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Possibilities for sustainable nutrient recycling by faecal separation combined with urine

Vinnerås, Björn (2002). Possibilities for sustainable nutrient recycling by faecal separation combined with urine. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 353
ISBN 91-576-6167-7
[Doctoral thesis]

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Household wastewater can be divided into three fractions by origin; urine, faeces and greywater. The largest nutrient and smallest heavy metal contents are found in the urine, which is easily collected separately using a urine-diverting toilet. The second most nutrient-containing fraction is the faecal matter. This fraction (faeces and toilet paper) has the smallest mass of the three, approximately 60 kg of wet weight per person and year. The nutrients in the urine and faeces have to be recycled to agriculture for society to be sustainable. The faecal matter can either be collected dry or, after a short waterborne transport, be separated from the flushwater in a separator that uses a combination of whirlpool effect, gravity and surface tension. Using this type of separation, between 58% and 85% of the faecal nutrients were separated in the measurements performed here. By recycling the urine and the faecal nutrients, much energy can be saved as the load on the wastewater treatment plant decreases and as mineral fertilisers are replaced in agriculture. To avoid transmission of diseases, the faecal matter has to be sanitised before recycling. If the faecal matter is collected dry, it is possible to perform the sanitation by thermal composting, preferably together with household biodegradable waste. A calculation method for determination of the safety margins for sanitation was developed. In a pilot-scale study, the safety margin for thermal composting of faeces and food waste, with old compost as an amendment, was approximately 37 times total inactivation of Enteroviruses, the most thermotolerant organism evaluated. Another sanitation method investigated was chemical disinfection using urea or peracetic acid. At a dosage between 0.5% and 1.0%, the highly reactive peracetic acid inactivated all investigated organisms within 12 hours of treatment. The high dry matter content (10% DM) meant that high dosages were needed. Lower dry matter content would decrease the dosage required for proper sanitation. A very promising treatment was the addition of urea. Addition of 30 g ureanitrogen per kg of wet weight faecal matter resulted in total inactivation of the monitored organisms, E. coli, Salmonella spp, Enterococcus spp, Salmonella typhimurium 28B phage and Ascaris suum eggs, within 50 days of treatment at 20°C. The spore-forming bacteria Clostridium spp in its dormant state was resistant to this treatment. As the urea has to be degraded to ammonia before it functions as a disinfectant, there is some delay in this treatment. Therefore, urea addition followed by 2 months storage is the preferred treatment for disinfection of separated faecal matter. As additional effects, urea increases the fertiliser value of the treated material and there is no risk of microbial regrowth. Changing to urine-diversion combined with faecal separation and disinfection by urea seems to be an interesting way to decrease the resource usage and possibly improve the hygienic standard of wastewater systems.

Authors/Creators:Vinnerås, Björn
Title:Possibilities for sustainable nutrient recycling by faecal separation combined with urine
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :August 2002
Number of Pages:88
ALLI. Vinnerås, B., Palmquist, H., Balmér, P., Weglin, J. Jensen, A., Andersson, Å. & Jönsson, H. The characteristics of household wastewater and biodegradable solid waste – a proposal for new Swedish norms. Submitted to Urban Water. II. Vinnerås, B. & Jönsson, H. (2002). Faecal separation for nutrient management – evaluation of different separation techniques. Urban Water in press. III. Vinnerås, B. & Jönsson, H. (2002). The potential of faecal separation and urine diversion to recycle plant nutrients in household wastewater. Bioresource Technology 84:3, 275-282 IV. Vinnerås, B. Björklund, A. & Jönsson, H. (2002). Thermal composting of faecal matter as treatment and possible disinfection method – Laboratoryscale and Pilot-scale studies. Bioresource Technology in press. V. Vinnerås, B. Holmqvist, A. Bagge, E. Albihn, A. & Jönsson, H. Potential of disinfection of separated faecal matter by Urea and by PAA for hygienic nutrient recycling. (Submitted to Bioresource Technology)
Place of Publication:Uppsala
ISBN for printed version:91-576-6167-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F04 Fertilizing
P Natural resources > P10 Water resources and management
Subjects:Not in use, please see Agris categories
Agrovoc terms:household wastes, urine, faeces, solid wastes, nutrients, cycling, recycling, fertilizer application
Keywords:Faecal separation, urine-diversion, nutrient recycling, wastewater composition, wastewater reuse, disinfection safety margins, sanitation, disinfection, thermal composting, chemical disinfection, urea, peracetic acid
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ID Code:332
Department:(LTJ, LTV) > Institutionen för lantbruksteknik
Deposited By: Staff Epsilon
Deposited On:21 Aug 2003 00:00
Metadata Last Modified:02 Dec 2014 10:03

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