We are renovating an old building and we have discovered this mould behind the macerator and the kitchen units. The white stuff it is growing on seems to be polystyrene - perhaps an attempt at insulation. The kitchen is very damp and in the basement. The macerator was leaking so we removed it and this is how we discovered the mould. I would appreciate any suggestions as to what type of mould it is and how to remove it, and stop it reoccurring.