Process for the production of a terephthalate polyester, comprising: a) a stage of preparation of an esterification feedstock comprising at least one mixing section fed with at least one terephthalic acid feedstock and one diester monomer feedstock comprising bis(2-hydroxyethyl) terephthalate (BHET), in the liquid form, said mixing section being additionally fed with a diol monomer feedstock, the amounts of at least said terephthalic acid feedstock, said diester monomer feedstock and said diol monomer feedstock, introduced into said mixing section, being adjusted so that the ratio of the total number of moles of diol units of formula -[C (n+1) H (2n+2) O 2]-, n being an integer greater than or equal to 1, introduced into said mixing section, with respect to the total number of moles of terephthalate units of formula -[CO-(C 6 H 4)-CO]-, introduced into said mixing section, is of between 1.0 and 1.5, said mixing section being operated at a temperature of between 100°C and 150°C and at a pressure of greater than or equal to 0.1 MPa, b) a stage of esterification of said esterification feedstock resulting from stage a), in order to produce at least one reaction effluent and one aqueous effluent, said esterification stage comprising at least one reaction section, operated at a temperature between 150°C and 400°C, at a pressure between 0.05 and 1 MPa, and with a residence time between 1 and 10 h, and at least one separation section, c) a stage of polycondensation of said reaction effluent obtained in stage b), in order to obtain at least said terephthalate polyester and a diol effluent, said stage comprising at least one reaction section comprising at least one reactor in which the polycondensation is carried out and which is operated at a temperature between 200°C and 400°C, at a pressure between 0.0001 and 0.1 MPa, with a residence time between 0.1 and 5 h, said reaction section also comprising at least one withdrawal of a diol effluent, d) a stage of treatment of the diols, comprising a recovery section fed at least with all or part of the diol effluent resulting from stage c), in order to obtain a diol effluent to be treated, and a section for purification of said diol effluent to be treated, in order to obtain a purified diol stream. a) a stage of preparation of an esterification feedstock comprising at least one mixing section fed with at least one terephthalic acid feedstock and one diester monomer feedstock comprising bis(2-hydroxyethyl) terephthalate (BHET), in the liquid form, said mixing section being additionally fed with a diol monomer feedstock, the amounts of at least said terephthalic acid feedstock, said diester monomer feedstock and said diol monomer feedstock, introduced into said mixing section, being adjusted so that the ratio of the total number of moles of diol units of formula -[C (n+1) H (2n+2) O 2]-, n being an integer greater than or equal to 1, introduced into said mixing section, with respect to the total number of moles of terephthalate units of formula -[CO-(C 6 H 4)-CO]-, introduced into said mixing section, is of between 1.0 and 1.5, said mixing section being operated at a temperature of between 100°C and 150°C and at a pressure of greater than or equal to 0.1 MPa, b) a stage of esterification of said esterification feedstock resulting from stage a), in order to produce at least one reaction effluent and one aqueous effluent, said esterification stage comprising at least one reaction section, operated at a temperature between 150°C and 400°C, at a pressure between 0.05 and 1 MPa, and with a residence time between 1 and 10 h, and at least one separation section, c) a stage of polycondensation of said reaction effluent obtained in stage b), in order to obtain at least said terephthalate polyester and a diol effluent, said stage comprising at least one reaction section comprising at least one reactor in which the polycondensation is carried out and which is operated at a temperature between 200°C and 400°C, at a pressure between 0.0001 and 0.1 MPa, with a residence time between 0.1 and 5 h, said reaction section also comprising at least one withdrawal of a diol effluent, d) a stage of treatment of the diols, comprising a recovery section fed at least with all or part of the diol effluent resulting from stage c), in order to obtain a diol effluent to be treated, and a section for purification of said diol effluent to be treated, in order to obtain a purified diol stream.