Decomposition dynamics of cooking-oil-soaked waste paper in media with low inorganic nitrogen content

Abstract

Many paper-related products are in daily use all over the world. Although paper is one of the most recycled materials in the European Union, no end-of-waste criteria have been defined. Typical paper and cardboard should be recycled, but paper materials with impurities, such as cooking oil, sand, or plastic, are much more problematic. In particular, paper contaminated with cooking oil or butter (e.g., pizza boxes) is difficult waste. Also baking parchment paper cannot be stored as waste paper after use. Composting could be a solution, but in many municipal solid waste collection systems, this waste types are collected with the mixed waste stream, what finally leads this material to landfilling or incinerating processes. Parchment paper and pizza box cardboard contain a lot of cellulose and in landfills are a source of CO2 and CH4. Incineration of these materials also leads to CO2 emission. The aim of this study was to investigate the degradation of cooking-oil-contaminated paper in media with a low inorganic nitrogen content. Cardboard usually used for packaging purposes was used as pre-test material. Two types of paper usually used in the kitchen were used: pizza box cardboard and parchment paper highly contaminated with cooking oil. Two types of low inorganic nitrogen media were tested: mature municipal waste compost (MSWC) and leaf mold (LM). The decrease of mass of both paper sample types was correlated with process time. Both tested sample types: dry cellulose materials and paper with cooking oil added, were partly or completely decomposed after 6 weeks of bioprocessing in aerobic conditions without an additional dose of inorganic nitrogen. According to waste separation rules, wet paper or paper contaminated with cooking oil have to be stored with other wastes which are „not possible for further use”. This work show possibility to change these rules.