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Report, 1995

Näring, kadmium och bakterier i hushållsavlopp: en fältstudie av ett urinsorterande avloppssystem med lecabädd i Östhammar

Carlsson Anna Lena

Abstract

The solutions we have today for on-she treatment of human effluents do not include recirculation of plant nutrients from households to agriculture. Instead nutrients leak in to nature and that results in over fertilized groundwater, rivers, lakes and seas. At the same time as water becomes polluted, agriculture needs a continued flow of nutrients from outside to maintain food production. The challenge today is to find solutions for wastewater treatment that inc1ude recirculation. In Uppland urine separation toilets combined with a leca filter for two households were installed in 1993. The leca layer acts as an absorbing medium of phosphorus as the wastewater passes. When the lee a has become saturated with phosphorus it will be used as a fertilizer in agriculture. This study aimed to evaluate this type of wastewater systems, with urine separation combined with a leca filter. One part of the evaluation was to calculate quantities and distribution of plant nutrients, cadmium and pathogenic bacteria in the wastewater. Another part was to investigate the reduction of nitrogen, phosphorus, pathogenic bacteria and organic matter in the leca filter. The investigation was done during seven weeks, May to July in 1995. Samples were taken from fresh and stored urine, the septic tank and from urine-separated wastewater into and out from the leca filter. The households' consumption of water was measured. The study showed that the amounts of nitrogen and phosphorus in the wastewater were higher than standard values according to report nr 4425 from Naturvårdsverket. The contents of nitrogen were 10 percent higher than standard values and of phosphorus 30 percent higher. The potassium contents, however, were 10 percent lower than the standard values. The percentage of potassium was considerably higher than what was found in literature. The cadmium contents of the wastewater were low. The urine separation system separated only half of the urine, probably because of toilet users' lack of precision and the toilet design. The reductions of nitrogen, organic matter and pathogenic bacteria in the leca filter were as high as in a sand filter. The reduction of phosphorus however was lower. Urine separation systems enable recirculation of plant nutrients to take place but the study shows that it is very important how the toilets are used otherwise urine may not be separated. The possibility to use humane urine as a source of plant nutrients in agriculture is high as the contents of plant nutrients in urine are high and of cadmium low. The function of the leca filter is not yet sufficient. It needs to be improved

Keywords

hushållsavlopp; kalium; näringsmängder; fosfor; kadmium; urinsortering; lecabädd

Published in

Meddelanden från Jordbearbetningsavdelningen
1995, number: 19
Publisher: Institutionen för markvetenskap, Avdelningen för jordbearbetning, Sveriges lantbruksuniversitet

Authors' information

Carlsson, Anna Lena
Swedish University of Agricultural Sciences, Department of Soil Sciences

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Fish and Aquacultural Science

URI (permanent link to this page)

https://res.slu.se/id/publ/30624