Plastic is everywhere, and sadly, it often ends up in many green waste bins. This causes composting site operators a lot of problems: they have to carefully separate unwanted bags and other plastic components from the organic waste in order to comply with legal regulations, including those of the German Fertilizer Ordinance (DüMV). However, composting site operators also want to achieve their own goal and offer high quality products to their customers, who are involved in the compost, gardening and agriculture industries.
For this reason, the Germany Federal Compost Association (BGK - Bundesgütegemeinschaft Kompost), responsible for awarding the RAL (German National Committee for Delivery Conditions) quality seal to compost products, has stiffened up requirements concerning unwanted materials. Currently, only 15 square centimetres of plastic elements per litre of compost will be tolerated, instead of 25 square centimetres, as previously. And very soon, organic farming regulations will only permit usage of composts with less than ten square centimetres of plastic.
All this is creating huge challenges for composters, which they can barely overcome just by using even finer screening: they would simply lose too many sellable fractions and find themselves in a precarious economic situation.
Doppstadt, which specializes in environmental technology, has created the Airflex 1500, which provides the technical solution for processing compost.
According to the company, wind sifters minimize the losses of compost product by improving its quality. To achieve this, the compost undergoes initial rough screening at 15 mm. The fines < 15 mm are than efficiently separated from unwanted materials in the Airflex 1500 in two stages. In the first step, a powerful centrifugal fan separates heavy materials such as glass, stones and metals. In the second step, a suction fan pulls away unwanted plastic films etc.
The result is a near plastic-free compost that complies with the requirements of the RAL quality seal.