Submersible mixers made by Landia have successfully completed eight years of untroubled operation at one of the largest wastewater treatment plants in Germany.

Submersible mixers made by Landia have successfully completed eight years of untroubled operation at one of the largest wastewater treatment plants in Germany. At the Bremen-Seehausen WWTW, which handles approx 62.8 million m3 of wastewater every year, Landia mixers have been working non-stop, 24-hours per day, seven days per week for a full eight years. One of the benefits that the 26 submersible Landia POP-I mixers bring to the plant is the highly efficient mixing of wastewater with activated sludge, which has to meet stringent environmental requirements laid down by German law.

'The mixers have operated satisfactorily through the years and so far we have had no problems', says Mr Sven Wedderman, Head of Process Technology at the Bremen-Seehausen WWTW (hanseWasser Seehausen WWTP).

The utility value of the biological process and the quality of the treated wastewater at Bremen-Seehausen depend very much on the reliability of the Landia mixers, which apart from routine servicing, have proved virtually trouble-free.

Landia POP-1 mixers continue to ensure that all bacteria and organic matters in Bremen-Seehausen are equally suspended throughout the whole tank volume, creating optimum homogenised wastewater for a biological process that has a cleaning performance of 91% for COD, 92% for phosphorous and 79% for nitrogen.

The slow-speed Landia POP-I 1.5 kW-150 rpm flowmakers are also very energy efficient, designed to to provide a gentle treatment of the medium with thorough, efficient mixing, achieved by a low number of propeller revolutions.

This greatly improves flocculation and ensures the biological balance.

The low number of revolutions also creates less turbulence on the surface and thus prevents oxidation in the anoxic tank.