Ecotechnological and Thermochemical Tools for Sustainable Sanitation

Significant amounts of fecal and sewage sludge are waiting for environmentally and economically sustainable treatment and recycling

Fecal and sewage sludges are valuable and hazardous materials at the same time. Their high concentrations of organic carbon and plant mineral nutrients are accompanied by biotic and abiotic pollutants. Due to the environmental and health risks of uncontrolled fluxes of pathogens, organic contaminants, heavy metals, main elements of plant mineral nutrition and greenhouse gases, the direct recycling of fecal and sewage sludges as soil amendments is of growing concern.

At the same time as the possible pollution of soils and foodstuffs, water bodies and the atmosphere put increasing pressure on the reuse of faecal and sewage sludges in agriculture, forestry and landscaping, their disposal in landfills has been permitted in many countries. Direct soil application and landfilling as low-cost treatment have therefore to be replaced more and more by other treatment options.

The development of sustainable sanitation systems has to meet technical, economic, social and environmental challenges

As a matter of fact, new sludge treatment and reuse systems have to be traced by measures that optimize the material, energy and (socio) economic balance of sanitation under given settings. To that effect, their design must be based on the current state of existing and the feasibility of future infrastructures, the quantity and quality of available feedstocks and interrelated aspects that refer inter alia to the use of the conditioned materials, such as their physicochemical characteristics, the climate and soil properties and the land use of the application sites. Against this background the UBZ is addressing two concepts of sludge treatment and reuse based on (i) ecotechnological conditioning and (ii) thermochemical conversion.

Ecotechnological Treatment of Sewage Sludge

Thermochemical Sludge Treatment and the Sewchar Concept

The so-called sewchar concept is based on the thermal carbonization of faecal and sewage sludge and the use of their charred products as carbon-sequestering soil amendments. Sewchar systems are conceptually and technically sophisticated and are aimed to be implemented into non-waterborne and waterborne sanitation systems.