forms such as sulfate so 4 2 u2212 sulfite so 3 2 u2212 thiosulfate s 2 o 3 2 u2212 sulfide s 2 u2212 and elemental sulphur 5 u00b0 the key forms of sulphur present in wastewater can be used as electron carrier to transfer electrons from organic carbon to oxygen through luxury p uptake and release anaerobic carbon uptake phas storage heterotrophic sulphur reduction poly s 2 u2212 s 0 storage and heterotrophic autotrophic denitrification and autotrophic nitrification by the sulphur cycle based poly phosphate accumulating organisms paos as a new type of process using paos which is not found in the conventional carbon based ebpr process this process can be described as a sulphur cycle based pao process which differs from processes in other biological wastewater treatment plant processes using paos in terms of operation the feed and the reaction of an aerobic sequencing batch reactor sbr can be combined into a single step moreover to enable a more efficient operation it is also possible to use a combination of several similar or identical biological p removal reactors and nitrification reactors operating in parallel in order to smooth out the operations through the sd ebpr process it is possible to achieve biological nutrient removal from wastewater while at the same time minimizes sewage.