| 1. |
- Blomkvist, Pär, 1961-, et al.
(författare)
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Entrepreneurship and alignment work in the Swedish water and sanitation sector
- 2023
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Ingår i: Technology in society. - : Elsevier BV. - 0160-791X .- 1879-3274. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- Water and sewage (WS) systems are, like most grid based infrastructural systems, often centralised and hierarchical and the end user has almost no possibility to influence the technical standards, business models or system architecture. The preferred method for connecting new areas to the grid are underground water pipes and gravity flow for sewage. Thus, the WS system is “tightly coupled”. It is hard to change and conservative in its system culture, exhibiting a strong “momentum” or “path dependence”. In this article we investigate an unusual case in the development of WS-systems. As a rule, WS-systems, as most infrastructural systems, develop gradually through incremental innovations, and system owners/utilities traditionally build their systems “from the inside out”. In our case, we investigate a situation where the end users took the initiative to connect a residential area, Aspvik, part of the municipality of Värmdö, outside Stockholm, Sweden, to the municipal grid and thus expand the WS-system, not from the inside out, but from the outside in. Furthermore, we highlight another unusual feature: the role of a resident that acted as the “entrepreneur” in this process of WS-system expansion. The entrepreneur had unique trust building abilities in the local community, which the regime actor (the WS utility), could not match. Historically, inventor-entrepreneurs have been common, acting as “system builders” in the establishment phase of new infrastructural systems. However, entrepreneurs outside the regime are not common in the WS sector. Although atypical in mature WS systems in developed countries, these types of local initiatives or hybrid solutions are common in developing countries. In this article, we argue that there are lessons to be learnt from our case, when dealing with system expansion processes both inside and outside the Global North.
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| 2. |
- Bouzidi, B., et al.
(författare)
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Optimization of photovoltaic water pumping systems for date palm irrigation in the Saharan regions of Algeria : increasing economic viability with multiple-crop irrigation
- 2021
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Ingår i: Energy, Ecology and Environment. - : Joint Center on Global Change and Earth System Science of the University of Maryland and Beijing Normal University. - 2363-7692 .- 2363-8338. ; 6:4, s. 316-343
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Tidskriftsartikel (refereegranskat)abstract
- The Saharan regions of Algeria, which represent almost 90% of the total area of the country, have severe energy problems due to insufficient or lack of energy access. The sustainable development of those areas must aim at securing and increasing primary production, especially in the agricultural and pastoral sectors. The production itself depends on the supply of water available at great depths. However, the potential volumes of water pumped by photovoltaic water pumping systems are generally greater than the annual requirements for crop irrigation. In this study, we optimized the photovoltaic array, the storage tank and efficient use of the water produced by the pumping system for the irrigation of one hectare palm grove. This excess water produced was reduced by a judicious association by planting other crops (tomato, wheat and sweet pepper). The utilization rate has been improved from 56% to 86%, on the one hand. On the other hand, the impact of the yield and the prices on the economic viability was studied. The project is economically viable for a price per kg of date of 500.00 DA and a yield varying from 20 to 50 kg/tree, and the payback period varies from 3.34 to 1.22 years. The project is not economically viable for a price per kg of date of 100.00 DA/kg for a yield less than or equal to 30 kg/tree. A sensitivity analysis has shown that the photovoltaic water pumping system becomes more competitive than conventional diesel water pumping systems for diesel price beyond 53.98 DA/l (0.38 €). The results are very encouraging for the wide use of photovoltaic water pumping systems for multiple-crop irrigation in the Saharan regions.
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| 3. |
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| 4. |
- Diehl, S., et al.
(författare)
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Steady-state analyses of activated sludge processes with plug-flow reactor
- 2017
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 5:1, s. 795-809
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Tidskriftsartikel (refereegranskat)abstract
- Activated sludge processes (ASPs) consisting of a plug-flow reactor (PFR) and a settler are analyzed in steady-state operation using a reduced model consisting of one soluble substrate and one particulate biomass component modelling the dominating biological process. Monod biomass growth rate is assumed. Two settler models are studied. One is the commonly used ideal settler, or point settler, which is assumed to never be overloaded and to have unlimited flux capacity. The other recently published steady-state settler model includes hindered and compressive settling, and models a realistic limiting flux capacity. Generally, the steady-state concentration profiles within the PFR and the settler are governed by nonlinear ordinary differential equations. It is shown that the steady-state behaviour of the ASP can, however, be captured by equations without derivatives. New theoretical results are given, such as conditions by means of inequalities on input variables and parameters for a steady-state solution to exist. Another novel finding is that, if the incoming substrate concentration is increased from a low or moderate stationary value and the solids residence time is kept fixed, then this results in a lower effluent concentration in the new steady state. The steady-state equations are solved numerically for different operating conditions. For common parameter values, numerical solutions reveal that an ASP having a PFR, instead of a continuously stirred tank reactor, is far more efficient in reducing the effluent substrate concentration and this can be obtained for much lower recycle ratios, which reduces the pumping energy considerably.
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| 5. |
- Färm, Carina
(författare)
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Constructed Filters for Metal Reduction in Storm Water
- 2002
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Ingår i: Vatten. - 0042-2886. ; :3, s. 185-191
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Tidskriftsartikel (refereegranskat)abstract
- Increased demand for storm water treatment has created development in filtration technologies for storm water. Manufacturers are using different filtration facilities and different filter materials. Therefore there is a need - from manufacturers, universities and government organisations - to put together current knowledge and to clarify important aspects concerning constructed filter systems. The first part of this paper reviews filtration facilities for storm water, filter substrates that have been tested for heavy metal reduction, and processes for contaminant transport through filter substrates. The second part of the paper presents an investigation of pine bark, used as a substrate in gully-pot filters for metal reduction in storm water.
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| 6. |
- Färm, Carina
(författare)
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Evaluation of the accumulation of sediment and heavy metals in a storm-water detention pond
- 2002
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 45:7, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- Accumulation of sediments and water quality were investigated in a wet storm-water detention pond in central Sweden. The drainage area surrounding the pond was covered by a section of highway and secondary roads. Sediment samples were collected from the pond and heavy-metal concentrations analysed subsequently in the laboratory. The depth of accumulated sediments was measured at several points around the pond. The investigation showed that during the 18 months that had passed since the pond was constructed, a 5-8 cm layer of sediments had accumulated near the inlet, and a 1.5 cm layer near the outlet of the pond. Storm water passing through the detention pond showed an average reduction rate of 26-84% for total metal content, 67% for total N, 78% for total P and 92% for COD.
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| 7. |
- Färm, Carina
(författare)
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Filtration of Storm Water for Metal Reduction using Natural Filter Substrates
- 2002
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to immobilise pollutants in storm water—such as heavy metals that are either dissolved or bound to small particles—filter systems featuring various different filter substrates can be constructed to filtrate storm water. Two important parameters for the design and functioning of such a filter system include the load capacity and removal efficiency of the material used in the filter bed. These are essential considerations in the design of the filter itself. A sound knowledge of the operational and maintenance activities of these systems is also necessary for achieving reliable treatment systems. This paper describes an experiment where storm water from a section of highway and surrounding roads has been filtrated through experimental columns filled with specially selected natural filter materials—calcium silicate rock (opoka), zeolite and pine bark. Filtration was performed in a downward direction under unsaturated conditions. The efficiency of copper and zinc removal of a number of combinations of these filter substrates has been analysed. The average reduction of these metals in filtrated storm water was around 63–81%, depending on the combination of metal and filter substrate.
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| 8. |
- Färm, Carina
(författare)
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Metal Sorption to Natural Filter Substrates for Storm Water Treatment - Column Studies
- 2002
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Ingår i: The Science of the Total Environment. - 0048-9697. ; 298:1-3, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Storm water generated from road runoff contains pollutants such as metals that are either dissolved in storm water or bound to particulates. Using detention ponds for the treatment of storm water from road runoff, where particles can settle, can reduce the level of particulate-bound metals in the water, while small particles and dissolved matter pass through the detention pond. Some of these metals can be removed by filtrating water through specially constructed filter systems. This investigation is a laboratory study where different filter substrates were tested in order to evaluate their efficiency in reducing heavy metals from water. Metal solutions were filtered through columns filled with various substrates consisting of combinations of calcium silicate rock (opoka), zeolite and peat. The metal-removal efficiency was correlated to hydraulic load, and for the metal species the reduction efficiency decreased with increased hydraulic load. Mixtures of opoka and zeolite were found to be superior to the other filter-substrate combinations tested with regard to both hydraulic aspects and removal efficiency. Peat mixed with the calcium silicate rock was not successful due to clogging which stopped the experiment. A manufactured product made from the calcium silicate rock (burned opoka) was found to be less useful because of its calcium oxide (CaO) content. Among the tested filter substrates, mixtures of opoka and zeolite seemed to be the most useful compositions with respect to reduction-efficiency and clogging aspects. The removal capacity of metals varied from 0.6 to 1.8 kg m(-3) depending on the metal and the filter substrate.
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| 9. |
- Färm, Carina
(författare)
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Removal of heavy metals in water by pine bark
- 2003
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Ingår i: Vatten. - 0042-2886. ; :1
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Tidskriftsartikel (refereegranskat)abstract
- Metals that are dissolved in storm water can be removed by filtrating water through specially constructed filter systems. Pine bark is an interesting material for this purpose, but it needs further investigations regarding its removal efficiency of metals. This paper presents a laboratory study where pine bark was tested to evaluate its efficiency in reducing heavy metals in water. Metal solutions were prepared and used in batch tests with pine bark. The metal removal efficiency was correlated to different metal concentrations in the solution and different contact times between the pine bark and the metal solution. The results showed that a high metal removal was achieved after a short contact time. The metal removal was low for low metal concentrations (0.1 mg/L) and higher for metal concentrations from 1 to 10 mg/L. The removal capacity was found to be 2.6 g Cu, 1.3 g Zn and 3.8 g Pb per kg pine bark. An investigation of the influence of chloride in the metal solution showed that the metal removal decreased by 15-23 %, depending on the metal, in the presence of chloride. Sorption isotherms of Zn, Cu and Pb on pine are also presented in the paper.
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| 10. |
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