Separately collected organic waste is usually taken to fermentation and/or composting plants. These convert it into high-quality compost and fermentation residues, which can then be used in agriculture and home gardens as fertilizer and for soil improvement.

Specifically, green waste and organic waste from Mainz are transported to the Essenheim biomass plant. The plant uses a combination of fermentation (without oxygen) and composting (with oxygen). It converts the delivered organic waste into energy and high-quality compost in around 42 days.

This compost or garden soil enriched with it can also be purchased by hobby gardeners in Essenheim. However, what no hobby gardener or farmer wants is microplastics in their fields, and that's where impurities come into play. There are still far too many plastic bags and other plastic items in Mainz's organic waste bins. A significant portion of these are sorted out as contaminants during the processing and end up in waste incineration. But some of the plastics cannot be sorted out and are broken down into tiny plastic particles during organic waste treatment through mechanical processes, which then end up back in our food as microplastics via the fields.

Since the stricter BioAbfV regulations came into force, composting plant employees can refuse to accept organic waste that contains more than three percent impurities. To ensure that organic waste does not end up in garbage collection vehicles in the first place, bins are usually inspected during collection.

Incorrectly filled organic waste bins are left behind. A sticker indicates that the bin has been filled incorrectly. In addition, the owners of the organic waste bins are contacted in writing and receive information materials. Those affected now have the option of either sorting the organic waste themselves or requesting a special collection as residual waste. The special collection must be paid for and only takes place on the day of regular residual waste collection. If organic waste bins are filled incorrectly on several occasions, the bin will be removed.

Regardless of what is written on the bag, plastic bags have no place in the organic waste bin in Mainz. Manufacturers of "compostable" waste bags are now required to include a notice on their products advising consumers to observe regional disposal regulations. Nevertheless, many of these plastic bags are still used for household organic waste disposal. The process used in the biomass plant, which turns organic waste into compost in only about 42 days, does not decompose the plastic bags during this time. These must be sorted out mechanically and end up as impurities in waste incineration. Plastic bags are strictly prohibited in organic waste in Mainz.

In principle, it is a good idea to collect organic waste separately. According to the Federal Statistical Office, we produced a total of 433 kilograms of household waste per capita in 2023. Of this, approximately 120 kilograms was separately collected organic waste (biowaste) that was recycled.  However, this is only part of the organic waste produced.

In Mainz, the costs for the separate disposal of organic waste up to a certain volume are included in the residual waste fees. This means that there are no additional costs for using an organic waste bin. These bins are for organic waste of plant or animal origin, i.e., kitchen and garden waste. In addition to vegetable peelings, this also includes cooked fruit, vegetables, and food scraps. However, liquid waste (soups or oils), cheese rinds with wax or plastic coating, and materials contaminated with feces (diapers and small animal litter) do not belong in the organic waste.

For the sake of simplicity, organic waste should be collected separately from residual waste. A small bucket within easy reach of the kitchen work area is particularly practical. The waste can then be packed in paper bags or newspaper for transport to the household's own organic waste bin. This also prevents the bin from

becoming dirty too quickly. Even more important than collecting organic waste separately is not producing it in the first place. According to a report by the German government, a total of around 11 million tons of food waste was thrown away along the food supply chain in 2020. Contrary to popular belief, 59 percent of this was generated in private households. You can find tips on food use in our list of links below.