Håkan Jönsson
Swedish University of Agricultural Sciences
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Featured researches published by Håkan Jönsson.
Resources Conservation and Recycling | 1997
Magnus Dalemo; Ulf Sonesson; Anna Björklund; K. Mingarini; Björn Frostell; Håkan Jönsson; T. Nybrant; J-O Sundqvist; Lennart Thyselius
A simulation model, ORWARE (ORganic WAste REsearch), for the handling of organic waste in urban areas has been constructed. The model provides a comprehensive view of the environmental effects, pla ...
Environmental Monitoring and Assessment | 2000
B. Beck-Friis; M. Pell; U. Sonesson; Håkan Jönsson
Composting can be a source of N2O andCH4 production. In this investigation, differentcompost heaps of organic household waste weremonitored with the focus on potential formation ofCH4 and N2O in the heaps and emission ofthese gases from the heaps. The studied compost heapshad different compost ages, turning intervals andcompost sizes. The analysed compost gases containedbetween 1–3421 μL of N2O-N L-1 and 0–470 mL of CH4 L-1. The emission rates ofN2O and CH4 from the compost heaps werebetween 1–1464 mg N2O m-2 day-1 and0–119 000 mg CH4 m-2 day-1. These verylarge differences in compost gas composition andemission indicate the importance of compostmanagement. The results also give an understanding ofwhere in the composting process an increasing emissionof N2O and CH4 can occur.
Compost Science & Utilization | 2003
B. Beck-Friis; Sven Smårs; Håkan Jönsson; Ylva Eklind
Source-separated household organics were composted in a reactor at three oxygen levels, 16%, 2.5% and 1% in the compost gas. Short-chained fatty acids were initially present in the compost material, and were also produced during the mesophilic phase at all three oxygen levels. This indicated that partial anaerobic conditions existed. No NH3 emissions occurred during the mesophilic phase due to acidic conditions. Composting at 2.5% and 1% O2 concentrations prolonged the mesophilic phase and reduced the microbial activity as compared to 16% O2. This led to delayed and decreased emissions of NH3. Nitrous oxide was not formed during thermophilic conditions. Methane, which was measured at 2.5% and 1% O2, was only found during thermophilic conditions. The emission of methane indicates that anaerobic conditions occurred during the thermophilic phase. The main reactions regulating pH during composting were outlined involving the ion species VFA, NH4+/NH3 and CO2/HCO3−/CO32−.
Bioresource Technology | 2003
Björn Vinnerås; Anders Björklund; Håkan Jönsson
When using toilets where the urine and faeces are collected separately for reuse as nutrients in agriculture, the collected matter should be disinfected. One way to do this is by thermal composting. Composting of different material mixes was investigated in a laboratory-scale experiment. This showed that the best mixture for dry thermal composting was a mix of faeces, food waste and amendment. The urine was collected separately by use of urine-diverting toilets. A new method was developed to mathematically evaluate and estimate the safety margins of pathogen inactivation during thermal composting. The method is based upon a mathematical calculation of the number of times total inactivation (at least 12log(10) reduction) of the organisms is achieved. In a pilot-scale experiment, the disinfection of a faeces/food waste mix was performed with a calculated safety margin of more than 37 times the total die-off of Enteroviruses and some 550 times that of Ascaris. Thus, well functioning composting seems to be effective for disinfection of faecal matter. To get a high temperature in all of the material, the reactor has to have sufficient insulation. A major disadvantage is the initial need for handling the raw un-disinfected material. The degradation of the organic matter in the compost was almost 75%, resulting in a small final volume that could safely be recycled.
Bioresource Technology | 2002
Sven Smårs; L. Gustafsson; B. Beck-Friis; Håkan Jönsson
Earlier studies indicated that the activity in the initial phase of composting may be reduced when the temperature rises too fast under low pH conditions. A compost reactor experiment on household waste was designed to test whether the degradation time could be reduced by actively preventing the temperature from rising until the pH had reached a certain value. This experiment was performed by monitoring pH in the condensate from the cooled compost gas. The results from 3 + 3 runs with and without temperature control confirmed our hypothesis and a considerable reduction in composting time was achieved. One possible explanation for the results is that the microbes active in the low pH phase are hampered by high temperature. The abrupt rise in pH when the fatty acids are consumed seems to be a good marker of the point when temperature control can be discontinued.
Bioresource Technology | 2003
Björn Vinnerås; A. Holmqvist; Elisabeth Bagge; Ann Albihn; Håkan Jönsson
No efficient, reliable, and scale independent disinfection methods for toilet waste are available today for safe recycling of plant nutrients. Therefore, two chemical treatment methods, addition of urea or of PAA (a quaternary mixture of 15% peracetic acid, 15% hydrogen peroxide and 30% acetic acid), were evaluated for disinfection of faecal matter.Degradation of the added urea resulted in 30 g of ammonia nitrogen per kilogram of treated matter and a pH increase to approximately 9.3. This produced an efficient disinfection of E. coli, Enterococcus spp., and Salmonella spp. within 3 weeks (>6log(10) reduction) and a reduction of the chemical resistant Salmonella typhimurium 28b phage, corresponding to a decimal reduction within 7.5 days. No viable Ascaris suum eggs were found after 50 days of treatment. No reduction of spore forming Clostridia spp. was observed. Urea treatment proved to be efficient for disinfection of source separated faecal matter in a scale independent method used for safe recycling of nutrients found in the faecal matter.PAA reduced all of the above indicator organisms within 12 h after application. For this faecal material, with a dry matter content of approximately 10%, an addition of 0.5-1% of PAA (active substance, corresponding to 3.3-6.7% of the Proxitane 15 used) was required before no viable organisms were found in the material. However, this was not tested for the A. suum. No viable spore-forming bacteria or phages were detected. A high rate of bacteria regrowth occurred at 0.15% dosage and 5 days of treatment. PAA is an efficient alternative for disinfection of separated faeces if a rapid treatment is needed.
Waste Management | 2013
Cecilia Sundberg; Dan Yu; Ingrid H. Franke-Whittle; Sari Kauppi; Sven Smårs; Heribert Insam; Martin Romantschuk; Håkan Jönsson
Highlights ► High odour emission from food waste compost was correlated to low pH. ► Microbes in high-odour samples included Lactic acid bacteria and Clostridia. ► For odour prevention, try high initial aeration rate and recycled compost as additive.
Waste Management | 2009
Charles B. Niwagaba; M. Nalubega; B. Vinnerås; Cecilia Sundberg; Håkan Jönsson
In urine-diverting toilets, urine and faeces are collected separately so that nutrient content can be recycled unmixed. Faeces should be sanitized before use in agriculture fields due to the presence of possible enteric pathogens. Composting of human faeces with food waste was evaluated as a possible method for this treatment. Temperatures were monitored in three 78-L wooden compost reactors fed with faeces-to-food waste substrates (F:FW) in wet weight ratios of 1:0, 3:1 and 1:1, which were observed for approximately 20 days. To achieve temperatures higher than 15 degrees C above ambient, insulation was required for the reactors. Use of 25-mm thick styrofoam insulation around the entire exterior of the compost reactors and turning of the compost twice a week resulted in sanitizing temperatures (>or=50 degrees C) to be maintained for 8 days in the F:FW=1:1 compost and for 4 days in the F:FW=3:1 compost. In these composts, a reduction of >3 log(10) for E. coli and >4 log(10) for Enterococcus spp. was achieved. The F:FW=1:0 compost, which did not maintain >or=50 degrees C for a sufficiently long period, was not sanitized, as the counts of E. coli and Enterococcus spp. increased between days 11 and 15. This research provides useful information on the design and operation of family-size compost units for the treatment of source-separated faeces and starchy food residues, most likely available amongst the less affluent rural/urban society in Uganda.
Biodegradation | 2005
Cecilia Sundberg; Håkan Jönsson
Inhibition of the degradation during low pH conditions has been observed in fed-batch composting systems. To analyse this phenomenon, fed-batch composting of food waste with different amounts of starting culture was examined in laboratory reactor experiments. Changes in temperature, carbon dioxide evolution, pH, solids, ash and short chain organic acids were measured. In reactors with a daily feed rate of 24% or less of the starting culture, thermophilic temperatures occurred and the pH and carbon dioxide evolution were high and stable after a starting period of 4–5 days. In reactors with a daily feed rate of 48% or more of the starting culture the composting process failed, as the pH dropped below 6 and remained there and the temperature and carbon dioxide evolution were low. It was concluded that the use of adequate amounts of starting culture consisting of active compost can efficiently prevent low pH conditions and process inhibition in fed-batch composting of food waste.
Bioresource Technology | 2011
Cecilia Sundberg; Ingrid H. Franke-Whittle; Sari Kauppi; Dan Yu; Martin Romantschuk; Heribert Insam; Håkan Jönsson
Large-scale composting of source-separated household waste has expanded in recent years in the Nordic countries. One problem can be low pH at the start of the process. Incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. The pH of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81 mmol kg−1. The bacterial diversity in the waste samples was high, with all samples dominated by Gammaproteobacteria, particularly Pseudomonas and Enterobacteria (Escherichia coli, Klebsiella, Enterobacter). Lactic acid bacteria were also numerically important and are known to negatively affect the composting process because the lactic acid they produce lowers the pH, inhibiting other bacteria. The bacterial groups needed for efficient composting, i.e. Bacillales and Actinobacteria, were present in appreciable amounts. The results indicated that start-up problems in the composting process can be prevented by recycling bulk material and compost.