THE IMPACT OF FOOD WASTE DISCHARGE INTO THE MUNICIPAL SEWERAGE ON COD CONCENTRATION IN URBAN WASTEWATER IN OLSZTYN

The operators of wastewater treatment plants in Poland have been observing an increase in the concentration of raw sewage for several years. In particular for organic substances. This is the effect of water consumption reduction, restoration of the sewerage networks, growing wealth, widespread waste of food. The most serious adverse, influencing on the municipal wastewater composition is colloid mills application in gastronomical objects and the discharge of shredded food waste to sewer. That widespread behavior has been noticed and negated, in 2010 year, by the common position of GIS and the ME. Far too late, which confirms the situation observed at the Olsztyn wastewater treatment plant, where the biggest increase of COD values was observed in 2008–2010. The average concentration of COD of sewage in the period 2011–2014 was almost twice higher than in 1996, real PE is close to the design value, despite the fact that the hydraulic load of the object slightly exceeded 50% of design value. Removing such large organic pollutant loads generates high costs, that could be avoided by reasonable food waste management.