At Öresundsverket wastewater treatment plant in Helsingborg,Sweden, they have problems with filamentous sludge during springtime, as do many other activated sludge plants. With ozonation of the return sludge flow Öresundsverket has drastically reduced the amount of filamentous sludge and significantly increased the quality of the water.
Ozone is a very strong oxidant, In the treatment of sludge containing filaments the ozone breaks up the filaments and improves the settling characteristics of the sludge, without any negative effect on the nitrification process. Before selecting ozonation a pilot study was carried out. Sludge Volume Index was reduced while the biological processes were not affected.
The complete ozone plant can be housed in a small container . At Öresundsverket the plant was complete with a dissolution system and a reaction tank. The container solution means that you do not need a new or existing building to install the plant. In addition, it can easily be placed close to the activated sludge process.
The ozone process has been used throughout Europe to treat filamentous sludge and for overall sludge reduction.