Malmö, Sweden
Malmö, Sweden
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Gustavsson D.J.I.,VA SYD | La Cour Jansen J.,Lund University
Water Science and Technology | Year: 2011

Biological treatment in wastewater treatment plants (WWTPs) is a source of nitrogen oxides (N 2O, NO and NO 2) emitted to the atmosphere. Aerobic ammonia-oxidising bacteria (AOB) have been suggested to be the main source of these emissions. In a full-scale sludge liquor treatment plant at Sjölunda WWTP, it was shown that significant emissions of N 2O, NO and NO 2 do occur. The plant is operated with nitritation alone, which gives an environment enriched in aerobic AOB. During normal operation, emissions of N 2O, NO and NO 2 were found to be 3.8%, 0.06% and 0.01% of the ammonium nitrogen load. The N 2O emissions were larger than the recommended estimated figure of the Intergovernmental Panel on Climate Change (IPCC) for a complete wastewater treatment plant. The N 2O emissions correlated positively with the length of the previous anoxic period, i.e., settling and decantation, and with the ammonium oxidation rate. The NO and NO 2 emission profiles were similar and dependent on ammonium oxidation and DO level, but the NO 2 concentrations were always lower. © IWA Publishing 2011.

Gustavsson D.J.I.,VA SYD | Nyberg U.,VA SYD | La Cour Jansen J.,Lund University
Environmental Technology | Year: 2011

The separate treatment of sludge liquor, produced by dewatering anaerobic digested sludge at wastewater treatment plants, gives rise to extreme environments for nitrogen removal. A full-scale sequencing batch reactor was operated with the aim of introducing and studying denitritation as a supplement to nitritation in order to reduce operating costs. Since the main plant only has problems with ammonium reduction capacity, the initial strategy was to have sufficient ammonium reduction with optimal alkalinity production by denitrifiers, i.e. low carbon dosage and minimum alkalinity and residual oxidized ammonium in the effluent. This strategy led to an unbalanced and sensitive process because the denitrifiers were often inhibited. High dissolved oxygen (DO) readings and no decrease in oxidation-reduction potential (ORP) during anoxic phases with simultaneous ethanol dosage indicated inhibition of denitrifiers, probably by the intermediate product NO, which may have interfered with the DO sensor. Nitric oxide production was believed to be favoured in the beginning of the anoxic phase as a result of low pH and high nitrite concentration. A stable nitritation-denitritation process could be achieved when the aerobic hydraulic retention time (HRT) was decreased to the same length as the anoxic HRT, which resulted in increased unused alkalinity. © 2011 Taylor & Francis.

Bernstad A.,Lund University | Davidsson T.,Lund University | Tsai J.,Lund University | Persson E.,Lund University | And 2 more authors.
Waste Management | Year: 2013

An unconventional system for separate collection of food waste was investigated through evaluation of three full-scale systems in the city of Malmö, Sweden. Ground food waste is led to a separate settling tank where food waste sludge is collected regularly with a tank-vehicle. These tank-connected systems can be seen as a promising method for separate collection of food waste from both households and restaurants. Ground food waste collected from these systems is rich in fat and has a high methane potential when compared to food waste collected in conventional bag systems. The content of heavy metals is low. The concentrations of N-tot and P-tot in sludge collected from sedimentation tanks were on average 46.2 and 3.9. g/kg TS, equalling an estimated 0.48 and 0.05. kg. N-tot and P-tot respectively per year and household connected to the food waste disposer system. Detergents in low concentrations can result in increased degradation rates and biogas production, while higher concentrations can result in temporary inhibition of methane production. Concentrations of COD and fat in effluent from full-scale tanks reached an average of 1068. mg/l and 149. mg/l respectively over the five month long evaluation period. Hydrolysis of the ground material is initiated between sludge collection occasions (30. days). Older food waste sludge increases the degradation rate and the risks of fugitive emissions of methane from tanks between collection occasions. Increased particle size decreases hydrolysis rate and could thus decrease losses of carbon and nutrients in the sewerage system, but further studies in full-scale systems are needed to confirm this. © 2012 Elsevier Ltd.

Bernstad A.,Lund University | La Cour Jansen J.,Center for Chemistry and Chemical Engineering | Aspegren H.,VA SYD
Waste Management and Research | Year: 2011

The environmental impact of an extended property close source-separation system for solid household waste (i.e. a systems for collection of recyclables from domestic properties) is investigated in a residential area in southern Sweden. Since 2001, households have been able to source-separate waste into six fractions of dry recyclables and food waste sorting. The current system was evaluated using the EASEWASTE life cycle assessment tool. Current status is compared with an ideal scenario in which households display perfect source-separation behaviour and a scenario without any material recycling. Results show that current recycling provides substantial environmental benefits compared to a non-recycling alternative. The environmental benefit varies greatly between recyclable fractions, and the recyclables currently most frequently source-separated by households are often not the most beneficial from an environmental perspective. With optimal source-separation of all recyclables, the current net contribution to global warming could be changed to a net-avoidance while current avoidance of nutrient enrichment, acidification and photochemical ozone formation could be doubled. Sensitivity analyses show that thetype of energy substituted by incineration of non-recycled waste, as well as energy used in recycling processes and in the production of materials substituted by waste recycling, is of high relevance for the attained results. © The Author(s) 2011.

Gustavsson D.J.I.,VA SYD | Tumlin S.,Gryaab
Water Science and Technology | Year: 2013

This study estimates the carbon footprints of 16 municipal wastewater treatment plants (WWTPs), all situated in Scandinavian countries, by using a simple model. The carbon footprint calculations were based on operational data, literature emission factors (efs) and measurements of greenhouse gas emissions at some of the studied WWTPs. No carbon neutral WWTPs were found. The carbon footprints ranged between 7 and 108 kg CO2e P.E.-1 year-1. Generally, the major positive contributors to the carbon footprint were direct emissions of nitrous oxide from wastewater treatment. Whether heat pumps for effluents have high coefficient of performance or not is extremely important for the carbon footprint. The choice of efs largely influenced the carbon footprint. Increased biogas production, efficient biogas usage, and decreased addition of external fossil carbon source for denitrification are important activities to decrease the carbon footprint of a WWTP. © IWA Publishing 2013.

Bernstad A.,Lund University | La Cour Jansen J.,Lund University | Aspegren A.,VA SYD
Resources, Conservation and Recycling | Year: 2013

Comparisons were made between two groups of households in a multi-family residential area in order to investigate how oral information through a door-stepping campaign can influence household food waste recycling behaviour from a quantitative as well as qualitative perspective. Source-separation behaviour was assessed both through weakly weighting of all source-separated food waste and dry recyclables as well as residual waste generated over a period of 104 weeks, as well as repeated waste composition analyses. Introduction of source-separation of food waste for biogas production significantly decreased the generation of residual waste in the whole case-study area. An average generation of 0.72 and 0.71 kg, household-1, week-1 of separately collected food waste was found amongst households receiving and not contacted through the door-stepping campaign respectively. The difference between the groups was not statistically significant. Four waste composition analyses show that the average source-separation ratio of food waste was higher and the ratio of incorrectly sorter material lower in the food waste fraction amongst households where oral information had been provided. A decrease over time in the source-separation ratio of food waste amongst households receiving oral information suggests a low durability of the door-stepping campaign. No signs were seen of increased source-separation ratio or decreased ratio of incorrectly sorted material amongst dry recyclables. The study supports previous findings pointing at accessibility as a key factor for increased recycling behaviour. However, results also suggest that such systems must address convenience also in the household interior. © 2012 Elsevier B.V.

Modin O.,Chalmers University of Technology | Gustavsson D.J.I.,VA SYD
Water Science and Technology | Year: 2014

Microbial bioelectrochemical systems (BESs) utilize living microorganisms to drive oxidation and reduction reactions at solid electrodes. BESs could potentially be used at municipal wastewater treatment plants (WWTPs) to recover the energy content of organic matter, to produce chemicals useful at the site, or to monitor and control biological treatment processes. In this paper, we review bioelectrochemical technologies that could be applied for municipal wastewater treatment. Sjölunda WWTP in Malmö, Sweden, is used as an example to illustrate how the different technologies potentially could be integrated into an existing treatment plant and the impact they could have on the plant's utilization of energy and chemicals. © IWA Publishing 2014.

Bengtsson L.,Lund University | Milloti S.,VA Syd
Hydrological Processes | Year: 2010

Short-term very intensive storms in the years 1980-2007 from rain gauges in Malmö have been analysed to find intensities of long return periods and to investigate trends. Observations from different stations have been pooled into series to which probability functions have been adjusted. Quality control of short-term precipitation records is emphasized. In order to investigate whether high rain intensities are different today compared to back in time, new and old rain data have been compared. Trends over the last 25 years have been computed for storms of duration 10 min to 1 h, and for 89 years of daily rains. A literature review of investigations of changing rain intensities is presented. It is found that 10- to 25-year long rain series from single stations are too short to give good estimates of storms of long recurrence time because a single event influences much. The largest observed rains in Malmö in the investigated period have a return period of about 20-50 years. For the very short-term storms, 50-year old intensity-duration-frequency curves do not differ much from those derived from new data. Trend analysis shows changing short-term high storm intensities only for storms of 10-min duration. © 2010 John Wiley & Sons, Ltd.

Bernstad A.,Water and Environmental Engineering | La Cour Jansen J.,Water and Environmental Engineering | Aspegren H.,VA SYD
Waste Management and Research | Year: 2012

A system with property-close source-separation of thirteen different solid household waste fractions in a residential area in southern Sweden, including the implementation of new systems for source-separation of food waste, waste electric and electronic equipment, hazardous waste and fat, oils and grease was monitored over a 2-year period. Continuous weighing of disposed waste and repeated waste composting analyses were used to investigate recycling behaviour of households in the area and to monitor the composition of disposed waste. Results show that 34% of the total amount of generated waste was currently diverted to material recycling. The removal of recyclables from residual waste could be significantly increased, as more than 80% of all waste in the area (bulky waste excluded) was either covered by the Producer Responsibility Ordinances on packaging and newspaper or constitutes food waste suitable for biogas production. Food waste still represented almost 30% of all residual waste in the study area and was thus the fraction with the greatest potential (on weight basis) for increased source-separation. © International Solid Waste Association 2012.

Bernstad A.,Lund University | la Cour Jansen J.,Lund University | Aspegren H.,VA SYD
Waste Management | Year: 2011

Through an agreement with EEE producers, Swedish municipalities are responsible for collection of hazardous waste and waste electrical and electronic equipment (WEEE). In most Swedish municipalities, collection of these waste fractions is concentrated to waste recycling centres where households can source-separate and deposit hazardous waste and WEEE free of charge. However, the centres are often located on the outskirts of city centres and cars are needed in order to use the facilities in most cases. A full-scale experiment was performed in a residential area in southern Sweden to evaluate effects of a system for property-close source separation of hazardous waste and WEEE. After the system was introduced, results show a clear reduction in the amount of hazardous waste and WEEE disposed of incorrectly amongst residual waste or dry recyclables. The systems resulted in a source separation ratio of 70. wt% for hazardous waste and 76. wt% in the case of WEEE. Results show that households in the study area were willing to increase source separation of hazardous waste and WEEE when accessibility was improved and that this and similar collection systems can play an important role in building up increasingly sustainable solid waste management systems. © 2010 Elsevier Ltd.

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