Prevention of M-A-P-fouling using DLC in a sewage treatment plant

This research deals with applications for coatings with amorphous carbon films, also called Diamond-Like Carbon (DLC) in the wastewater sector for the prevention of fouling with magnesium ammonium phosphate (M-A-P, MgNH4PO4, struvite). In a major sewage treatment plant a 300 mm long DN100 pipe was installed, which was coated inside with a-C:H:Si (hydrogenated amorphous carbon coating doped with silicon) coating of 5-10 µm thickness using a PACVD reactor at the Wels Campus of the University of Applied Science Upper Austria. The test trials (1 month, 5 months) showed heavy M-A-P fouling with uncoated test-tubes made of stainless steel of 1,5 mm and 15 mm. In contrast DLC-coated tubes had no contamination at all. Furthermore, there is an economic estimate about using DLC-type coatings inside pipe-stocks presented which showed the need for further scale-up and for the development of a suitable welding technology for DLC-coated pipe-stocks.