildsen, P, et al.
(författare)
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Improved nutrient removal using in situ continuous on-line sensors with short response time
- 2003
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Ingår i: Water Science and Technology. - 0273-1223. ; 48:1, s. 95-102
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Tidskriftsartikel (refereegranskat)abstract
- Nutrient sensors that can be located directly in the activated sludge processes are gaining in number at wastewater treatment plants. The in situ location of the sensors means that they can be located close to the processes that they aim to control and hence are perfectly suited for automatic process control. Compared to the location of automatic analysers in the effluent from the sedimentation reactors the in situ location means a large reduction in the response time. The settlers typically work as a first-order delay on the signal with a retention time in the range of 4-12 hours depending on the size of the,settlers. Automatic process control of the nitrogen and phosphorus removal processes means that considerable improvements in the performance of aeration, internal recirculation, carbon dosage and phosphate precipitation dosage can be reached by using a simple control structure as well as simple PID controllers. The performance improvements can be seen in decreased energy and chemicals consumption and less variation in effluent concentrations of ammonium, total nitrogen and phosphate. Simple control schemes are demonstrated for the pre-denitrification and the post precipitation,system by means of full-scale plant experiments and model simulations.
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| 10. |
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