The quality of composts prepared in automatic composters from fruit waste generated by the production of beverages

[Display omitted] •Organic compounds determined in compost leachate indicate ecotoxicity.•Terpenes dissoluble in water represents the highest ecotoxicity risks.•The addition of biochar does not decrease the leachability of toxic organic compounds.•The addition of sawdust increases the leaching of toxic tannins and methoxyphenols.•Bentonite effectively decreases toxicity for Daphnia magna and Poecilia reticulata. Ensuring the processing of food waste from the production of food and beverages intheautomatic composters can be difficult because of the physicochemical properties of input raw materials. Very often, the final product does not meet the requirements forcomposts according to the European Compost Network. Optimisation of input food waste from theproduction ofbeverages was performed by the addition of the bulk materials such assawdust and clay minerals (bentonite). Toxicity of the compost is caused by organic compounds with polar and non-polar properties. These compounds belong to the groups ofalcohols, aldehydes and ketones, carboxylic acids, tannin, and phenols, coumarins and terpenes. Phytotoxicity is mostly influenced by the group of terpenes. The addition ofsawdust used as bulking agent decreases the concentrations of almost all chemical compounds. Thegroup of tannin and compounds containing phenols represents an exception because these compounds are released from sawdust.