The biological desulfurization process produces sulfate (SO4) and elemental sulfur (S). The SO4 is drained out but the elemental sulfur will stick to the packing media and has to be removed on a regular bais. Biogasclean’s QSR® – Quick Sludge Removal – system is a vast improvement. Cleaning is required 2-4 times a year and can be done within one working day. During QSR® cleaning the tank is filled with water and pressurized air is injected in the bottom of the tank so the packing media is washed like in a big washing machine. The QSR® system makes it possible to clean the tank for sulfur and gypsum sludge without emptying the tank for packing media.