Topological order in two dimensional systems is closely related to fusion categories. For example, in PEPS topological order emerges due to certain MPO symmetries of the defining tensors, where the MPOs themselves are identified with the fusion category. In this talk we show that the MPO symmetries can naturally be interpreted as representations of certain algebras (weak Hopf algebras), providing an alternative (but completely equivalent) language to talk about the MPO symmetries.