In the last couple of years Mycolata has become an increasing problem when it comes to foaming in activated sludge wastewater treatment plants in both Denmark and other countries. At the moment Kemira Water A/S is developing a new product concept called Kemira Water Bulk Control 100 (BC-100). The purpose of this product is to control Mycolata and thereby reduce problems with foaming. BC-100 has therefore been tested in a full scale survey at Øster Hornum Wastewater Treatment Plant over a period of 10 weeks. The test showed that BC-100 can in fact control Mycolata and reduce foaming in the process tank. It also revealed that BC-100 has an effect on the filaments identified as Type 0041/0675 (Chloroflexi). This can be very useful information considering the fact that Type 0041/0675 is one of the most common filaments creating bulking problems in activated sludge wastewater treatment plants in Denmark. Unfortunately the product also had a strong influence on the floc forming bacteria in the sludge. Therefore it is necessary to conduct more experiments that can clarify the effect and efficiency of the product so that the use of BC-100 as a control chemical against problems regarding filaments can be optimized. An analysis of the designs and processes at both Øster Hornum Wastewater Treatment Plant and Hvilsom Wastewater Treatment Plant showed that both plants have a large unused capacity that can be used for denitrification in the future. This may also help controlling Mycolata.