RESULTS

The following results were achieved during the experimental campaign of the LIFE LO2X project:

• >99% elimination of organic matter. The COD of SCWcO effluent is in average lower than 200 mgO2/L, reaching values even lower than 25 mgO2/L.

• 100% elimination of pesticides. Imazalil is degraded through SCWcO up to 350 mg/kg, four orders of magnitude higher than the concentration removed by anaerobic digestion.

• 100% elimination of pathogens. Escherichia coli, Clostridum perfringens and Salmonella spp. are eliminated. SCWcO leads to complete sterilization.

• >85% heavy metals are recaptured for safe handling. Heavy metals are mainly detected in inorganic solid fraction of the SCWcO effluent.

• Recovery of nutrients. Mineralization of nitrogen and phosphorus facilitates the nutrient recovery in order to be used as building blocks of fertilizers. Nitrogen occurs in the liquid phase (NH4~2 g/L) while phosphorus is present in the inorganic solid fraction of the SCWcO effluent (P2O5~25%).

• No highly harmful gases are produced. CO2 is the main gas generated by SCWcO. Typical undesired gaseous products from the combustion processes as NOx and SOx are not produced.

• 98% reduction of sewage sludge leaving WWTP. Total solid reduction higher than 90%. The inorganic solid fraction from SCWcO is a resource for phosphorous industry whereas wastes from anaerobic digestion may end up in the landfills.

• Zero heat consumption. The heat produced by the oxidation under supercritical conditions (highly exothermic reaction) makes pumping to be the only significant energy-consuming step (i.e., 1 kWh/kg dm) through SCWcO.

• >10% reduction in sludge treatment cost. The gate fee thanks to co-substrate treatment by SCWcO allows reducing the cost of sludge treatment below the cost of anaerobic digestion
  
  The figure below shows some experimental samples showing the clear differences between the feed (left) and the output effluent (centre), which soluble phase was comparable to the softened mains water sample (right).