A collection and treatment system for organic waste and wastewater in a sensitive rural area

Abstract

In the municipality of Sund, located in a sensitive rural area in Åland, a demonstration project is now carried out with the overall objective to move the most concentrated fractions of wastewater from the coastal area to a treatment plant situated close to arable land. Blackwater and greywater septic sludge from about twenty households and two tourist camps are treated together with energy rich organic material from a nearby potato-chip factory. The collection concept is based on the use of extremely efficient water-saving toilets, with separate systems for the blackwater and greywater in the households. The collected materials are co-treated in a batchwise aerobic thermophilic treatment process (wet composting process), where the materials reach at least 55°C during a minimum of 10 hours. The dry matter content of the collected material was about 2%. After stabilisation and sanitation (by the temperature rise caused by microbial activity during the treatment process), the compost slurry is utilized as a liquid organic fertilizer on arable land.

Assessing the sustainability of on-site sanitation systems using multi-criteria analysis

“…Other treatment options such as anaerobic digestion could also be considered if the aim is to increase the energy recovery in the form of biogas and reduce the emissions. 74 Wet composting of BW, on the other hand, would generally require some energy input for stirring and aeration 12 and to increase the temperature, 75 and the O&M costs can be twice that of urea treatment. 63 In comparison, the urine diversion alternative S2 had a higher risk of pathogen discharge since the feces were treated in a sand filter on-site.…”