Green waste and organics – ever since these material streams have been collected separately in Germany, AKG Achauer has been an important player and frequently a development pioneer.

December 11, 2019

Andreas Achauer took over the company from his father, who founded it. With several locations, it treats waste for municipalities in southwestern Germany, as well as for private customers. The focus: composting and the production of biomass fuel.

In order to make high-energy fuel as well as quality compost from green waste input, it is separated into woody and weedy fractions upon arrival. “It took us a while to get our suppliers used to doing it, but now the process works quite well,” says Achauer.

The woody fraction is shredded and then screened. A new Multistar L3 has been doing the screening for a few months now. “There’s nothing better. Performance, screening results, energy consumption – it’s all good!” As usual, the medium fraction goes to cogeneration plants as fuel and the overlengths are reshredded. Achauer is trying something new with the fine fraction – using it as bedding in cow stalls. “It’s still a very new application, but it has potential” he says confidently. The larger weedy fraction is also shredded and composted in windrows. This gives 80,000 m3 of quality compost, most of which goes for substrates and to adjacent earthworks.

It is something of a challenge to get good compost out of the organic waste. The very high content of contraries, mostly plastic film, in many collection areas necessitates expensive screening and cleaning steps. But despite varying input quality Achauer is able to make clean compost. “We only use 20 percent of the permitted limit value for the surface index (Quality label german compost quality assurance organisation). I’d like to go even lower, but that isn’t economically viable.” Because quality has its price, or more precisely, effort. The screen overflow is reshredded and rescreened. A large of part of the compost is recovered in this way, so it doesn’t end up as a contrary that has to be taken to a waste incinerator for disposal.