Reduction of Excess Activated Sludge By a High Pressure Jet Device

We have developed a simple, cost-effective and maintenance-free high pressure jet device (HPJD) to reduce excess activated sludge.  An HPJD consists of a tubular pipe with the edge of a nozzle and high pressure pump. Batch treatment of activated sludge by HPJD reduced sludge volume and increased dead cells. Based on these results, we investigated the effect of sludge volume reduction of high pressure jet device using a continuous reactor. We operated two pilot-scale activated sludge systems with HPJD and without HPJD. In comparison with the control system without HPJD, excess activated sludge production was reduced with HPJD by 63% and 65% for 37 day and 108 day operation. The application of HPJD did not deteriorate activated sludge sedimentation and reactor performances regarding organic carbon removal and nitrification but resulted in emergence of different microbial communities compared to those in the control system without HPJD.